Full text of "Notes on building construction, arranged to meet the requirements of the syllabus of the Council on Education, South Kensington"

See other formats

This is a digital copy of a book that was preserved for generations on library shelves before it was carefully scanned by Google as part of a project
to make the world's books discoverable online.

It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject
to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books
are our gateways to the past, representing a wealth of history, culture and knowledge that's often difficult to discover.

Marks, notations and other marginalia present in the original volume will appear in this file - a reminder of this book's long journey from the
publisher to a library and finally to you.

Usage guidelines

Google is proud to partner with libraries to digitize public domain materials and make them widely accessible. Public domain books belong to the
public and we are merely their custodians. Nevertheless, this work is expensive, so in order to keep providing this resource, we have taken steps to
prevent abuse by commercial parties, including placing technical restrictions on automated querying.

We also ask that you:

+ Make non-commercial use of the files We designed Google Book Search for use by individuals, and we request that you use these files for
personal, non-commercial purposes.

+ Refrain from automated querying Do not send automated queries of any sort to Google's system: If you are conducting research on machine
translation, optical character recognition or other areas where access to a large amount of text is helpful, please contact us. We encourage the
use of public domain materials for these purposes and may be able to help.

+ Maintain attribution The Google "watermark" you see on each file is essential for informing people about this project and helping them find
additional materials through Google Book Search. Please do not remove it.

+ Keep it legal Whatever your use, remember that you are responsible for ensuring that what you are doing is legal. Do not assume that just
because we believe a book is in the public domain for users in the United States, that the work is also in the public domain for users in other
countries. Whether a book is still in copyright varies from country to country, and we can't offer guidance on whether any specific use of
any specific book is allowed. Please do not assume that a book's appearance in Google Book Search means it can be used in any manner
anywhere in the world. Copyright infringement liability can be quite severe.

About Google Book Search

Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers
discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web

at|http : //books . google . com/

Godfrey Lowell CABOT SCIENCE LIBRARY

ofiht Hartttfd Colitgt Librafj

TTiis book is
FRAGILE

and circulates only with permission.

Please handle with care

and consult a staff member

before photocopying.

Thanks for your help in preserving
Harvard's library collections.

Medium 8to, with 826 woodoats, lOi. Hd,

NOTES ON BUILDING CONSTRUCTION

AmngBd to meet tlie reqnirementB of the Syllabiu of the Science and Art Depart-
ment of tiie Committee of Council on Education, South Kensington.

Pabt L— FIBST STAGE» ob ELEMENTART COUBSE.

EXTRACT FROM CONTENTS.

Oharib L

WAULDSO Am) ARGHB : Waim— Abchw Pamb or Wau*— APBaxoue or Wau*— Wood
boilthroWaua

Okafibb IL

BBICKWOBK : J>uman BovDe-^uircnoir or Waiu at Rmbt Ahgub— Oauobd Wobk— Brick
Abcbsb— Abcrh otbb OnmxoB nr EzmuiAL Wau«— Abchbb otbb Omriirot nr IxmaiAL
Walu— Jaxbb or Wmoow axd Door OmoNie— Pamb or Bbiok Walu.

OKApna m.
MASONRY : Waluvg— Sxom Awcmw Jonna axd OowinBOMOw— Da—nraa.

OKApna TV.

GABPBNTBT: iotnB—Lapping'-FiaiUiit--Seoupiff~Do9t^^ etP.

itei— FAgTKimwia--P>a»~Jgoyte Stnp§—Shoe», tt9.

Obafrb Y.

FL0OB8: Ckm^fiaiiUm--Oirdtn^WaU PltUa Joi«te-Btnittlng--TrtaMniag--JHigy<iiy Boairdtng
Jointi CdUmg /oiifi OotmlUnce, •te.

OKApna YL
PABTinONB : Qmrt§nd PorMMoa*— IteMd wtth and wttbont Doofwaya— Ooimnmi ParMMo*-

OsAPna YIL

TIMBIB BOOFB : DxTRBBar Foam BcAMTLOfoa— Pakw or a Kiao-Foar Boor— flOAaiuvaa^
Boora or Wood amd Ibov oomuiaDL

lYUL

IBON fiOOFS : CToifywrtoa Booia with Stbaioht BArnaa— Pab» or laos TBcawni Dinaa-
aioaa.

OHAFtm IZ.

8LATINO: PUek-^Namu nf pwrti^Pnparimg and laying SkOu—BATm and BIdge Oooiaea— Hips
and Bldgofl Clatliig for Iron Boolb— Shouldering— Bendexing—Toiehlng— Sins and Weighta of
BlMtfla Wyatya PKtflnt Slating— Slate Slaba— Ornamantal BlatiB^-Open Slating.

Ohaptbr X

PLU1IBEB*S WOBK: £oyiNaSkMllM4-BoI]a--Noritt0i-Seama-I>ripa-FiD(iia£tadfoJrai^
^-Lmd DoU^FuuMmgp-Lmd GvUtn—Zim (hiiUn^lMmn Pifm Ridgtt and Hif^^-SubtUMu
Jbr Lmd FtatkitngB—OUUmt.

OBAm XL
OAflT-IBON QIBDKBS^ ^BESSUMBBS^ ajid OANTILBYBBS.

CHAPna XIL

JOnnEBY : BwwUngB—ScilMng— Chamfering, ete.— Jonin of difltaent Vfnilt Faiin¥ti Paweniag
of diflerent }dik6a^J>oOBB~-Ltdg9d^Brw8d~'Fir9m$A-~PandUd, diffluent Jrlnrti Door Fnmm
WuiMiwa Fmrnu Solid— Ceoed- &nti^ hnng In dUfcrent wayi CammonU riarimg Ftwwm

Medium Syo, with 800 woodcuts, 10«. (kL

NOTES ON BUILDING CONSTRUCTION

Arranged to meet the reqiiiraments of the Syllabtu of the Science and Art Deport-
ment of the Committee of Conncil on Education, South Kensington.

Pa&t IL— OOMMSNCEMEin: OF SECOND STAGE, ok ADVANCED. COUBSE.

EXTRACT FROM CONTENTS.
Cbaftmr XUL
BBICKWORK AND MABONBT— OimMntifd: GoMFOUin> Walls— PaBynrnov or Damp or Walu
— jilr Drains— Damp-prw^Cown^-^D(mp'pn€fWdU§^HcUow Wott§—Jonm, different Uiids—
Yabxous BoiaM vor mbitiovkd or Pabt L^Bakimg Bond—Oardm Bond^-Bond Comma BrUk
lH§n~-Bond^Waat Jbrmlng Obhue and AmU A%gU§-Sn§ai§ vUk Spla^ Jaml» Anikm—
Bond Timb$n Hoop Iron Bond— Bbick Dbaixb amd Scwxba— GBomTB— ^mmgMiiml qfFImm
— C&iMiMy Skcffio—CMmmog Cof—Finplaoto^Htcaih^^Bond qf Ckimmti/ Skafi»-SUm* CMm-

GRAnaa XIY.
UMBEB B00F8— CiMtfmiMl: Kim§ amd Qusm Po$t AoQ^JSoq/l Jbr Spaiu ffrmim Am 60 >M—
Bof4^ oompomd ^ Wood tmd Iron far Spam qfmort than 40 fiU—FAvn or a QuasM-Posr Boof—
Boofs of YABioim BiiAFBii aho thkib PAan— Bulib ahd Tablbb voa ScAinuao or Boor
TniBBBS— BsBT Foaaa or Boors roa DirrxaaiiT Spaxs.

GRARBa XV.
BOOF G0YBBING8— GimMmMd; Gmurai BMNorfct-PMA ij Boqfk-Skitlmg—Tiim-Thaltk Iron
'-'Liad--Coppar-'21no--^km--A9phaUed FOL

CBAPraa ZTI.
BUILT. UP BBAMB, OUBVBD BIBS. TIMBEB AND IBON QIBDBBS: Onrvtd JNte-
SraairaTHsnvG Tnaaa Qikditb FlUek Btamt Tnumd (Krdfn— laov Qisnaaa Cnti Iron

Oirdan—WronffiU Iron Okdtn,

OiAPiaa XVIL
GENTBBBb

GHAPiaa XYIIL
JOINEBT— OmiMimmJ; IfouLDnraa-Jonrss— Fuivo JomaBs* Woaa— OaoxniDS— AaaBxraATas—
BKumiraa— Dado Am SuaaAsa— Lumios— 43HxrmB8— SKTuaaxB aid LAiiTxaRS.

GHAPffaa XEC
BTAIB8 : DiFraaaiiT FoaMS or Btaibs— Sioira Staibs— Stone Stepo-^qpax^-Dlffertni ArrangtmnUa
of 8Uni4 Stain— KoGDEX Staxbs— Parte of Voodtn ataHro—Dffforont Fonu—HoMdruOing—
Balmttmt genewrf Bmatrkt on Pkmning StaWo,

OBAPiaa XX.
BIVBTINO : DigbroiU Forou of JUvete— Proporltone— Pttd^BiraxaD Jouiis DyerenI Foraie-
(kmparaHMStron§tkqfdif$r§iU 1timd$ ^f lUotttd Jolnto-KmuMali ofOood Strnttng-'Cemm ^
FaOwrt,

CBAPraa XXL
FIBEPBOOF FLOOBS : Oeairal BomartB—BnglUk Siftt*m§~-Frmek SiftUmM,

CHAPTKa XXIL
IBON B00F8— GraHmiei : Trn$Md Baftor Bot^f^—Quttn Sod Jtoq/k— Pasib or Ibov Boor Tbubbbb
— lanlenw and VmUUaioro-CoooHng$ Jbr Iron Boofk—Dtotgning Iron Boo^ToUU ofSoamtiitnga
qflronBooJk

GHAPTBa XXin.
PLASTEREBS' WOBK : JTotorteb aeal &y tJu Plattormr-'IatMnQ-'PlagfninQ—BtndoHng-^krnimt
MoMtdingB, and Qmaienfe Stueeo-SeUniiie PUutor^Bough Coit'-^wrMoia—Pvgging—SoagUota
~-ArrU$$.

GBAPiaa XXIV.
PAINTING-PAPERHANOINO--OLAZINO : MaioHaU mei in PMnMn^-Pofnlln^ WoodwoH^
PnlmHng Ploiler— PtoinMn^ Canoai and PcqMr— Clear CWi BtpaiMtmg Otd WoHo^Pailmtlng Iron-
work gtfdlag— PAPaaHABOuio— OLABorOi

GBAPiaa XXY.
BXCATATI0N8— SHOBINa— 8CAFF0LDIN0 : BzoATAiiav— SBoamo ard Srainmo— Saoanro
BuiLDivos— ScAiroLDiHO— BHeUoyenT See^folde— JToeon^ Soafoldo-^Spteiai SoagMo^-Qamiriu
~^D§ni«t Cnmee— Ifettodi q^fMarin^ etonee to 5e lified,

GBAPfaa XXVL
FOUNDATIONS : Ocnena Bemaiks— CftoraeleriiNe* qf a good FomndaHon—ClaMHJtoailon^PrtUm-
inarg Oporationo—InoomprmibU SoO^-Boek-Oroond partly Herd end partly Soft— Greyal—
Chalk-Glay— SoiZe rt^iriag Laiorai Coi^lnmMni Sand— Qnlckeend end SUt— Con|>rieriMe
ArfZe— Oidinaiy Earth or Soft Glay— Very Soft SoUe-Conerele FowndaMone-POce and POe
FoaNdoMone— Timber Files— POe Foondatiooe— Oaoses of FeUun of Pile Fonndationa-IroB
rUes-IPitt FoandaMoae-Pik Engines Drawing PUss-Iarwted Arebea.

NOTES ON BUILDING CONSTRUCTION

PART IIL
MATERIALS

NOTES ON BUILDING CONSTRUCTION

Arranged to meet the requirements of the Syllabus of the Science and Art
Department of the Committee of Council on Education, South
Kensington.

In Four Parts. Medium Svo, SMs^arately.

Part L — ^Flrst Staffe, or Blementary Oouraa With 325 Illustrations^
los, 6d,

Part n. — Ctommenoement of Second Sta^e, or Advanced Ctourae.

IVitJk 300 Ilhutrations, lOf. 6d.

Part in. — ^Sffaterlala Advanced Course, and Course for honours.
With 188 Illustrations. 2ls.

Part IV. — Oaloulatlons for Stmoturea With Illustraticns.

Opficial Report on thb Examination in Building Construction, bbld bt the Scibncb
AND Art Dbpartbcbnt, South Kensington, in Mat 1875.— "The ^"^^^ of a text •bode in this
subject, arranged in aooordance with the publiahed Syllabus, and therefore limiting the students and
teachers to the prescribed course, has lately been well met fay a work published by Messrs. Rivingtoos,
entitled ' Noitt m BuUdtng Cmm/tmcA'm.' "

"Those things which writers of elementary books generally pass over are here explained with
BUBUteness. . . . Altogether the book is one which it is a pleasure to reoommend. Its primary
object may be to support the Science and Art Department, but it will be found to be of wider use ; and
if the parts which are to follow are prepared as carefully as this is, the ' Notes on Building Constmo-
tion' will far surpass any work of the kind hitherto published. "~^nArY«r<.

" Something of the sort was very much needed. • . . The whole series when published will
be a great boon to young students.**— i^M&im

"One of the most sensible end really reliable aids to students of coastructioo we have seen for a
long time. If the remaining ParU are up to the standard successfully aimed at b Part I., the work
cannot fisil to become the standard text-book for students.'''AK£UrV Ntwn.

" It very rarely happens that explanations are given with such clearness as those in ' Notes on
Building Construction,' and the dullest student cannot £ul to gniq> the idea intended to be conveyed.
. . . As a work ofreferenoe it will at once take a leading place.**— ^wftM^« ^«fii(r ^49^*0^

"Certainly the four parU will, judging finom the first, Ibnn the best text-bode on the subject ex-
tant**—fN^AM Mtckamu.

"The work throughout is got up in the most admirable style, and is profusdy illastiated with
well-drawn engravings."— TYwJirr Tradi^ loumaL

"The whole will fisTm a compendious series of vdumes of very great value to 'prsctical' men.
The text Is prepared in an extremely simple and consecutive manner, advancing from rudimental
and geaersl statements to those which are comparatively advanced ; it is a thoroughly coherent self-
sustained account . . . We can testify that its contents justify the promises of the title, that we
have missed nothmg which we looked for and had a right to expect would be included in the
volume.*'— i< tMenamm.

RIVINGTONS: WATERLOO PLACE, LONDON.

NOTES

BUILDING CONSTRUCTION

ARRANGED TO MEET THE REQUIREMENTS OF

THE SYLLABUS OF THE SCIENCE 6^ ART DEPARTMENT

OF THE COMMITTEE OF COUNCIL ON EDUCATION,

SOUTH KENSINGTON

PART III.
MATERIALS

ADVANCED COURSE AND COURSE FOR HONOURS

SECOND EDITION, REVISED AND ENLARGED

ORIVINGTONS
WATERLOO PLACE, LONDON

MDCCCLXXXIX

^^ (.0^^^

JUN 20 13i.7

lKANS>'tpir?£D ro
niMMt\nu COLLEGE LUaArtlf

i^:.\^

PREFACE TO PART III.

FTIHESE Notes axe intended to famish a Student with
information amply sufficient to enable him to pass the
Honours Examination of the Science and Art Department,
so far as a knowledge of Building Materials is concerned.

They have, however, been extended somewhat beyond
what is actually necessary for this purpose by the addi-
tion of Tables and information of a practical nature,
which it is hoped may be useful to young Engineers,
Architects, and others engaged in the design and erection
of structures of different kinds.

It was considered that a work upon materials, written
merely to meet the requirements of students in the Second
Stage of the Science Examinations, would be unsatis-
factory.

Such a work would contain very elementary information
on the subject It would be so condensed that it would
not give a fair idea of the great differences which exist in
the characteristics and qualities of even ordinary building
materials; and being thus narrowly restricted, it would
tend to encourage the pernicious practice of cramming.

In order to keep the bulk of the work within reasonable
bounds, it has been necessary strictly to limit the scope
of the Notes.

It will be well, therefore, to state exactly what they are
meant to contain and what is purposely excluded.

viii PREFACE,

They deal with the nature, characteristics, qualities, and
defects of the materials used in Building and Engineering
works ; and they describe the methods of examining and
testing such materials.

The information given is restricted to that required by
an Engineer, Architect, or Builder, in order to select and
understand the materials with which he has to deal.

The principal varieties of building materials used in
Great Britain and Ireland are described or noticed, but no
reference is made to materials used only abroad — in India
or the Colonies.

Descriptions of the manufacture of materials, or of the
methods by which they are procured, have been excluded,
except in so far as some such knowledge is necessary for
an intelligent appreciation of the characteristics of the
material.

The actual cost of materials has also, as a rule, been
excluded. This varies from time to time, and must be
ascertained from the annual Price Books.

The methods of measuring and valuing materials must
also be studied in works devoted to those subjects.

It was originally intended to include in Part III. the
information regarding stresses in parts of Structures required
for the Advanced Course.

The bulk of the volume, however, renders it necessary to
reserve these subjects for another Part, which will contain,
as far as possible, all the remaining information that is re-
quired for the Examinations of the Science and Art
Department in Building Construction.

NOTES ON BUILDING CONSTRUCTION.

Note to Part III

Thb following List contains the names of the books which have
been referred to and consulted in the preparation of these
Notes.

Information derived from them has been acknowledged as far
as possible upon the pages where it is given.

The writer is indebted also to many friends and to others for
valuable particulars regarding special points.

On all sides, — from scientific and professional men, from quarry
owners, manufacturers, and merchants, — the information asked for
has been most willingly given.

The writer is glad to have this opportunity of expressing his
thanks for the valuable assistance he has thus received, and for
the very kind manner in which it has always been afforded to
hiuL

Abney's Chemistry of Bailding Materials.

Anderson's Strength of Materials.

Ansted's Practical Geology.

Barlow's Strength of Materials.

Bauennan's Metallurgy of Iron.

Bemays' Lectures on Chatham Dockyard Works.

Bloxam's Metals.

„ Chemistry.
Box on Heat
Britton on Dry Rot
Brown's Forester.
Bumell on Limes and Cements.
Bums's Guide to Bricklaying, Plastering, etc
Clark on Koads and Streets.

„ Manual of Rules and Tables.
Cooke's Aide M6moire.
Couche's Railways.
Cres/s EncyclopsBdia.
Dana's Mineralogy.
Davidson on House Paintiog.
Davies' Slate and Slate Quarrying.

NOTE TO PART IIL

De la Beche*8 Report on the Gkology of Ck>niwall, Deyon, and Somerset.
Dent's Chemistxy of Building Materials.
Dobson and Mallet on Brick and Tile Making.
Downing's Construction.
Ede's Management of Steel.

Experiments on Steel by a Committee of Civil Engineers.
Fairbaim's Application of Iron to Building PuiposesL
9, Iron Manufacture.

„ Useful Information for Engineers.

Qalton's Hospitals.

GUlmore on Limes, Cements, and Mortarai
Gordon's Lead Poisoning of Water and its Prevention.
Greenwood on Steel and Iron.
Gwilt's Encyclopaedia of Architecture by Papworth.
Hartwig's Sea and its Living Wonders.
Haupt's Military Bridges.
Hill's Lectures on Machinery used by Engineers.
Holtzappfel's Mechanical Manipulation.
Hull's Building and Ornamental Stones.
Humber on Water Supply.
Hunt's Guide to the Museum of Practical Geology.

„ Handbook to the Exhibition, 1862.

„ Mineral Statistics.
Hurst's Architectural Surveyor's Handbook.

„ Tredgold's Carpentry.
Hutton's Practical Engineer's Handbook.
Kirkaldy's Experiments on Iron and SteeL
Ejiapp's Technology.
Knight's Dictionary of Mechanics.
Laslett's Timber and Timber Trees.
Latham on Wrought Iron Bridges.
Latham's Sanitary Engineering.
Lipowitz on Manufacture of Portland Cement
Lyell's Geology.
Matheson's Works in Iron.
Miller's Organic Chemistry.
Molesworth's Pocketbook of Engineering Formnlff.
Mushet on Iron and Steel.
Newlands' Carpenter's and Joiner's Aitfristant
Page's Economic Geology.
Parkes' Hygiene.
Percy's Metallurgy.
Pole on Iron.

Rankine's Applied Mechanics.
„ Civil Engineering.
„ Useful Rules and Tables.
Beid and Lipowitz, Practical Treatise on Manufacture of Portland Cement.

„ on Concrete.

„ on Portland Cement, its Manufacture and Uses.
Report on the Exhibition of 1871.

NOTE TO PART IIL xi

Report on tlie Exhibition of 1876.

Eeport of the Royal Commission on the Selection of Stone for building the

New Houses of Parliament
Report of Commissioners appointed to inquire intn fhe application of Iron

to Railway Structures.
Richardson's Timber Importei^s Guide.
Roorkee Treatise^ Qvil Engineering.
„ „ Applied Mechanics.

Scddon's Builder's Work.
Sheffield Standard list
Smith's Lithology.
Spon's Illustiated Price Book.

y, Workshop Receipts.
Stevenson on Harbours.
Stoney on Strains.
Tredgold's Carpentiy.
Unwin's Iron Bridges and Roofs.

yy Elements of Machine Design.
Ure's Dictionary of Arts, Manufactures, and Mines.
Vicat on Cements. Translated by Capt J. T. Smith, F R.&
Whichcord's Observations on Kentish Ragstone.
Wilkinson's Practical Geology of Ireland.
Woodward's Recent and FoesQ Shells.
Wray's Application of Theory to Construction.
Wray on Stone.
Proceediugs of the Chemical Society.

Do. Institution of Civil Engineers.

Da Institute of Engineers.

Da Institution of Mechanical Engineers.

Do. Iron and Steel Institute.

Do. Institute of Naval Architects.

Do. Society of Arts.

Do. Philosophical Society of Glasgow.

Professional Papers of the Corps of Royal Engineers.
The Professional Journals relating to Engineering, Architecture, Building, etc.
Circulars and Catalogues of several Manufacturers and Merchants.

Note for Students,

The Syllabus of the Science and Art Department contains the
following particulars regarding the examination in materials : — ^

Examination for Sbcond Stags or Advanced Course.

This includes questions upon '' the nature, application, and characteristic
peculiarities of the following materials in ordinary use for building purposes,
ra, —

^ Bricks of different kinds in common use ; York, Portland, Caen, and

^ There is do examination in materials for the First Stage or Elementary Course.

xii NOTE TO PART III.

Bath stones (or stones of a similar description) ; granite, pure lime, hydiaolic
lime, Portland and Roman cement, mortars, concretes, grout, asphalte, timber
of different kinds in common nse, cast and wrought iron, lead."

Examination fob Honours.

The candidate ''must possess a more complete knowledge of building
materials, their application, strength, and how to judge of their quality ;
and, in the case of iron, of the process of manufacture, and the points to be
attended to in order to insure sound castings and good riYeting." ^

In the following pages the information of an elementary
character required for the Second Stage is given in large print

Candidates for the Honours Examination should study the
whole volume, with the exception of the tables, lists of brands,
recipes, and other similar matters, most of which are in veiy
small print, and are intended chiefly for use in practice.

* Eireting is dealt with in Part II.

Note to the Second Edition.

In this Edition the Chapters generally have been revised, and
in some cases extended. The Notes on Portland Cement have
been practically rewritten.

ERRATA

Line from

topofpag*.

For
Mill HQl,

Read
New Mill,

Madun.

Madron.

Do.

Cornwall

Birsmon.

Birsmore.

Torres.

Tom's.

Footnote.— Add

.^and sometimes

in oversailinj

144

228

239

159

4 from foot

181

193

161

305

195

162

170

218

should be

218

will

should

258

290

804

265

268

262

267

843

355

270

7 from foot

857

355

274

260

832

296

276

290

296

262

276

806

809

323

808

811

825

317

248, 249

262, 263

824

806

320

828

304

818

882

10 from fool

) 256

270

887

Footnote.—

Omit— (Bower).

848

821

335

848

273

287

854

Footnote

319

817

422

898

418

Col. 9 /or Fulwell read Bxdy^eW,

178

for Abuthar read Aberthaw.

CONTENTS OF PART III.

Chafteb I.
STONE.

Stone. — Gbnkral Remarks. — CharaoterlBtios of Building Stone
— BwrabUity — Atmospheric Influence — ^Physical Stnictuie — Faeility
for Working — Hardness — Strength — Weight — Appearance — Position in
Quarry — Seasoning — Natural Bed — Agenis which destroy SUmes:
Lichens, Mollu8C&

Examination of Stone. — Fracture — Tests — Crashing — Absorption
— Brard's Test — Acid Test — Smith's Test — Practical vxty of ascer-
taining Weathering Qualities — Qttarrying.

ClasBifioation of Stone. — Scientific — Practical

Qranite. — Common — Syenite — Syenitic Granite — Talcose — Chloritic
— Schorlaceoos — Graphic and Porphyritic Granites — Quarrying and
Dressing — Uses to which Granite is applied — Varieties in Common
Use — Scotch, Cornish, Leicestershire, Guernsey, and Irish Granites.
Table of the Principal Granite Quarries in Great Britain and Ireland.

Igneous Bocks other than Granite. — Porphyries — Gneiss — Schists —
Trap Bocks — Varieties in use — Basalts.

Slates. — Qiuirrying — Characteristics — Hardness and Toughness — Colour
— Absorption — Grain — Pyrites — Table of Sizes — Weight, etc., of Slates
— ewo%— Thickness — Tests— Different Forms of Slate — Slab*—
Blocks — Enamelled — Varieties in use — Welsh, English, Scotch,
Irish. Table of the Principal Slate Quarries in Great Britain and
Ireland — Stone Slates.

Serpentine. — Composition — Colour — CJiaracteristics — Uses. Varieties in
common use — ^EngHsh, Scotch, Irish — Ancient

Sandstones. — Composition — Colour — Classification : Practical, Scien-
tific— Tests: Fracture, Brard's, Smith's — Absorption — Grain — Thick-
ness of Layers — Varieties in common use: Bramley Fall, Yorkshire,
Scotgate Ash, Forest of Dean, Mansfield, Craigleith. Table of
Principal Sandstone Quarries in Great Britain and Ireland.

^iy CONTENTS.

liimeBtoneB. — (hmposUion — Texlwre — CkunJUatum: Sdentifie, P»e-

ticaL
Marbles. — U8e9--DiffemU Forms — "Encrinal, Madrepore, Andent"

Vcaietia — ^English, Scotch, Irish. Table of ih$ Prineipai Marl>U

Quarries in Qreat Britain and Ireland.
CbifPAOT LiMBSTONBS — Qbanxtlab Ldcbstonsb — Shkllt LmsTon

— ^MAGinESIAN LiMBSTONBB.

Vabietibs of Limestone ih common use — Bath, Portland, Chilmark,
Kentish Rag, Yellow Mansfield, Caen. Table of ihs Principal Lime-
stone Quarries in Qreat Britain and Ireland.

Artifioial Stone. — Ransm^s—Apcmite— Victoria Stone — SUicated Stone
—Sorel Stone--Ghanc^s Stone—Ruses Vitrified MarUe.

I^oBervation of Stone — Preparations containing Organic Substances
— Paint — Oil — Paraffin — Soft Soap — Paraffin in Naphtha — Bees-
wax in Naphtha — ^Wai Vamish.

Preparaticms not containing Organic Substances. — Alkaline Silicates —
Kuhlmann's Process — ^Bansome's Indurating Solution — Szerekaey'B
Stone Liquid — ^Petrifying Liquid — Other processes.

Tables illustratinq the Properties of Different STONsa — Resist-
ance to Crushing — Tensile Strengtk — Transioerse Strengtih — AbsorpHon
Weight and BuUeinsss — Resistance to Wmar Pages 1-84

Chapter IL

BRICKS, TILES, TERRA COTTA, etc.

Bricks. — ^Brick Earths — GowdiiiwpnU — Alumina — Silica — Idme —
Pyrites — Carbonaceous matter — ^Alkalies — Salt — Oxide of Iron —
ProAiaaX OlassifiMtion — Strong Ckys — Loams — ^Marls — ^Malm — A
good Brick Earth — Characteristics of Different Kinds of Brick Earth —
Colow of Bricks.

BRiOKMAKiNa. — Preparation of Brick Earth — ^Unsoiling — ^Digging and
Weathering — Cleaning from Stones — Grinding — ^Tempering — Pre-
paration of Malm — Malm Bricks — ^Washed Bricks — Quantity of Clay
required — Hand Moulding — Slop Moulding — Sand Moulding — Bear-
ing off— Drying — In Sheds — Out of Doors — Hacking — Scintling —
Machine Jif ouWwiflH-Plastic Clay— Dry Clay— iVewei Bricks— Dressed
Bricks — PoUshod Bricks — Frog.

Burning. — Clamp Burning — Building the Clamp — ^Time of burning —

CONTENTS. XV

Quality of Bricks — KUn Bwnwng — Scotch Kiln — Modification of
Scotch Kiln — Com^pa/raJtwe Admmtage of KUn and Ckmp Burning —
Hoflhiann's Kiln — Modifications of Hoffmann's Kiln — BnlFs Semi-
continnons Kiln — Oupoku — Other fonns of Kiln.

Olassifioation of Bricks. — Cutters or Rubbers — Ordinary Bricks —
Underbumt Bricks — Characteristics of each Class.

Names of Different Varietiee of Bricks — Classification of Qamp-bumt
Bricks : of Eiln>bumt bricks.

Varistiss of Brickb in thb Mabiobt. — White Bricks — Qault Bricks —
Suffolk — ^Beaulieu — ^Ballingdon— Bearf s TsXentStc^ordshireBlue —
Dust Bricks—Red and Drab — ^Tipton Blue — Black Bricks— Fareham
Bed — NoUingham Patent — Lancashire Red — Clinkers, Dutch — ^Ada-
mantine— Terro-metallic — Enamelled Bricks — Sotted Bricks — Moulded
Bricks — Pether's — Pallette Bricks — Concrete Bricks — Bodmer's —
Wood's — Slag Bricks,

Charactbbibtics of Good Bricks. — ^Freedom from Flaws — Shape —
Absorption — Texture.

CharaeterisUcs of Good Rubbers — Method of distinguishing Olamp-bwmt^
KUn^bwmty and Machine-made Bricks.

Size aito Weioht of Bricks. — ^Table.

Tests fob Bricks. — Fractured Surface — BrarcPs — Absorption — Table of
Absorption.

Strength of Bricks. — Resistance to Compression — Table — Strength of
Columns of Brickwork — Transverse Strength — Tensile Strength,

Different Forms of BRiCKa — Ordinary — Purpose-made — Arch — Com-
pass— Side-wedge — Bullheads — Perforated — Splits — Soaps — Hollow
Bricks — ^Tubular Bricks — Plinth, Cornice, and String-Course Bricks
— Round-ended — Bull-nosed — Splay and Double Cant Bricks —
Payings — Gutter and Drain Bricks — Copings — Kerb Bricks — ^Tunnel
Heads — Boiler Seatings — Sink Bricks — Manger and Sill Bricks.

CoLOURiNa Bricks.

Fireclay^ — Uses — Where found — Composition — Analysis — Grain.

Firebricka. — Varieties of — Strength of.

Terra Gotta. — Making — Nature of Clay — Building — Blocks — Advantages
— Disadvantages — Colour — Porous Terra Cotta — Inferior Terra Cotta,

Stone'^ara — Clay — Burning — Glazing — Characteristica

Pipes and MiBoellaneoiis Clay Wares. — Unglazed Earthenware —
Fireclay Ware — Stoneware — ^Terra Cotta — Glazino — Transparent —

xvi CONTENTS.

Salt — Lead — Opaque — Burning, Pipks — Agricoltoial — Sewer —
Socket — Half Socket — Benda — JnnctioiiB — Taper — Saddles and
Chairs — Lidded and Capped Pipes — Syphon Traps — Tegt% for Sewer
Pifu — Stanfor^i Patent Joint
MlaoeUaaeoua Clay WareB. — Air Bricks — Damp-proof Courses —
Bonding Bricks — Wall Facings — Sleeper Blocks — Rue Pipes —
Chimney Pots — ^Invert Blocks — Junction Blocks — Segmental Sewers.
Tiles. — Common — Paving — Roofing — Plain — Pan — Double Roll —
Corrugated — Taylor's — ^Venetian — Wade and Cherry's — Ridge — Hip
and Valley — Wall-tiles — Encaustic — Inferior — Dry — Tesserse —
Majolica — Mosaic — Uses — Chemical Analtbib of a Brick Earth

Pages 85-144

Chapter III.

LIMES, CEMENTS, MORTAR, CONCRETE, PLASTERS, AND AS-
PHALTES.

LimeB and Cements. — Terms in use — ConslituenU of Limestone ihat
do not produce Hydraulicity — Carbonate of Lime — Sand — Con-
stitiunts ihaJt produce Hydraulicity — Clay — Soluble Silica — Carbo-
nate of Magnesia — Alkalies — Sulphates — Classification of Limbs
AND Cements — Table of Composition of Limestones and Cement Stones
— Rough Tests — Rich or Fat Limes — Stained Fat Limes — Poor Imms
— Hydraulic Limes — Vicafs Classification of — Varieties of Lime in
Common Use — Fat Limes — Grey Chalk — Lias — Carboniferous — Mag-
nesian — Artificial Hydraulic Lime.

Cements. — Classification — Natural Cements — Carbonate of Magnesia
— Cement Stones — Roman Cement — ^Weight — Strength — Storing —
Uses — Market Forms — Medina, Hancich, Sheppey, Whitby , Mul-
grav^Sy Atkinton% Calderwood, East Kilbride Cements — Table of
Strength — Artificial Cements — Portland Cement — Manufacture
from Chalk and Clay ; from Limestones and Shale — Tests of Quality
— Fineness of Grit — Weight — Method of Weighing — Colour — Ten-
sile Strength — Briquette : Method of making ; Shape — Nature and
Proportion of Water — Tests for Coolness — Additional Rough Tests —
Storing — Strength vnih Sand — Limit to increase of Strength with age
— Market Forms — Mixing and using.

ScoTT*fl Processes. — Scott^s Cement — Selenitic Cement — Nature of Lime —
Fineness — Proportion of Sulphate — Where used — Strength — Selenitic

i'j. r^^. WL"'- ' «.*

CONTENTS. xvii

Chf — Strength of Selenitic Mortar — Methods of artificially produeiing
EydroMlicUif — ^Pozznolana Mortals — ^Alkaline Silicates.

Testing Tensile Stsenoth op Ceiibnts. — Adu^s No. 1 Mcuih/ins —
— Cement Mould Press — Split Mould — Adu^s No. 2 MaMne —
MicheUi, Reid and Baileifsy and Thunton'i Machines,

Lna AND Cement Bdbninq. — Clamps — Kilns — ^Tunnel — ^Flaie — Con-
tmuous System — Intermittent System — Tunnel or Draw Kilns —
Flare Kilns — Portland Cement KUns — Common Form — Michele-
Johnson's — Roman Cement Kiln — Oeneral Bemarhs on Burning —
Qradnal Heating •*- Appearance of Stone — Temperature — Size of
Lumps — Quantity of Fuel — Portland Cement Clinker — Ikbngerous
Limes and Cements — Overbumt — Underbumt — Dead^mt lAms —
Flar&^mmt Lime.

Sand. — Pit — River — Sea — Screening — Waging — Examination — Substi-
tutes FOR Sand — ^Bumt day — Crushed Stone — Scori» — Slag —
Clinker — Crnders — Posssmolanas — Trass — Ar^nes — Psammites —
Disintegrated Granites, etc. — ^Artificial Fozzuolanas.

Hortar« — ^Ordinary — Cement — Uses — DssoRiFnoN of Lime ob Cement
to be used — Fat Limes, Evils of — EydrauUc Limes — Cem^enJts —
Deeoriftion of Sand to he used in Mortar — Substitutes for Sand — Water
— Salt — ^Dirty — Strength of Mortar — Proportion op Inqredisnts —
Table of Strength — Preparation and Mixing — Slaking — Quantity
— Time — Ground Lime — ^Water — Mixing — Methods — Quantities —
Bulk of Mortar produced — Selenitic Mortar — ^Methods of Mixing
— Selenitic Mortar made with Ordinary Lime — Strength of Selenitic
Mortar — Mixture of Lime and Cement — Precautions in using Mortar,

Conorete. — The Matrix — The Aggregate — Shape — Size — Aggregates in
common use — ^Broken Brick — Breeze — Burnt Clay — Gravel — ^Ballast
— Shingle — ^Broken Stone — Flints — Chalk — Slag — Size of Aggregate
— Voids — ^Packing — Proportion of Ingredients on different Works
— Concrete for Paving — Mixing — Materials all mixed together —
Mortar mixed separately — ^Relative Advantages of the two Methods —
Laying — In Trenches — Under Water — ^The Cementing Material
— ^Fat Limes — Hydraulic Limes — Cements — Gypsum — Bulk of
Concrete produced — ^Different Examples — Selenitic Concrete —
Expansion of Concrete — Uses op Concrete — B4ton — Coignefs
— Strength of Concrete — Resistance to Compression — Tab Con-
CRETE — Iron Concrete — Lead Concrete.

sviii CONTENTS.

Mortar-Mixing and Conorete-Mixing Machinery. — ^Mobtab-Mix-
IKQ Machinbs — Mortar MUU — Steam, Portable, Hone, Hand —
Ck)NCBBTB-MixiNa Maohojobs — Inclined Cylinder — ^Measenfa — ^Le
Mesnrier^s — Ridley's — Stoney'e — American.

On the Action of Foreign Constituente in Umestones and
CementB. — ^Fat Lihb8 — OaJk/vnaJbion — Slahkiff — Settinff — Mortar —
Action of Sand — Htdbauuo Ldobs akd Cbmbntb containino Clat
— Clay — Lime-— OolGUia^tofi — Proportion of Clay — ^Effect in Cements
burnt at a moderate Temperature — ^Effect in Cement burnt at a high
Temperature — OomposUion of Clay — Effects earned hy different Degrees
of Cakination — ^Hydraulic Limestonee — Cement Stones containing a
small proportion of Clay — Cement Stones containing a large propor-
tion of day — Slaking — Setting — Proportion of Clay — Composition of
Clay — ToMe of BeeuUe — Pomuolaiiar—(Jarbonate of Magnesia — Sul-
phates,

Efflorescence on Walla. — ^Appearance — Composition — Causes — ^Disad-
vantages— ^Remedies — ^Analsrsis of laimea and Cements — ^Test —
Analysis.

PlasterB, etc« — ^Matxbiau used bt Plastbbbbs — Cements^ etc — Plaster
of Paris — Portland — ^Boman — ^Eeene*s — Parian — ^Martin's — ^MetaUic
and Lias Cements — ^Portland Cement Stucco-John's Stucco Cement
— Uses — Mastiob — Hamelin's — Matbbials ttsbd in Obdinabt
PLASTBBmci — ^Limes — ^Hair — Coarse StuJBT— Fine StuJBT — Pksterer^s
Putty — Gauged Stuff — Selbkitio Plabtbb — On Lath Work — Setting
Coat and Trowelled Stucco — Selenitic Clay Finish — Outside Plas-
tering— BouoH Cast — Sruooo — Common — ^Trowelled — Bastard —
Rough — ^Abtifioial Marblbs — Scagliola — Marezzo — ^Enriohments
— Plaster Ornaments — Composition Ornaments — Papier-Mach^ —
Carton Pierre—Fibrous Plaster — Dennbtt'b Firbpboof Material.

Asphaltes. — Uses — Advantages — Disadvantages — Oharaeteristics — Lat-
ino— Molten — Powdered — On Slopes — ^Vabibtibs in the Mabket
— Seyssel — Qualities — Mixing — Laying — Val de Trovers — ^Hot com-
pressed Process — Liquid Process — Limner — Brunswick Bock — Mon-
troOer — Mcistic — Bamet^s — Trinidad — PcUent British — Inferior As-
phaltes— Pitch — Bitumen — Coal-tar Pitch.

Whitening and Colouring. — Whiteioash — Common Colouring — WTiUing
— ^Distbmpeb — White — Coloured — Table ofQuarUity of Materials used
for Plastering — Weioht of Limbs, Cements, ETa Pages 145-256

CONTENTS. xix

Chapter IV.
METALS.

Oies — ^Dxeflsiiig — Calculation — Roasting — Smelting.

Iron. — Production — Obbs — Bribuik VarietieB — Blackband — Hnmatite
(Red and Brown) — ^Magnetio — Spathic — SMSLTma — Hot Blast —
Cold Blast — ^Flnx — Slag — OorHparative Advantage$ of Hi^ and Cold
Blagilnm.

Fig-Ironu — Different MaUriaU produced from Pig4nm — ^Fobbign Sub-
BTANOBS IN PiGhiBON — Carbon — Effect of Oarbon on Oast Iron — In
the state of Mechanical Mixture — ^In the state of Chemical Combina-
tion— ^Impubtties nr Piq-ibon — Silicon — Phoepkorua — Mangameee —
Sulphur — Copper — Arsenic — Tin — Tungsten — AfUiimanif — Titanium ;
and their effects upon Cast Iron, Wrought Iron, and Steel — Classi-
fication of PichiBON — Bessemer — Foundry — Fori^e — Nos. 1, 2, 3, 4,
5, and 6 — Cinder Iron — Mine Iron.

Oast Iron* — Remelting — Grey Cast Inm — ^Nos. 1, 2, 3 — WkiU Cast Iron
— Mottled Cast Iron — To distis^gudsk Grey from White — Chillbd Ibon
— ^Mallbablb Cast Ibon — Touohbnbd Cast Ibon — Descriptions of
Pig-iron for Castings — Castings in Sand — Pattern — Cold shut — Core
— Head — Casting Pipes — Casting in Loam — Form of Codings — Second
Mdting — Softening Castings — Examination of Castings — Pipes — Tests
for Cast Iron,

WroQgiht Iron. — Befinisig — Puddling — Shinning — Boliing, Effect of—
Different Qualities of Bar Iroiir— Paddled— Best— Best Best— Best
Best Best — Scrap — Manufacture of T and I Iron — ConiraeHon of
fFrougM Iron— Cold Boiled Iron—DefecU in Wrou^ Jvvnr-Oold
Short— Hot Short.

Tests fob Wbought Ibon. — ^Tensile Strength — Ductility — Kirkald/s
Experiments — ^Uniformity — Different Methods of Testing — Testing
MaMnee— Tensile Teds for Wrought Iron — India Office — Admiralty
— Bough Teds for Wrought Iron — ^Porge Tests — Eivds — Appearance of
Fractured Surface — Eirkaldy's Conclusions — Impact Test

Diffbbbnt Desgbiftionb and Mabkbt Fobmb of Wbought Ibon, and
thbib Rblatiyb Value. — Swedish — ^Best Yorkshire — Other Fork-
shire — Staffordshire — Scotch — Cleveland — Newcastle — Middles-
borough — Welsh, etc — ^Mabket Fobics of Wbought Ibon — Ordi-
nary Dimensions — Dead Lengths, etc. — Bar Iron — Angle and T Irons
—^Jhemnd Inm—BoUed Girder Inm^Miscdlameous Sections—BaU

CONTENTS,

Ban — Market SecHom — Rivet, Chain, Eane-Shoej tmd NaU Iron —
Plate Iron — Charcoal Plate— Tin Platea — ^Teme Plate — ^Mallet's —
Buckled Plates— Flitch Plates— S»«rf Jim Gauges— Corragated
Gauges — Galvanised Iron — Continued Galvanised Sheets — Hoop Irtm
— MiUs Wroughi Iron Caxtingt.

Bblativs Yalub of Difterent Dbbobiptionb and Fosmb of Wrought
Iron — Price OwrrerU — Ban — Plates — Sheets — Hoop — Sash — ^Fancy
— ^Bnlb— Tyre — Joist — Girder — Channel — ^Lkt of Extras charosd
on British Iron — Staffordshire — ^North of England — ^Welsh — Scotch
— ^Yorkshire — Brands on Iron — ^Pig-iron Brands — YorhMn —
SeoUih — North of England — IFelsh — EcBmatite — NorthamptonMn
ShrapMre — Staffordshire — ^Wrouoht Iron Brands — StaffordshiA
List Brands — Good Marked Iron — Common Iron — Midland and other
Districte—North of Englofn/d-'Waies — Sootlaikd— Swedish Iron.

BteeL — Definitioni — Charadensties — Hardening — ^Tempering — Anumnt
of Carbon in Steel — ^Varieties of Steel — Methods of making Steel —
BKeter Sfee^— Spring Steel— ^S'A«ar £f(ee^— Double Sheai^— Single Shear
— Cast ;Stee{— Crucible Cast Steel— Huntsman's, Heath's, Heaton's,
and Mushet's Processes — Bessemer, Basic, and Siemens' Processes —
Modifications of Siemens' Process — Siemens-Martin Process — Whit-
Vforth's Compressed Steel— Puddled £^(00/— Natural Steel— German Steel
— Tungsten, Manganese, and Chrome Steel — Homogeneous Metal.

Hardening Steel — Tempering Steel — Tempering Masons' Tools —
Very Small Tools — Table of Temperatures and Colours — Methods of
Heating — Degree of Heat — Cooling — Hardening and Tempering in OH
— Toughening — Blazing — Annealing — Case-hardening — Ordinary
Method — Rapid Method — ^Tbsts for Steel — To distinguish Steel
from Iron — Fractured Surface — Trial — Tensile Tests — ^Admiralty Tests
for Steel — Lloyds' Tests — Tests by repeated and falling Loads — Steel
for Bridges and Roofs — Market Forms of Steel — Relative Value
OF Different Kinds of Steel — Extras upon Steel Plates — Brands
ON Steel.

Strength of Cast Iron, Wrought Iron, and Steel— Ultimate
Strength and Daotility. — Strength of Cast Iron — Average
Strength — Tables of Crushing and Tensile Strength — Influence of various
circumstances upon the Strength of Cast Iron — Size of Section — ^Re-
peated Remeltings — ^Temperatu7&>-Mijdng Brands — Strength and
DucniiiTT OF Wrought Iron — Average Strength — Table of Teneile
Strength ae^ DuiUilitf — ^Bars — Plates — ^Angle Iron — Rivet Iron —

CONTENTS. xxi

Elastic lAmU — Emdance to Compreasion — Shearing Strength — Effect of
different Processes and Circumstanees upon the Strength of Wrought Iron —
Rolling — Turning — ^Forging — ^Annealing — ^Welding — Sudden Stress
— Hammering — Hardening — Cold Rolling — Qalvanising — Frost —
Frost and Sudden Stress — ^Temperature— Strength and Duotilitt
OF StebIi — Average Strength — TensiU Strength — Table of Tensile
Strength — Elastic Limit and Ductility of Cast Steel — Tensile Strength
and Ductility of different kinds of Steel — ^Tensile Strength of Steel
Plates with and against the Qrain — Tensile Strength and Ductility
of Steel Bars — Plates — Tensile Strength and Ductility of Landore
Steel — Tensile Strength and Ductility of Whitworth's Compressed
Steel — ^Elastic Limit — Steel Wire — Besistanee to Compression — Shearing
Strength — Effect of Different Processes and Oircwmstances upon the
Strength of Steel — Tempering in Oil, Water, Tallow, Tar, Ashes, etc.
— ^Annealing — Influence of Carbon.

8afb or Working Stresaes for Cast Iron, Wrought Iron, and
Steel. — Fagtobs of Safety — Table for Different Structures —
Working Stresses in Tension, Compression, Shearing, and
Bearing — Cast Iron — Wrought Iron — Built-up and Plate Girders —
Rolled Qirders — Roofs — Braced Girders — Board of Trade Rule —
Bearing Strength — Steel — Opinion of Committee — Resistance to Com-
pression— Bearing.

Iiimit of Elastioity. — ^Definition — Permanent Set — Fatigue of Iron—
False Permanent Set — Set caused by continued Load — Elastic Limit
raised by Stretching — Other Definitions of Limit of Elasticity,

Elastic Limit of Cast Iron, Wrought Iron, and Steel.

live and Moving Ijoads. — Repeated Loads — Vibration — Extreme
Cold— Forging — Forging Iron — The form to be given to Forgings —
Overheating — Forging Steel — Shear — ^Blister— Cast Steel — ^Welding
—Wrought Iron— Steel— Other Metals.

Corrosion and Preservation of Iron and Steel. — Corrosion — Cast
Iron — ^Wroughtlron — Steel — Preservation — Galvanising — Painting
— Cast Iron — Wrought Iron — Dr, Angus Smithes Process — Bower-
Barff Process — Bright Ironwork — Bronzing — Gilding.

General Bemarks. — Carbon in Iron and Steel — Characteristics and
Uses of Cast Iron, Wrought Iron, and Steel

Copper. — Uses — Ores — Properties — Oxidation and Corrosion — Market
Forms — Sheet — Wire — Wire-cord — ^Wire-covered Steel Sash Line.

wii CONTENTS.

'LMd,^U8e9--Orei-'Prop&rtie8—UAaja£ Fobms—^S^m^— Oast— Milled
— Laminated — Action of Water upon Lead — Lead Pipee — Sizes and
Weights— (7oa(tn^ Pipee to prevent Poieoninff — ^M'Doagal's Patent —
Schwartz's TAteDt — Leadreneaeed Ptpw—Weightr— Strength— JVvC
Lead — Sizes, etc.

Sano. — Usee — Oree — Propertiee — Mabkbt Forms — Sheets — Qauges.

Tin. — Ueee — Oree — Propertiee — Tin Tubing — Composition Tubing —
Weight — Tin Pioto— Teme Plate — ^Block Tin— Doubles — Crystallised
Tin Plate— Tinned Copper.

Alloys. — General Bemarks — Bbass — Composition — Colour — Properties
— ^MuNTZ MjfiTAL — ^Dblta Mbtal — Brohee — Qun Metal — Bell Metal
— Alwmniwnh Bronze — PhoepKor Bronze — Manganeee Bronze — SterrO'
Metal — Babbit*e Metal — White Braee — Table of Comfosihob of
Various Allots — Pbwtbb.

SoLDEB. — Hard — Soft — Hard SMere — Spelter Solder — Silver Solder —
Brazing — Soft Soldere — Fine — Coarse — Table of Ingrediente — Melting
Points and Usee of Soldere — Soft Soldering — ^Fluxes for Hard and Soft
Soldering.

Tables. — Propertiee of Metale — Contraction of Metale in Cooling — Melting
Points of Alloys — Metal Qauges — Imperial Standard Wire Oaiuge —
Birmingham Wire Gauge — ^Whitworth's Standard Wire Gauge —
Birmingham Plate Gauge — Sheet and Hoop Iron Gauge — Weight of
Metals per Square Foot Pages 257-357

Chafteb V.
TIMBER

OeneraL — Growth of Tbees — ^Annual Rings — ^Medullary Rays — Sap-
wood — Heartwood — ^Felling — Squaring — Chabacteribticb of Good
Tdcbeb — Defects ik Tdcbeb — Heartshakes — Starahakes — Cup-
shakes — Rind GaUs — ^Upsets — ^Foziness — Doatiness — ^Twisted Fibres
— Classification of Tdibbb — Pine Wood — Leaf Wood — Soft Wood
— Hard Wood — ClaseifUation of Fir Timber — ^Pine — ^Fir or Spruce.

Mabkei Fobmb of Tdcber — Log — ^Balk — Fir — Hand Masts — Spars —
Inch Masts — Balk Timber — Pknks — ^Deals — Whole Deals — Cut
Deals — Battens — ^Ends — Scaffold and Ladder Poles — ^Bickers. Oak
— Rough Timber — Sided Timbez^-Thick Stuff— Planks — Wane^f
Timber — Compaee THmber.

J>6soription» Appearanoe» Characteristios, and Market Forms of
Different Kinds of Timber. Fine Wood or Soft Wood.

— ^KoBTHEBN Pike — ^Appearance — ^Varieties in use — BaUo — Dantzic

CONTENTS. xxiii

— Memel — Riga — Norway — Swedish. Planks^ DedU, and Battens —
Yellow — Prussian — Russian — Finland — Nyland — Norwegian —
Swedish.

Ahbbican Pine. — Red — ^Tellow — Claasification — Quebec YeUow Pme.

Pitch Pinb — ^Whitb Fib or Spruce — BaUio — American, Larch —
European — ^American. Cedar — Ctpress — Oregon Pine — Eawrie
Pine.

Hard Wood or Leaf Wood. — OAK—BriHsh — Stalk-fruited— Cluster-
fruited — Dunnast Comparison of Different Varieties — American —
Canadian — ^Live — Iron — ^Baltimore — Dantsne — French — Riga — Ital-
tan — African — Wainscot — Clap Boarding, BbeOh — ^Alder — Syca-
more— Chestnitt — AflH — BriHsh — American, Elm — BrUish — Com-
mon English — ^Wych — Dutch — Corkbarked — Canada Bock Elm.
Acacia — Sabicu — Poplar. Mahoqant — Honduras — Cuba or Span-
ish— Mexican — St. Domingo — Nassau. Jarrah — Teak — Oreen*
heart — ^MoRA — Hornbeam.

ICarks «nd Brands upon Timber. — General Remarks — Baltic Fir
Timber — ^Baltic Planks, Deals, and Battens — Swedish Qoods — ^Ameri-
can Qoods — ^Mahogany — Cedar — Vahu of Timber ^ Deals, etc.

Seleotion of Timber.

Seasoning Timber. — Natural Seasoning — Water Seasoning — Boiling and
Steaming — Ho^Aiir Seasoning — APNeil^s Process — Smoke-Drying —
Second Seasoning.

Decay of Timber^ — ^Bor — Dry Rot — PositionB in which Dry Rot
occuiB — Wet Rot — Detection of Dry Rot.

Freservation of Timber. — Painting — Tarring — Charring — CreosoUng
— ^Eyan's, Boucherie's, Gardner's, Margaiy's, Bumef s, and Payne's
Processes — Preservation from Fire.

Conversion of Timber. — General Remarks — Atmospheric Influence —
Floor Boards — Conversion of Oak — Conversion of Fir.

Destmction of Timber by Worms and Inseots. — Worms — Teredo
navalis — Xylophaga dorsalis — Limnoria tertians — Tarwis vittatus —
Chelvra terebrans — Lycoris fucata — Protection against Worms —
Ants — Black Carpenter — Dusky — Yellow — White Ant — Protection
against the White Ant — Other Insects.

Varieties of Timber usefiil for Different Purposes — Piles — Posts
— Great Strength — Durable in Wet — Large Timbers — Floors — Panel-
ling—Joinery —Sills— Sleepers— Treads of Stairs— Handles— Patterns.

xxiv CONTENTS.

Stren^h of Timber. — TabU of Weight and Strength — Rendance to
Ortuhing across Fibres — Besistance to Shearing • Pages 358-405

Chapter VI.
PAINTS AND VAKNISHES.

Qeneral Bemarks. — XBases — Vehicles — SolYents — Drien — Colouring
Pigmeuts.

Bases. — ^White Lead — Adulteration — Market Forms — Clichy White —
Qenuine Dry White Lead — Newcastle, Nottingham, Roman, London,
Erems, Vienna, French Silver, Flake, Whites, Venice, Hamhuig,
Dutch and Holland Whites — Old White Lead — Uses, Advantages, and
Disadvantages — Test for Sulphate of Baryta — Red Lead — Uses,
Adulteration, and Tests — Antimont Vermilion — Oxide or Zinc —
Uses — OxT-SuLPHiDB OP Zinc — Oiudb op Iron.

Vehicles. — Oils, Fixed — Drying, Non-drying — Volatile — Oil of Turpen-
tine— Petroleum Oil, Naphtha — Petroleum Benzoline.
Linseed Oil. — Uses — Raw Linseed Oil — Boiled Linseed Oil. — ^Dark Dry-
ing Oil — Pale Drying Oil — ^Boiled Oil to be used with Zinc Paint —
Drying Oil for common work.

Poppy Oil — ^Nut Oil.

Oil of Turpentine. — Characteristics and Qualities — Uses.

Driers. — ^Action of — Litharge — Massicot — Sugar of Lead — Oxide of
Manganese — Japanners' Gk>LD Size — ^Verdigris — ^Red Lead —
Sulphate op Manganese — Sulphate of Zinc — Patent Driers —
Terebine — Xerotine Siccative — PrecatUions in using Driers.

Colouring Figments. — General Remarks : Blacks. Lamp, Vegetable,
Ivory, Bone, Blue, Frankfort, Grants, and Bideford Blacks.

Blues. — Prussian, AnJtwerp, Berlin, Haerlem, Chinese, Indigo, Ultramarine,
Cobalt, Smalt, Saxon, Royal, Celestial, Brunswick, Damp, Bremen Blues,
and Blue Ochre. Yellow& — Chromes — Middle, Lemon, Orange —
Naples, King's, Chinese — Arsenic Yellows — ^Yellow Orpiment — Turner's
— Casseffs — Verona — Montpellier — Patent and Cadmium — Ochres —
Yellow, Spruce, Oxford, Stone — Terra de Sienna — Raw Sienna —
Yellow Lake. Browne — Raw and Burnt Umber, Vandyke, Purple^
and Spanish Browns — Burnt Sienna — Brown Ochre — Brown Pink —
Bistre — Vandyke — Cassel — Egyptian — AsphaUum — Sepia — Light and
Deep Cappagh Broiotu. Reds. — Carmine — Red Lead — Vermilion:
Tests ; German. Indian, Chinese, Light, and Venetian Reds — Rose
and Dutch Pinks,

CONTENTS. XXV

Lakes. — Drop^ Scarlet, Florentine, Hamhurg, Chinese, Roman, Venetian, and
Carminated Lakes, Oranges. — Chrome Orange — Orange Ochre — Mars
Orange — Orange Bed. Greens. — Bnmswick and Mineral Green —
Verdigris — Green Verditer — Malachite, Prussian, Brighton, Mountain,
Marine, Saxon, African, French, Patent, EmeraM, ScheeWs, Vienna, and
Chrome Greens, Terre Verte and Buiman's Green.

Uses of Pigments under different circumstances.

Proportions of Ingredients in Mixed Faints — ^Lead Paints — Table
Stowing composition of different Coats of White PaiiU — Repainting old
Work — Painting in Cold Weather — White Lead Paint — Coloured Lead
Paints — Mixing Lead Paints — Injurious Effect of Lead Paint

Zmc Paint. — Characteristics and Uses.

Coloured Paints. — Common, Superior, and Delicate Colours — Pig-
ments FOR Coloured Paints. — Common Colour — Stone — Drab-
Buff — Greys — Browns. — Superior Colours — ^Yellows — Green — ^Salmon
Fawn. — Delicate Tints — Sky-blue — Peargreen.

Special Faints. — Inodorous — Freeman^s Non-poisonous White Lead
— Charlton White — Charlton Enamels — Duresco — Patent White —
Sidphide of 2^nc — Griffith's Patent White — Albarine — Oxide of
Iron Paints — Torbay — Black Oxide of Iron — PulforcPs Magnetic —
Purple Brown — Silicate Oxide Paints — Titanic — Anticorrosion
— Enamel Paint — Indestructible, Gay's — Silicate Paints —
Griffith's Silicate Enamel Paint — Szerelmet's Compositions —
Granitic Paint — Bituminous Paints — Tar Paint — Tarring — Sili-
cate— ZopissA — Asbestos Paints — Crease's Antiwater Enamel
AND Anticorrosion — Granulated Cork Paint — Luminous Paint.

(General Bemarks on Varnish. — Qualities — Uses.

Ingredients of Varnish. — Gums — Balsams — Resins — Resins — Comr-
mon — Amber — Gum Anirn^ — Copal — Mastic — Dammar — Gum Elemi
— Lac: Stick, Seed, Shell — Sandarach — DragorCs Blood — Solvents
— Boiled Linseed Oil — Turpentine — Methylated Spirit — Wood Naphtha
— Driers — Litharge — Sugar of Lead — White Copperas.

Different Kinds of Varnish. — Oil Varnishes — Turpentine Varnishes —
Spirit Varnishes — Water Varnishes — Mixing Varnishes — Mixing Oil
Varnish — Mixing Spirit and Turpentine Varnishes — Application of
Varnish.

Becipes for Varnishes. — Oil Varnishes — Copal Varnishes — Best Body
Copal — Best Pale Carriage Copal — Second Carriage — Pale Amber —
White Coburg — Wainscot Varnish — Spirit Varnishes — Cheap Oak

d CONTENTS.

— Copal — White Hard— Brown Hard — French Polish — Hardwood
Laeqtur — Lacquer for Brass.
TuBFBNTiNB Yabnisheb. — Black for Metal Work — Bmnswick BlacL
Varnish for Iron Work — Crystal Varnish — Water Yarnibh — Light

Coloured — Ordinary — ^Vabkish fob Papbb.
Japanning — Stains — Liqwd Stains — Mahogany — Black Walnut — ^Wal-
nut Oak — Black and Bed Stains — Wash fob bxmovino Paint —
CUaming old Paint — Extbaot of Lbthibium — Mabvel Fluid — Mor-
dant to make paint adhere to Zinc , . . Pages 406-436

Chaftbb VIT.

GLASS. — Genebal Revabks.

Gbowk Glabs. — Manulactore — ^Market Forms — ^ThicknesMe — Qnantity
in Crates — Sizes — Qualities — Chaiacteristics.

Sheet Glass. — ^Manufeu^ture — Qualities — Thickness and Weight — Sixes
— Market Forms — Chaiacteristics — Oylinder Glass — Gwman Plate
Glass—British Sheet Glass.

FhOed Sheet Glass — Patent Plate Glass or BUnon Plate — Manufacture —
How to distinguish from British Plate — Qualities — Colour — ^Thick-
ness and Weight — Sizes.

Bbitibh Plate Glass. — ^Advantages — Bough Oast Plate — Quality — Sixe
and Thickness — TJB»-'Bough BoUed P^o^^— Plain— Fluted — Sizes —
Thicknesses — Uses.

Bbitish Polished Plate Glass. — Qualities — Thickness — Sizes — ^IJses —
Patent Diammd Bough Plate— Patent Quarry Bough Plate— Sues.

Pebfobated Glass — Cathedbal Glass — Patent BoUed — Sheet — Sanded
Sheet.

Qbound OB Obsoubed Glass — Enamelled Glass — Stained Enamelled
Glass — ^Embossed Glass — Coloubed Glass — Flashed Colours — Pot
Metals — Special Klsdb of Glass — Glass Tiles — Glass Slates —
Intbboeption of Light bt Glass . 437-444

chaptbb ym.

PAPERHANGINQ.

Wall Papebs. — Common or Pulp— Satin — ^Pbinting — ^Machine, Hand
— Distinction in Appearance hetwem different Classss of Paper —
Mabket Fobmb — Sizes — English Papers — French Papers — Borders —
Lining Paper — Coloubs — Poisonous Colours — Test for Arsenite of

CONTENTS. xxvii

Cofper — LiNORUBTA Walton — Damp Walls — Yarnibhino and
Painting Wall Papsbb — Washable Papbrhanginos — Papbr-
HJJ7QII3G — Uses . • .^^ • • • Pages 445-447

Chapter IX.
MISCELLANEOUS.

Qlxxe. — ^Manufacture — ^CharacteristicB — Preparation — ^Uses — Strength —

Qlue9 to rentt Moisture — Motvm Ghie.
Biae. — Manufacture — Dovhle Siese — Patent Size — KUvin Dry — Clear Cole

— ParehmeiU Size — Gold Size — Oil Gold Size — Burnish Gold Size —

Japanners' Gold Size.
Knotting. — Ordinary — First Size — Second — Patent Knotting — Hot

Lime.
Paste. — ^Recipes for four varietiea

Gold Iieaf.— Market Forms— Pa/« Leaf Goldr— Dutch Gold— Gold Paint.
Putty. — Painteri^ and Glaaieri — Hard — Very Hard — Soft — Plasteren

Putty — Thermoplastic Putty.
Bust Cement; — Manufacture — Quick-setting — Slow-setting.
Ijaths. — Plasterer^ — ^Thickness — Market Forms — Metal^ Slate or Tiling

Laths.
Vnlcanlaed Indiarabber.
Tar. — Coal Tar— Naphtha—Creosote — Pitch — Wood Tor— Stockholm

— Archangel — ^American — Pitch — Mineral Tar.
Creosote. — Htgeian Rock.
Felt. — ^Asphalted — Sarking — Inodorous Bitumen — Fibrous AsphcUte —

Hair Felt — Cement for FeU — Tarring FeU.
Asbestos. — ^Raw — Concrete Coating — Roofing — Sheathing — ^Felt.
Willesden Fabrics. — Paper — Canvas — Wire Wove Roofing — Emery

— SiLiOATB Cotton.
Kails. — Fine — Bastard — Strong — Tenpenny — Fowrpenrvy^ etc
Cast — Malleable — Hanp - wrought — Cut — Patent Machine -

WROUGHT.

Rose Nails. — Rose Sharp Points— Yine — Canada — Strong. Rose Flat

Points — ^Fine — Strong. Rose Clench.
Clasp Nails. — Wrought — Fine-^Strong — Cut Brads — Flooring —

Cabinet — Glazier^ Sprigs.
Clout Nails — Fine — Strong — Countersunk
Wire Nails — ^Pointes de Paris.

iii CONTENTS.

Doa Nails — Spikes — Tacks — JSom, CloyJt^ FUmisky Blackedy Bluedj

Tinned,
Copper Nails — ^Composition Nails — Slating Nails — Cast — Malleable

— Zinc — Copper — Composition — TUe Pegs — Steel Nails.
Lath Nails — Miscellaneous — Weight op Nails — Spikes — Pound

Nails — Table of Sizes and Weights of Nails — Adhesive Force op

Nails — Holding Power of Tenpenny NaUs — Adhesive Force of Kails

in Dry Deal — Holding Poicer of Spike Na/ils in Fir
SorewB. — Strong — Middling — Fine — Flatheaded — Ronndheaded —

Wood-screws — Patent Pointed — Nettlefbl^s — Coach Screws — Handr

rail Screws — Brass Screws — Screws for Metal.
Wliitfworth's Standard Thread— Table— WhUworl^Cs Gas Thread— TabU —

Stove Screws — Adhesive Power of Screws — Making Screws — Screw

Plates — Stocks and Dies — Master Taps — Bolts and Nuts

Pages 448-466

APPENDIX.

Fhysioal PropertieB of Materials, and Ijoads and Stresses to
which they are subjected.

Load — Dead — Live — Illustration — Breaking Load — Factor of Safety
for different Materials — BiUe for Compound Factor of Safety — Working
Load — Proof Load,

Stresses. — Stress and Strain — Diflferent Bonds, with mode of Fracture —
Intensity of Stress — Ultimate Stress — Proof Stress — Working Stress,

Strength. — Tensile — To resist Crushing — Transveru — SheaTing — Tor-
sional— Bearing — UUimats Strength — Proof Strength.

Pliability — Stiffness — Rigidity — Elasticity — Perfect — Set — Elastic
Limit — Modulus of Elasticity — Deflection — ^Resiliencb — Mal-
leability — Ductility — Brittleness — Hardness — Softness —
Toughness — Fusibility — Weldability — Hardening — Temper-
ing . . . 467-470

Chapter I.

STONE.

Gtoneral Bemarks. — ^In the following Notes no attempt will
be made to describe the appearance and characteristics of all the
different kinds of stone used in this country.

Such a task would be almost endless, and it would also be
unprofitahla No description upon paper would give a practical
idea of the appearance of the different varieties, and moreover the
aspect and qualities of stone firom the same quarry vary as dif-
ferent beds are reached.

It is therefore proposed to describe the characteristics which
are common to most building stones, and to point out the quali-
ties that are necessary to ensure a good material for building or
engineering work.

A knowledge of these will form a guide in selecting stone for
such purposes from any quarry, new or old, whether in this coun-
try or abroad.

This having been done, a few of the best known British build-
ing stones will be described, in order that the student may have
some idea of their peculiarities and uses.

Tables will be added, giving the names of the principal quarries
in the country, which will serve to impress upon the student the
numerous varieties of stone which exist, and the localities in which
they occur.

It is hoped that these Tables will be of use to the practical
man, but, in order that they may be so, it will be advisable to
describe exactly how they were prepared.

They include all the quarries reported upon by the Royal Oommis-
sioners who selected the stone for the Honses of Parliament^ except a few
which have since cieased work.

This list was extended hj adding to it the names of the principal qnazries
given in the official report on Mineral Statistics, hy Mr. Hunt

Next are added a few important quarries mentioned in Hull's BuUdifkg
SUnus^ De la Beche's Report, Wraj on Sione, Gwilt's EneydopadAa of ArM-
tae<iir», and some known to the author personally.

The list thus formed was completed as far as possible by comparison with
B. C. — ^m B

3 NOTES ON BUILDING CONSTRUCTION.

the specimens in the Museum of Practical Geology and with those in another
good collection of building stones.

The list was then sent to a great many different parts of the country, to be
checked and supplemented by professional men having local knowledge, and
also to a London stone merchant of great experience.^

With regard to any important stones of which the author had no personal
knowledge, special information was obtained from experienced men on the
spot

The Tables are arranged to show the geological formations
from which the different varieties of stone are obtained.^

These Kotes do not, however, enter at aU upon the subject from
a geological point of view \ the relative position of the different
geological strata must be ascertained from works specially devoted
to that subject

Any reference to the quarrjdng, workings or cost of stone has
also been avoided.

CHAEACTEEISTICS OF BUILDING STONR

In selecting a stone for a building or engineering work, inquiry
and investigation should be made to ascertain whether it possesses
certain important characteristics mentioned below : —

Durability, or the power of resisting atmospheric and other
external influences, is the first essential in a stone for almost any
purpose.

The durability of a stone will depend upon its chemical compo-
sition, its physical structure, and the position in which it is placed ;
and the same stone will greatly vary in its durability according
to the nature and extent of the atmospheric influences to which
it is subjected.

To make sure that a stone will *' v?eather," — ^that is, will wear
well under exposure to the weather— -many points have to be in-
quired into.

Chemical Composition. — ^The chemical composition of the stone
should be such that it will resist the action of the atmosphere,
and of the deleterious substances which, especially in large cities,
the atmosphere often contains.

^ For this edition the list has been again revised by a London stone merchant— «id
corrected and enlazged from the valuable articles on Stone Quarries which appeared
in the Builder during 1886, and also from other sources of information.

* The quickest way of finding a stone in the Tables is to look it out in the Index
at tha end of this volume.

CHARACTERISTICS OF BUILDING STONE. 3

These destaroying substances are taken up by the moisture in
the air, or by the ndn, and are thus conveyed into the pores of
the stone.

The sulphur acids, carbonic acid, hydrochloric acid, and traces
of nitric acid, in the smoky air of towns,^ and the carbonic add
which exists even in the pure atmosphere of the country,^ ulti-
mately decompose any stone of which either carbonate of lime
or carbonate of magnesia forms a considerable part.

The oxygen even in ordinary air will act upon a stone contain-
ing much iron, and the fumes from bleaching works and factories
of different kinds very soon destroy stones whose constituents are
liable to be decomposed by the particular acids which the fumes
respectively contain.

In addition to the direct chemical action of the sulphuric and
sulphurous acids upon the constituents of stones, sulphates are
sometimes formed by them which crystallise in the pores of the
stone, expanding and throwing off fragments from the surface.

The durability of a stone depends, therefore, to a great extent
upon the relation between its chemical constituents and those of
the atmosphere surrounding. A stone which will weather well in
the pure air of the country may be rapidly destroyed in the smoke
of a large town.

Natwre and Extef/U of Atmoapherie Injliience. — The same stone
will weather very differently according to the nature and extent
of the atmospheric influences to which it is subjected.

From what has been said above, it is evident that most stones
will stand a pure atmosphere better than one which is charged
with smoke, or with acids calculated to attack the constituents
of the stone.

It is also evident that the stone will be less attacked in dry
weather than during rain ; the destructive acids cannot penetrate
so deeply, and the frost has no influence whatever when the
stone ia dry.

The number of days on which there is rain in any district has
Uierefore a great influence on the durability of stone used in that
district.

^ Dr. Angas Smith calculated tliat 15,000 tons of carbonic add were daily eyolved
in Manchester. The air contained from *04 to *08 per cent of carbonic acid ; the
rain from 1*4 to 5*6 graina of anlphnrio add per gallon, and aa moch aa 1^ grain of
hydrochloric add. «

' Dr. Angus Smith found *08 per cent of carbonic add in the pnre air of the
moontains of Scotland.

4 NOTES ON BUILDING CONSTRUCTION

Wind has a considerable effect upon the durability of stone.

A gentle breeze dries out the moisture, and thus favours the
lasting qualities of stone.

A high wind, however, is itself a source of destruction; it
blows sharp particles against the face of the stone, and thus grinds
it away. Moreover, it forces the rain into the pores of the stone,
and may thus cause a considerable depth to be subject to the
effects of acids and frost

** Variation of temperature, apart from the action of frost, is also
a cause of decay, the expansion and contraction due to it causing
the opening of undetected natural joints, but its effect must be
comparatively slight as a destructive agent."^

The Fositian of a Stone in a Building may very much influence
its durability.

The stone in that side of any building which faces the prevailing
rain is, of course, more liable to decay than it is in the other sides.

Any faces of stone that are sheltered altogether from the sun
and breeze, so that the moisture does not quickly dry out, are
very liable to decay.

This may be noticed especially in buildings of an inferior stone
situated in a bad atmosphere. In these it will be seen that the
soffits of arches and lintels, the shady sides of window jambs, and
parts of carvings which the sun never gets at, are always the first
portions of the building to decay.

Any stone exposed to very different degrees of heat on its dif-
ferent faces is liable to crack from imequal expansion and con-
traction.^

The Phydoal Strudwre of a stone is of the greatest importance,
for upon it depends greatly its power of resisting the action of
the atmosphere.

White chalk and marble are of the same chemical composition
— both nearly pure carbonate of lime — ^yet the latter, especially
when polished, will resist an ordinary atmosphere for a long tune,
while the former is rapidly disintegrated and destroyed.

Hence stones which are crystalline in structure are found to
weather better than those that are non-crystcdline.

No stone intended for the exterior of a building should have a
porous surface, otherwise the rain conducts the acids from the
atmosphere into the pores of the stone, which soon becomes do-
oomposed.

1 Wray On Sitm€.

JvmWiP^ t'l ^ vfs, .f > . J %^s

CHARACTERISTICS OF BUILDING STONE. 5

Again, in winter the wet penetrates the pores, freezes, expands,
and disintegrates the surface, leaving a fresh surface to be similarly
acted upon, until the whole stone is gradually destroyed.

If the chemical composition and remaining qusdities of two
stones are the same, then the stone which has the closer and
finer grain of the two is likely to be more durable than the other.

It is important that a stone should be homogeneous in its struc-
ture. If the grains and the cement uniting them are both of
lasting material, the stone will be very durable. If the grains be
easily decomposed and the cementing material remains, the stone
will become spongy and porous, and then liable to destruction by
frost. If the cementing material is destroyed, the grains will fall
to pieces.

It is important that the stone should contain no soft patches or
inequalities; unequal weathering leaves projections which catch
the rain, etc., and hasten decay.

fruity for Working. — ^The readiness with which stone can
be converted by the mason into the various shapes in which it
is required for different kinds of work is of importance from an
economical point of view.

The characteristics of a stone in this respect will depend in
some cases upon its hardness, but will also be influenced by the
soundness of its texture ; by its freedom from flaws, shcJces, vents,
etc. ; and also by its natural cleavage and other peculiarities.

A soft stone of even grain and without distinct beds would
naturally be selected for carved work, while a hard stone in thin
layers, easily separated, would be well adapted for building good
and economical rubble masonry. (See Part I.)

Hardness. — The hardness of stone is often of importance,
especially if it is to be subjected to a considerable amount of wear
and friction, as in pavements. It is, moreover, important when
the stone is to be used for quoins, dressings, and other positions
where it is required to preserve a sharp angle or " arriAr Hard-
ness combined with toughness is also essential in good road
metalling, which should not, however, be liable to splinter or to
grind readily into dust

It does not follow because a stone is hard that it will weather
well ; many hard stones are more liable to atmospheric influence
than those of a softer texture, whose chemical composition is of a
more durable nature.

Stone used for work exposed to the action of water should be

6 NOTES ON BUILDING CONSTRUCTION.

hard; running or dripping water soon wears away the surface.
The blocks of stone in marine works are subject to serious injury
not only from the impact of the waves themselves^ but from the
sand and stones thrown against them by the force of the sea.

Strength. — The strength of stone should be ascertained if it is
to be subjected to any excessive or unusual stresses.

Stones in ordinary building or engineering works are generally,
under compression, occasionally subject to cross strain, but never
to direct tension.

It is generally laid down that the compression to which a stone
should be subjected in a structure should not exceed ^ of the
crushing weight as found by experiment.

Practically, however, the compression that comes upon a stone
in any ordinary building is never sufficient to cause any danger of
crushing.

The greatest stress that comes upon any part of the masonry
in St. Paul's Cathedral is hardly 14 tons per square foot. In St
Peter's, Home, it is about 15^ tons per square foot

By a reference to page 81 it will be seen that these stresses
would be safely borne even by the softer descriptions of stone.

The weakest sandstones that exist will bear a compression of
120 tons per foot, while the resistance of ordinary building stones
ranges from 140 to 500 tons per square foot, and in the case of
granites and traps rises as high as 700 or 800 tons per square foot

It is possible, however, in some forms of arches, in retaining
walls, and in other structures, that a considerable pressure
may be concentrated upon certain points, which are liable to
be crushed.

Weight. — ^The weight of a stone for building has occasionally
to be considered.

In marine engineeiing works it is often advisable to use heavy
stones to resist the force of the sea.

A light stone would be best adapted for arches, while heavy
stones would add to the stability of retaining walls.

Appearance. — ^The appearance of stone is often a matter of
importance, especially in the face work of conspicuous buildings.

In order that the appearance may be preserved, a good weather-
ing stone should of course be selected, free from flaws, clayholes,
etc.

AU varieties containing much iron should be rejected, or they
will be liable to disfigurement from unsightly rust stains caused

CHARACTERISTICS OF BUILDING STONE,

by the oxidation of the iron under the influence of the atmo-
sphere.

Stones of blotched or mottled colour should be regarded with
suspicion. There is probably a want of uniformity in their che-
mical composition, which may lead to imequal weathering (see
p. 5).

Position in Quarry. — In order to obtain the best stone that a

y^wgjj^-^g

^J^^A^-*^ Mould.

^^g^ew-g^'

^Yr- *"^\^^'^-£*r^ Clay and shingly matter ; dUbris of Purbeck
- '^ * ^ ^^^ ^^'- ' " stone.

Slaty beds of stone.
^^''^zJlZS^^^^^^^:^-^\^^^^ Bacon tier, with layers of stone.

■^

■** '■'ft ly'^^jf-i ■* '

MAT v^'^^Xf

L stone.

Soft Burr.

Dirt bed, containing fossil trees (Cycades).

Cap rising.

Top cap, 8 or 10 feet thick.

Scnll cap.

Roach (true), 2 or 8 feet thick.

Whitbed, 8 to 10 feet thick.

Curf ; flinty.

Curf and Basebed roach.
Basebed stone, 5 or 6 feet thick.

Flat beds or flinty tiers.

Fig. 1.

8 NOTES ON BUILDING CONSTRUCTION.

quany can fumisli, it is often important that it should be taken
from a particular stratum.

It frequently occui*8 that in the same quarry some beds are
good, some inferior, and others almost utterly worthless for build-
ing purposes, though they may all be very similar in appear-
ance.

To take Portland stone as an example. In the Portland quar-
ries there are four distinct layers of building stone.

Fig. I is a section showing approximately how the strata in a
Portland quarry generally occur.

Working downwards, the tirst bed of useful stone that is
reached is the True or Whithed Boach — a conglomerate of fossils
which withstands the weather capitally. Attached to the Boach,
and immediately below it, is a thick layer of WhUbed — a fine even-
grained stone, one of the best and most durable building stones in
the country ; then, passing a layer of rubbish, the Bastard-Bocuik,
Kerf, or Cvfff is reached, and attached to it is a substantial layer
oi BasAed,

The Bastard'Boach or Baseibed-Boach and the Basebed are stones
very similar in appearance to the True Boach and Whiibed; but
they do not weather well, and are therefore not fitted for out-
door work.

Though these strata are so different in characteristics, the good
stone can hardly be distinguished from the other even by the
most practised eye.

Similar peculiarities exist in other quarries.

It is therefore most important to specify that stone from any
particular quarry should be froin the best beds, and then to have
it selected for the work in the quarry by some experienced and
trustworthy man.

The want of this precaution led to the use of inferior stone
(though from very carefully chosen and good quarries) in the
Houses of Parliament.

Seasoning. — Nearly all stone is the better for being seasoned
by exposure to the air before it is set

This seasoning gets rid of the moisture, sometimes called
''quarry sap," which is to be found in all stone when freshly
quarri^.

Stone should, if possible, be worked at once after being
quarried, for it is then easier to cut, but unless this mois-

CHARACTERISTICS OF BUILDING STONE. 9

tore is allowed to dry out before the stone is set, it is
acted upon by frost, and thus the stone, especially if it be
one of the softer varieties, is cracked, or, sometimes, disinte-
grated.

The drying process should take place gradually. If heat is
applied too quickly, a crust is formed on the surface, while the
interior remains damp, and subject to the attacks of frost.

Some stones (see p.. 59) which are comparatively soft when
quarried, acquire a hard surface upon exposure to the air.

ITataral BecL — All stones in walls, but especially those that
are of a laminated structure, should be placed " on their natural
bed," — ^that is. either in the same position in which they were
originally deposited in the quarry, or turned upside down, so that
the layers are parallel to their original position, but inverted. If
they are placed with the layers parallel to the face of the wall, the
effect of the wet and frost will be to scale off the face layer by
layer, and the stone will be rapidly destroyed.

In arches, such stones should be placed with the natural bed
as nearly as possible at right angles to the thrust upon the stone,
— ^that is, with the '' grain" or laminse parallel to the centre lines
of the arch stones, and perpendicular to the face of the arcL

In cornices with undercut mouldings the natural bed is placed
vertically and at right angles to the face, for if placed horizon-
tally, layers of the overhanging portion would be Uable to drop off.
There are, in elaborate work, other exceptions to the general rule.

It must be remembered that the beds are sometimes tilted by
upheaval subsequent to their deposition, and that it is the original
position in which the stone was deposited that must be ascer-
tained.

The natural bed is easily seen in some descriptions of stone by
the position of imbedded shells, which were of course originally
deposited horizontally. In others it can only be traced by thin
streaks of vegetable matter, or by traces of laminae, which gener-
ally show out more distictly if the stone is wetted.

In other cases, again, the stone shows no signs of stratification,
and the natural bed cannot be detected by the eya

A good mason can, however, generally tell the natural bed of
the stone by the " feel" of the grain in working the surface.

A stone placed upon its proper natural bed is able to bear a
much greater compression than if the laminae are at right angles
to the bed joints.

xo NOTES ON BUILDING CONSTRUCTION.

Sir William Fairbaim found by experiment that stones placed
with their strata vertical bore only ^ the crushing stress which
was undergone by similar stones on their natural bed.^

Agents which deetroy Stones. — ^The two principal classes of
agents which destroy stone have already been described.

They are — Chemical agents, consisting of acids, etc., in the
atmosphere; and Mechanical agents, such as wind, dust, rain,
frost, running water, force of the sea, etc.

There are other enemies to the durability of stones, which may
just be glanced at, viz. —

Lichens.

Worms or Molluscs.

LiCHBNS. — In the country lichens and other vegetable substances collect
and grow upon the faces of stones.

These are in many cases a protection from tbe weather, and tend to increase
the durability of the stone. The line rootlets spread themselves over the
surface and into the interstices, covering the face from the action of wind and
weather.

In the case of limestones, however, the lichens sometimes do more harm
than good, for they give out carbonic acid, which is dissolved in rain water,
and then attacks the carbonate of lime in the stone.

Molluscs. — The Pholas dactylus is a boring mollusc found in sea water,
which attacks limestone, hard and soft argillaceous shales, clay, and sandstones
It also attacks wood, but granite has been found to resist it successfully.

These animals make a number of vertical holes close together, so that they
weaken and eventually destroy the stone.

By some it is supposed that they secrete a corrosive juice,' which dissolves
the stone ; others consider that the boring is mechanicsdly done by the tough
front of the shell covering the Pholas.' These animals are generally small,
but sometimes attain a length of five inches — the softer the rock the bigger
they become. The shale beds, on which was founded the quay wall at Kirk-
caldy, were so perforated by Pholades that they crushed under the superin-
cumbent pressure, and a settlement resulted.*

The most notable instance of injury done by Pholades is at Plymouth break-
water, where, in consequence of their attacks, the limestone blocks had to be
replaced by granite.*

The Saxioava is another small mollusc, found in the crevices of rocks and
corals, or burrowing in limestone, the holes being sometimes six inches deep.
It has been known to bore the cement stone (clay-ironstone) at Harwich,
the Kentish Bag at Folkestone, and the Portland stone used at Plymouth
Breakwater.

^ Rankine, Civil Bnffvneering.

* Hartwig's The Sea and its Living W<mden.

* Woodward's Recent and FostU Shdls.

* Stevenson On Harbours.

EXAMINA TION OF STONE. 1 1

EXAAHNATION OF STONR

Speaking generally, in comparing stones of the same class, the
least porous, most dense, and strongest, will be the most durable
in atmospheres which have no special tendency to attack the con-
stituents of the stone.

Fraotnre^ — ^A recent fracture, when examined through a powerful mag-
nifying glass, should be bright, clean, and sharp, with the grains well cemented
together. A dull, earthy appearance betokens a stone likely to decay.

Tests. — In examining a stone it may be subjected to various tests, some of
which afford a certain amount of information as to its characteristics.

BeMistanee to Onuking, — ^The strength of the stone as regards resisting com-
pression may be ascertained by crushing specimens of suitable form (see
pp. 81, 82).

This is not a very important test, for the reasons given at page 6, but some
authorities consider that it affords an idea of the powers of the stone with
regard to resisting frost

Ahsorpticn, — ^A more important guide to the relative qualities of different
stones is obtained by immersing them for twenty-four hours, and noting the
weight of water they absorb. The best stones, as a rule, absorb the smallest
amount of water.

The Table at p. 83 shows the amount of water absorbed in twenty-fouz
hours by several of the most important English stones, some known to be
durable, and others the reverse. This will afford a useful guide in judging of
the quality of any new stone after ascertaining its powers of absorption.

Brar(F$ Test. — Small pieces of the stone are immersed in a concentrated
boiling solution of sulphate of soda (Glauber's salts), and then hung up for a
few days in the air.

The salt crystallises in the pores of the stone, sometimes forcing off bits
from the comers and arrises, and occasionally detaching larger fragments.

The stone is weighed before and after submitting it to the test The dif-
ference of weight gives the amount detached by disintegration. The greater
this is, the worse is the quality of the stone.

The action of the salt was supposed at one time to be similar to that of
frost, but Mr. C. H. Smith has pointed out that it is essentially different, inas-
much as water expands in the pores as it freezes, but the salt does not expand
as it crystallises.

Acid Test. — Simply soaking a stone for some days in dilute solutions con-
taining 1 per cent of sulphuric acid and of hydrochloric acid, will afford a
rough idea as to whether it will stand a town atmosphere.

A drop or two of acid on the surface of the stone will create an intense
effervescence if there is a large proportion present of carbonate of lime or
carbonate of magnesia.

Mr. 0. H. SmitKs Test was proposed for magnesian limestone, but is useful
for any stone in determining whether it contains much earthy or mineral
matter easy of solution.

** Break off a few chippings about the size of a shilling with a chisel and a
smart blow from a hammer ; put them into a glass about one-third full of
dear water ; let them remain undiBturbed at least half an hour. The water

12 NOTES ON BUILDING CONSTRUCTION.

and specimens together should then be agitated by giving the glass a circular
motion with the hand. If the stone be highly crystalline, and the particles
weU cemented together, the water will remain clear and transparent, bnt if
the specimens contain uncrystallised earthy powder, the water will present a
turbid or milky appearance in proportion to the quantity of loose matter con-
tained in the stone. The stone should be damp, almost wet, when the fing-
ments are chipped off."

The best way of carrying out this test is to pulverise the stone and then
treat it as above described. The heavy particles will sink to the bottom and
the earthy turbid matter will settle more slowly.

Practical Way of ascertaining Weathering Qualities. — -The
durability of a stone to be obtained from an old established
quarry may generally be ascertained by examining buildings in
the neighbourhood of the quarry in which the stone has been used

If the stone has good weathering qualities^ the faces of the blocks, even in
very old buildings, will exhibit no signs of decay ; but, on the contrary, the
marks of the tools with which they were worked should be distinctly visible.

Exposed cliffs or portions of old quarries, or detached stones from the
quarry, which may be lying close at hand, should also be examined, to see
how the stone has weathered.

In both cases care should be taken to ascertain from what stratum or bed
in the quarry, the stones have been obtained.

Quarrying. — This is too large a subject to be entered upon in
these Notes.

It will be sufficient to remark that in quarrying stone for building purposes
there should be as little blasting as possible, as it shakes the stone, besides
causing considerable waste.

Care should be taken to cut the blocks so that they can be placed in the
work for which they are intended with their natural beds at right angles to
the pressure that will come upon them.

If this is not attended to, the blocks will be built in in a wrong position,
or great waste will be incurred by converting them.

SoientifLo Classifioation. — The different kinds of stone used
for building and engineering works are sometimes divided into
three classes : — 1. The Siliceous. 2. The Argillaceous. 3. The Cal-
C6u:eous ; according as flint (silica), clay (formerly called " argile "),
or carbonate of lime,^ forms the base or principal constituent

Fraotioal Classifloation. — In describing the physical character-
istics of stones, for practical purposes it will be better to classify
them as follows : —

1. Granites and other igneous rocks.

2. Slates and Schists.

3. Sandstones.

4. Limestones.

^ Calcium Carbonate.

GRANITE. ij

GRANITE AND OTHER IGNEOUS ROCKS.

Granite is> as its name implies, a stone of ciystalline granular
fltracture.

True OP Common Granite. — There are several varieties of
stone practically known as granite, but true granite consists of
Grystals of quartz and felspar mixed with particles of mica.

Composition. — The quartz is a veiy hard glassy substance in
grey or colourless amorphous lumps, occasionally in crystals.

The felspar should be crystalline and lustrous, not earthy in
appearance ; its grains are of different shapes and sizes, and tiieir
colour may be white, grey, yellowish pink, red, or reddish brown.

The mica is in dark grey, black, brown, flexible, semi-transpa-
rent glistening scales, which can easily be flaked off with a
knife.

Granite generally contains more fdspar than quartz, and more
quartz than mica.

The colour of the stone depends upon that of the predominat-
ing ingredient, felspar.

*' An average granite may be expected to contain from two to
three fifth parts of crystals of quartz or crystalline quartz ; about
the same, more or less, of felspar, also partly crystalline and chiefly
in definite crystals ; and the remainder (one-tenth part) of mica.
But the mica may form two or three tenths, and the quartz three-
fifths or more, while the proportion of the felspar, as well as the
particular composition of the felspar, both vary extremely."^

The durability of the granite depends upon the quantity of the
quartz and the nature of the felspar.

If the granite contains a large proportion of quartz, it will be
hard to work ; but, imless the felspar is of a bad description, it will
weather weU.

The felspars that occur most commonly in granite are potash
felspar (prihoekue) and a lime and soda felspar (pligoclase).

Sometimes both these varieties are found in the same stone.

Of the two, potash felspar is more liable to decay than the
other.*

Mica is easily decomposed, and it is therefore a source of
weakness.

^ Axuted's Practical Otology, * Wray.

U NOTES ON BUILDING CONSTRUCTION.

If the mica or felspar contain an excess of lime, iron, or soda^
the granite is liable to decay.

" The quantity of iron, either as the oxide or in combination
with sulphur, must affect the durability of granite, as well as of
all other stone.

'* The iron can generally be seen with a good glass, and a very
short exposure to the air, especially if assisted in dry weather by
artificial watering (better still, if 1 per cent of nitric acid be added
to the water), ought to expose this.

" The bright yeUow pyrites crystallised in a cubical form
appear to do little harm. The white radiated pyrites (marcasite),
on the contrary, decompose quickly.

" Where the iron stains are large, uneven, and dark coloured,
the stone may fairly be rejected, at any rate for outside work.

"When the discoloration is of a uniform light yellow, it is
probable that little injury will be done to the stone in a moderate
time, and unless appearance is a matter of great importance, such
granite would not be rejected.

"In the red granites, the discoloration from iron does not
show so easily, but still sufficiently to guide the engineer if bad
enough to cause rejection." ^

The quality of granite for building purposes depends upon
its durability, and upon the size of the grains. The smaller these
are, the better can the granite be worked, and the more evenly
will it wear.

"In using granite for ornamental purposes, the coarser-grained
stones should be placed at a distance from the eye, the finer-
grained stones where they can be easily inspected. Without
attention to this point, very little better efiect is produced than
by a stone of uniform colour." ^

Syenite and Syenitio Granite are generally included by the
engineer and builder under the general term granite.

True Syenite consists of crystals of quartz, felspar, and horn-
blende, the latter constituent taking the place of mica in ordi-
nary granita It derives its name from the granite of Syene, in
Upper Egypt, though it has been shown that the latter is really
a syenitic granite of the composition mentioned below.

Symitic Oranite consists of quartz, felspar, mica, and horn-
blende, the last-named constituent being added to those of ordi-
nary granite.

* Wmy.

GRANITE. 15

CJiaracteristtcs. — ^The syenites and syenitic granites are gener-
ally of darker colour than ordinary granite, caused by the grains
of hornblende.

''The syenitic granites are on the whole tougher and more
compact than the ordinary granites, take on a fine polish, and are
exceedingly durable.

" They occur less abundantly in nature ; but their rarer use
most frequently arises from the darker tints imparted to them by
the hornblende." ^

The following varieties of granite may be briefly noticed,
though they are of no great importance in connection with build-
ing and engineering works: —

Talcosb Gbanitb contauis, in addition to the ingredients of common
granite, talc, a material which scales ofif in thin flakes, having a whitish
colour and unctnons feeL

Such granites are said not to weather welL

Pbotooenb contains talc instead of mica.

GHLOBmo Granitb contains chlorite, an olive-green mineral, generally
granular, and of a pearly lustre,

ScHORLACEOus Granitb Contains pieces of tt^iorl, '^ a black, hard, brittle,
mineral crystallised in masses or long crystals^ sometimes columnar, and
radiating from a centre." '

Gbaphio Giunite is composed of long parallel prisms of quartz and
felspar, the ends of which when broken across look like the letters of cunei-
form inscriptions.

This granite contains very little mica, and is not much used for building
purposes.

PoBPHTBrnc Gbanttb Ib the name given to those varieties in which laif;e,
distinct, independent czystals of felspar occur at random interspersed through
the mass.

These ciystals are sometimes called " horse's teeth.''

Quarrying and Dressing. — Granite is quarried either by
wedging or by blasting. The former process is generally re-
served for large blocks, and the latter for smaller pieces and road-
metaL

It is better to have the blocks cut to the desired forms in the
quarries ; first because it is easier to square and dress the stone
while it contains the moisture of the ground or " quarry-sap ; "
also because the local men, being accustomed to the stone, are
able to dress it better and more economically, and part of the
work can be done by machinery, generally to be found at the
principal quarries. Moreover, the bulk of the stones being
reduced by dressing, the cost of ccurriage is saved, without much

> Pace's Praeiieal Otology. * Wray On Stone,

i6 NOTES ON BUILDING CONSTRUCTION.

danger of injuring the arrises in transit, as the stone is very
hard.

1X868 to which Granite is applied. — Granite is used chiefly
for heavy engineering works, such as bridges, piers, docks, light-
houses, and breakwaters, where weight and durability are re-
quired. It is also used especially for parts of structures ex-
posed to blows or continued wear, such as copings of docks,
paving, etc. The harder varieties make capital road metaL

In a granite neighbourhood the stone is used for ordinary
buildings ; but it is generally too expensive in first cost, trans-
port, and working, and is therefore reserved for ornamental fea-
tures, such as polished columns, pilasters, heavy plinths, etc.

The granular structure and extreme hardness of granite render
it ill adapted for fine carving, and its surface is entirely destroyed
by the effects of fire.

Varieties in Common Use. — Granite is found in Aberdeenshire, Kirk-
cudbrightshirey Aigyleehirey and the Islands of Moll and Arran. Also
in Cornwall, Devonshire, Leicestershire, Cumberland, and the islands of
Guernsey and Jersey, llie Irish granites occur chiefly in the comities of
Wicklow, Wexford, Donegal, and Down.

The Scotch Granites are most esteemed for beauty and for durable
qualities, especially those from the two great districts of Aberdeen and
Peterhead — ^the stone from the former is generally grey, and that from the
latter red.

The other best known varieties of Scotch granites are those from RvhidoM^
Stirling Hill, Dalbeattie^ Bose of MuU^ Kmmay^ KiMtearyy etc

The Cornish and Devonshire granites, sometimes called moorstones,
have not so high a character. They contain a large proportion of felspar,
which in some cases weathers very badly. The potash felspar of these
granites, when decomposed, tarns into Kaolin or porcelain day.

The Leioestershiee Granites are, generally speaking, syenites — ^veiy hard
and tough, difficult to dress, and therefore not much uaed for building pur-
poeea They are well adapted for paving sets, and make capital road metaL

Jersey and Guernbet Granite is also syenitic. It is a good weathering
stone, very hard, durable, used for paving purposes, but rather apt to become
slippery.

The Irish Granites are very numerous. Grey varieties are obtained
horn Wicklow and Dublin. Those of a reddish tint from Galway. A good
bluish grey granite comes from Castle WeUand, County Down; Counties
Donegal and Mayo produce good red granites. Several colours and varieties
come from Carlow. Newry supplies a greenish syenite.^

^ Wilkinson's PtaeHcal Oeology ^Ireland.

The following Tables give a list of some of the principal
Granite Quarries in Great Britain and Ireland. The quarries
are very numerous, but it is hardly worth while to mention many
of them in the following Tables : —

B. 0. — III

NOTES ON BUILDING CONSTRUCTION

l-H

(z3

o
o

C/3

5*2 SS gj

S ae K

I
C5

. d » .

iir-

no o

I 9

: §"§5

fl ^

(S K^o

35^

-3
ft

I llU 1

=3
s

o d

W -H

s^ s

^ -J

"'2

D
or

b
O
»

of
o

«4 ut^

►- 5 & s o
S 2 P g E 'o ^

GRANITES.

ll|^ If

ill

to • ,-1

8
o

lilll

•I -1^

1 H

' n «

K U H

5^ ^ -< S g -< H a

O O

« O O W o su^
A4 ^OkffiPQCO

NOTES ON BUILDING CONSTRUCTION

o
o

li
11

: «o

1^^- il

Mil
«ii|t

= E

&§ ^r<

is4
o

3
8

■a
1

. .1 ,1- .

Hi'

t3 O

QQCI

^<a

OQP

<Sc

III
III

2 .h £.§ 2 2

"IsLsll-SsI

l-^t't

e'en C « * a,l S S

(l4

HI "^

112

(Spqf3»SM HOPQ0H

Em
O

-< o

H & S td g S O

Mf§> ^ ^ "< ^

►,5 2ri>Sl|

3 at

n
(4

S
CQGQ

•*v-^ :>»,--... .-«-r,_

GRANITES.

c g c 3

III!

III

I II I If

a
S

:oft

d <5

Si . .
js s o d

8|^

^ ^

!i Hi II

(§3

Q^^

"U II

I A I

5 11.

coo Mn^

5^ Je;o(2

t2 NOTES ON BUILDING CONSTRUCTION

IgneooB Books other than Granite. — There are several rocke
which more or less resemble the granite in their characteristics^
and are generally associated with it in the classification of build-
ing stones.

These rocks are, however, seldom used for building or engi-
neering works, except in the immediate neighbourhood of the
place where they are found.

Th% Porphyriei '* generally occur as dykes and eraptiye masses inteisectiiig
the older schiBts and slabs, and are usually much fissured and jointed, and
for this reason incapable of being raised in massive monoliths like the
granite."^

There are two principal varieties foimd in Great Britain. Each consists of
a general mass or base, through which are scattered crystals varying in sise
from small grains to f inch in length. The stone breaks with a smooth
surface and conchoidal fracture.

FeUUme Porphyry consists of a base, which is an intimate miztme of
quartz and orthoclase, known as FMU^ with independent crystals of fel-
spar.

Quartnferoiu Porphyry has a base consisting of a granular crystalline com-
pound of quartz and felspar, with individual crystals of felspar and quartz.

CharacUrUtics, — ^' Both varieties appear in many tints — ^red, flesh-coloured,
fawn-coloured, black, bluish-black, and bluish-green ; and both varieties may
contain, in subordinate quantities, other crystals than those enumerated
above.^

^Incapable of being raised in large blocks, they are polished only for
minor ornaments ; their principal use in Britain being for causeway-stones
and road metal, for which their hardness and toughness render them specially
suitable.

*^ Though chiefly used for road material, in some districts they are emr
ployed in the building of country mansions, farm sheds, and walls ; and when
properly dressed and couraed make a very fair structure (especially the fawn-
coloured sorts), and are perfectly indestructible." ^

Some of the darker varieties are too sombre for building purposes, except
when used for ornamental purposes to relieve surfaces of lighter stone.

Elvan (a term originally peculiar to Cornwall and Devon) is found in
dykes or veins traversing Uie granite or slate ; the dykes varying in width
from a few feet to 300 or 400.

It usually differs from granite in the absence of mica and in the fineness
of its grain. It sometimes contains schist.

^ It is much used as a building stone in Cornwall, and is found to be very
durable/'* also as road material in competition with Quemsey granite.

Stone locally known as Elvan ia also met with in County Wexford.

GNsms is composed of the same constituents as granite, but the mica is
more in layers, and the rock has therefore a stratified appearance.

The rock splits along the layen with facility, and breaks out in slabs from
a few inches to a foot in thickness.

» Pa«e. • Wray.

TRAP, 23

It is uBed both as a building material in the bodies of walls (with dressiiigs
of brick, or more easily dressed stone) and for flagging.^

Mica Schist, sometimes called Mica Slate, is composed chiefly of mica
and quartz in thin layers : the mica sometimes appears to constitute the
^hole mass.

Its colour ia grey or silveiy grey, and it has a shining surface, owing to the
quantity of mica present*

It breaks out in thin even slabs, and the more compact varieties are used
for flagging, door and hearth stones, and furnace linings.^

HoRNBLENDB S0HI8T, or EtmbUneU SktU, is usually black, composed
principally of hornblende, with a variable quantity of felspar, and sometimes
grains of quarts.

It resembles mica schist, but has not so glistening a lustre, and seldom
breaks into thin slabs. It is tougher than mica schist, and is an excellent
material for flagging.^

Trap Bocks. — Oreenstane, also called Trap or Whinstone, is a
mixture of felspar and hornblende.

It has sometimea a granular crystalline structure, and at other
times it is very compact without apparent grains.

It is generally of a greenish colour, but varies in tint from
li^t-greemsh grey to greenish-black or black.

It is extremely hard and tough, and makes capital road
metal — is very often split up by joints, so that it is well suited
for paving setts, but not for large blocks. Its colour is too
sombre for the walls of houses.

Some of the stratified varieties are dangerous as buUding
stones, being liable to decomposition on exposure to the weather,
even where there is no frost.

VaarietieB in Common Uae. — Fmuna^nmawr Stcne from N. Wales is
laxgely used throughout the counUy for paving setts. It is very easily split by
cutting a fine line with an axe in the direction required, and then giving the
stone a few smart taps with a hammer.'

Bardon Sill SUm$ from Leicestershire is also much used for road metal in
the central counties.

Stone of this description is also found in Cornwall, near Edinburgh, in
Aigyleshire, at CarHn KwmoH and other places in Fifeshire, and also in
Goanty Wexford.

WhimUms is found in Wigtownshire, near Selkirk, in Kincardineshire, near
Haddington, near Edinburgh, at Falkirk, in Perthshire, Fifeshire, Invemess-
ehire. Boss-shire, and other places in Scotland.

Basalt resembles greenstone, but is composed of lime felspar,
sogite,' olivine, and titano-ferrite.^

1 Dana and Wray. ' Seddon.

' Black and greenish-black crystals of anhydrous silicate of magnesia

^ Titanic iron.

24 NOTES ON BUILDING CONSTRUCTION.

It occurs in dykes or sheets penetrating or lying between
older rocks, or upon the surface, and is sometimes stratified, some-
times columnar.

" It varies in colour from greyish to black. In the lighter
coloured felspar predominates ; in the darker iron or a ferruginous
augite."^ It is often of a dark green.

This stone afifords a great resistance to crushing, and is
eminently adapted for paving curbs, etc

Bowley Sag is a basalt found in Staffordsbire, and used for road material,
paving Bets, and also for making artificial stone.

This material is found also in the counties of Armagh, Antrim, and Lon-
donderry.

SLATES AND SCHISTS.

Clay Slate. — ^The ordinary slate used for roofing and other
purposes is an argillaceous rock, compact and fine grained. It
was originally a sedimentary rock, but it will no longer divide
along the planes of bedding, but splits readily along planes called
" planes of slaty cleavage."

This facility of cleavage is one of the most valuable character-
istics that slate possesses, as it enables masses to be split into
thin sheets, whose surfaces are so smooth that they lie close
together, thus forming a light and impervious roof covering.

These planes of cleavage are caused by intense lateral pres-
sure.

Planes of cleavage are either coincident with the layers of deposit or lie at
angles with them. When they are in the same plane, or nearly so, the rock
is converted into slahs for paving ; or planed, if it is soft enough, and made
into cbtems, etc The reason that it cannot he made into roofing slates is
that the lamina of the bedding and the lines of cleavage run into each other
and render the surface rough and uneven.

There is another line of imperfect cleavage, which will jield to the chiseL
Along this line the hlocks of slate are split up longitudinally. It is along
this line that fracture occurs when a slate is accidentally broken. The split
along this Une is called by quarrymen the *' Plerry"

Quarrying. — ^The rock is worked in ''Floors,** or tunnels one above
another.

Powder is used to detach the blocks, which are plerried into widths suit-
able for making the best-sized slates ; then split into thicknesses of about three
inches ; cut by circular saws into suitable lengths ; split by skilful hands
with the aid of thin inch chisels ; and squared, either by machinery or by
hand.

^ Dana's Mintralogy,

CHARACTERISTICS OF SLATES. 25

GBiubrian slates are not sawn, because natural joints occur at distances
about equal to the length of the slates. They are generally squared by hand.

Slate rock becomes more compact and the blocks are generally laiger and
more valuable the deeper they are &om the surface ; but the rule does not
always hold good, and there is apparently a limit to it The blocks are split
more easily when fresh from the quarry.

CHARACTERISTICS OF SLATES.

Hardneas and Tonghneaa. — ^A good slate should be both hard
and tough.

If it is too soft it will absorb moisture^ the nail holes will be-
come enlarged, and the slate will be loose.

If it be brittle it will fly to pieces in the process ofv squaring
and holing, or at any rate will break on the roof if any one walks
over it, which is often necessary when the roof is being repaired.

A good slate should give out a sharp metallic ring when struck
with the knuckles — it should not splinter under the slater^s zax
— should be easUy "holed" without danger of fracture, and
should not be tender or friable at the edges.

Coloiir. — ^The colour is not much guide to the quality of a
slate. Some people think, however, that the black varieties
absorb moisture, and decay.

The colours of slates vary greatly. Those most frequently met
with are dark blue, bluish-black, purple, grey, and green.

Red, and even cream-coloured slates have been found.

Some slates are marked with bands or patches of a different
colour — e.g,, dark purple slates often have large spots of light
green upon them. These are generally considered not to injure
the durability of the slate, but they lower its quality by spoiling
its appearanca

Absorption. — ^A good slate should not absorb water to any
perceptible extent

The amount of absorption may be ascertained by the test given
at page 28.

Qrain. — ^A good slate should have a very fine grain.

The grain of the rock is easily seen, and the slates are cut so
that the grain is in the direction of their leugth, in order that if
a slate breaks when on the roof it will not become detached, but
will divide into longitudinal pieces, which will still be held by
the nails.

16 NOTES ON BUILDING CONSTRUCTION.

VeinB are dark marks nmning through some slates. They are
always objectionable, but particularly when they run m the direc-
tion of the length of the slate, for it will be very liable to split
along the vein.

Pyrites. — Crystals of iron p}rrite3 are often found in slates,
especially in those from Scotland, etc.

They are often considered objectionable. It should, however, be
borne in mind that there are two varieties of pyrites, of the same
chemical composition but of different crystalline foim, and very
different in their resistance to atmospheric influence.

Ordinary Iron Pyrites, consisting of yellow brassy crystals,
generally cubical, weathers welL The crystals have been found
perfectly bright and firm in their places in roofs 100 years old,
even in the atmosphere of Glasgow.

White Iron Pyrtt^ (or marcasite), on the other hand, is easily
decomposed, and slates containing it ought to be rejected. This
form of pjnrites is generally dull and wanting in lustre, and i^
tlierefore not easily seen.

Sises. — ^The slates sent to the market are squared in the
quarry — sometimes roughly by hand, sometimes by machinery —
to certain sizes, which are distinguished by different names,^ as
shown in the following Table.

In buying and selling slates in this country, a '* thousand *' is
generally understood to mean 1200 or 1260.

The Table shows the weight and cost of 1200 slates of each
description; it also shows the number of slates required per
square (100 superficial feet) of roofing, and the weight pei
square.

' These nunes ai« lued in the building trade, but not much in the qoarriee.

CHARACTERISTICS OF SLATES,

•-»

■**

o»

s
^

c«^

•M

•;3

(•x

-2

■^

•i

« a

,£:

•■5

-g

«S J3

''^

•M

1-^

>i 6 6 6 6 6 d 0' d d d d d d d d d d d d d d

^/« TS T3 T3 T3 *« TU T3 na TS T3 T3 '«'«'« TU 13 T3 'O »« T3

f-4 f-4 1-1 l-l f-4

'Q 0 0 «> «> 0

c> 00000 ^^

d : : : : : : 0 : 0 : : »o : : lo : 0 : : : S ^
0 . : : : . ;^ : : :.h : : : : : : 0

So*

^ 00«000 00 0 «0«D «> 0«>00 000

of : * 0 ot^o 0 oto tot^t^t^kd 09 »o kd 0 10 ^ • •

C»l Oi «^ «D CO 0 ^ 00 00 <N <N « 00 « <M r-l r-l r-l r-l

C> 0000(N««OIOIOIO <N0«0«00

ci : : 0 0 «o ot^w «^t^ « <N 0 «^io*^ tfj 01 0 0 : :

^ . . r-* r^ r^ T-i r~» 1-* 1-* ft

-^OlOlf-HOOOfcOOiOOOOOIOOOOt^t^OO
i-<i-<r>^i-«i-Hi-< rH f-4r>^i-l

: :xxxxxxxxxxxxxxxxxx : :

s;s§3§j§s2ssss;^?;s;2:;s2s *

at
5

^0000000«00«0«0«OOCOOOOOOOCO«D
^0»00 0»QO»OI^W>C*C<e«»OI^»OtfJOO»0»0<N<M

c4i^ooi-«o«^t^«o^-*^eoeooocoeo<N©i«i-ii-<f-4rH

"^ r-l r-l i-< r-l

C>0 000 0 0 0C<©1«00C<00<N0W0(N0 0
rJOlOiOlOOO«a<Nt«»«^«OlO«OiO©10«^»Ot^'*lO

^00000«>0«00000«0«D«00000000
.lOOOOOC9kOt^kOOOOC4X^C9kO>0»000»OtO

c4i»o»oeoi-io*oo«oiO'^'*^'*eO'*ooooc«c^03i«i-<i-<

C>000 0000<N««OOOIOO«0©10«00
r50iOtOOOtOkOC4t^tN.iOkOC4 0lQOIOt^k<»t^^tO

«OiO"*<N<Ni-<000*00* ^00 CQOOOOt^t^OOOOO

xxxxxxxxxx x^x xxxxxxxxx

SSSSSSSSSS2S «^S 33221SS222SS

««^

•§

•43

§^

§-r

•^s.

■gi

s >>>

3 -t^

o-g

.a 4

;^"

MCO

I .«»^ '3 ^

W 50 or^To" g §
_^c^ 00 «o 10 £ ^;

° C^ SI

M ^~ « g «

28 NOTES ON BUILDING CONSTRUCTION

Quality. — ^The market qualities of slates are classed in the
quarries according to their straightness, smoothness of surface, fail
even thickness, and in the Cambrian quarries according to the
presence or absence of discoloration.

Slates are generally divided into 1st and 2d qualities ; in some
cases a " medium quality ** is quoted.

All slates for good work should be hard, tough, non-absorbent,
of uniform colour, free from patches, from veins, iron, cross-
grain, and with smooth and even surfaces.

Thickness, — ^The thickness increases with the area of the slate,
and the rule for the proportionate thickness varies in different
quarries but for Welsh slates is somewhat as follows : — ^

THICKNESS,
lit QuUty. 2d Quality.
Dndiesses and Marchionesses . . . iV ^cli i*r uich.
Goontesaes and large Ladies ... ^ „ i „

Doubles A »i A »>

The best qualities of Welsh slates generally split easily into
even sheets with smooth surfaces, and holding their thickness
close up to their edges, even after being squared.

Irish and Scotch slates are often of very uneven thickness,
being thicker in the middle than near the edges, and very much
stouter and more substantial than Welsh slates of the same area.

Slates are sometimes split too thin, so that they are not strong
enough for roofing purposes. The Ffestiniog quarries have pro-
duced (for exhibition as specimens of perfection of cleavage) slates
5 feet to 10 feet long, 6 inches to 12 inches broad, only -^ inch
thick.*

Tests. — The following rough tests are generally recommended,
but they are not of a practical character, nor can they be relied
upon. Experience is required to judge of a slate by the eye.

1. Weigh the slate carefiilly when dry, steep it in ¥^ter for 24 houis, run
the water off, and weigh again — any difference of weight will show the
amount of absorption.

2. Stand the slate in water up co half its height — ^if it be of bad quality
the water wiU rise in the upper half, but in a good slate no sign of moisture
wiU be seen above the water-line.'

3. Breathe on the slate. If a clayey odour be strangljf emitted it may be
inferred that the slate will not *' weather.'* *

^ Wray. « Hunt » Owilt. * I)«mp8ey.

DIFFERENT FORMS OF SLA TE. 29

DIFFEEENT FORMS OF SLATE

Slate Slabs. — ^Besides the smaU thin slates used for roofing, large and
thick alabsy and even blocks of slate, are quarried out and used for many
purposes connected with building and engineering works.

Slate in these forms is particularly useful on account of its strength.
^ The strength of slate 1 inch thick is considered equal to that of Portland
stone 5 inches thick/' ^ aud ''its resistance to shearing is said to be greater
than that of any other stone.** '

Slate slabs are easily obtained of any length under 6 or eren 8 feet, and
containing from 10 to 30 superficial feet

Their thickness ranges from 1 inch to 3 inches.

Larger slabs may be obtained by paying extra. The Exhibition of 1862
contained one sent by the Llangollen Slate Company which measured
20 X 10 feet, and weighed 4^ tons ; also several from the Ffestiniog quarries
of the Welsh Slate Company averaging 14 feet by 7 or 8 feet'

They may be procured either self-faced — that is, as they are split from the
blocks — trough sawn, quarry planed, or polished.

The edges are sawn square, planed, filed, or rounded.

Such slabs may be fitted with great accuracy, and are used for cisterns,
urinals, troughs, mantelpieces, baths, window and door^sUls, skirtings, floor-
iiigy wine-bins, steps, landings, etc

Slate Blocks/ containing as much as 2 or 3 cubic feet, can easily be
obtained.

Li Wales and other slate districts they are sometimes used for the walls of
buildings, and slate in scantlings is substituted for much of the wood work,
€»g., in door and window frames.

Slate is also sent out from the quarries in the form of steps, sills, etc

The same material is used for making ridge rolls of different patterns i6x
roofs, dowels for heavy masonry, etc etc.

Enamelled Slate is prepared by painting slate slabs, baking them, colour-
ing to pattern, covering them with a coating of enamel, rebaked and rubbed
down several times alternately, and then polished.

It is often made to represent different varieties of marble, and is much in
request for chimney-pieces and other purposes for which marble is used, abo
for sanitary purposes.

VarietieB in use. — There axe many slate quarries throughout
Great Britain and Ireland, on the Continent^ also in Canada and
the United States.

Some American slates have been imported during late years,
but the great bulk of the slates used for building are from home
quarries.

Welsh Slates. — ^The finest slates found in the United Kingdom come
from Wales.

1 Papworth, 667. « Wray.

' Hunt's Handbook, Exhibition 1862.

30 NOTES ON BUILDING CONSTRUCTION.

The slates fiom the SUurian formations of Merionethshire, Montgomeiy-
shire, etc, are generally of a blue or grey colour, and of beautifal cleavage;
splitting very thin, and sawn square by machinery. The best-known quanies
are those in the Ffestiniog district, such as the Oakeley quarries and those of
the Welsh Slate Company.

The slates of the GcmbHcm formation in Carnarvonshire are of varied
colours — blue, purple, green, and dark grey. They are more siliceous tluin
the Lower Silurian slates, and not so easily cleaved. They are therefore
thicker and heavier, but they are very hard and ring well when struck.
Their edges are not sawn, for the reasons given above. The best- known
quarries are those of Penrhyn and Dinorwig.

Many of the quarries produce also slabs of first rate quality.

English Slates are generally thicker and coarser than those from Wales —
hard, tough, and very duraUe. The best known are the green slates from
Westmoreland, and the slabs from Delabole in Cornwall.

Scotch Slates are also thick and coarse, and generally contain a large pro-
portion of iron pyrites, which, however, does not interfere with their good
weathering qualities.

The best known quarries are those of Ballachulish, Easdale, and Cnllipool.
They are generally blue.

Irish Slates. — ^Many of the best qualities resemble the Welsh yarieties,
others are thicker and coarser.

Among the best known Irish roofing slates are those from Killaloe, or from
the county Kilkenny Slabs of a high quality are exported from Valencia 12
county Kerry

TABLE OF SLATE QUARRIES.

TABT.Fi OP SLATE QUAE

RIES.

•

QUABRT.

{

NEAREST PORT

county.

NATURE OP SLATE

OR station.

AND REMARKS.

Welsh SUtes.

Bangor Rotal

Slate Co.

Bangor

Carnarvonshire

Purple rooflng sUtes and slabfl.

Braiohoogh, ^

Oabwbrn, and

other Quarries .

Machynlleth ..

Montgomeryshire

Blue do. do.

CAMBRIANSLATXCk).

UangoUen

Denbighshire

Blue do. do.

CiLOWYN .

Camaryon

Carnarvonshire .

Blue, purple, and spotted do. do.

Craig Dhu

Blaenan

Ffestiniog .

Merionethshire .

Blue slates.

CWMORTHBI

Ffestiniog and

Slate Co.

Portmadoc .

Do.

DiNORWIO .

Port Dinorwic .

Carnarvonshire .

Blue, purple, and green do. do.

D1PHWT8 Casson

DuflFwrys .

Merionethshire .

Blue and grey roofing do do.

i Dorothea .

Carnarvon

Carnarvonshire .

Pale green, blue, and red do. do.

Llawfair Royal

Slate Co.

Bangor .

Do.

Llangollen

Slate Co.

Llai^[ollen

Denbighshire

Renuu-kable for the sise of the slabs
produced.

Llbchwedd or

1 Greaves

Rhiwbryffdir .

Merionethshire .

Blueandgreyrooflngslatesan 1 sUbe.

! Maenoffbrn

Duffwys .

Do.

Do. do.

Oarblet

Ffestiniog and

Portmadoc .

Do.

Blue roofing slates and slabs.

Oakelet

Rhiwbryfidir .

Do.

Do. do.

Penrhyn .

Bangor .

Carnarvonshire .

Roofing slates and slabs ; generally
blue or purple, some green.

Pen-y-groes

Do.

Purple slates.

1 Rhiwfacbno

Penmachno

Do.

Blue slates and slabs.

1 Rhostdd .

Ffestiniog

Merionethshire .

Blue and grey roofing slates and slabs.

Several Qnarries .

Corris

Do.

Slabs ; bluish-grey slates.

. Welsh Slate Co.

Ffestiniog and

Portmadoc .

Do.

Blue roofing slates and slabs.

Whitland Abbey

Whitland

Caermarthenshire

Green roofing slates.

Wrysoan .

Ffestiniog

Merionethshire .

1 SnglishSlAtM.

' Amblebidb .

Windermere

Westmoreland

Green roofing slates.

1 BoeCABTLE .

Boscastle.

Cornwall

Burlington

Slatb Co.

Ulyerstone

Lancashire .

BURNSTALL, Long-

foid. . .

Tavistock

Devonshire .

Booflqg slates ; nearly worked out

Camel

Wadebridge .

Cornwall.

Cann .

Plymouth

Devonshire .

Roofing slates, slabs.

C0NI8TON .

Ulverstone

Lancashire .

Bongh slates— flags— green slates.

Dri.abolb Slate

Co. .

Camelford

Cornwall .

Greyish-blue slabs ; very llKht,strong,
and durable ; also roofing slates, etc

Grooby

Bardon .

Leioestenhire

Roofing slate.

Kirby Ibklsth .

Ulverstone

Lancashire .

Do.

Lahodale .

Windermere

Westmoreland

Green roofing slates.

Launceston

Cornwall.

Maryport .

Cumberland

Greenish slates.

Pbnricca .

Totness .

Devonshire .

Green roofing slates ; used at Royal
Exohange.

32 NOTES ON BUILDING CONSTRUCTION.

TABLE OP SLATE QUARRIES— Con<M»««t

QUARBT.

NEAREST PORT
OB STATION.

COUNTY.

NATURE OF SLATB
AND REMARKS.

BngUali Slates—

C^iOimiMd.

POMFHLBT .

Plymoutli

Devonshire .

Block! for building— ilabs for paT-
ing and chimney-piecet.

SWITHLAND

Barrow-oii-8oar

Leicestershire

Very durable blue alabs and roofing

Thrang Crao .

Windermere

Westmoreland

TiLBERTHWAITB .

Trewarnet (Tin-

Coniston .

Lancashire .

SevenQ small quarriea of green ekte.

tagel Slate Co.)

Padstow .

Cornwall

Roofing elates and slabs.

WlROHSCOMBB

Wellington

Somersetshire

Rooang slates.

Woodland .

Newton Abbott

Deronshire .

Green roofing slater

Yeolmbridoe

Padstow .

Do.

Slabs for paving and chimnfly-
pieces.

Sootoh Slates.

Aternshill

Crieff

Perthshire .

Roofing slates.

Ballaghulibh .

Fort- William .

Aiigyleshire .

Rough— ftill of pyrltes—weathen
well-dark blue.

Bekledi .

Achray .

Perthshire .

Roofing slates.

BiRNAM

Dunjteld .

Do.

CULLIPOOL .

...

Do.

Dalbeattie

Do.

Drumabttrn

Perth

Do.

Eabdals

Oban

Ai^leshire .

Rougii- fUl of pyrites— weathen
Wai-darkblue.

Foudland .

Huntly

Aberdeenshire .

Roofing slates.

Gartley .

Do.

Glenalmond

Perth .

Perthshire .

Do.

Glbnshee .

Do.

Hoyston .

Forfar

Do.

SUb and block.

Lanriok .

Crieff .

Do.

Turin

Forfar

Do.

Blabs and blocks.

Taniemouth

Bathven .

Banff .

Roofing.

Irish SUtes.

ASHFORD .

...

Wicklow . .

but thicker and coarser.

Benduff .

Leap
Cork

Cork .

Dark colour— nearly given out

Clonakilty

Do.

Good quaUty— Ught and durable.

Killalob (Im-

perial Slate Co.)

Kilkloe .

Tipperary . .

Dull bluish grey. Durable. Coarser,
thicker, and heavier than WeLsh
sUtes.

Enockrob .

Carrick-on-Snir

Kilkenny .

Dark blue— veins of felspar.

Mealouohmore .

Do.

suites of fair quaUty.l

Rathdrum .

Wicklow .

Slab and roofing.

Yalbnoia .

Yalenda .

Kerry.

Light bluish-grey or greenish-blue |
slates. Slabs and flags for export- '
atlon. Thicker and more uneven ;
than those of Killaloe.1 Blocks |
average 8 feet 6 inchea wide :
some 6 feet e inches ; 6 inches to
12 inches thick ; length 10 to 12
feet, sometimes as much as 80
feet!

Yiotoeia Slatb

Co.. . .

Canick-on-Siiir

Kilkenny .

Light green— very good.

^ Wilkinson.

SERPENTINE. 33

^one Slatee. — So called ''slates/' being merely thin slabs of
stone which splits into thin layers along the pltuies of beddings
are found in various parts of the country^ and used for roofing
purposes. They are tilestones rather than true slates.

Among others may be mentioned the CoUywiston and Stones-
•field ''slates/' found in several quarries of the oolitic limestone
formation, near Stamford in Northamptonshire^ and Stow-on-the-
Wold in Somersetshire.

Tliey are good non-conductors of beat, so that they keep a honse cool in
summer and warm in winter ; but they are very heavy, especially when
soaked with wet, and therefore require roofs of heavy scantlings to support
them.

SERPENTINE.

Serpentine derives its name from the mottled appearance of its
surface^ which is supposed to resemble the skin of a serpent.

Composition, — ^Pure serpentine is a hydrated silicate of mag-
nesia, but it is generally found intermixed with carbonate of lime,
with steatite or soapstone (also a silicate of magnesia), or with
diallage, a foliated green variety of hornblende and dolomite.

Colowr. — ^The prevailing colour of serpentine is generally a rich
green or red, permeated by veins of the white steatite.

Some varieties have a base of olive-green, with bands or
blotches of rich brownish-red or bright-red, mixed with lighter
tints, or olive-green, with steatite veins of greenish-blue ; some
are red, studded with crystals of green diallage ; some clouded,
and some striped.

Charaderistics. — Serpentine is massive or compact in texture,
not brittle, easily worked, and capable of receiving a fine polish.
It is so soft that it may be cut with a knife.

It is generally obtained in blocks from 2 to 3 feet long, and
it has been foimd that " the size and solidity of the blocks in-
crease with their depth from the surface."^

Use8, — This stone is greatly used in superior buildings for
decorative purposes. It is, however, adapted only for indoor
work, as it does not weather well, especially in smoky atmo-
spheres, for it is liable to attack by hydrochloric and sulphuric
acids. The red varieties are said to weather better than those of
a greenish hue, and it is stated that those varieties especially
which contain white streaks are not fit for external work.

^Hunt
B. c. — m D

34 NOTES ON BUILDING CONSTRUCTION.

It. is much used for indoor work, such as tables, shafts, pilasters,
jambs for chimney-pieces, and ornaments of different kinds.

VarietleB in Common Use. — English. — Lusard Serpentine, from the
Lizard promontoiy in OomwaU, is perhaps the best known and most exten-
siyely nsed in this country.

There are three varieties of this Serpentine to be found in the locality.

1. *^ The principal mass, like that of some other districts, is of a deep olive-
green, but this is variegated by veins or bands and blotches of rich browniab-
red or blood-red, mixed with lighter tints." ^

<< The best places for obtaining the red-striped varieties which we have
seen, occur at the Balk near Landewednack, at the Signal Staff Hill near
Cadgwith, at Kennack Cove, and on Goonhilly Downs.''

2. '' A variety, with an olive-green base, striped with greenish-blue steatite
veins, is found . . . near Trelowarren." ^

3. ^'An especially beautiful variety is found at Maen Midgee, Eeritb
Sands, in which the deep reddish-brown base is studded with crystals of
diallage, which, when cut through and polished, shine beautifully of a
metallic green tint in the reddish base.*' '

Anglesea, — Greenish and reddish serpentines are found at Llanfechell axid
Ceryg-moUion ; and a serpentinous marble at Tregola, near Llanfechell and
near Holyhead.

SooTOH. — Serpentine rocks occur in several localities in Scotland.

That of ForUoff, in Banffshire, " is very rich and varied in colour. It passes
from soft green to deep red, and is variegated with veins of white steatite."

Serpentine is also found in the Oehil Hills, Aberdeenshire, at Killin in
PertiiMre, and in the Shetland Isles, where it forms the matrix of the
chrome iron ore.

Irish. — Connemara (Go. Galway) furnishes a serpentine in large blocks
commonly known as Connemara Marble or ** Irish Green'* marble. It is of
two kinds.

The first is of a deep uniform shade of dark-green, but the other is
mottled, and made up of bands and stripes of greens of different shades, in-
terlaced with white streaks.

The principal quarries are near BaUinahinch, Letterfraek, and Clifden.

Other green serpentines are found at Grohy Head, and Aughadovey in
Donegal, and near Lough Gill in county Sligo.s

Akcient. — Vert Antique is a name applied to many varieties of green ser-
pentinous rock used by the ancient Romans. '*lliese ornamental stones,
exported from the ruins of buried cities, have been recut and polished, and
are now used in the internal decorations of modem buildings." * A detailed
description of the different varieties will be found in Professor Hull's Treatt$e
on the Building and Ornamental Stones of Oreat Britain and Foreign Countries,

SANDSTONES.
Oompoflition. — Sandstones consist generally of grains of qnarts

^ Hull's Building and Ornamental Stones.

* Beport on the Geology qf OomvxiU^ Devon, and Somerset, by Sir H. de la Becha

» Hull. < Wray.

SANDSTONES. 3S

— i.e, 8and--K^meiited together by silica, carbonate of lime, car-
bonate of magnesia, alumina, oxide of iron, or by mixtures of
these substancea.

In addition to the quartz grains there are often other sub*
stances, such as flakes of mica, fragments of limestone, argillaceous
and carbonaceous matter, interspersed throughout the mass.

As the grains of quartz are imperishable, the weathering
qualities of the stone depend upon the nature of the cementing
substance, and on its powers of resistance under the atmosphere
to which it is exposed.

Sometimes, however, the grains are of carbonate of lime, em-
bedded in a siliceous cement ; in this case the grains are the first
to give way under the influence of the weather.

Colour. — Sandstones are found in great variety of colour —
white, yellow, grey, greenish-grey, light brown, brown, red, and
blue of all shades, and even black.^

The colour is generally caused by the presence of iron.

Thus carbonate of iron ^ gives a bluish or greyish tint ; anhydrous sesqui-
oxide ^ a red colour ; hydrated sesquioxides ^ gives various tints of brown or
yeUow, sometimes blue and green. In some cases the blue colour is produced
by very finely disseminated iron pyrites, and in some by phosphate of iron.

ClasBifieation. — The sandstones used for building are gener-
ally classed as follows, either practically according to their phy-
sical characteristics, or scientifically according to their geological
position or the nature of their constituents.

Practical Classification. — Liver Rock is the term applied, perhaps more
in Scotland than in England, to the best and most homogeneous stone which
comes out in large blocks, undivided by intersecting vertical and horizontal
joints. In Yorkshire it is known as ** Nell**

Flag»tone$ are those which have a good natural cleavage,. and split there-
fore easily into the thicknesses appropriate for paving of different kinds.
The easy cleavage is generally caused by plates of mica in the beds.

Tilestones are flags from thin-bedded sandstones. They are split into
layers — sometimes by standing them on their edges during frost, — and are
much used in the North of England and in Scotland as a substitute for slates
in covering roofs.

Freestone is a term applied to any stone that will work freely or easily with
the mallet and chisel — such, for example, are the softer sandstones, and some
of the limestones, including Bath, Oaen, Portland, etc

OrtU are coarse-grained, strong, hard sandstones, deriving their name from
the millstone grit formation in which they are found. These stones are very
valuable for heavy engineering works, as they can be obtained in large blocks.

SciBNTmo Classification. — ^The geological formations from which the
different varieties of sandstone are obtained are shown in the Tables, pp. 39-48,

' ThuB Mansfield stone is pale salmon colour ; Red Corsehill, a brick red ; Robin
Hood, pale bine ; Pennant, dark bine.

* FerrouB Carbonaia, » Ferric Oxide, * Feme IfydraUs,

36 NOTES ON BUILDING CONSTRUCTION

but any fttrther notice of their cUssiflcation from a geological point of view
would be out of place in these Kotea. With regard to their constituent^
they may be divided into the following claflses : —

Micaceous Sandilones are those which contain a very large proportion of
mica, distributed oyer the planes of bedding.

QilGarcout Sanditorut contain a large proportion of carbonate of lime.
' FeUpathic SandiUmu contain a large proportion of felspar, genendly pro-
duced by the disintegration of granite or other felspathic rocks. The weather-
ing qualities of these depend upon the nature of the felspar. (See p. 13.)

Metamt>rphic Sand»Umei are those which have been subjected to heat They
are too hard to work for building purposes, but are very suitable for breaking
into road metaL

Testa. — Fracture, — The recent fracture of a good sandstone, when ex-
amined through a powerful magnifying glass, should be bright, clean, and
sharp, the grains well cemented together, and tolerably uniform in siae. A
dull and eiuthy appearance is the sign of a stone likely to decay.

Brar<r$ and Smith's Tuts, — A sandstone may be subjected to Smith's teet
or to Brard's test, described at page 1 1.

Weight and Absorption, — Recent experiments "led to the conclusion that
any sandstone weighing less than 130 lbs. per cubic foot, absorbing more than
6 per cent of its weight of water in 24 hours, and effervescing anything but
feebly with add, is likely to be a second-class stone, as regards durability,
where there is frost or much acid in the air ; and it may be also said that a
first-class sandstone should hardly do more than cloud the water with Mr.
Smith's tesf'i

Qrain. — ^It is generally considered that the coarse-grained
sandstones, such as the millstone grits, are the strongest and most
durable. This, however, seems doubtful ; at any rate, some of the
finer-grained varieties are quite strong enough for any purpose,
and seem to weather better than the others.

'' It appears probable that for external purposes the finer-grained
sandstones, laid on their natural bed, are better than those of
coarser grain." *

Thiokness of Layers. — ^In selecting sandstone for undercut
work or for carving, care must be taken that the layers are thick ;
and it is of course important that stones should rest in most
cases (see p. 37, Part I.) on their natural beds.

XJses. — ^The hardest and best sandstones are used for import-
ant ashlar work ; those of the finest and closest grain for carving ;
rougher qualities for rubble ; the well-bedded varieties for flags.

^Some of the harder sandstones are used for sets, and also
for road metal, but they are inferior to the tougher materials, and
roads metalled with them are muddy in wet, and very dusty in
dry weather." ^

»Wray.

SANDSTONES. 37

Prinoipal Varieties in oommon use. — A. few of the best
known sandstones will now be described, after which a list will
be given of some of the principal quarries in Great Britain and
Ireland.

BramloT FaU. — ^The original stone known under this name was a moderately
coarse-grained sandstone of the millstone grit formation, from Bramley, near Leeds.
It held a very hieh character for darabilily and strength.

It was found in large blocks, and was specially suited and used for heavy engineering
works.

Thin stones of good quality cannot be produced from the best beds of the quarries
without great waste. When therefore such stones are specified, they are sometimes
supplied from the upper beds, which are of inferior quality.^

Since the introduction of railways the ori/y^al Bramlev Fall quarries have almost
ceased to be worked, but a great deal of similar stone is found to the north of Leeds,
and is sold under the same name, which has become a generic name for the class oif
stone wherever it may be quarried.

As a rule the stone sold under this name has considerable strength and durability,
but in some cases an excess of grains of potash-felspar makes it weather badly.

" Owin£ to its cheapness — and also to a want of knowledge that the best stone
rises in krge masses—many gentlemen specify their stones for templates, pad
stones, bases, steps, and landings and copmgs to be worked out (^ Bramlev fall
only 7 or 8 inches thick. This mistake has caused some quany men and producers
to substitute inferior top rock for good stone, because the inferior top stone frequently
rises in thinner lifts."'

Bramley Fall stone has been used for the most massive engineerinff structures in
the country. Its weathering qualities may be observed in Kirkstul Abbey, near
Leeds, which was built with this stone in the twelfth century.

Torkshlre Sandstones. — ^There are so many quarries producing stone of very
similar quality and characteristics, classed under this head, that it would be useless
to descrioe them in detail.

These stones come chiefly from the coal measures and millstone grit series ; a few
come from the new red sandstone formation.

In consequence of the large number of quarries in Yorkshire, the stone is commonly
known as larkMre stone^ But a great deal of similar stone is found in the adjacent
counties.

Of these stones the finer grained are suitable for building purposes, while the
grits are more adapted for heavv engineering works.

The sandstones from the millstone srit or coal measures are considered to o£fer the
greatest resistance to iiguiy by fire, for which reason Minera stone was selected for
the National Safe Depont Co. 'a buildings.'

A few of the quarries are mentioned in the Table at pp. 89 to 48. There are several
round about the principal towns.

The best flags and landings come fit>m near Bradford and Halifax.

Scotgate Ash. — ^This stone is produced frt>m quarries somewhat recently opened
near Harrogate. Several specimens of it were shown at the International Exhibi-
tion of 1872.

The (quarries produce landings of anjr size up to 150 feet superficial, steps up to
20 iiset in length, sets, paving and buildmg stones.

Some of the stone is white, some of a light creen tint, and a bed called the ragstone
is specially recommended by the proprietors for heavy engine bases, foundations, etc

Forest of Dean Stone.— -This very useful stone is found in the coal measures
near Lydney and Goleford in Gloucestershire.

There are three distinct series or beds of considerable thickness. Of these the
upper series consists of a soft, easilv worked stone of various degrees of hardness,
llie second series in harder than the first, and the third harder than the second, and of
a finer grit Both the second and third series can be quarried in blocks of any size.

> Mr. Trickett in Building Nem, 25ih June 1871.

3 Mr. Trickett in BuUden' Wukly B^mUr, 2dd June 1875.

» Wray.

fi NOTES ON BUILDING CONSTRUCTION.

The first and second. series are of a grey colour, the third is bluci. Some
of the stone has a brownish tint

The stone weathers well if placed npon its natural bed. Some used in the
churches of Newland, Staunton, and Mitcheldean, that has been exposed 400
years, still retains the tool-marks as sharp as erer, but this of course was from
the best quarries, carefully selected.

There are a great many quarries in the hands of different proprietors. It
is unnecessary to give their names.

The stone is admirably adapted for building, or for heavy engineering
work such as bridges and docks.

Whtre uted. — It has been used in the construction of Cardiff, Newport,
Qloucester, and Swansea docks ; Folly Bridge, Oxford ; Cardiff Castle and
National Provincial Bank, Marlborough ; Cardiff new Barracks ; port of Uan-
daff ; interior of St John's and Exeter Colleges ; Taylor and Bandolph's
buildings, Oxford ; Easton Castle and Witley Court, Doncaster, etc etc

Mansfield Stone is one of the best known and most important building
stones in the country.

It is a sUiceous dolomite (see p. 59), and is found near Mansfield, Notting-
hamshire, in the Permian system, between the new red sandstone and the
carboniferous series.

There are several beds found in the quarries, which differ consideFably
from one another both in composition and texture.

There are, however, two principal varieties of the stone sent into the
market, the white and the red, both of them good for building purposes.

Of these varieties the red is considered more durable than ^e white. Both
kinds last well in a clear atmosphere. They are all admirably adapted foi
the finest ashhur work, turned columns, mouldings, carvings, etc

Whttb Mansfield. — ^There are several beds of this stone. The top bed of
all has a coarser grain than the others. The second and third beds supply a
very good fine-grained stone, fit for the finest ashlar work ; while the lowest
bed is much harder than the others, and is well adapted for stairs, paving,
landings, etc

Red Mansfield is more generally of uniform quality and appearance The
stones of the darkest colour are considered the best

This stone is qnarried by wedges, without blasting. It is procurable in
blocks weighing as much as 10 tons, and from 4 to 5 feet thick.

It can be sawn at the quarries into blocks and slabs, or turned on a lathe
into columns of any moderate diameter.

Where used. — Red, — Bilton House, Trafalgar Square, flagging of terrace ;
Hyde Pkrk, Albert Memorial, squares of flagging of terrace ; Burlington
House, ashlars, columns, and niches ; St Pancras Hotel and Station ; voussoiis
of arch in main entrance, plinth of hotel, corbels, etc

WhtU. — ^Town-hall, Mansfield, Clumber Lodge, etc

Craigleith Stone is perhaps the most durable sandstone in the United
Kingdom. It consists of quartz grains united by a sUiceous cement, with
small plates of mica. It contains 98 per cent of silica and only 1 per
cent carbonate of lime. It is found near Edinbuigh, and is used extensively
in that city, and also exported.

Many other sandstones of nearly equal importance to the abox-e
are mentioned in the following Tables : —

SANDSTONES.

It
11
if

i-5 E

5 ^tL-

•al

S g

Joi^

•I
•a

•s

«0 ^

% i

I?? c«

NOTES ON BUILDING CONSTRUCTION.

I«tii

tllil

ill

s s

(/J

■it

ti'i

III

S s

1 .2 . g
III S 11 II I §|i|

5
X

S i

< M

SANDSTONES.

«■?•

1-1

<?«

<?*

? 5 i

g :

l-l 1-1

1-1

l-H

r-l

1-1

I-H

r-l

I3o

1
5

^ ^1 ^iS

I iiH

oiz;

1 -

? &%f

s*^

(2cQPQc-

npspa

' P4

£8

B H ;j » »

OOQQQ

NOTES ON BUILDING CONSTRUCTION

jgS S| ft
o

|l |1 II

.6*

r" r"

•^ CO

<0 lA

^ s

■11 ■

111 J

•I

2 J
J 3

•s

•I-

^ ^

ooo

SANDSTONES.

1ill5

1-^ iH lO

qo 9^ 9 ^

lb o « 00

00 "« 00 -^

•J

t S^ II

1 1

IS I

^ a So

• 1 • • I
111 1 J I

>^»3>^j5

S CO

S. BO fid

S ? " P

o o >« 0*

0! OS & -<

COOK

3 g •

; I

r ^ o %

I 5^ a

B » »

o o

CCS

M >• b«

o o o

egg

en 53

NOTES ON BUILDING CONSTRUCTION.

9 e^ ^3 o^

£
I

l^i

fill

0!2

s|3

: 1^ ©d

00 !"« Ok Ok
»0 00 OO 00

O t»

00 "^

o
,3

Jig ?..

a'-^ •r;fl if I Igl",

Ills
iiil

_^ II 145.

^s^

^><

1 1^

•§J

I II

•a 1 •st-a.a'

I I

^•3^

(^ I llll J

o S S
PH Q >*

1 Fl

21 i §*,g|Jl

p
or

^ 9 t, (4
O -< M -

pi -I

0>3 »; ►• X

^S h K M

^ ^ S ^ d

8 2 tf fid 04
Shoo

u o

SANDSTONES.

i >^

I ll
B Is

3 £-3

i I-"
i|»a

I? 16^ I

^ f

I id

I 1

' 1

ill i .

I il 81
11

l!ll It

iii^«j

« !>•

o C

- o»

III
i ill S

■Mil I •5'-^-'

o o o

'5 o o

-goo

.§

a I ^1 %&

1«1

P3Kn

ta o

H Q

. 09 W

^ ^ O

o o o

P^QQGQ

.3 h <=) >«

^ S^ C3 fe O

! bd W -

A4 H ^ i< h9 -.

n o Oi H

CQCQQQ OQ

S< 5 M «

PA .

PJ §
fct>

*« o

P > H

sin

JVOTES ON BUILDING CONSTRUCTION.

Xfl

ii? ^3 p Pm g

ft" D

00 <?»

S »0» 00f-<

O
D

p
o

s 3

0SH

OJ3

till-

1$ 1

£ !:a »

5«

SANDSTONES.

iliii

ii«Fiiiijp

S..

1 I
I

III!

I-

1 •! 11,1 |i&i
I *l nil IP^

..%

lUI

I a ' "111

!5a

J..

p3 ^ c ^ S S S

NOTES ON BUILDING CONSTRUCTION.

I H

1 sr

'9 1 III
I III ^1 ^

\lllPV

(/2

s|3

f£

S
8

•3

^ • • •

J.. .

0 o

I
I

o
»

LIMESTONES. 49

LIMESTONES.

The term liqaestone is applied to any stone the greater propor-
tion of which consists of carbonate of lime ; but the members of
the class differ greatly in chemical composition^ texture, hardness,
and other physical characteristics.

Composition. — Chalk, Portland stone, marble, and several other
varieties of limestone, consist of nearly pure carbonate of lime,
though they are very disHimilar in texture, hardness, and wear
thering qualities.

Other limestones, such as the dolomites, contain a very large
proportion of carbonate of magnesia. Some contain day, a large
proportion of which converts them into marls, and makes them
useless for building purposes. Many limestones contain a con-
siderable proportion of silica^ some contain iron, others bitumen.

The carbonate of lime in stones of this class is, of course,
liable to attack from the carbonic acid dissolved in the moisture
of ordinary air, and is in time destroyed by the more violent acids
and vapours generally found in the atmosphere of laige towns.

Texture. — A great deal depends therefore upon the texture of
the stone.

The best weathering limestones are dense, uniform, and homo-
geneous in structure and composition, with fine even small
grains, and of a ciystalline texture.

Some limestones consist of a mass of fossils, either entire, or
broken up and united by cementing matter. Others are entirely
made up of round grains of carbonate of lime, generally held
together by cement of the same material (See p. 56.)

The Soyal Commissioners gave a preference to limestones as a
class, '' on account of their more general uniformity of tint, their
comparatively homogeneous structure, and the facility and economy
of their conversion to building purposes ;'' and of this class they
preferred " those which are most crystalline."

Many of the most easily worked limestones are very soft when
first quarried, but harden upon exposure to the atmosphera

" This is said to arise from a slight decomposition taking place,
which will remove most of the softer particles and leave the
hardest and most durable to act as a protection to the remainder."^
By others it is attributed to the escape of the " quarry damp."

> Qy/fde to Mumm o/PraeUcal Otology, hj R. Hiint» F.R.S.
B. C. — m B

50 NOTES ON BUILDING CONSTRUCTION.

ClaasifLoation. — Limestones are classed: — 1st, Scientifically
from a geological point of view ; or, 2A^ Practicallj, according to
their physical characteristics.

SciKNTiFio Clabsitioation. — Lime«tone8 are known as GarbonifexouB, lias,
etc., according to the formation from which they are obtained. These fonna-
tions aie shown in the Tables, pp. 67 to 73, but thej need not be fnrthez
referred to.

Pbactioal Classifigation. — The terms Lwer roek, FrmUme^ FlagsUme, are
applied to limestones in the same way as to sandstones (see p. 35).

The difference in the physical characteristies of limestones leads to their
classification by the engineer as follows : —

Marbles.

Compact limestones.
Qranular „
Shelly „

Magnesian „

These will now be described in turn.

MARBLES.

Marble is the name practically given to any limestone which
is hard and compact enough to take a fine polish.

The name is frequently, however, erroneously applied to other
stones, such as serpentine, merely because they are capable of
being polished.

Some marbles — such, for example, as those from Devonshire —
will retain their polish indoors, but lose it when exposed to the
weather.

Marble is found in all great limestone formations. It con-
sists generally of pure carbonate of lime. The texture, degree of
crystallisation, hardness, and durability, of different varieties vary
considerably.

Marble can generally be raised in large blocks. The hand-
somer kinds are too expensive for use, except for chimney-pieces,
table slabs, inlaid work, etc

The less handsome varieties are used for building in the neigh-
bourhood of the quarries.

The appearance of the ornamental marbles differs greatly.
Some are wholly of one colour, others derive their beauty from a
mixture of accidental substances — ^metallic oxides, etc., which
give them a veined or clouded appearance. Others receive a

MARBLES. 51

Taxied and beautiful '' figure " from shells, corals, stems of en-
crinites, eta, embedded in them.

Uses. — ^Marble is used in connection -with building chiefly for
columns, pilasters, mantelpieces, and for decoration.

The weight of marble makes it suitable for sea-waUs, break-
waters, etc., when it is cheaply obtainable, but some varieties are
liable to the attacks of boring molluscs. (See p. 10.)

In the absence of better material marble may be used for road
metal and paving setts, but it is brittle and not adapted to with-
stand a heavy traffic. Boads made with it are greasy in wet
weather and dusty when dry.

Bifteent forms of Marble. — Enanmol and Shell Marbles are those
which derive their figure from emhedded fossils, encrinites (lilj-^haped pknts
with jointed stems), or fossils of ordinary shells.

Madrepore Marbles are made up entirely of fossil corals.

Ancient Marbles. — ^Many of the marbles used by the ancients, and handed
down to ns in the shape of works of art, are not now known m their natural
state.

Their markings and tints are frequently imitated in artificial marbles, and
the ancient names are applied to the imitationa

Varieties. — ^A good deal of the marble used in this country
comes from the Continent

Of the varieties found in England, the best known are those of various
colours from Devonshire ; black and grey marbles from Derbyshire ; the
Parbeck marble from Dorsetshire ; Mona marble from Anglesea.

There are many varieties in Scotland^ but they are chiefly used locally,
and burnt for lime.

Ireland supplies marbles of all colours. Black from Qalway, Kilkenny,
and other counties ; dark grey and sienna from King's County ; white from
Don^^ ; red from County Cork. ' The so-called Connemaia marble is a
serpentine (see p. .')4)l

[Tabus.

NOTES ON BUILDING CONSTRUCTION.

i ^^•

III
III

ill
'^1

1
I

11^

"11

■1

s
? .

'■3

5
§

MARBLES.

I ^

?a II
IJ Si

III *
III I
Hi %

<s'<^

11"

1 l^^^l ll

'3 ^

S3 ^^^«S 6?

I I ^11 ll

I . I

•« -SrS

I I

III

.g!

§ Si

P4 P4

II-

I III

OPQPQO

#^ ^ JS O « ,!^

NOTES ON BUILDING CONSTRUCTION

MARBLES.

|l||lill^

^la

H i

'V3

I 5

-t^i

111 -IS

6 6

: o

It
1=

•a .

II i

I
I

>6 NOTES ON BUILDING CONSTRUCTION.

Ck>mpaot Limestone. — Composition and Structure. — Compact
limestone consists of carbonate of lime either pure or in combinar
tion with sand or clay.

It is generally devoid of crystalline structure, of a dull earthy
appearance, and of a dark blue, grey, black, or mottled colour.

In some cases, however, it is crystalline and full of organic
remains. It is then properly known as a crystalline limestone.

Some of the Carboniferous limestones are of the compact dass^
also the Lias limestone, which contains a considerable amount of
day, and is used for making hydraulic lime ; also Kentish Bag from
the Cretaceous system, which is more fully described at page 64.

Uses, — The compact limestones are good for building purposes*
where their dull colour and the difficulty of working them are not
objections.

They are useful for paving sets and road metal under a light
traffic

They are chiefly ujsed however as flux in blast furnaces ; for
agriculture, bleaching, tanning, and other industrial purposes.

JFeighi. — They weigh from 153 to 172 lbs. per cubic foot^and
absorb very little water, taking up generally less than 1 per cent
of its weight in twenty-four hours.

Granular Limestones. — Composition and Structure. — These
limestones consist of grains of carbonate of lime cemented together
by the same substance, or by some mixture of carbonate of lime
with silica or alumina.

Size of drains, — They are generally found in the Oolitic (or
eggstone) formation. The grains vary greatly in size. In some
cases they are very small and imiform, very few being of a larger
size, as in Caen stone. When the whole of the grains are somewhat
larger,as in Eetton stone, they constitute what are called "Boestones,'*
the structure resembling that of the roe of a fish. When the grains
are still larger, as big as peas, the stones are known as Pisolites, or
pea stones.

These stones nearly all contain fossil shells. In some cases
the shelly matter occurs in larger quantity than the grains. They
are then called shelly gramUar limestones.

Colour. — The colour of these stones is very variable, being
sometimes white, light yeUow, light brown, or cream-coloured.

Weathering Qualities. — ^The granular limestones are generally
soft and somewhat absorbent They are therefore liable to the
attacks of acid atmospheres, and of frost, but otherwise are fairly
durable.

LIMESTONES. 57

Ifia^wral Bed, — ^This stone ''is generally obtainable in kige
blocks, and it is often difficult when the stone has been sawn to
detect its natural bed. This may be sometimes done by directing
a jet of water on the side of the block, and it is well to do this
as it is of great importance with some of the leas durable sorts
that they should be set upon their natural bed." ^

Weight cmd Abaorption. — The weight of this dass of stone varies
from 1 1 6 to 1 5 1 lbs., the lighter and more absorbent stones being, as
might be expected, less durable than those of a more compact order.

Their absorption of water in twenty-four hours is hardly ever
less than 4 per cent of their weighty while it is sometimes as much
as 12 per cent.^

Varieiies. — This dass affords some of the prindpal building
stones of this country, many of which will hereafter be described
more in detail

The very fine grained stones may be represented by Chilmark
(see page 63); those with larger grains by Portland, Ancaster,
and Painswick; and those with large spherical grains by Eetton
and Casterton ; while Bath stone has large egg-shaped grains.

Uses. — Some of these stones — such, for example, as certain
varieties of Portland — are well adapted for outdoor work ; others
— such as Bath, Caen, Painswick — ^for internal work, carving, etc.;
while some of the harder kinds — such as Seacombe, Painswick, and
some of the beds of Chilmark and Portland — ^are adapted for in-
ternal staircases where there is not likdy to be much wear.

Shelly Limestone. — ^There may be said to be two classes of
this stone.

Strudure, — ^The first consists almost entirely of small shells
cemented together, but shows no crystals on fracture.

Purbeck is an example of this dass.

Stones of the second dass consist chiefly of shdis, but break
with a highly cryBtaDine fracture.

Of this dass Hopton Wood stone is an example.

CoUmr. — This is given in the Table, pp. 67-73.

Uses, — Stone of this class is chiefly used for paving.

Weight and Absorption, — ^The weight of this class of stone
is from about 157 to 169 lbs. per cubic foot, and its absorp-
tion is very small, generally much less than 2 per cent of its
weight

Hagneeian Limestones. — Composition, — Magnesian limestones

» Wray.

58 NOTES ON BUILDING CONSTRUCTION.

are composed of carbonate of lime and carbonate of magnesia in
variable proportions, together with a small quantity of silica, iron,
and alumina.

Many limestones contain carbonate of magnesia, but those with
less than 15 per cent do not come into the class now under
consideration.

The better varieties of magnesian limestone are those in which
there is at least 40 per cent of carbonate of magnesia^ with 4 or
6 per cent of silica.

When the magnesia is present in the proportion of one mole-
cule of carbonate of magnesia to one molecule of carbonate of lime
(i.e. 54*18 carb. magnesia and 45*82 carb. lime), the stone is
called a Dolomiie}

Professor Daniel states that the nearer a magnesian limestone
approaches dolomite in composition, the more durable it is likely
to be.

Structure. — ^It is not merely the nature of the constituents or
their mechanical mixture that gives dolomite its good qualities ;
there is some peculiarity in the crjrstallisation which is all
important

Mr. C. Smith says, '' In the formation of dolomite, some peculiar
combination takes place between the molecules of each substance;
they possess some inherent power, by which the invisible or
minutest particles intermix and unite with each other so inti-
mately as to be inseparable by mechanical means. On ATftmining
with a highly magnifying power a specimen of genuine magnesian
limestone, such as that of Bolsover Moor, it will be found not
composed of two sorts of crystals, some formed of carbonate of
lime others of carbonate of magnesia, but the entire mass of stone
is made up of rhomboids each of which contains both the earths
homogeneously oystalUsed together. When this is the case, we
know by practical observation that the stone is extremely durable."'

Some magnesian limestones contain sand, in which case their
weathering qualities are greatly injured.

Some are peculiarly subject to the attacks of sulphuric acid,
which forms a soluble sulphate of magnesia easily washed away.

Awdyia. — ^The following Table gives analyses of some of the principal
magnesian limestones. The red and white Mansfield contain a laige propor*
tion of silica and are generally classed among the sandstones (see p. 38).

^ After a French geologist Dolomien, who was the first discorerer of this mineral
in the Alps. ' Smith's LUholoyy.

LIMESTONES.

1
Dolo-
mites.

2
Bols-
over
Moor.

Hud-
dleston.

*ftoach
Abbey.

FliTk

Nook.

0
Hans-
field.
Bed.

7
Mana.
field.
White.

Mansfield

Wood-

house.

0
Fulwell

North
Anston.

11
Steetley

Carbonate of
Magnesia

Carbonate of
Lime

SUica

Iron and

Water and
Loss

45-82
5418

40-2

61-1

8-6

1-8

8-8

41-87

54-19

2-58

0-80

1-61

89-4

57-5

0-8

0-7

1-6

41-6

55-7

0-0

0-4

2-8

16-10

26-50

49-40

8-20

4-80

7-80
41-80

-60-00

1-40

42-60
51-65

8-7o|

2-06

82-75

62-80

Trace.

2-80

2-15

48-07

54-89

0-66

0-78

076

48-78

63-96

0-44

0-64

1-19

100-0

100-00

100-00 100-00

10000

1000

100-0

Cols. 2 8 4 6 from the Bepori of the Boyal Commission,
16 7 8 Smith's Lithology,

9 Page's Ectmomic Geology,
10 11 BwOdw, 20th November 1886.

Prinoipal Varieties in common use. — ^A few of the most noted
varieties of limestone used in this country will now be described,
after which, at p. 67, will be given a list of some of the principal
quarries in Great Britain and Ireland.

Bath Stone is one of the best known and most eztenBlvely used building
stones in this country.

Qeological Position, — ^This stone is obtained from that division of the
Oolitic formation which is known as the Great or Bath Oolitic group.
Geologically speaking it lies below the Portland stone, being separated from it
by the Eimmeridge day, coral rag, and Oxford clay.

The building stone lies between beds of lagstone : dark veins run at right
angles to the beds.

Most of it is of a fine even grain, composed chiefly of carbonate of lime-
sometimes interspersed with shelly fragments.

Some of the varieties of this stone contain sand-cracks, vents, day-balls, etc ;
these should of course be avoided.

Cokur, — ^The colour varies from white to light cream colour and yellow.

Quarrying, — ^The quarries are worked by tunnelling, and the stone is pro-
duced in blocks up to 5 or 6 feet deep, and weighing as much as 10 or 12 tons.

It is important that Bath stone should be quarried in summer when it is
freed from the ground moisture or quarry sap. If quarried in winter it is
very likely to fall to pieces with the first frost.

Seasoning and Weathering, — The stone is very soft when first quarried, but
hardens upon exposure to the air (see p. 49). It is important that it should
be placed on, or paralld to its natural bed (see p. 9).

The stone varies greatly in quality : some varieties weather badly, while
others are fit for external work in ordinary atmospheres.

Size and, Uses, — As it is obtainable in large blocks, and is easily worked, it
is particularly valuable for mouldings and carved work.

Quarries. — There are several quarries in the neighbourhood of Bath,
among which may be mentioned the following : —

6o NOTES ON BUILDING CONSTRUCTION.

Box Gr<ntnd, — ^Found in beds from 10 inches to 4^ feet thick. A coaiae
but sound stone, which weathers well except in a smoky atmosphere and by
the sea. It is harder than Combe Down, but freer from vents. The stone ia
not now so easily worked as it used to be.

Oombe Down stone differs in quality according to locality. The old quarries
of this name are worked out. A new quarry, called Lodg$ SHU GomJbe, has
been opened, which is said to produce a stone particularly suitable for expo-
sure to smoky atmospheres or sea air, of a light colour, and in beds fiom 1
to 5 feet thick.

FarUigh Down stone is soft and yety fine grained. It occurs in different
beds, from 10 inches to 3^ feet thick, some of a yellow, and others of a red
colour. The former does not weather well, and is used for tracery and
internal work.

Wedwood Down is produced from a quarry somewhat recently opened, and
is stated to be a very superior stone, free from vents and defects, and pro-
curable in large and sound blocks.

Corsham Down, — ^This quarry consists of three principal varieties in several
beds. The ** soft scallet," in beds about 3 feet thick, is found about 90 feet
below the surface. The stone from these beds is of fine grain, and suitable
for sculpture and mouldings. Next below is the '^ comgrit," about 4 feet
thick, a harder stone, full of little pieces of flint ; of a good colour, sound,
and durable, but unable to resist frost It is difficult to work, but good for
caziying weight, and used chiefly for engine beds, columns, landings, steps,
etc. Below this again is the " bottom bed,** an excellent soft stone, about 4}
feet thick, but occasionally stained with blue patches.

Conham Ridge is also a recent quarry, and supplies good hard stone. It
was used for the face work and carved pediments of the Koyal Aquarium at
Westminster.

St6k» Qrownd is an old quany which has recently been worked with vigocor.
It consists of one bed about 6^ feet thick, yielding blocks up to 6 tons
weight The stone is of a light brown colour, soft, easy to work, fit for carv-
ing, and when seasoned for external work.

Portland Stone is obtained from the upper parts of the Oolitic seriesL

It has already been mentioned that there are four distinct varieties of
Portland stone used for building, of which, however, three only are generally
sent into the market

The section of a quarry given at page 7 is here reproduced for oonveni>
ence, but it will not be necessary again to describe the order in which the
different varieties occur.

Beginning at the top of the quarry and working downwards, we find (inter-
spersed with cap, fiinty tiers, and other beds useless for building purposes
four varieties of stone all more or less useful to the engineer or builder
These are Trw Roach, Whiibed, Battard Boaeh or Curf, and Batebed.

As these four varieties of stone differ greatly in their characteristics and in
the uses to which they may be applied, it will be well to describe them
separately.

Chemical Compotition, — ^The chemical composition of the different varieties
is almost the same, and it may therefore be given at once £ar the whoLs.

The following is the analyslB made by Professors Daniel and Wheatstone for the oam-
miisioDers who selected the stone for the Houses of Parliament : —

Silica 1-20

Carbonate of lime 95 '16

Carbonate of magnesia . • . 1*20

LIMESTONES.

Iron And alnmixui
Water and loss .
Bitumen

0-60
1-94
A trace.

It will be seen that the fitone consistB almost entirely of carbonate of lime.
^ The most durable stone has its cementing matter in a solid and half crystal-
line state ; in the least durable stone it is in an earthy and powdery state." ^

Mould.

Clay and shingly matter ; debris of Purbeck
stone.

Slaty beds of stone.

Bacon tier, with layers of sand.

Aish stone.

Soft Burr.

Dirt bed, containing fossil trees (Cycades).

Cap rising.

Top cap, 8 or 10 feet thick.

Scull cap.

Roach (true), 2 or 8 feet thick.

Whitbed, 8 to 10 feet thick.

Curf ; flinty.

Curf and Basebed roadL
Basebed stone, 5 or 6 feet thick.

rr Flat beds or flinfy tiers.

Fig. 2.

' Report of Commissioners respecting stone to be used in building the new Houses
of Parliament.

62 NOTES ON BUILDING CONSTRUCTION.

Roachy or True Roach as it is sometimes called, is a mass of fossils united
by a cement composed of carbonate of lime.

The stone also contains a great number of cavities, large and small, being
the moulds left by fossils that have dropped out.

Most of the fossils are merely casts, but in some cases portions of the shell
are left

The true roach may be distinguished from the other as it contailis the
peculiar fossil shown in Fig. 3, and known as the ^ Portland
screw," which is never found in the bastard roach. This is an
important distinction, as the true roach weathers for better
than the bastard roach.

True roach is one of the best stones that can be used for
heavy engineering works.

It is remarkably tough and strong, weathers admirably, and
resists the action of water particularly well

It has been much used for fortifications, breakwaters,
dock and sea waUs, and is suitable for massive plinths or
other ashlar work where a rough face is appropriate ; but
the numerous cavities it contains render it unsuitable for
fine work, and for positions where smooth faces or sharp
clear arrises are required.
Fig. 8.^ The colour of true roach is a very light brown.

IVhitbed, — ^This is the most valuable bed of the Portland
series. It immediately underlies the true roach stone, which is firmly
attached to its upper surface.

The stone consists of fine oolitic grains, well cemented together, and inter-
spersed occasionally with a small amount of shelly matter. The cementing
material is hard and crystalline.

Qood whitbed stone resists the weather admirably. It is easily dressed to
a smooth surface, and will take a very fine arris. It is suitable for the finest
class of ashlar work. Some of it is too hard and not sufficiently uniform in
texture for carving ; other blocks are quite fit for the most intricate work.
When examined through a microscope the grains of whitbed will be found to
have a more oolitic or roe-like appearance than those of basebed (see p. 63).
The grain is also more open, and the cementing material is stronger.

The colour is generally white, or nearly so, but some of the best stone
has a decidedly brown tint.

It is unfortunate that there is no more marked distinction between whitbed
and basebed, as the weathering qualities of the latter are greatly inferior. Base-
bed is fit only for internal work, and great disappointment is caused when it is
used, mistaking it for whitbed, in external work exposed to trying atmospheres.
The carver, however, prefers basebed, though it is not so durable, because it
looks better and is more easily worked.

Bastard Roach, Basebed Roach, or Cnrf,^ — This stone resembles true roach
in appearance, being a mass of fossils and cavities. The cementing material
is, however, inferior, the stone does not weather well, and it is not used for
building or enj;ineering works, except in the immediate locality.

The thickness of basebed roach varies considerably in different quarries. In

From Lyell's Oeology, * Sometimes written "Kerf."

LIMESTONES. 63

some there is scarcely any, in others the bed has a thiclcness of from 12 to 24
inches, or eren more.

These beds are sometimes interspersed with thin layers of flint

The basebed roach is suitable for foundations, for backing walk, and foi
internal work where it will not be subjected to blows or traffic

BasAed is not easily distinguished from whitbed. The extemsl appear-
ance of the stone from both beds is almost exactly the same.

The basebed is, however, more uniform in structure, and freer from shelly
matter. Its weaUieiing qualities are not so good as those of whitbed, but
as it is softer to work, it Ib often preferred by masons, and is known in the
market as hetlML

If basebed be required for external work, it should be seasoned for a year
before use, in order that it may have every chance of weathering well

The stone from this bed is well adapted for internal work and carving of
the highest class.

Quarries. — ^The Portland stone quarries are worked from open fSaceflL
Blocks of great size, such as 10 or 12 tons (140 or 170 cubic feet), can easily
be procured.

After experimenting upon stone from the different beds, Professor Abel
reported that ''on the whole the evidence may be considered a little in
favour of the opinion that an improvement in the strength of the stone is
effected, to some extent, by seasoning." ^

The whole island of Portland is full of quarries, each of which produces
the different beds of stone above described.

The conmiiasioners reported that ^ the best stone is in the N JS. part of the
island, the worst in the S.W. x^art"

Several of the quames belong to the Government, but some of the best
are in private hands, and the stone is worked in great quantities for the
market

The names of the principal quarries are Waycroft, Wide Street, Maggot,
Weston Independent, Inmosthay, Tout, Weetcliff, etc.

The Westcliff whitbed is considered the most durable, but it is hard to
work ; the whitbed quarried at the Bill is harder stilL

Buildings in which ti^d —Portland stone, chiefly whitbed, was used for
all buildings of importance erected in London from about 1600 to 1800.
It was also used for the west front of St. Paul's, for the Horseguards, Somerset
House, the General Post Office St Martins-le-Grand, the India House and
Foreign Offices in Downing Street, the Reform Club, and many other im-
portant buildings.

Chilmark Stone. — This stone is procured from the Portland and Pnrbeck
series of the oolitic formation as developed near Tisbury, Wardour Castle,
in Wiltshire.

It is known also as Wardour stone, and in London as Tisbury stone.

The siliciferous nature of the cement which binds the particles (carbonate
of lime) of the stone gives it excellent weathering qualities, while the softness
and even grain of some of the beds renders them capable of being elaborately
worked.

There are four distinct varieties of the stone.

* Prqfeiiional Papers, Royai Engineers, voL xii

64 NOTES ON BUILDING CONSTRUCTION

Th4 Trcugh or Hard Bed is of a doie even teztnie, of yeUowiBh-brown
colour.

It has an average thickness of 2 feet 6 inches, bnt stones may be obtained
3 feet 6 inches thick and of any leasonable length and breadth — ^the zandom
blocks averaging 16 cubic feet

It is osed principally for steps, also for coinioes, copings, sills, plinths,
chimney-pieces, paving, road metal, heavy engineering works, and in any posi-
tion exposed to wet and hard wear.

The Scott or Brovm Bed is of wanner edonr than the hard bed. Avenge
thickness of bed 3 feet, maTJmnm 4 feet, random blocks average 16 cubic feet

Principally used for ashlar mouldings, carvings, random rabble, and for
building purposes generally.

Ths General Bed^ from ike Garden quarry, is of a rich yellow tint and fine
texture. It is capable of being elaborately carved, and is chiefly used for that
purpose, also for ashlar, mouldings, etc

The average thickness of bed is 4 feet, maiimnm 5 feet

Strength,

Tenilla

to enubing Btrength per
per foot lup. aqoare Inoh.
Haidbed . 196 tons. 500 lbs.

Soott bed . 104 „ 206 „

General bed .. 100 ,, 855 ,,

Chemieal AnalyHi.

SiUea
Carbonftte of lime

„ magnesia
Iron alumina
Water and losi

10-4

79-0

8-7

2-0

4-2

Working. — ^The stone has to be cut with a wet saw, and the relative cost of
working llie beds compared with Portland is stated by the proprietors to be —

Portland and Hard bed . . . . I'O

Soott and Garden bed .... 0*6

BvxtdingB in vikich wed, — Salisbury Cathedral, Tisbuiy Church, Waidour
Castle, Fonthill Abbey, Priory Church, Christ Church ; Post Oflice, West-
minster Road, London ; Post Office, Exeter ; Sorting Post Office, Hampstead ;
London and County Banks, Hastings and Banbury ; restoration of Chichester
and Rochester Cathedrals, and of Chapter House, Westminster Abbey ; Long-
ford Castle, Wilts ; Crewe Hall, near Chester, etc etc.

Kentlflh Rag^ is found in the Greensand formation, in a district running
through the central part of Kent, about thirty miles long and from four to
ten miles broad, including the towns of Sevenoaks, Maidstone, Lenham, etc

Beds. — The RageUme is found in beds varying from 6 inches to 3 feet in
thickness, alternating with fine sand known as Hassock, which is frequentlj
so consolidated as to form a stone that can be used for building.

^ Taken chiefly from Olservathna en Kentish Bagstone^ by J. Whichoord.

LIMESTONES. 65

The haflsock is generally found adhering to the ragstone, and at the bed of
junction organic remainB often occur.

The ragstone itself is a very compact, heavy stone, which absorbs very
little water, and resists the weather welL

The hassock, attached to it, is a calcareous sandstone, soft, porous, and very
perishable under atmospheric influences.

There are several beds in a Kentish ragstone quarry ; many of them are
worthless. It may be interesting to mention a few of the most usefoL

After a top layer of mould and loam there are two or three beds of hassock
and ferruginous sand, after which come the more useful beds, the best of
which are mentioned below in succession.

Ldnd Rag. — About 8 or 10 inches deep ; dark grey ; free working. Below
this is a bed of fine hassock.

Header laying, — Thin dark stone used for headers.

Qreen Rag. — 10 inches thick; greenish colour; free working; not very
sound. Fossils generally found on top bed. Below this is a layer of work-
able hassock.

Yellow Rag, — Broken up into headers for pitching.

PeUea yields large hard blocks 12 inches thick ; difficult to quarry.

Next come two inferior and flinty beds interspersed with hassock.

Great Rag is a layer sometimes 3 feet deep, but split into two thicknesses
full of cross fissures ; no large stones from it. Broken up for headers, or
makes the best description of lime. A very superior layer of hassock (often
containing fossils) is found below this bed.

J^ewingtan Gleavee, — A flinty bed ; produces some large blocks. Then a
flinty bed between two layers of hassodc

WhiUlani Bridge produces blocks 12 feet long, any width, and 14
inches thick ; stone very free working ; bluish colour.

Main Bridge, — Like the last bed, but of sm^all scantling. Used for paving
kerbs. Alter the last bed comes some inferior hassock.

Chrl yields hard blocks of considerable side, used for headstones. Upper
and lower surfaces of the bed show a red colour.

EijTee Bridge yields blocks of good stone, 15 feet long and 16 inches
thick.

Beadetone la^ng yields blocks about 7 inches thick, used for headstones.
Then a deep bed of soft hassock.

White Rag^ which is of no use for building, as it tumbles to pieces upon
exposure to the air.

Thb Raostonb is used chiefly for rubble work, being very difficult to dress.
It does not gain in beauty by being tooled, because even the best kinds are
full of small hassocky spots, which show themselves upon a smooth face, turn
rusty upon exposure to the weather, and facilitate the decay of the stone.

The ragstone makes very good paving sets and curbs. It is also used for
road metal, but yields a good deal of dust in dry weather.

If used as ashlar, great care must be taken to place it on its natural bed,
otherwise it will decay.

The ragstone is not suitable for internal work, for, as it is non-Absorbent,
the moisture of the air condenses upon its surface, causing what is known as
sweating.

All ragstone used for external work should have the hassock carefully
knocked off.

a a — m p

66 NOTES ON BUILDING CONSTRUCTION

It is important also to see that the small '^ pockets " containii^ iron, which
often occur in the stone, are not exposed upon the face, otherwise the iroD
will oxidise npon exposure to the atmosphere, and cause ugly rust stains.

Thx Hassock is totally unfit for external work, but it is frequently used as a
lining to walls built of ragstone, by which the sweating above mentioned ia
avoided.

Quarries. — There are several quarries, among which may be mentioned the
Iguanodon, Chillington, Allington, all near Maidstone. Also quarries at
Aylesford and at Boughton.

(kfrnipotition. — The following are analyses of the Kentish Bag and Hassock
respectively : —

KewtiakBag,

Carbonate of lime with a little magnesia .02*6

Barthy matter ..... 0*6
Oxide of iron ... . O'ff

Carbonaceous matter . 0'4

100*0

J/as$ock,

Carbonate of lime . .... 26'2

Earthy matter . . . .72*0

Oxide of iron ... .1*8

100*0

Tallow Mansfield is obtained from quarries at Mansfield Woodhoam^ twc
miles from Mansfield It is crystalline, and has a warm yellow colour.

This stone almost exactly resembles the Bolsover Moor stone, which was
selected by the Royal Commissioners for the Houses of Parliament.

The only difference is *' that its colour is rather deeper, partly owing to its
having a greater number of minute black specks, which is a peculiarity more
or less to be found in all varieties of the magnesiau limestone rocks."

The chemical composition of Mansfield stone, and the characteristics which
it shares with other magnesian limestones, are given at pages 58, 59.

Uses, — It is useful for ashlar, mouldings, columns, etc, and is eminently
adapted for highly carved work.

Where used. — Amicable Life Assurance Office, Fleet Street Martyrs'
Memorial, Oxford.

Caan and Aubigny Stones are Oolitic limestones, which may be men-
tioned here, as they are a good deal used in this country, though they are
found in Normandy.

Caen Sttme is of a pale cream-yellow colour. It is very soft when first quarried,
but hardens upon exposure ; is easily worked and carved, but weathers very
badly ; weighs 120 lbs. per foot cube. Used in Henry VIL Chapel, West-
minster Abbey ; the Tower, Buckingham Palace, and many other buildings.

Avbigny Stone is similar to Caen, but more crystalline, harder, and heavier.
It also weathers badly. Used at St Mary's, Stoke Newington, and other
buildings.

Several other limestones of considerahle importance will be
found in the following Tables : —

LIMESTONES.

oh »

lit

II ii 1

eq 09

«a7
So

o
o

^►.

-a 2 §:§
;:3 o »

I s

■§

I I

I I'

.g
1

NOTES ON BUILDING CONSTRUCTION.

LIMESTONES.

ll HI i

Inn

P > PoS

•|i

•I

Do. .
Greenish

Brownish

•If

•So

£5 £

O »s rj a> »/;

5Eoig

> <5 d

S pp

NOTES ON BUILDING CONSTRUCTION

OD
D

IIS? Is

-<^ o

■•I

i».^

2 .

fl'S !§ .

-g-e ^^ «

3 V c

6
P

€

0} o ^ o u%

l^-"^

9>*

Ho -n
fc o ^

MM a

LIMESTONES.

7«

iir

J<Q 5 'pis

1-'

(5 JBQ^*

^11

Qnpa

S 5 o J

S M N« M

et « as H

e« M as a

< < •<■<

NOTES ON BUILDING CONSTRUCTION.

► ^ "S -C .5-3 5 55 o S 2

"^
o

•f.

OPQO

1^5

•s.

,1'

.-I
Mi-

^ I

i
li

b
O
H

•c

QQpqcQO

tfrjs -s 6

1 11^^

5.8 a

1^1

S 5 S

2 go ^ 1^ iE 6 &

Ps:i (4 o! b^ P

a <

O U

LIMESTONES.

Pip

■ss

OPQPQ

.a
O

'^'^ Cl^ PCpQ

« &

ii iiisil

74 NOTES ON BUILDING CONSTRUCTION.

ABTIFICIAL STONK

In consequence of the difficulty which exists in many localities
of obtaining durable natural stone at a moderate cost, many pro-
cesses have been invented for the manufacture of artificial stona

Some of these processes are successful in producing artificial
stones which compare favourably in all their qualities with
natural stones having a high character.

The expense of artificial stone is a bar to its extensive use for
ordinary blocks, but the facility with which it can be moulded to
the most intricate forms makes it very economical when it is
required to take the place of carvings or other enrichments in
natural stona

A few of the best known artificial stones will now be described.
Some of them are merely forms of concrete^ and will be mentioned
in the chapter devoted to that material

Bansome's Artifloial Stone is made by mixing artificiallj-dried aaiid
with silicate of soda (dissolved flint) and a small proportion of powdered stone
or chalk. These are thoroughly incorporated in a pug or mortar mill, and
forced by hand into moulds.

The blocks turned out have a cold solution of chloride of calcium poured
over them, and are then immersed in a boiling solution of the same, sometimes
under pressure, so that the pores of the material are entirely filled with the
solution, after which it is found to be as hard as most building stones.
The excess of chloride of sodium is then washed oif, otherwise it is apt to
cause efflorescence.

It will be seen that the above process depends upon the double decomposi-
tion of the silicate of soda and chloride of calcium. The chlorine and soda
combine to form chloride of sodium, which is washed out, and the silica
attacking the calcium forms silicate of lime, a strong and durable cement
which binds the particles of the stone together.

Characteristies. — ^This stone has a fine homogeneous structure, so that it can,
if necessary, be worked and carved like the best building stones.

The great advantage that it possesses is the fisusility with which it may be
moulded into any form required.

Several experiments have been made upon this material

It absorbs about 6*6 per cent of water.

Its tensile strength is about 360 lbs. per inch.

Its resistance to crushing about 2 tons per inch.

It weighs about 120 lbs. per cubic foot

Of course these figures vary according to the nature of the material used in
making the stone, the age of the specimen, etc.

The composition of this stone indicates that it will weather well, and some
experiments made by Professor Frankland show that its resistance to acids was
fully equal to Portland, Anston,Parkspring,and other of the best building stones.

Detfdls of the experiments made by different observers will be found col-
lected in Qwilt's Encyclopadia of ArekileUum^ page 485.

ARTIFICIAL STONE. 75

Utet. — ^This stone is well adapted for all purposes for which natural sand-
stones and limestones are used. It can, however, be most economically
employed for dressings (especially for those of an ornamental character), and for
imitation carved work, though its use for this purpose has been condemned
from an artistic point of view.

This stone is also used for caissons or hollow blocks for foundations, for
grindstones, filters, etc. ; and by substituting grains of corundum and oxide of
iron for the sand, a substance called solid emery is produced, which is formed
into wheels for sharpening tools, polishing metal surfaces, etc.

Bansome's stone has been used at St. Thomas's Hospital, the India Office,
the London Docks, the Brighton Aquarium, the Albert Bridge, and in several
other buildings both at home and abroad.

Aposnite is a variety of Bansome's stone, made with 5 parts of sand, 1 of Fam-
bam rock, 1^ of Portland cement, with the same proportion of silicate of soda.

It can be made more quickly, and is considered superior to the other.^ *

Moreover, it has the great advantage that it can be made on the works
where it is to be placed in position.

It is used for steps, balustrades, cylinder foundations, etc.

It weighs about 137 lbs. per cubic foot, and absorbs in 24 hours about 6^
per cent of its weight of water.

Victoria Stone consists of washed, finely-powdered granite, bound together
with the strongest Portland cement, and then hardened by immersion in sili-
cate of soda.

The silicate is formed by boiling ground Famham stone in cream caustic soda.

A mixture of four parts of crushed granite with one of Portland cement is
allowed to set for three days or more into a hard block moulded to the re-
quired shape. It is then immersed in the silicate of soda for some seven or
eight weeks.

The lime in the cement combines with the silicate, the whole mass being
indurated by the silicate of lime thus formed.

Characterutics and Utes. — ^This artificial stone is used chiefly for paving,
which is said to be more durable, to be cheaper, and to stand a greater crush-
ing force, than Yorkshire flags. It is used also for window sills, coping
stones, caps for piers, stairs, landings, troughs, tanks, sinks, eta

It weighs from 140 to 160 lbs. per cubic foot, and absorbs horn 2 to 6 per
cent of its weight of water in 24 hours. The thinner flags are less compact
and more absorptive than the thicker ones.^

** The white colour, semi-transparency, and extreme hardness of this oxy-
chloride, as well as the small quantity which is required for binding together
a considerable mass of any material, facilitate the production of imitations of
any description of stone, and render it highly probable that it will play an
important part in the future history of artificial stone." ^

Where used, — ^This stone has been used for the whole of the external stone-
work, except the cornice, at Fresh Wharf, London Bridge.

Also for the panels in the tower, and for the chimney shafts at Messrs.
Peek and Frean's biscuit manufactory at Bermondsey, and for paving in many
parts of London.

Silioated Stone is made in the same way as Victoria stone, and is used
for paving slabs and drain pipes.

Sorel Stone is so called after M. Sorel, a French chemist

* Dent « Wray.

76 NOTES ON BUILDING CONSTRUCTION.

Native carbonate of magnesia, or magnesite, is calcined and mixed with aand
or powdered marble. It is then wetted with waste liquor from salt works
containing a large proportion of magnesium chloride, P^igg^^ c^d then
rammed or stamped into iron, wooden, or plaster moulds.

It hardens rapidly, setting throughout its mass like ordinary hydraulic
cement In 24 hours it is hard enough to remove from the moulds, and the
blocks will bear handling in three or four days.

The proportion of magnesia to the inert material bound together varies
from 3 to 15 per cent.

This stone has been found to resist an enormous compression. The re-
sistance of 2-inch cubes varied in different experiments from 4923 to 21,562
lbs. per square inch.

Chance's Artifioial Stone is made by melting the Rowley Rag, a basaltic
rock found in Staffordshire, and then casting it into the shapes required for
different architectural ornaments.

Greenstone, whinstone, or any similar rock, may be treated in the same way.

The moulds are of sand in iron boxes, and are at a red heat when they
receive the melted stone. They should cool slowly, in order to obtain a haid
material like the original stone ; if allowed to cool too quickly the material
becomes brittle and glassy.^

Bust's Vitrifled Marble is produced by fusing together a mixture of glass
and sand. " The soft pasty mass is taken out of the pot on the end of an
iron rod, and placed in a small metal mould of any required shape or design.
The large proportion of sand used prevents the mass, when thus suddenly
cooled, from acquiring such a high state of tension as to be liable to fly to
pieces, which would be the case with glass alone. The material, when cool,
is either used in the form in which it is cast, or it is broken up into dmal!
pieces by the stroke of a light hammer, to be used in the construction of
mosaics for pavements, or other purposes.

" Any colour can be given to tiie mass when in a semi-fluid state by mixing
with it the oxides of iron, chromium, cobalt, or such other colouring materials
as are usually employed for fired ware. This vitrified marble has been used for
the bosses and coloured portions of the string course which extends round the
Home and Colonial Offices, and also at the Albert Memorial in Hyde Park." *

Other artificial marbles are made, which partake of the character of
plasters, and will be noticed in Chapter IIL

Artificial Paving Slabs and Paving Stones of many kinds are in the
market They are often composed of Portland cement concrete (see p. 2 1 0), very
carefully made, with hard aggr^ates and the very best cement. It is said
that the very finely ground German cement (see p. 164) is used for this pur-
pose. Silicates are sometimes added to give hardness to the mass.

PRESERVATION OF STONE.

In consequence of the rapid decay of some of our public build-
ings (especially the Houses of Parliament), the question of the
preservation of stone has of late years attracted much attention.

Several methods have been proposed — a great number of
dififerent solutions and preparations have been tried ; but none of
them combine efficiency and cheapness to such an extent as to
have come into very general usa

1 Descriptive Catalogue, Museum of Practical Geology, Jermyn Street ' Dent

PRESER VA TION OF STONE. 77

It is unnecessary to give a description of these preparations in
detail, but they naturally range themselves under two distinct
classes which may be noticed.

The first of diese classes consists of preparations containing
dissolved organic substances; these fill the pores of the stone,
and preserve it for a time, but they are themselves subject to
decay, and therefore can afford only a temporary protection.

The preparations of the second class are solutions of substances
which act either upon the constituents of the stone to which they
are applied, or upon one another (when more than one is appUed)
so as to form insoluble compounds which fill the pores and
harden the structure of the stone, at the same time making it also
denser, more impervious, and abler to resist atmospheric influences.

Many processes are successful in the laboratory of the chemist;
but none is likely to be of use in the practical execution of
engineering or building works, which is not economically applicable
on a large scale.

It has been recommended that stones should be placed in
vacuum chambers so as to introduce solutions more readily — also
that stones should be heated, or immersed in solutions. All these
methods are impracticable in dealing with large blocks, on account
of the expense and inconvenience attending the manipulation.

Any preservative solution, to be of practical value, must be
capable of application to the surface to be protected by means of
a brush.

Preparations containing Organic Bubetanoes. — ^Filling the Pobks
WITH Obganio Mattbr. — Paint — One of the meet common methods of pre-
serving the surface of stone is to paint it This is effectual for a time, but
the paint is destroyed bj atmospheric influence in the course of a few years.
** In London the time hardly amounts to three years even under favourable
circumstances." ^ Moreover, it cannot well be used in important buildings
where appearance has to be considered.

Oil has ako been used as a coating ; it fills the pores of the stone and keeps
out the air for a time, but it discolours the stone to which it Ib appUed.

Paraffin is more lasting than oil, but is open to the same objection ap
regards discoloration of the stone.

Softioap dissolved in water (| lb. soap per gallon), followed by a solution
of alum (^ lb. alum per gallon), has been frequently employed.^

Paraffin diiwlved in NaphUui, — ** 1^ lb. parafSn to a gallon of coal tar
naphtha, and applied warm, is perhaps superior to both the former for this
special purpose."

** There is, however, no evidence to show that any methods such as these
are likely to be successful in affording permanent protection to stone." '

^ Ansted. * Dent

7S NOTES ON BUILDING CONSTRUCTION,

Beeswax dissolved in coal tar NapKOia has also been proposed,^ or, when the
natural colour of the stone is to be preserved, white wax dissolved in doMe
distilled Gamphine,

Wax varnish to preserve statues and marble exposed to the air. — The follow-
ing is given in Spons' Workshop Receipts: — ** Melt 2 parts of wax in 8 parts
of pure essence of torpentine.''

The surface should be cleaned with water dashed with hydrochloric acid,
but should be perfectly dry, the solution applied hot and thin.

Preparationa not oontaining Organic Bubstanoes. — Soluble silica. —
There is a large class of preparations whose preservative influences depend
upon the presence of soluble silica, which combines with substances con-
tained in, or added to the stone under treatment.

By this means insoluble silicates are formed, which not only preserve the
stone from the attacks of the atmosphere but also add considerably to its
hardness.

Unfortunately the use of these substances sometimes causes efflorescence on
the face of the wall to which they are applied. The soluble alkaline salts
left in the pores of the stone are drawn to the surface ; these ciystallise in the
form of white powder, and disfigure, or in some cases injure, the walL

The soluble silica is sometimes found in the natural state.

A large proportion may be obtained from the Famham rock, or from the
lower chalk beds of Surrey and Hampshire by merely boiling with an alkali
in an open vessel.

Alkaline Silicates. — Ordinaiy silica in the form of flints may, however,
be dissolved by being digested with caustic soda, or potash, under pressure.

If a piece of porous limestone or chalk be dipped into this solution, part of
the silica in solution separates from the alkali in which it was dissolved and
combines with the lime, forming a hard insoluble silicate of lime ; part of it
remains in the pores and becomes hard.

Euhlmann*s Process consists in coating the surface of stone to be preserved
with a solution of silicate of potash or silicate of soda.

The hardening of the saiface is due to the decomposition of the silicate
of potash. If the material operated upon be a limestone, carbonate of potash,
silicio-carbonate of Ume and silica will be deposited ; besides which the car-
bonic acid in the air will combine with some of the potash, causing an efflor-
escence on the surface, which will eventually disappear.^

When applied to sulphate of lime, crystallisation takes place which disin-
tegrates the surface.

In order to correct the discoloration of stone sometimes produced by the
application of preservative solutions, M. Euhlmann proposed that the surfiaces
should be coloured.

Surfaces that are too light may be darkened by treatment with a durable
silicate of manganese and potash.

Those that are too dark may be made lighter by adding sulphate of baryta
to the siliceous solutions.

By introducing the sulphates of iron, copper, and manganese, he obtained
reddish-brown, green, and brown colours.

Ransome's Indurating Solutions consist of silicate of soda or potash, and
chloride of calcium or barium.

The surface of the stone is made thoroughly dean and dry, all decayed pait«
being cut out and replaced by good.

' (lillmore.

PRESERVATION OF STONE. -9

The silicate is then diluted with from 1 to 3 parts of soft water until it is
thin enough to be absorbed by the stone freeljr. The less water that is used
the better, so long as the stone is thoroughly penetrated by the solution.

The solution is applied with an ordinary whitewash brush. *^ After say a
dozen brushings over the silicate will be found to enter very slowly. When
it ceases to go in, but remains on the surface glistening, altiiough diy to the
touch, it is a sign that the brick or stone is sufficiently charged ; the brushing
on should just stop short of this appearance." . . . '* No excess must
on any account be allowed to remain upon the face.** After the silicate has
become ptrfecUy dry, the solution of chloride of calcium is ^ applied freely
(but brushed on lightly without making it froth) so as to be absorbed with
the silicate into the structure of the stone.*' ^

The effect of using these two solutions in succession is that a double de-
composition takes place, and insoluble silicate of lime is formed which fills
the pores of the stone and binds its particles together, thus increasing both its
strength and weathering qualities.

In some cases it may be desirable to repeat the operation, and as the sili-
cate of lime is white or colourless, ^ in the second dressing the prepared chlo-
ride of calcium may be ti^Ued so as to produce a colour harmonising with the
natnzBl colour of the stone.**

*' Before applying this second process the stone should be well washed with
rain water and allowed to dry i^ain.**

The following cautions are given in Messrs. Bateman*s circular : —

** 1. The stone must be clean and dry.

*^ 2. The silicate should be applied till the stone is fully charged, but no
excess must upon any account be allowed to remain upon ike face,

** 3. The oaleium must not be applied until after ike sUieaU is dry; a clear
day or so should intervene when convenient

*' 4. Special care must be taken not to allow either of the solutions to be
splashed upon the windows or upon painted work, as they cannot afterwards
be removed therefrom.

** 6. Upon no account use any brush or jet for the calcium that has pre-
viously been used for the silicate, or vice versd,"

The bottles or drums of silicate have a hlacJk secd^ those of calcium a red seaL .

Under ordinary circumstances about four gallons of each solution will be
required for every hundred yards of surface, but this will depend upon the
porosity of the material coated.

This material has been used with success not only for the preservation of
stone from decay, but also to keep out damp.

It has been used at St. George's Hall, Liverpool, for preserving the sculp-
ture ; at Trinity College, Dublin ; Cardiff Town Hall ; Greenock Custom
House, and for other buildings both in this country and in India.

It is applicable not only to stone and brick sur&ces, but also to those
rendered with cement or lime plaster.

SzsRBLMBT*s Stonb Liquid is stated by Professor Ansted to be " a combina-
tion of Kuhlmann*s process with a temporary wash of some bituminous sub-
stance."

The wall being made perfectly dry and dean, the liquid is applied in two or
three coats with a painter^s brush until a slight glaze appears upon the surface.

This composition was used with some success in arresting for a time the
decay of the stone in the Houses of Parliament

^ Patentee's circular.

8o NOTES ON BUILDING CONSTRUCTION.

The stone liquid is tianspaient and colourlesB, but Szerelmey's stone paint
is opaque and of different coloors, and is applied like oidinaiy paint (see p. 4 1 2).

The Petrifying Liquid of the Silicate Paint Company is stated in their <ax-
cular to be " a solution of silica," thinned with warm water, and applied to
clean wall surfaces, which must be wanned if they are not already dry.
1 cwt will cover from 120 to 150 square yards.

Othbr Progbssbb. — Among other processes which have been tried are —

SchUion of Baryta followed by solution of Ftrrthiilieic AM so as to fill
the pores of the stone with an insoluble ferro-silieate of baryta.

Solution of Baryta followed by solution of Superphoaphate of Lime pro-
ducing an insoluble phosphate of lime and phosphate of baryta.

Soluble Oxalate of Alumina applied to limeetones produces insoluble oxalate
of lime and alumina.

** These three processes last alluded to all possess the advantage of pro-
ducing by the changes they imdergo within the structure of the stone an
insoluble substance, without at the same time giving rise to the fonnation of
any soluble salt likely to cause efflorescence, which neceasarily attends the
use of alkaline silicates." *

Temporary ProteeHon of Stone Swfaeee. — During the erection of laige
buildings the surface of the masonry built in the earlier stages of the work
is smeued over with a sort of thin mortar, so as to preserve it from atmo-
spheric influence, and to make it easier to clean down.

Tables illustrating the Properties of Different Stones. — ^The fol-
lowing Tables give a selection from the results of a great number of ex-
periments upon stone made by various authoritiea

In many cases the figures given are not directly comparable with eeeh
other, inasmuch as the experiments have been made by different observen
and under different conditionsi

They afford, however, a useful indication of what may be expected in deal-
ing with stones of different descriptions.

The Table on page 81 shows the weight required to crush stones of different

IrinHa.

Experiments upon the resistance of stones to crushing have generaUy been
made upon cubes.

Professor Rankine says that these experiments indicate ^* somewhat more
than the real strength of the material"

The reason for this is that the fracture of stones under compression gener-
ally takes place by their shearing on a plane inclined at a slope having 1^
rise to 1 of base.

In order to ascertain the strength of any stone for a special purpose, experi-
ments should be made on prisms whose heights are about 1^ times their
diameters.

The hardest stones — such as basalts, primary limestones, slates, etc. — give
way suddenly. Other stones begin to crack rnder from ^ to } the crushing load.

It should be noticed that the size of cube^ experimented upon varies con-
siderably. With the same kind of stone the larger the specimen the greater
is the weight per square inch required to crush it

The working stress allowed in practice upon ashlar blocks should not
exceed A of the crushing weight given above.'

' Dent ' Stoney On Straine,

RESISTANCE OF STONES TO CRUSHING.

Sioin.

Crashing
Weight per
Square Inch

length
Side of

Autho-
rity.

Stoks.

Crushing
Weightper
Souare Inch

In Tons.

Length
Side of

Autho-
rity.

in Tons.

Cube.

Granites.

Inches.

Sandstones.

Inches.

Aberdeen (blue)

4-87

Weak specimens,

1-34 to 1-66

Do. . .

8-47

locality notstatec

Peterhead .

8-7

Runcorn .

0-97

...

L.aark

Do. .

2-8

Quartz rock on

11-38

...

HaUet

Comiflh

2-84

natiuulbed

Dartmoor .

1-64

Quartz rock,

6-25

Do.

Do. .

812

layers vertical

Herm

•86

Moant Sorrel
Killiney .
Ballyknocken .

6-74
4-81
1-41

F
W
W

Marbles.

White statuary .

Do.

1-43
2-7

R
R

Argyleshire

4-87

...

Black Brabant .

9-46

Iriah (variona) .

1-0 to 6-0

White Italian .

9-72

Basalts, etc.
Whinstone
Do. .

8-69
6-34

B
F

Devon (red)
Kilkenny (black)
Galway, do.

8-31
6-76
9

i"
1

R
W
W

Granwacke, Pen-

7-64

Limestones.

maenmawr

Compact (strong)

8-8

Felapathic

7-68

•••

Magnesiau, da

8-16

greenstone

Do. (weak)

1-86

Hornblendic

10-97

...

Portland .

1-66

greenstone

2-03

Irish (variona) .

3itol4i

Do.
Da

1-5
1-17

Slates.

Do.

1-74

Valencia on bed

Purbeck

4-08

Do. layers
Tertical

4-71

Ancaster

1-04

Bamack

0-79

Glanmore .

9-58

Eetton

1-14

Killaloe .

18-71

Do. (rag) .

4-01

Cahircivean

2-76

Bath (Box)

0-66

Da . .

0-64

Safidstones.

Chalk

0-5

Bramley Fall .

Bolsover .

8-36

Do. . . .

2-5

Bramham Moor

2-64

Craigleith .

1-4

Brodsworth

2-05

2-45

Cadeby . .

072

Da ! !

8-5

Chilmark .

2-84

Dundee .

8-86

HamhiU .

1-8

York paving .

2-56

Huddlestone

1-98

Binnie

2-24

Park Nook

1-93

Darley Dale

8 16

Roche Abbey .

174

Giffnenk .

215

Do.

0-69

Kenton

2-21

Tottemhoe

0-86

Mansfield (red) .

2-27

Anston .

1-86

...

Do. (white)

2-84

Anglesea .

3-38

...

L.Clarlc

Morley Moor .
Park Spring

2-21

Listowel .

8-88

8-38

Longhome

7-68

Stanley .

2-66

Ballyduff .

4-93

Strong Yorkshire,

4-38

Moyne

•8 -03

mean of 9 expta

Limerick .

3-9

Irish (various) .

•75 to 10-0

Irish (various) .

•5 to 14-0

I, Institntion of British Architects.
B, Buchanan, quoted by Stoney
R, Bennie.

C, Commissioners <

B.C. — m

B, Bramah.

F, Fairbaim, Um^ Injormalion for Engiiuen.
W, Wilkinson, Praetieal Geology, Ireland.
I Stone for Houses of Parliament.

NOTES ON BUILDING CONSTRUCTION.

Resistance of Stone to Onuhing. — The following results are from Mr.
Ku:kaldy's experiments with 6-inch cubes : —

Stohk.

Crushing
Weight per
Sqnare Inch

in Tons.

Stonv.

Crushing
Weightper
Square Inch

in Tons.

Scotgate

Bramley Fall .

Derbyshire do.

Craigleith

Red Corsehill .

Conliffe ....

Leigh Carr .

6-1
1-8
2-6
6-4
8-5
4-7
7-2

Qnarella (white)
Do. (green)
Grinshill

Wilderness (red) .
Hopton Wood .
SpinkwelP .

3-8
8-0
2-3
8-3
5-6
6-0

Tensile Strength of Stone.^^Stone is rarely employed so as tQ be subject to
a tensile stress. The following Table is chiefly from Mr. Stone/s work on
Strains^ and he remarks that it would be well to have the figures corrobo-
rated.

Matbbul.

Tearing

Weightper

Square Inch

in lbs.

Authority.

Arbroath paving ....

1261

Buchanan.

Caithness da

1054

Do.

Chilmark

500

Do.

Craigleith stone

453

Do.

Hailes .

836

Do.

Hmnbie .

283

Do.

Binnie .

279

Whinstone

1469

Biarble, white .

722

Hopkinson

Do.

551

Slate

9600 to
12,880

Rankine.

Transverse Strength of Stone? —

Sandstone
Skte

Modulus of rupture
lbs. per square inch.

1100 to 2360
6000

^ Fairbaim's Experiments.

* From Bankine's Us^d Rules and Tables.

ABSORPTION OF WATER BY STONES.

Ahtorptwik — ^Table showing the bulk of Water absorbed in twen^-foixx
hours by yaiious stones : —

Natubi of Biohs.

Bolk of Water

absorbed as

compared with

bnlk of stone

percent.

Anthoiily.

Seyeral specimens of good granite
and syenite . . . .

i per cent

Da do. indifferent specimens

1 »

Do. da veiybad

8 u

Trap and basalt . . . .

A trace .

Da da

Atoip.c.

Sandstones,

Craigleith— Very durable .

8 per cent

Park Spring Da

8 »

Giffiienk— Moderately durable

10 „

Heddon Da

10-4 „

Kenton Da

9-9 „

Mansfield Do.

10-4 „

HasBock— Very bad

20-0 „

LimeOmes.

Marble

A trace.

Portland-— Very durable

18*5 per cent

Ancaster — Durable .

16-6 „

Bath (Bozground) .

17 ,.

Ketton— Durable •

161 „

Chilmark

8-8 „

Roche Abbey— Durable

17-2 „

Kent Bag Da

li »

Banaome's stone (artificial)

12 „

Victoria Do. da

7-6 „

Apoenite Do. da

12 ,,

W, Deduced fhnn Expezlments detailed in Wray On Stont,
0, Royal Commission on Stone for Honses of Parliament

Weight of Stone. — A long list of stones, giving the weight per cubic foot of
each, was prepared by Mr. Q H. Smith for the Mineral Statistics published
at the Museum of Practical Geology.

The information contained in that list has been given in the Tables, pp.
18, 39, 67, et seq,, and it will therefore not be repeated.

84 NOTES ON BUILDING CONSTRUCTION

The following Table shows approzimately the weights of different cUtMes
of stone, and may be usefoL

Tablb giving the Weight and Balkinees of Different Varieties of Stone.

Granites and Syenites
Trap and Basalt
Slate .
Sandstones
Marble .

Limestones, Compact
,, Granular

Qoarta
Felspar

Shelly granular

Shelly

Magnesian

Kent Bag

Lias

Chalk

Weight per cubic
foot m lbs.
162 to 187

164 to 187
166 to 181
116 to 170
168 to 172

165 to 172

116 to 151
130 to 140
157 to 167

126 to 153
166

127 to 156

117 to 174
165

162

Resibtanoe to Weab. — Mr. Walker exposed the undermentioned descriptions of
granite and whinstone to very heavy waggon traffic for seventeen months, and fonnd their
vertical wear to be as follows i —

Guernsey granite
Hcrm yy ■

Baltic whinstone
Peterhead blue granite .

Inch.
•060
•076
•082
•181

Heytor granite
Aberdeen red granite .
Dartmoor granite
Aberdeen blue granite .

Inch.
•141
•159
•207

Mr. Newton's experiments on the flags used in Liverpool showed Kilmsh flags to be
most durable, Caithness flags next The flags found to be least dorable were those from
Uangollen and Yorkshire.^

1 D. Kinnear Clarke On Boads and SlruU.

Chapteb IL
BRICKS, TILES, TERRACOTTA, ETC.

THEEE are many different forms in which clay after it is
burnt or baked is used by the builder and engineer.

Some of the more importcmt of these will now be described
under the following classification : —

Bricks.

Fireclay and Fire-bricks.

Terracotta.

Stoneware.

Miscellaneous day goods of Earthenware, Fireclay, Stoneware,
Terracotta.

BRICKS.

Ordinary building bricks are made of clay and other earths
subjected to several processes (which somewhat vary according to
local practice, influenced by the nature of the material), formed to
the required shape in moulds, and burnt

BEICK EAETHS.

Ck>n8titaentB of Briok Earth. — The earths used for making
ordinary bricks generally consist of alimiina and silica, either
alone or in combination with other substances, such as lime,
magnesia, iron, etc.

It is beyond the province of these Notes to go into the chemistry

of the subject, but it will be useful just to glance at the part

played by each of these constituents, and the effect that it has

upon earth considered as a material for brickmaking.

It may here be remarked that mere inspection or even chemical analysis

86 NOTES ON BUILDING CONSTRUCTION

of a clay gives very little information as to its suitableness for brickmaking.
No test is satisfactory but that of actually trying the clay by making a few
bricks with it.

In the absence of facilities for burning full-sized bricks, a fidr indication
of the quality of a clay for brickmaking may be arrived at by making it
into a small brick about 3 inches long by 1^ inch wide by 1 inch thick.
This small brick may be burnt in a common house fire, being protected from
contact with the fuel by placing it inside a shield made by roughly rolling a
piece of sheet-iron round into a hollow cylinder of about 2 inches diameter.

Alumina is a principal constituent in nearly every kind of day. It gives
the material its plastic qualities, but it shrinks and cracks in drying, warps,
and becomes very hard under the influence of heat.

Sildea exists to a greater or less extent in all clay, in a state of chemical
combination with the alumina, forming Silicate of alumina.

It is found also in nearly all clays in an uncombined state — as sand.

Silica is infusible alone, or in the presence of alumina only, except at veiy
high temperatures.

If, however, the silica and alumina be in nearly equal proportions, the
presence of a small quantity of oxide of iron will render them fusible at a
comparatively low temperature.

Pure silicate of alumina is plastic, but shrinks when diying, and warps
with heat

The action of sand is to prevent cracking, shrinking, and warping, and to
provide the silica necessary for a partial vitrification of the materials, which
is generally desirable.

The larger the proportion of sand present, the more shapely and equable
in texturo will the brick be.

An excess of sand in clay renders the brick made from it too brittle.

The difference between the silica which is in a state of chemical combina-
tion and that which exists merely as sand is not shown in ordinary chemical
analyses, and this is one reason why they are not so useful as they might be
in determining the value of a day for brickmaking. ^

Lime has a twofold efiiect upon the day containing it

It diminishes the contraction of the raw bricks in diying, and it acts as a
flux in burning, causing the grains of silica to melt, and thus binding the
partides of the brick together.

An excess of lime causes the brick to mdt and lose its shape.

Again, whatever lime is present must be in a very finely divided state.
Lumps of limestone aro fatal to a day for brickmaking. When a brick con-
taining a lump of limestone is burnt, the carbonic acid is driven off^ the lump
is formed into " quicklime,^ and is liable to sUke dirocUy the brick is wetted
or exposed to the weather. Pieces of quicklime not larger than pin-heads
have been known to detach portions of a brick and to split it to pieces.

The presence of lime may be detected by heating Uie day with a little
dilute sulphuric add. If there is lime present an efiervesoence wiU take
place.

Bricks containing lumps of quicklime should be immersed for several hours

^ Silica sometimes exists in day in a soluble condition combined with lime ; it is
then iigurious, as it may absorb moistore which has been known to destroy walls by
making the bricks swell.

BRICK EARTHS. 87

before use, 80 as to kill the lime and prevent it from slaking after the bricks
are made, or even built into the work.

Irfm, Pifrites often occurs in clays, and should be carefully removed.

If not, the pyrites is partially decomposed in the kiln, will oxidise in the
biick, crystallise, and split it to pieces.

Carbimaceous matter, when it exists natnrally in clays to any considerable
extent, is objectionable. ^ When not burnt completely out in the kiln, which
is sometimes with the denser clays difficult, the bricks are of a different colour
in the interior and exterior, and will not bear cutting for face work without
spoiling the appearance of the brickwork.

*^ But, worse than this, such bricks when worked in the wall occasionally
pass out soluble compounds like those absorbed from soot by the bricks oi
flues, and like those (when used again in new work) discolour plastering or
stucco work." ^

AlktUtes^ when they exist in day to a considerable extent, make it unfit far
the manufacture of bricks. They act as a flux, and cause the clay to melt
and become shapeless.

Salt, — ** Common salt is nearly always present in minute quantity in days ;
but when these are taken from the seihehore, or without or beneath the sea-
washes, or from localities in and about the salt formations (Trias), they fre-
quently, though in all other respects excellent clays, are unfit for burning into
good brickflL

*^ Chloride of sodium ^ is not only a powerful flux when mixed even in very
small proportion with days, but it possesses the property of being volatilised
by the heat of the brick kilns, and in that condition it carries with it in a
volatile state various metallic compounds, as those of iron, which exist in all
days, and act as fluxes. The result is that bricks made of such clays watp,
twist, and agglutinate together upon the surfaces long before they have been
exposed to a suffident ftnd sufficiently prolonged heat to bum them to the core
into good hard brick. Place bricks can be made of such clay, but nothing
more, and these are nearly always bad, because never after free from hygro-
metric moisture.** ^

Oxide of Iron in day influences the colour of the bricks to be produced (see
p. 89). The tint resulting after burning depends upon the proportion of
iron in the day and the temperature to which it has been raised.

When in the presence of silica and alumina whose proportions are nearly
equal, iron renders them fusible.

PraoUoal ClasaiiLoation of Briok EartliB.— Brick earths are
generally divided into three classes.

1. Plastic or Strong Clays (called by the brickmaker "fovi days*'),
which are composed of silica and alumina, with but a small pro-
portion of lime, magnesia, soda, or other salts. These are also
known as pure days.

2. Loams or MUd Clays, consisting of clay and sand, and some-
times called sandy days.

3. Marls or Calcareous Clays, which contain a large proportion
of carbonate of lime.

^ Mallet On Brickmaktng, ' Common saIl

NOTES ON BUILDING CONSTRUCTION

Malm is an artificial imitation of natural marl^ and is made by
mixing clay and chalk in a wash mill. It is sometimes called
washed clay.

It generally happens that a clay as found in' nature is unfit for
brickmaking by itself.

It will probably turn out to be deficient in some necessary
quality which has to bo supplied by mixing it with other clays,
or by adding the constituent required, such as sand or lime.

A good Brick Earth should contain sufficient flux to fuse its
constituents at a furnace heat, but not so much as to make the
bricks run together and become vitrified.

Such earths contain from -^ to ^ alumina, and from ^ to ^ silica,
the remainder consisting of carbonate of lime, carbonate of mag-
nesia, oxide of iron, etc.

The bricks made from such clays are a silicate of alumina and
lime or other fluxes.

The following Table gives the analysis of some brick clays : —

Burham Clay.^

London
Brick Clay.^

Loam.^

Marl.*

Silica .
Alumina .

42-92
20*42

49^5
34 3

667
27 0

}

4300

Oxide of iron .

6-00

7.7

1-3

300

Carbonate of lime

18-91

1^4

0-6

46 •SO

Carbonate of mag-

•12

5^1

•••

3-50

nesia

Potash and soda
Water .

•33

6-68

•••

•••
•••

}

4:00

Organic matter .

6-01

...

Characteristios of different kinds of Briok Earth — The quality of
the bricks produced depends to a very great extent on the selection and mixing
of the clay.

Pure or Foul Clats are sometimes used for bricks without the addition
of other substances. In such a case any sand they contain acts merely to
prevent excessive contraction. For want of a flux it does not become fused
80 as to bin^ the particles of the brick together.

Bricks made from such clays are rather baked than hwmed. They are not
so well able to resist the action of the weather as those which are partly
vitrified through the aid of a flux.

Pure clays are therefore very much improved by the addition of sand or loam,
by adding lime to act as a flux, or ashes to provide alkalies for the same purpose.

Abney.

' Knapp.

!■«« V» -WP"

BRICKMAKING. 89

LoAKS are so loose and sandy that they require a flax to fuse and bind the
particles together, and to take up the excess of sand that would otherwise
remain in an uncombined state.

Marls are, of all the clays, the best suited for making bricks without mixture
with other substances, though they are often mixed with chalk or lime when
there is any deficiency in that constituent.

The Coloiir of Bricks depends upon the composition of the
day, upon the kind of sand used for moulding, on the state of
dryness of the bricks before burning, on the temperature at which
they are burnt, and upon the amount of air admitted to the kiln.

Pure clay, free from iron, will bum white, but the colour of
white bricks is generally produced by adding chaXk to the clay.

The presence of irim produces a tint which varies from light
yellow to orange and red; the colour increases in intensity
according to the proportion of iron contained in the clay.

To obtain a clear bright red brick the clay should be free from
impurities, and should contain a large proportion of oodde of iron,
which is converted by burning into the red oxide, but not fused.

When there is from 8 to 10 per cent of oxide of iron, and the
brick is raised to an intense heat, the red oxide of iron is con-
verted into the black oxide, combines with the silica, and fuses,
producing a dark Uue or purple colour.

When a small quantity of rruinganeae is present, with a large
proportion of iron, the brick becomes darker still, Uue or even
ilack.

A little lime in the presence of a small quantity of iron pro-
duces a cream colour ; an increase of the iron changes the colour to
red, and an increase of the lime produces a hroum colour.

Magnesia in the presence of iron makes the brick yellow.

A clay containing alkalies and burnt at a high temperature
becomes a bluish green,

BRICKMAKING.

The operations involved in brickmaking are very numerous,
though not intricate ; they differ in several particulars in different
localities, according to local custom, generally influenced by the
nature of the clay.

To describe these operations in sufficient detail to be of any
practical value would require a separate treatise of considerable
bulk and profusely illustrated.

90 NOTES ON BUILDING CONSTRUCTION

Such descriptions would be beyond the province of these Notes,
and would be unnecessary, for the practices in the brickfields of
different localities are fully described in Dobson On Brick and Tils
Making, one of Weale's series of very valuable technical works.^

It may be useful, however, to give a general sketch of the
operations involved in brickmaking — ^not such details as would be
of practical use to the brickmaker, but just so much as will enable
any one using bricks to understand and appreciate more clearly
the qualities and peculiarities of different varieties, many of the
characteristics of which are caused by differences in the processes
of manuf actura %

With this object the various operations will now be rapidly and
shortly sketched in successioiL

Preparation of Brick Earth.- — Uhsailing. — ^The surface of the
site from which the day is to be obtained is first stripped of its
turf and mould, which is removed to a spoil bank and kept to be
respread over the site after the clay has been dug out.

The mould is sometimes called encaUow, and the process of
removing it eneaUowing.

Clay-digging and WeaiJiering, — ^In the autumn the clay is dug,
and the various descriptions which it is intended to mix, together
with the ashes which are to be incorporated in the mixture, are
wheeled to heaps, in some places called ker/$, in which they
remain during the winter, sometimes during two or three winters,
so that they may be thoroughly disintegrated by the action of
frost.

This mellowing of the clay renders the bricks made from it less
liable to warp.

Clearing from Stones. — If the clay contain pebbles or pieces of
ironstone they must be carefully picked out by hand ; or if they
are found in large numbers, the clay must be washed in small
quantities and strained through a grating so as to separate all the
stones from the mass.

Orinding, — ^When the clay is of a hard marly qbaracter and
full of lumps, or contains fragments of limestone, known by brick-
makers as ra4^, it requires to be ground between cast-iron rollers,
which must be set sufficiently close to reduce the hard particles U
powder.

Tempering. — ^This is done after the winter's frosts, generally
in March or April, before the brickmaking begins.

^ Now puUiBhed by Messrs. Crosby Lockwood and Company, Stationers' HaU
Court, £.a

BRICKMAKING. 91

It consists in digging and tuming over the kerfe or heaps of
day ; sometimes the day is also well trodden under foot, in some
places it is passed through a pug-mill, and occasionally, for the
veiy best bricks it is kept damp in cellars for a year or two to
ripen.

Preparation of Malm. — ^The clay is dug in the autumn and
at once tipped, together with a proportion of ground chalk in pulp,
into a wash milL This consists of a brick-lined circular tank in
which are revolving harrows, knives;, or implements of some kind
to disintegrate and mix up the clay and chalk.

The exact proportion of the chalk differs according to the com-
position of the day, but in some cases the chalk is about -^ of
the bulk of the day.

The mixture having been reduced to a creamy consistence is
strained off through fine gratings into large shallow tanks called
hwiks, and there left tiU it is nearly solid.

After that it is soiUd in layers from 1 to 3 feet deep, Lt.
covered about \ its bulk with screened cinders, and allowed to
remain during the winter.

In the spring the hades are dug out, the layers of day and
ashes beiog thoroughly incorporated in a pug-mill.

In some places the preparation of malm is known as washing.

Malm bricks are made with the mixture of clay and chalk de-
scribed above.

Washed Bricks, — ^These contain a certain proportion of malm,
and are made in two ways.

In some parts of the country — in Essex for example — they are
composed wholly of an inferior malm, made like the malm
described above, except that the proportion of chalk is only one
half of that in the ordinary malm, and the cinders are unscreened.

In other brickfidds, including those near London, a certain pro-
portion of ordinary liquid malm is poured over unwashed clay, and
mixed with it so that the whole becomes an inferior maimed clay.

Quantity of Clay reqvdred, — ^The quantity of day used for
making bricks is very variable, depending upon the nature of the
day and the processes to which it is subjected.

The quantity required for 1000 bricks of ordinary si/^ ranges
from If to 3^ cubic yards, measured before digging. The stronger
the clay, the more of it is required.

Hand-Moulding. — ^The moulds used are rectangular boxes
without top or bottom, about 10 inches long, 5 inches wide, and
3 inches deep, the exact size depending upon that of the brick

92 NOTES ON BUILDING CONSTRUCTION.

required, and upon the contraction of the clay in burning, which
may be about tt or ^^ of the linear dimensions.

The moulds are sometimes made of wood edged or lined with
iron, or of sheet-iron strengthened at the sides with wood, or, as
in the best works, with sides and ends of brass protected by wood.

The mould stands either upon the table at which the moulder
works — ^in which case the bottom of the brick is flat — or it rests
upon a stock board, or bottom made to fit the mould, and upon
which is a raised projection which forms an indentation or frog ^
in the bottom of the brick.

The process of hand-moulding consists in dashing a clot of clay
into the mould, and pressing it home so as thoroughly to fill every
comer.

When a stock board is used the lower side of the brick rests
upon it The superfluous clay protruding above the top is swept
or scraped off by a strike or straight-edge of wood or steeL

Thus the lower surface of the brick is indented by the frog on
the stock board, but the upper surface is struck smooth.

When there is no stock board the bottom of the brick rests
upon the moulding-table, and the top surface is formed by means
of a plane, which is a piece of board about 9 inches by 3
inches with a short vertical handle near one end.

Slqp-motUding is the term used when the mould is dipped
frequently in water to prevent the wet bricks from sticking to it

Sand-motdding is when the mould is sprinkled with sand or
fine ashes for the same purpose, and is considered to produce
cleaner and sharper bricks than slop-mouldiag.

Bearing off. — ^As each brick is moulded it is disposed of in
one of two ways —

1. It may be carried by a boy in the mould to the drying floor
or ground, and tliere deposited, the mould being taken off and re-
turned to the moulder. Or,

2. It may be deposited upon a pallet (a piece of board f inch
thick, the same width as the mould but longer), and placed by
the boy upon a bearing-off or Aacfc barrow for removal to the
drying ground. These barrows are made with springs, and run
upon smooth wrought-iron wheeling plates, so as to shake the
brick as little as possible.

Drying. — The raw moulded bricks maybe dried either in aheds
under cover or out of doors.

Drying in Sheds. — Drying sheds are extensively used in

^ Sometimes called a kick.

BRICKMAKING. 93

Nottuighamshire and the Midland counties, and they insuie the
great advantage of being independent of weather in drying the
bricks.

Where coals are cheap the sheds may be warmed by flues run-
ning under the floor. This secures the raw bricks against the
efifects of frost, and enables the brickmaking to be continued
throughout the winter.

Dryino out of Dooes. — Hcuikmg. — Bricks to be dried out of
doors are placed upon hacks, which are long parallel banks
raised about 6 inches from the ground. They have a slight in-
clination toward the kiln to facilitate drainage and transport of
the bricks, and are sometimes made of brick rubbish and ashes so
that they may be quite dry.

The bricks are placed upon the hacks, sometimes laid square
in plan, sometimes diagonally, and piled up. They should not
be more than eight courses deep, or the lowest course would be
liable to be crushed.

Sdntling, — ^When the raw bricks are half dry they are scirUled,
that is, placed diagonally and a little distance apart, so that the
wind may pass between them. They therefore take up more
room in plan, but as the bricks are drier, about fourteen courses
may be piled up instead of eight as before.

The bricks on the hacks are generally protected from the wea-
ther by light coverings or roofs, made of straw, called lev^s, or by
boards or tiles.

In permanent brickyards the hacks are sometimes covered by
sheds, with sliding roofs so that they may be uncovered in favour-
able weather and closed in case of rain, or when the sun is so
strong as to warp the bricks.

The time of drying varies according to the weather. The raw
bricks generally take about ten days befoi'e being scintled, and
about three to six weeks for the whole process of drying.

Maohine-Moulding, — ^When there is a large number of bricks
to be made at the same spot, it pays to set up machines for
moulding, and in cases where the clay is very hard, stony, or in
any way refractory, machines become a necessity.

There are several varieties of machines for brick-moulding, but
they may be divided into two general classes. These will be just
referred to, but to describe even the most common brickmaking
machines in detail would be beyond the province of these Notes.

Plastic Clay Machines. — In these the clay is first pugged in the
machine, next forced through an opening of about 10 inches by 5

94 NOTES ON BUILDING CONSTRUCTION

inches in a plastic band, from which the bricks are cut off by
means of wires, and then dried or burnt as usual

Machines of this class are suitable for any plastic clay firee from
hard lumps or stones, which, if they exist, must be taken out or
crushed.

Dry day Machines in which the clay is first reduced to powder,
then filled by the machine dry into a mould, and subjected to
enormous pressure which consolidates it, and forms a well-shaped
brick with hard even surfacea

These machines are well adapted for stony and marly clays,
and they are economical inasmuch as they save the expense and
time employed in drying, which process is, of course, unnecessary

Some machines receive the clay in a semi-dry condition, and
deal with it in the same way as the dry clay machines just men
tioned.

Pressed Bricks are made by placing oidinaiy law bricks when nearly diy
in a metal mould or die, and subjecting them to poweiM compreedon under
a piston.

This may be done in hand presses, or in larger machines worked by steam
power.

Such treatment giws the bricks good faces and arrises, hut they requin
more care in drying and burning, and the oil necessarily used, gives them a
glazed surface, which peels off upon exposure to the weather.

Dressed BrUks after being moulded are beaten with a dresser shaped like a
small cricket bat, and sometimes tipped with iron. This toughens the clay,
corrects its warping, and improves the arrises of the brick

** Polished Bricks, as they are called, are rubbed upon a bench plated with
iron, to make their surfiiees perfectly even, and are also dressed with a dresser
as before described.

<< This process is only gone through with the very best bricks, and its cost
is such that it is not employed to any very great extent" ^

Frog. — Most hand-made bricks have a hollow on one of the
larger surfaces called the " frog " or " kick."

The object of this is to aSbrd a key for the mortar. The reason
why there is not a hollow on both sides in hand-moulded bricks
is that the top of the brick is struck off to a flush surface by the
moidder.

Bricks should be laid with the hollow uppermost.*

Wire-cut bricks (see above) have, of course, no frogs.

In some machine bricks made by pressure there is a frog on
each side.

Burning. — Bricks are burnt in ''dampsj' or in ** kilns" ac-
cording to the practice of the locality.
1 Dohson. ' Except when they are to receive a layer of asphalte for a damp oomse.

BRICKMAKING. 95

Clamp Bubning. — Clamps are stacks of dried zaw bricks
dexterously built up over a system of flues roughly formed
with burnt bricks, and leading from Iwe^hoks or eyes at which the
fire is introduced.

Clamps in a permanent brickfield are made in a very elaborate
manner, which is fully described in Dobson On Brick and TiU
Making,

The following brief notes refer merely to the rough kind of
damp used in a temporary brickfield.

Bricks intended to be burnt in clamps should always be made
from clay mixed with ashes or breeze, so that they contain fuel
which enables the fire to seize upon them and bum them through-
out more readily.

Building the Clamp, — Before building a clamp the ground is
first made firm, thoroughly drained, and sometimes formed to a
dish-shaped section.

On the ground is placed a foundation of burnt bricks on edge
dose together to keep out the moisture from the earth, so that the
bricks may lean inwards towards the centre of the clamp, and not
tend to fdl outwards.

[This foundation course is sometimes omitted, especially if the
ground has been the site of a recently burning damp, so that it
is pretty dry.]

The clamp itself is commenced by laying two courses of
burnt bricks on edge, in parallel lines. In the lowermost
course of these two the paralld lines run diagonally across the
damp, with spaces about 2 inches wide between the lines.
The uppermost course is laid crossways upon the lower, the lines
of bricks being paralld to the end of the clamp, and the bricks
close together. The spaces between the bricks are filled in with

In laying these courses the live-holes^ about 9 inches square
are left right across the damp, filled up with faggots &i^d the
whole covered with breeze from 5 to 7 inches thick (marked p in
Kg. 6).

Upon the layer of breeze, j>, is placed the first course of raw
bricks as headers; along the clamp, above this course, anothw
layer of breeze, o, from 4 inches to 7 inches thick ; and then
alternate heckling and stretching courses of raw bricks on edge^

1 In many cases there is onl j one liTe-hole— near the end of the damjv &> in Fig.
4. I^ however, the burning does not keep pace with the building of the dampw
Hye-holes are formed at interrals, so as to start the burning at other points.

96 NOTES ON BUILDING CONSTRUCTION

ap to a height of 10 or 12 feet^ On the uppermost course
of raw bricks a 3 -inch layer of breeze is sometimes spread, and
the top of the clamp is covered with a casing of burnt bricks
two or three courses deep.

In some cases a thin layer of breeze (about f inch thick) is
spread over the top of each course of raw bricks throughout the
damp. In other cases a little breeze is inserted only at the
edges of the courses.

In rough clamps used for temporary works, the ends and sides
are smeared with clay. In permanent brickfields they are cased
with burnt bricks.

The bricks nearest the outside of the clamp are tilted a little
upward by the insertion of bats, so that they may not have a
tendency to fall outwards. ^

Figs. 4 to 7 are taken from measurements of a clamp in one
of the Kentish brickfields.

Fig. 4 is a plan of one end of the damp, showing the live-
hole and the arrangement of the bricks in the first course.

Fig. 5 is a plan of part of the second course.

Fig. 6 is an enlaiged section of one of the sides of the
damp, showing at ; how the bricks are packed so as to give a
batter to the outer wall of burnt brick.

0 is a layer of breeze 4 to 7 inches thick, p a layer 5 to 7
inches thick.^

Fig. 7 is a longitudinal section of the damp — which may
be of any length.

Time of Burning. — The operation of burning takes from two
to six weeks. A good deal depends, however, upon the situation
and direction of wind. The nearer the live-holes are together the
quicker the burning.

The completion of the burning process is indicated by the
settling down of the top of the clamp, caused by the shrinking of
the bricks as they become burnt

Qwality of Bricks, — ^The bricks taken from a clamp will be
found very unequal in quality. Those from near the eyes are
often fused together, or misshapen, forming hwrrs. Those near
the outside are underbumt and soft, and are called Place bricks.

Again, much depends upon the proportion of breeze used in the
clamp. Too much will cause the bricks to be weak and porous,

^ In some clamps a third layer of breeze some 2 or S inches thick is introduced
between o and the mass of raw bricks above it.

BRICK-BURNING,
Illustrations op Parts of a Clamp.

Fig. 4.

Section of part of Clamp on line C D,
Fig. 6.

Pl<m ofarrcmgemmt of

Second Course,

Fig. 6.

Broken Section on Une A B.

Bwrnt Brick shown thus
Fig. 7.

B.a — ^m

NOTES ON BUILDING CONSTRUCTION.

The quantity of breeze required will vary a good deal accord-
ing to the quality of the clay, but the following may be taken as
an approximation per 1000 bricks: —

Mixed with the clay — ^ chaldron ; in the clamp— ^ chaldron.
Besides about 2 to 3 cwts. of coal in each fire-hole, that is about
^ cwt. per 1000 bricks.

Kiln Burning. — There are several descriptions of kilns used
for burning bricks, but it will only be necessary to refer to those
that are likely to be used by the engineer or builder in estab-
lishing a temporary brickfield to supply bricks for special works
in progress.

Several forms of kiln, used chiefly in permanent brickmaking
yards, may be excluded, or very lightly touched upon, as being
interesting to the brick-manufacturer rather than to the engineer.

Scotch Kiln.^ — The form of kiln most commonly used in the

tftttttttttttttttt

Fig. 8. JSlevation.

Fig. 9. Oround-plan.

United Kingdom for making a moderate supply of bricks is

known as the Scotch kiln.

The Scotch kiln is a rough rectangular building, open at the
top, and having wide doorways at the
ends. The side walls are built of old
bricks set in clay, and in them are seve-
ral openings called fire-holes, or *' eyes,"
(e e, Fig. 9), built in firebricks and fire-
clay, opposite one another.
Fig. 10. Cross SecHm, ^^ ^^ ^^ ^^^j^^ ^^ arranged in

the kilns so as to form flues connecting the fire-holes or eyes, and
^ Sometimes called tlie Dutch Kiln.

BRICK-BURNING. 99

they are packed so as to leave spaces between the bricks from
bottom to top, through which the fire can find its way to and
around every brick.

After the dried bricks are '' crowdedl' i,e, filled into the kiln,
the ends are built up, and plastered over with day.

At first the fires are kept low, simply to drive off the
moistura

After about three days the steam ceases to rise ; the fires are
allowed to bum up briskly ; the draught is regulated by par-
tially stopping the fire-holes with clay, and by covering the top
of the kiln with old bricks^ boards, or earth, so as to keep in the
heat.

In from 48 to 60 hours the bricks will be suflBciently burnt,
and they wiU be found to have settled down.

The fire-holes are then completely stopped with clay, all air
excluded, and the kiln is allowed to cool very gradually.

jPW. — ^About a half-ton of soft coal is required for burning
1000 bricks. The exact quantity depends upon the nature of
the clay, the quality of the fuel, and the skiU in setting the kiln.

Size of KUn, — ^A convenient size for a kiln is about 60 feet
by 11 feet internal dimensions, and 12 feet higL This will con-
tain about 80,000 bricks. The fire-holes are 3 feet apart. These
kilns are often made 12 feet wide, but 11 feet is enough to bum
through properly.

Time of Burning and Produce, — A kiln takes on an average a
week to bum, and, including the time required for crowding and
emptying, it may be burnt about once every three weeks, or ten
tunes in an average season. This will produce about 800,000
bricks, that is about as many as would be tumed out by two
moulders in full work.

The bricks in the centre of the kiln are generally well bumt
Those at the bottom are likely to be very hard, some clinkered.
Those at the top are often badly bumt, soft, and unfit for exterior
work.

A modificaium of the Scotch KUn is used in Essex and Suffolk. The floor
is made with openings like lattice work, through which the heat ascends
from arched furnaces underneath.^

Ck>mparative Advantages of E^iln and Clamp Burning. — The
following advantages are claimed for kiln-burning over clamp-
burning: —

1 DoljflOD.

BRICK-BURNING. loi

1. In kilns the bricks are nearly all turned out of the same
quality, being equally burnt^ and are more uniform in colour; where-
as the bricks produced from different parts of the same clamp
vary greatly in quality, and many of them are almost useless.

2. For kiln-burning the bricks need not stand so long on the
hacks to dry, because the fires in the kiln can be r^ulated so as
to drive off the moisture gradually.

This prevents warping, which often occurs with bricks clamped
in too moist a condition.

3. Though the kiln-burning requires more fuel, yet the speed
with which the crowding, burning, and discharging take place, the
absence of waste, and the superior quality of the bricks produced,
render it preferable even from an economical point of view.

Hoffmann's Kiln is naed chiefly in brick-maniifactories on a large scale,
where a great number of bricks is required annnally,and a continuous supply
has to be kept up ; but it is also employed in making bricks for very ezten-
sive works where several millions of bricks are required.

This kiln is circular in plan.

It oonsiBts of an annular tunnel-shaped chamber (marked 1 to 12, Fig.
1 1) of brickwork lined with firebricks.

At certain equidistant points there are grooves formed in the sides of this
aiiTtnUr chamber, so that it can be screened across by an iron shutter tem-
poraijly inserted (see S, Fig. 1 1) at any of these points.

The portions of the kiln between these points are called ^ chambers " or
^ compartments."

They are marked 1 to 12 in Fig. 1 1 ; each of them is connected by means
of a flue, fy with a high central chimney, C.

The number of compartments varies in different kilns from 8 to 24, but a
IS-chambered kiln is found in practice to be the most convenient for the
purpose of the engineer in providing a temporary brickfield to supply special
works.

Each flue can be cut off from the chimney by lowering upon it a cast-iron
damper, d.

Each compartment has a doorway leading outside the kiln, marked D in
the figure. This doorway can be filled up by dry brick walls with sand
packed in between them.

Kre-holes with covers are provided at /A, /^ by which fuel in the shape of
powdered coal may be supplied to the bricks.

The object of these arrangements is to utilise aU the heat produced by
the fuel, and thus to save expense in firing.

Thus in a 12-chambered kiln on a certain day the chambers might be in
use as shown in Fig. 1 1.

The annular chamber is dosed by an iron shutter at S, between compart-
ments 12 and 1.

The flue from No. 12 is placed in communication with the chimney \fj
mising the damper, d^ ; all the other dampers are closed.

The state of things is then as follows ; —

I02 NOTES ON BUILDING CONSTRUCTION.

Chamber No. 1 is being filled with raw bricks.

„ No. 2 is being emptied of cold burnt bricks.

„ Nos. 3, 4, 5, 6 contain bricks which have been burnt and are

cooHng.
„ Nos. 7, 8 contain bricks which are being burnt, fuel being sup-

pli^ to them through the fire-holes, f\ fh.
„ Nos. 9, 10, 11, 12 are drying and becoming very hot under the
influence of the heat firom Nos. 7, 8.

The cold air is entering through the open doors of 1 and 2, and proceeds
in the direction shown by the arrows. Becoming partly heated by passing
over the cooling bricks in 3, 4, 5, 6, it enters 7 and 8, whence it goes on in
a highly heated state to dry and heat the raw bricks in Nos. 9, 10, 11, 12.
Meeting the screen between 12 and 1, it passes through the flue Z^,, goes up
at <f J, into the chimney.

The next day

No. 2 would be filled with raw bricks.

No. 3 would be emptied of cold burnt bricks.

Nos. 4, 6, 6, 7 would contain burnt bricks cooling.

Nos. 8, 9 would contain bricks burning.

Nos. 10, 11, 12, 1 would be drying.

The screen would be between 1 and 2, and the smoke, etc, would escape up
the chimney through the flue /i, the damper d^ being raised, and all the other
dampers down. The doors Di D3 would be open ; all the other doors shut

A similar change is made each day, so that the kiln bums continuously^
never being allowed to go out except for repairs.

Size and Produce of Kiln, — ^Each chamber, if made about 36 feet long, 15
feet mean width, and 8 feet high, will hold 26,000 bricks.

12 X 25,000 = 300,000 bricks may therefore be burnt in the whole kiln
every twelve days, or (as the bricks are not filled in or unloaded on Sundays)
say once a fortnight.

Such a kiln will therefore bum some four or five million bricks per annum.

Disadvantages, — The great drawback to the use of Hofimann's kiln is the
first cost of its constraction.

It is necessary to bum some six to ten million bricks before the saving in
fuel has compensated for the cost of building the kibi.

It is therefore not adapted for burning bricks for special works unless they
sre on a very large scale.

It is, however, the most economical form of kiln for permanent brick-
making works turning out a large annual supply of bricks.

Advantages, — ^The advantages of Hoffmann's kiln are —

1. Eeonomtf of FiuL — ^In Scotch and similar kilns a great deal of the heat
from the burning fuel, and also all the heat from the bricks when cooling,
passes away and is wasted ; by this kiln they are both preserved, and utilised
in drying and heating the bricks before burning.

The result is that only 2 to 3 cwt of eoal dust and slacks costing 4d. 01 5d.,
are required per 1000 bricks, instead of half a ton of good coal, costing 48. or 5a

The prices given are those quoted by the patentees, and vary of course in
different localities.

2. There being no rapid draught, the hot gases fill the chambers, and the
bricks in all parts of the kiln are bumt equally well

BRICK-BURNING. 103

3. The bricks can at any time be examined, and the burning regulated,
through the fire-holes.

4. As the fuel is thrown into the chambers after they are at a high heat,
wood, turf, or coal can be used.

5. The charging and emptying of the kiln goes on continuously and with-
out interruption, so that a regular supply of bricks can be maintained.

6. The height of the chambers, only 8 or 9 feet, is such that there is no
danger of crushing the lower courses when the bricks are raw or at a high
temperature.

7. The bricks are not liable to injury by sudden changes of temperature.

8. There is no smoke, as the combustion of the fuel is perfect.
ModificaJtioM of HoffmomrCi Kilm are used in different parts of the country.

In many of them the chambers are differently arranged. They are often placed
in a straight line, and the waste heat from each is utilised in a somewhat
similar manner. Among these may be mentioned Lancaster's, Morand's.
Clayton's, Pollock and Mitchell's, and Chamberlain and Wedekind's kilns.

BulVi patent Semi-eontimums Kiln is said to utilise the waste heat and
thoroughly to consume the fuel, without expense in construction of a yery laige
kiln. The expenditure of coal is stated to be about 3 cwts. per 1000 bricks.

The bricks are packed in a somewhat elaborate manner. The whole con-
struction is fully explained in Engineering of the 2 2d October 1875.

Cupolas, or, as they are locally called, ovens, are small circular domed
kilns. They are used in Staffordshire for the celebrated bricks of that dis-
trict (see p. ] 08). They are sometimes used in other localities, and also for
burning firebricks.

Other Forms of Kiln. — An immense number of different kilns are in use
for burning bricks and tiles of special descriptions. New forms of kiln are
invented nearly every week. It would be impossible, for want of space, to
describe even a few of these, and such a description, if given, would be inte-
resting to the manufacturer rather than to the engineer or builder.

Classifloation of Bricks. — Building bricks may, for the pur-
poses of the engineer or architect, be divided into three classes.

1. Cutters or Biibbers, i,e, bricks intended to be cut or rubbed
to some shape different from that in which they were originally
moulded.

2. Ordinary Bricks, intended to be used without cutting except
where required to form the bond.

The best of these are selected for fronts, and are termed facing
bricks.

Specially hard varieties are used for coping, also for paving,
quoins, and other positions where they will be subjected to unusual
wear.

3. Vhderbumt and misshapen Bricks, only fit for inside work.
Of each of these classes there are in most brickfields several

varieties, varying in quality according to circumstances. Their
general characteristics are, however, as follow : —

I04 NOTES ON BUILDING' CONSTRUCTION

CuTTEBS or EuBBERS are purposely made sufficiently soft to be
cut approximately to the shape required with a trowel, and then
rubbed to a smooth face and to an accurate shape.

To ensure this they are made of washed earth carefully freed
from limips of all kinds, and uniform in composition throughout
its mass.

The best rubbers are burnt to a point a little short of vitrification.

Inferior kinds are often stinted in firing ; the cohesion between
the particles is small, and they are easily destroyed by rain or frost.

For the sake of durability it is better to avoid rubbers in all
exposed work, and to use ''purpose-made" bricks moulded to the
shape required and thoroughly well burnt

This is often done in good work.

The characteristics of good rubbers are mentioned at page 111.

Obdinary Building Bbicks. — ^The second class of bricks in-
cludes the bulk of those required for building. The qualities and
characteristics of these vary, not only in different localities, but
also in the same brickyard (see p. 105).

Such bricks are made either from washed earth or malm, from
partly washed earth, or from earth which has merely been tem-
pered, not washed at all.

They should be hard and well shaped, those most uniform in
colour being selected for facing, and the whole of the remainder
being fit to use for good soimd work.

Undebbubnt and Misshapen Bbicks. — ^The underbumt bricks
of the third class are generally known as grizzU or fkice bricks,
in some places as samd bricks.

They are always soft inside, and sometimes outside also, are
very liable to decay, and unfit for good work.

They are, however, often used for the inside of walls.

Names of diflbrent VarietieB of Brioks. — ^As before mentioned,
the names given to different classes of bricks vary in different
districts, and even in different brickfields of the same district

Classification of Clahp-burnt Bricks. — The subjoined list of the
names for damp-bnznt bricbs, adopted in a Kentish brickfield supplying the
London market, may be taken as a specimen.

Following it is a description of some of the more important vatietiea.

The bricks are divided geneiall j into three classes — MaitM^ Wathtd^ and
Ccmmon — according to the manner in which the earth for them is prepared
(see p. 91). For the third or (kmnum class the earth is not washeii at alL
All three classes are moulded and homed in exactly the same manner, and
are then further sorted into a number of varieties according to the manner
in which they have been affected by the fire.

VARIETIES OF BRICKS.
The claBses are subdivided as follows : —

105

Malms

Washed

Common

Price per Thousand at Brickfield.

/Cutters

140/.

Best Seconds .

70/.

Mean do.

80/.

Brown Facing

Paviors . 66/.

Hard Paviors .

60/.

Shippers

32/6.

Bright Stocks

37/6.

Grizzle

19/.

VPlace

16/.

/Shippers

28/6.

Stocks

20/.

Hard Stocks

20/.

1 Grizzles

17/.

V Place

13/.

/Shippers

28/.

1 Stocks

24/.

Grizzles

16/.

1 Rough Stocks

16/.

VPlace

12/.

The prices above mentioned were those current when these Notes were
revised. The prices vary of course from time to time, and depend upon
seasons, etc. The differences between them serve, however, to show the
relative value of the different classes of bricks.

Of the above classes miltien have already been described.

Seconds are similar to cutters, but with some slight unevenness of colour.

Bright FrorUt are the corresponding quality from '< washed " earth.

Fcicing Pernors are hard-burnt malm bricks of good shape and colour
used for facing superior walls.

Hard Favicrs are rather more burned, and slightly blemished in colour.
They are used for superior paving, coping, etc.

Shippsrs are sound, hard-burned bricks, not quite perfect in form. They
are chiefly exported, ships taking them as ballast.

Stocks are hard-burned bricks, fairly sound, but more blemished than
shippers. They are used for the principal mass of ordinary good work.

Hard Stocks are overbumt bricks, sound, but considerably blemished both
in form and colour. They are used for orddnary pavings, for footings, and in
the body of thick waUs.

OrimU and Place bricks are underbumt They are very weak, and two
out of five ^ common " or unwashed place bricks are allowed to be bats, the
stones left in the unwashed earth making them very liable to breakage.

These two last-mentioned descriptions are only used for inferior or tem-
porary work, and are commonly covered with cement rendering to protect
them from the weather when intended to be permanent

Ckuffs are bricks upon which rain has fSallen while they were hot, making
them full of cracks, and perfectly useless.

Bwrrs are lumps of bricks vitrified and run together. They are used for
rouffh walling, artificial rock-work. etc.

io6 NOTES ON BUILDING CONSTRUCTION

Bats are broken bricks.

Of the above varieties those from '< common " or unwashed day are hardly
ever quite perfect in form on account of the stones left in the earth, which
make them shrink unequally, and become distorted in burning.

Bricks from " washed ** clay suffer in the same way to a less degree.

Classification of Eiln-burnt Bricks. — Eiln-bumt bricks are generally
pretty equally burnt, and are classed chiefly according to the process by which
they are made.

Thus in one yard the classification is as follows : —

Patent bricks.
Common hand-made.
Copper moulds.
Pressed bricks.
Dressed pressed bricks.

Id another yard the classes are

Best white pressed.
Second do. do.
Pink do. do.
White wire cut.
Second do. do.
Pink do. do.

The Barham Company's bricks are thus classified in their circulars : —
No. 1. Pressed Gault (Facing).

2. Da (Mingled).

3. Do. (Paviors).
No. 1. Wire Cut (Facing).

2. Do. (as they rise from kiln).

3. Do. (Mingled or discoloured).

VarietieB of Bricks in the Market. — The bricks used in ordi-
nary buildings generally are, or should be, the best that are made
in the neighbourhood.

Some descriptions of bricks, however, are universally known,
and are used even outside the locality in which they are made,
either for special purposes, or in buildings of such importance as
to justify incurring the expense of carriage.

A few of the more important of these varieties may now be
noticed.

White BriokB. — ^The best materials from which to make white bricks
are a refractoiy clay, which will naturally bum to pale yellow or white, and
a fine white or yellow sand, which vitrifies slightly under a strong heat

In the absence of such material, however, every clay which does not con-
tain more than 6 per cent of iron will bum into a white brick, provided
it is strong enough to stand & sufficient quantity of chalk mixed with it.
In Ihe case of very refractory clays the mixture with a large proportion
of chalk will render the resulting brick friable.

The processes usually gone through in the manufacture of white bricks
do not differ very materially from those appUed to other bricks.

VARIETIES OF BRICKS, 107

''The best mode of manufacture is to grind the clay dry, mix it tho-
roughly with sand while dry, and then through a press.*' ^

White bricks are frequently burnt in close kilns, carefully protected
from smoky flames and soot, thoroughly burned in a dead heat, and allowed
to cool down ; gradually, or the feusee will be full of cracks.

The days firom which white bricks are made are generally heavy, and
they are in such case lightened by being made hollow or perforated.

Qreen stains are often noticed on the surface of white bricks if they are
underbumt

These stains can generally be rubbed off when the brick is dry ; if they
reappear they can be permanently removed '^ by mixing up a wash of clay
and sand of which the brick was made with sulphate of copper, painting
over the brick with it, and leaving it till it is perfectly dry, and then
rubbing it off with a brush." ^

White bricks may be procured firom several parts of England. Some of
the best come from Suffolk, Essex, Araley, Ewill in the district of the Med-
way ; firom Dorsetshire (Beaulieu bricks and others) ; from the London brick-
fields ; from Exbury and Cowes. Others are made in Cambridgeshire,
Devonshire, Lincolnshire, and the Midland counties.

A few of the best known varieties will be further noticed.

Gault Bricks are made fix)m a band of bluish tenacious clay which lies
between the Upper and Lower Greensand formations.

This day in its natural state contains sufficient chalk to flux the mass,
and to give the brick a white colour.

The bricks made from this clay are of very good quality ; extremdy hard
throughout, very durable, but difficult to cut.

They are generally white, but the lower qualities have a pink tinge
caused by irregularities in burning.

Bricks made from Gault clay are generally very heavy. To remedy this
a large frog is sometimes formed in tiie brick, or it is perforated through-
out its thickness.

Bricks of this description are manufactured by the Burham Company at
Burham, near Rochester, and at Aylesford, near Maidstone ; also at Folke-
stone, near Hitchin, and at other places.

Suffolk white Bricks are also made firom the Gault day.

They contain a very large proportion of sand which makes them useful
for rubbers.

They are rather soft for ordinary building purposes, but harden in time,
which is attributed to the silidc acid in the clay acting upon the chalk so
as to form some of it into a silicate of lime.

Beaulieu Brickt, of a light straw colour, are made from clay dug upon the
Beaulieu river, near SouthamptoiL

BaUingdon Briekt^ made by Beart's process near Sudbury, in Suffolk, are
much used for facework.

Beast's Patent Bricks are made at Arsley,near Hitchin, from the Gault day.

There are different classes. ^* White rubbers, hand-made, moulded, solid
brick, equal to the best Suffolks. No. 1, best sdected white facing brick
(pierced) and ordinary. These two are of uniform colour, hard and well
burnt, and used extensively for facings. No. 2, mingled red and pink, vaiy

^ Building News, Sept. and Oct 1874.

io8 NOTES ON BUILDING CONSTRUCTION.

from the above only in colour, and aie equal in every respect to the beat
made stock bricks.'' ^

The day contains lime, and requires to be burnt with great care, or the
lime will remain in a quidL state, and slake after the brick is in use.

Staffordshire Blue BriolcB are made from the clays and marls of that
county^ which contain from 7 to 10 per cent of oxide of iron.

They are burnt in circular ovens with domed tope, being raised to a very
high temperature, which causes the peroxide or red oxide to be converted
into the protoxide or black oxide of iron.

These bricks are generally of a dark-blue or nearly black colour, with
smooth glassy surfaces. They are very durable, impervious to water, and
will resist enormous pressure.

Bricks of this description are extensively used throughout the country for
paving, coping, channels, and other special purposes in which great hardness
and durability are required.

For building ordinary strong work the second-class Staffordshire bricks are
more suitable than the first quality, as the former have router surfaces to
which the mortar adheres more firmly.

An inferior class of these bricks is made by the use of a surfiEuse wash of
iron. These look well for a time, but the colour does not wear well.

Dtut Bricki are blue bricks, for which coal-dust is used in moulding instead
of sand. They have glossy surfaces, are very hard, and are used for paving. >

Bed and Drah coloured bricks are alao made in Staffordshire. The former
are used for building, and the latter chiefly as a fire-brick, where intense
heat is not required.'

Tipton Blue Brieki are Staffordshire blue bricks from the neighbourhood of
the town after which they are named.

Black BridkB are obtained fr*om Cowbridge in South Wales, from Maiden-
head in Berkshire, and fr*om other places.

Some inferior black bricks are made with a mixture of soot, and are weak
and almost useless.

Fabbhah Rbd Bricks are made from a moderately plastic day, which is
found in very deep beds around the town of Fareham, and in other places in
the neighbourhood.

They are dressed or batted (as described at p. 04) when partially dry,
and thus brought to a very true surface. They are also carefully burnt in
small oven kilns holding from 20,000 to 30,000 each.

These bricks are of a fine deep-red colour, and have been much used in
London for superior buildings.

The facework of St Thomas's Hospital is of Fareham bricks, and many
are being used in the new Law Courts.

Sometimes these bricks are rubbed so as to obtain very fine surftuses and
thin mortar joints, but this removal of the outer skin is bad, as it tends to
make the brick decay quickly imder atmospheric influences.

NoTTiNOHAX Patbiit Brickb are made by the dry clay process, the clay
being ground and subjected to pressure of about 200 tons on the brick in
moulding.

They are very dose in texture, aod have good surfaces and anises, but they
appear to be defldent in toughness, and do not *^ ring" properly or weather well

They are of a dull red colour. Many of them are burnt in Hoflbiann't

1 Qwilt > DobBon.

VARIETIES OF BRICKS. 109

kilns, in which case the ends are genenllj of a yellowish shade. This is
owing to the ends being exposed to the fire, whereas the other parts of the
brick are protected.

Sometimes bricks are pnrposely packed on end, so as to protect the ends
from fire, make them red, so as to afford headers of an nniform colour.

These bricks were nsed for part of the St Pancras Station.

Lanoashibb Rbd Pbsssbd Faoino Bricks are made by Platt^s patent
brickmaking machine.

I>atoh dinkars are small bricks, well burnt, very hard, vitrified through-
out, and sometimes warped.

They are used almost entirely for paving.

AdamamHiM Clinkers are similar bricks, harder, denser, and heavier, of a
fine pink- white colour and smooth suriiEioe.

They are sometimes chamfered on the edge so as to give a firmer foothold
when used for paving.

Terr(HnetaUie Clinken are bricks of the same size and shape, made from a
clay which is burnt veiy hard to a dark-brown or nearly black colour.

Enamelled Brioks have a white or light yellow glazed surfeice like that
of china.

This is produced by a thin coating of white material over the brick, which
in inferior descriptions is apt to peel off.

Bricks of this kind are much used for the sake of cleanliness in lavatories,
urinals, butchers' shops, dairies, etc ; also in order to obtain reflected light^
as in some of the undexground railway stations.

Salted BridkB have a thin glaze over their sux&ces, produced by throw-
ing salt into the fire during the buming process.

Moulded Bridka are produced in every variety of pattern, from simple
sections like those of cornice, plinth, and string-course bricks, already men-
tioned, up to the most elaborately decorated blodu of different forms, such as
voussoirs for arches, diaper patterns for walls, panek, string-courses, etc.

The simpler patterns are made in moulds furnished with shifting sides and
ends on which the pattern is raised or sunk. These can be screened up
against the soft clay, and then released so as to liberate the moulded brick.

Sometimes the pattern is formed on the stock-board, or on a plaster cast
which takes its place.

In the more elaborate patterns iron moulds are used, which are opened
and closed by simple machinery.

Peihei^s OfTumental Bricks are made by the Burham Oompany from Qault
elay forced into a hinged iron mould.

They can be made to almost any design, however elaborate, and afford a
cheap and very durable means of decoration.

Pallette BtIoIcb ^ rebated on edge so as to hold a l^inch fillet securely
in the wall, splayed from { inch at one edge to \ inch at the other, have been
occasionally used of late but are not recommended, as the advantage gained \b
not to be compared to the extra labour and expense involved." >

Gonorete BtIoIcb should hardly be noticed in this chapter, as they are
not made of clay, and they do not require buming.

Bodmet's Bridsi consist of a species of fine concrete, the constituent parts
of which vary, some being of about ^ to ^ of its weight of sand with selenitic
lime or cement, others of black furnace slag mixed with about A of its
weight of lime or cement according to quality.

^ Seddon.

no NOTES ON BUILDING CONSTRUCTION.

The ingredients are filled into monlds, and subjected to considerable pres-
sure which binds the particles together.

The moulded bricks are then left to ripen and harden out of doors for a
period which varies with the setting properties of the lime or cement used.

The resulting bricks are hard and dense, with good arrises and surfaces,
and they weigh about 58 cwts. a thousand.

The cost of labour for making these bricks is said to be from 3s. to 3s. 6d
per thousand.^

Wood! 8 Patent Concrete Bricks are similar to those just described. They are
made at Middlesborough from slag reduced by agitation in water to the state
of sand. The slag sand is ground and mixed with | its bulk of lime. The
mixture is forced into moulds under a pressure of about half a ton per square
inch. The bricks are dried in the air, and are then ready for use.

These bricks may be made with ordinary sand or crushed stone instead of
slag sand.

Slag Bricks are made by running molten slag into iron moulds. The
blocks are removed while the interior is still molten, and then annealed in
ovens.

GharaoteriBtios of good Bricks. — Freedom/ram Flares or Lumps.
— Good building brick should be sound, free from cracks and
Haws, also from stones, or lumps of any kind.

, Lumps of lime, however small, are specially dangerous ; they
slake when the brick is exposed to moisture, and split it to pieces.

A smaU proportion of lime finely divided and disseminated
throughout the mass is an advantage, as it affords the fiux neces-
sary for the proper vitrification of the brick.

In examining a brick, lumps of any kind should be regarded
with suspicion and tested.

Shape and Surface, — In order to ensure good brickwork the
bricks must be regular in shape and uniform in size.

Their arrises (or edges) should be square, straight, and sharply
defined.

Their surfaces should be even, not hollow ; not too smooth, or
the mortar will not adhere to them.

Absorption, — The proportion of water that a brick will absorb
is a very good indication of its quality.

Insufficiently burnt bricks absorb a large proportion and are
sure to decay in a short time.

It is generally stated in books that a good brick should not
absorb more than -^ of its weight of water.

The absorption of average bricks is, however, generally about
I of their weights, and it is only very highly vitrified bricks tha^
take up so little ^ ^ or n^. (See p. 114.)

^ Spons' niuetraUd Price Book.

SIZE AND WEIGHT OF BRICKS. xii

TtoAurt, — Good bricks should be hard, and burnt so thoroughly
that there is incipient vitrification all through the brick.

This may be seen by examining a fractured surface, or the
surface may be tested with a knife, which will make hardly any
impression upon it unless the brick \& underbumt

A brick thoroughly burnt and sound will give out a ringing
sound when struck against another. A dull sound indicates a
soft or shaky brick.

A well-burnt brick will be very hard, and possesses great
power of resistance to compression. (See p. 115.)

Chabactbkistics of Good Eubbbrs. — ^A really first-class rubber
(see p. 104) will not be easily scored by a knife even in the
centre, and the finger will make no impression upon it.

Such a brick will be of xmiform texture, compact, regular in
colour and size, free from flaws of any description.

Method of dittinffuishing Clamjhbumt, Kiln-burnt, and Machine-made
Bricks. — In clamp-bnint bricks the traces of the breeze mixed with the clay
can generally be seen.

Eiln-bumt bricks very often have light and dark stripes upon their sides,
caused by their being arranged while burning with intervals between them.
Where the brick is exposed it is burnt to a light colour ; where it rests upon
or against other bricks it is dark.

In some cases care is taken to prevent this, and the best kiln-burnt bricks
are of an uniform colour.

Machine-made bricks may generally easily be distinguished, if wire-cut, by
the marks of the wires ; if moulded, by the peculiar form of the mould, letters
on the surface, etc., or sometimes by having a frog on both sides.

In many cases the marks made by pronged forks, used for hacking the
bricksy may be seen on their sides.

Sise and Weight of Bricks. — Before the year 1839 a duty
was paid upon bricks ; their size was then practically fixed by Act
of Parliament, and it has since remained materially imaltered.

Ordinary bricks in the neighbourhood of London are about 8^
inches long, 4^ wide, and 2-^ inches thick, and we^h about 7
lbs. each.

In different parts of the country the size and weight vary
slightly ; in the north of England and in Scotland they are larger
and heavier. (See p. 113.)

A very large brick is inconvenient for an ordinary man to grasp,
guid a heavy brick fatigues the bricklayer, who has to lift it when
wet and lay it with one hand.

In order to obtain good brickwork it is important that the
length of each brick should just exceed twice its breadth by the
thickness of a mortar joint.

112

NOTES ON BUILDING CONSTRUCTION

The following Table gives the Size and Weight of some of the
best known varieties of Bricks in this coimtiy. See also Tables,
pages 114, 115.

WdOHT.

Lbs.

Weioht

FKRlOOOlN
CWTB.

London Stock

6-81

60}

Red Kiln .

7.-0

Fareham Reds

8-6

416

2-6

6-8

56-2 G

Do. Rubbers .

10-9

4-8

2-9

8-8

78-6 G

Catty Brook Pressed Brick (near
Bristol)

9-6

Bridgewater Red Brick

8-76

4-8

2-75

Tianrashire Red Flossed Facing Brick

8-9

Pressed Brick from Leeds .

9-6

4-5

8-6

Scotch Brick from Sandyfauld, near
Glasgow

9-5

4-5

8-5

86-6

Bricks made from Blaize near Glasgow

4-3

8-4

8-6

Scotch Brick from Elgin (used for
partitions)

Irish Brick from Athy

Burham Wire Cut .

8-6

4-0

2-6

6-4

68-2 Q

Do. Pressed .

875

4-2

6-1

64-^ G

Suffolk Brimstone .

4-6

2-6

6-8

607 G

Do. White

9-2

4-8

2-6

6-8

66-2 G

Staffordshire thin Paying .

8-9

Do.

6-1

i56

Staffordshire Brick-on-edge, for edge
paving

7-8

Tipton Blue

Adamantine Clinker

Dutch Clinker

1-66

Tho Figuns mariced G are from Grant's Ezperiments, Proceedings InsL do, Engimten,
▼oL xzv. p. 8&

BRICKMAKING. 113

Tests for Brioks. — ^The best method of testing bricks is to
see if they ring when struck together ; to ascertain their hardness
by throwing them on to the ground, or by striking them against
other bricks.

The firactured surface should also be examined in order to
ascertain if it exhibits the characteristics mentioned at page 111.

Brard's test is sometimes used for bricks, but is not of much
practical benefit, for the reasons stated at page 11.

The amount of water absorbed by bricks is to a certain extent
an indication of their quality, and their resistance to compression,
either singly or when built into brickwork, will show whether
they are strong enough for the purpose required.

The following Table shows the weight and absorption of seve-
ral different classes of bricks. The results marked L are from
experiments made by Mr. Baldwin Latham.^ The remainder are
the results of experiments made by a Mend of the present
writei^s.

' Ltttbftm*e SamUary Bngineering.

B C. — HI

114

NOTES ON BUILDING CONSTRUCTION

Table showing Absorption of Water by Different Varieties

OF Bricks.

description op brick.

Weiohts
whbvDrt.

Pebccmtaob of
Watbb

AIMWHIBILH

LB.

oz.

Malm Cutters

Malm Best Seoonds .

Malm Brown Facing Payiors

Do. Hard Paviora .

Washed Bright Yellow Fronts

Malm Shippers

Malm Bright Stocks .

ISi

Washed do. . .

Common Shippers .

Common Grey Stocks

104

Do. Hard do. .

Malm Grizzles

184

Do. Place ....

Common Place

Washed Shippers

Do. Hard Stocks

164

Do. Grizzle

Common Grizzle

Washed Place

Staffordshire Dressed Bine .

2-8 L

Do. Pressed Blue .

8-7 L

Do. Common Blue .

6-6 L

Do. Bastard

* 9

11-8 L

Machine-made Red .

9-9 L

Do. from Leeds .

100

Wire-cut White Gault

190 L

Flressed Gault

19-6 L

Brown Glazed Brick .

8-6 L

BRICKMAKING.

Strength of Bricks. — In practice bricks are subjected to com-
pression, and sometimes to transverse stress, but not to tension.

The compressive stress brought upon evenly-bedded bricks is
generally far less than they are able to bear.

In some cases, however, as in arches and retaining walls, the
stress may be concentrated upon a small portion of the brick, or
the same efifect may be produced by the bed of the brick being
uneven.

Such concentrated stresses are apt to crack the portion of the
brick upon which they act.

Resistance of Bricks to Compression.

Dimenaions of

Average

Weight
reqalred

to crush
Brick.

DESCRipnox OF Bugs.

Specimen.

Area
expoeedto
Crashing.

Weiffht
nnder

Weight
requ&ed

Authority.

Length.

Breadth.

Thickneaa.

which

Brick

Cracked.

to crush
Brick.

Sq. Inchea.

Tons.

Unbnrnt Brick

8-876

4-876

2-876

38-83

1-0

9-0

•23

Common Red .

907

4-27

3-0

88-7

9-6

67-0

0-96

Machine-made formed

9-8

4-4

8-3

40-9

•791

Red

Common Stock

8-9

4-07

2-66

36-2

128

3-668

Sittingbonrne Stocks

8-81

4*13

2-60

36-36

6-7

33-9

•93

Fareham Reds .

8-50

4*26

2-62

36-13

8-42

26-1

•72

Da Rubbers

10-19

4-88

2-94

49-64

1-40

16-7

•32

Tipton Blue

8-76

4-81

2-60

37-73

21-26

96*20

•39

Exbory Best .

8-876

4-26

2-76

37-73

21-0

28-6

•76

Do. Second

8-876

4-26

2-76

87-73

210

39-0

-77

Do. Third . .

8-60

4-1

2-6

85 06

11-8

290

-83

Suffolk Brimstone .

9-06

4-66

2-69

41-34

31-0

•77

Da Best Whites .

9-19

4-66

2-62

41-9

6-1

19-6

•47

Gault

8-76

4-26

2-76

37-18

12-7

36-1

•94

Wire-cut White Gault

9-04

4-38

2-72

391

110

1-36

Pressed Gault .

8-9

4-88

2-68

88-2

8-0

46-6

1-23

|Gault Wire-cut, No. 2

8-63

4-0

2-63

84-60

6-4

32-90

•96

Do. Pressed, No. 1

8-76

419

2-69

86-64

7-4

36-80

1-0

Staffordshire Dressed

9-07

4-47

2-97

40-3

15-6

114*

2-808

Blue

Staffordshire Pressed

8-98

4-46

2-88

39-8

21-5

1-861

Blue

Staffordshire Common

9-89

4-38

3-01

41-1

18-0

•964

Blue

Staffordshire Bastard

9-28

4-68

8-21

41-2

27 0

41-6

1-006

Brown Glazed Brick

9-0

4-39

3-39

39-6

•679

0, Grant's Bzpeii

menta, Pnctedingt Ifu

1 die. Efigifuen, vol. '

DCV. pp. 85-

88.

Baldwin L(

fttham'sAn

liiary Engi^

Mtriftg, p.

ISS.

Ii6

NOTES ON BUILDING CONSTRUCTION

The resistance of bricks to crushing is much reduced when
they are built into work, being greatly influenced by the nature
of the mortar used.

The following are the results of experiments made by Mr.
Kirkaldy for the new Blackfriars Bridge : —

BbICU 178KD » PiXRfi.

Size of
Pieni.

Cementliig MsterUL

Toms pkb

Foot bup.

At which
fitiluie

At which
crashing

began.

took place.

Inches

Common Stocks, recessed one side

14x14

lime Mortar

Do. do.

Do.

Red Bricks (machine made)

Do.

Do. (hand made) .

Do.

Gault Bricks . . . .

Do.

Roman Cement

9x9

Do.

Clark's Sudbury (machine made)

Do.

Portland Cement

Uzbridge Red (band made)

Do.

Tra7i8v&rse Strength of Bricks, — The only records, known to
the writer, of experiments on the transverse strength of bricks
do not state how the weight was applied, so that they are value-

Tmsile Strength of Brick. — ^The tenacity of brick is given by
the late Professor Bankine as varying &om 280 to 300 lbs. per
square incL

The writer is not aware of any reliable record of experiments
on this point

Different Forms of Bricks. — The different forms in vhich bricks are
made for special purposes are almost innumerable.

It would not be worth while, even if space were available, to describe
them all ; but a few of the principal varieties may be mentioned.

Ordinary Bricks are of rectaDgnlar section, both longitudinally and trans-
versely, and solid throughout They have already been described.

Purpose-made Bricks are those which are specially moulded to shapes suited
for particular situations, such, for example, as the voussoirs of arches struck to
a quick curve, the comers of obtuse-angled structures, etc. etc.

There are several advantages in having the bricks thus purpose-moulded :
cutting is saved, and the surface-skin of the brick is left inttict, which enables
the brick to resist the weather fur better than if the suriaoe were removed by
cutting.

Arch Bricks are shaped as vousBoiis of arches.

Compass Bricks taper in one direction at least If they taper in thickness
they are suitable for the voussoirs of an arch, and are called Arch bricks or
Side^wedge hriekt. If, however, the thickness is constant^ and they vary
gradually in width, they are useful for steining walls, and are aometimes
called Bullheads.

The name Compass bricks is sometimes applied only to bricks tapering in

^ HunVB Battdbook.

BRICKMAKING. 117

both directiosfly as in Fig. 13. Such brickB are used for parts of foniaces
etc etc.

Perforated Bricks (Pig. 14) have cylindrical holes through their thickness,
which makes them easier to bom (because the fire can penetrate them more
thoroughly), and lighter to handle.

Such bricks are often made from the denser and heavier clays. .

An objection sometimes stated against them is that they transmit sound
readily.

SipUti are bricks of the ordinary area, but of reduced tV^iftlmpaaj being 9
inehee by 4^ inches wide, and 1, 1 J, or 2 inches in thickness.

Soapz are bricks 9 inches long, 2^ inches wide and 2^ inches thick.

^X'X^

Angle Brick. Stretcher, Header,
Pig. 18. Kg. 14. Pig. 16. Pig. 16. Pig. 17.

Some varieties of these bricks, pierced with elaborate patterns, and used for
ventilating purposes, are made in stoneware and terracotta (see p. 134).

Hollow Bricks should be moulded from the best and most homogeneous
clay. They may be of laige size, as their shape enables them to be thoroughly
burnt, and makes them lighter to handle.

There are a great many forms of these bricks used for building hollow
walls^

Figs. 15, 16, 17 show hoUow bricks made by Messrs. Clayton, Son, and
Hewlett's machines.

The three figures show an angle brick, stretcher, and header in position
as for the angle of a wall, but spread out so as to show their construction.
They are so arranged that a solid side or end is always presented on the face
of the walL

In other forms the peif oratLons are somewhat different ; for example, as in
Figs. 18, 19 —

Stretcher.
Fig. 18. Pig. 19. Pig. 20.

The form and use of other hollow bricks are shown by the section, Fig. 27.

Tubular Bricks are hollow bricks in which there is one large perforation
running through the length of the brick.

Tubular bricks are also made in the form shown in Fig. 20, so that several
of them built up together form a pillar.

Somewhat similar bricks, but flat, instead of round, are made for building
up pilasters.

ii8 NOTES ON BUILDING CONSTRUCTION

Plinth, Ccmice, and String-Course Bricks are made of Beveial patterns.

Fig. 21.

Fig. 22. Fig. 28.

Fig. 24.

Thej have to be arranged so as to be built in as headers and stretchers,
and also for angles.

Thus Figs. 21 to 24 are all plinth bricks : a is a stretcher, b a header,
c an external angle, d an internal angle.

Those that are intended to project should have a throat on the lower side,
as in Fig. 25.

Sometimes several different forms of moulded bricks are combined to form

Fig. 26.

Fig. 27.

a cornice, as in Figs. 26, 27, which are from an advertisement by the Broom-
hall Company.

Bricks shaped like 0, Fig. 26, are known as Hollow Cornice; those of
section like p are Full Cornice, while q and r are Moulded Cornice bricks.

G> G) Q> (3>

Fig. 28. Fig. 29. Fig. 80. Fig. 81.

Fig. 29. Fig. 80. Fig. 81.

Round-ended and Bull-noeed Bricks. — Figs. 28 and 29 are for use at comers
where sharp arrises would be liable to damage.

Splay Bricks are bevelled oft on one side, like Fig. 30. They are some-
times odled slopes.

Double Cant Bricks have a splay on both sides, like Fig. 31.

Fig. 82. tig. »». Fig. 84. Pig. S5. '

Pavings are made generally of dark blue Staffordshire ware, very hard, the

BRICKMAKING.

119

sorfiBkces rendered less slippery by being indented with Antes, or with a
diamond pattern. See Figs. 32, 33.

QyOer Bricks, called also Channel and Sough bricks, are made of various
sections, such as that in Fig. 34, which shows a gutter brick with stop end.

Drain Bricks are of the form shown in Fig. 35. A number of these
placed side by side form a suitable floor for a cattle-shed, or for any
building where much liquid falls on the floor, and has to be carried off
at onca

Coping Bricks are made of several different sections to suit walls of dif-
ferent thicknesses.

Fig. 36.

When they are to project they should always be throated as in Fig. 37.

They are either prepared to receive palisades, as in Fig. 36, or left plain
with a curved or an angular top as in Fig. 37.

Copings for Platforms and Wing Walls are for railway or other platforms,
and for retaining and wing walls. They are made either plain, or (for plat-
forms) with indented or fluted surfaces.

Fig. 88.

Coping bricks are made of considerable size, even as large as 18 inches
by 6 inches by 6 inches.

Stopped ends and angles are made for all coping bricks.

Fig. 89.

Fig. 40.

Fig. 41.

Kerif Bricks for footpaths are made of the section shown in Fig. 39, and of
other sections.

Tunnel Heads are of the form shown in Fig. 40, and are made gener-
ally in fireclay for parts of furnaces.

Boiler Seatings, of the shape shown in Fig. 41, are also made in fireclay.

Besides the forms of bricks above illustrated, there are several which
cannot be described, such as Sini bricks, made in the form of a dished sink -

I20 NOTES ON BUILDING CONSTRUCTION.

Mannger (rtdby which when put together fomi a manger ; 3%ll Irkhf which
are shaped like the centre and ends of a stone sill.

Colotizing Brioka^ — ^BrickB may he coloured either (1) by mixing rab-
Btanoes with the day which will produce the reqimed colour when burnt ; or
(2) by dipping the brick in colouring matter after it is burnt

The former method may be adopted when the colouring matter is cheap
and plentiful ; the latter when it is expensive.

(1.) When the colours are mixed with the di^ it should be remembered
that red ochre bums yellow.

Yellow ochre bums red.

Iron bums red at low temperature ; black at high temperature.

Manganese bums black.

IndLni«d \ '®**"^ *^^ colours when exposed even to a white

French ultramarine, )

The above-mentioned colours may be mixed with the day in different pro-
portions according to the tint required.

(2.) When brides are to be coloured by dipping, the colouring matter is
added to a mixture of linseed oil and tnipentiney containing a little litharge
as a drier.

The colouring matters used are as followB : —

In dark red bricks, Indian red.

,, blue y^ French ultramarine.

,, black „ manganese.

M grey „ white lead and manganese.

llie bricks are heated on an iron plate, and dipped when hot, then dightly
washed with cold water, and allowed to dry.

If the brick be bumt after being dipped, it wiU be covered with a glaie.

The colour penetrates about \ inch into ordinary porous bricks (not so £u
into terracotta), and it stands the weather weU,

If the bricks cannot conveniently be heated and dipped, the liquid may be
heated and laid on.

FIEECLAY AND FIEEBEICKS.

Fixeolay is the name given to any clay which ib capable of
standing a high tempeiataie without melting or becoming soft.
Such days are also cidled rejmdory.

ZTaes in Building. — ^Fiieday is required in buildings for setting
stoTes, ovens, backs of ranges, etc.

It is also used for the manufacture of firebricks, fire lumps,
drain pipes, chimney pots, and other similar articles.

fFherefowuL — Clay of this description abounds in the coal-
measures, just beneath the several seams of coaL

The following list gives some of the counties in which fireclay
^ Roorkee TrttUim uf CfivU M^ritmring,

FIRECLA Y AND FIREBRICKS. WJ

is found, together with the localities producing the beet known
descriptions : —

Ayrshire . . EOmamocky Dean, Hfllhead, FeioetoiL

Buckinghamshize Hedgerley.

Cornwall • . .St Austella.

Derbyahiie . Borton-on-Tzent

Devonshiie . Plympton.

DonetBhiie . Poole.

Fife . . . LiUyhilL

Lanarkshire Qanikirk^ Olenboig.

Monmouthshire . Newport

Northomberland Newcastle-on-Tyne.

South Wales . Dowlais, Neath

Staffordshire Brierly HiU, Wolverhampton.

Worcestershire . \ Stourbridge, Dudley, Tipton, Hanford,

( Gomal, etc.
Yorkshire Wortley (near Leeds), EUand, Stannington, etc.

Cbmpa0t^to9^. — ^A refractory firedaj will contain nearly pure
hydrated silicate of alumina.

The more alumina that there is in proportion to the silica> the
more infusible will be the day.

The composition of different fireclays varies, however, con-
siderably.

They contain

From 59 to 96 per cent silica.
,, 2 to 36 „ alumina.
„ 2 to 5 „ oxide of iron.

A veiy small percentage of lime/ magnesia^ potash, soda.

The fire-resisting properties of the clay depend chiefly upon
the relative proportions of these constituents.

If the oxide of iron or the alkalies are present in large propor-
tion, they act as a flux, and cause fusion ; the clay is no longer
fireproof or refractory.

It will not, however, be necessary to enter in detail upon the
part played by each of the constituents that are found in fire-
clay. These constituents are the same as those found in brick
earth (though their proportions are different), and the effect they
produce upon the clay is the same in both cases (see p. 86).

The presence of an extremely small proportion of lime, potash,
or soda, may, however, improve the clay, by soldering the par-
ticles firmly together.^

When a day containing iron requires the addition of sand to

^ rent's MeUiUuray.

122

NOTES ON BUILDING CONSTRUCTION.

prevent its cracking, it is a common practice to add burnt day
instead, so as to produce the same beneficial effect without risk
of making the clay fusible.

The chemical analysis of a day is not a very safe criterion of
its qualities. The silica shown may be either soluble silica in-
fluencing the chemical constitution of the clay, or it may be sand
which is chemically inert.

In the analysis there is no distinction made between the two.

" A good fiireday should have an uniform texture, a somewhat
greasy feel, and be free from any of the alkaline earths." ^

The following Table shows the Analyses of different Clays
used for the manufacture of Firebricks : —

SiO,.

Al.O^.

KO.

NaO.

CaO.

MgO.

FeO.

Fe.O,.

Water.

Organic]
Matter. 1

i
1

Brierly HiU, Stafford-
ahire, P

61-80

30-40

...

Trace

...

0-60

4-14

...

13-11

Burton-on-Trent, G

68-08

36-89

-20

1-88

•66

•14

...

2-26

Cornwall, P

46-32

39-74

...

0-86

0-44

0-27

...

24-75

Dinas, G

97-62

1-4

-10

•29

...

-49

Dowlais, best, P

67 12

21-18

2-02

...

0-32

0-84

1-85

6-21

1-90

Glascote, near Tarn-
worth, P

60-20

32-69

2-82

...

0-86

0-44

8-62

12-69

Glasgow, P

66-16

22-64

...

1-42

Trace

6-31

...

8-14

Hedgerley, Bucks, G

84-66

8-86

...

1-90

•86

4-25

Howth, near Dublin, P

74-44

19-04

2-07

0-46

0-27

...

0-61

3-71

Ireland, P

79-40

12-26

...

0-60

1-80

6-20

Kilmarnock, Ayrshire, G

68-92

86-66

1-14

1-06

-89

-86

...

2-49

Newcastle, P

66-60

27-76

2-19

0-44

0-67

0-76

2-01

10-53

Plympton, Devon, G

74-02

21-37

•82

•09

•40

-86

...

1-94

Poole, Dorset, P

Stourbridge, Worces-
tershire, P

48-99
63-30

82-11
28-30

8-81

...

0-43
0-78

0-22

2-34
1-80

...

11-96

•30

Teignmouth, Devon, P

62-06

29-38

2-29

...

0-43

0-02

2-37

...

12-83

Wortley. Leeds, G

65-26

29-71

-48

-12

-40

•61

Titanic

Acid

-41

3-07

P, Percy's MtiaXlMTgy.

O, Capt Qpover, R,E. Prof. Papen, voL xlx.
' Page's FcoHomie Oedogy,

FIRECLA Y AND FIREBRICKS. laj

Orain, — It should be remarked that the infusibility of fire-
clays does not depend altogether upon their chemical composition,
but also upon their degree of fineness. A fireclay with a coarse
open grain will probably prove more refractory than one with a
close even texture.

FirebriokB are made from fireclay by processes very similar to
those adopted in making ordinary bricka

The clay is dug, weathered, tempered, ground under rollers,
passed through riddles to remove lumps, pugged, moulded, burnt
in cupolas or in Hof&nann's kilns at a heat slowly increasing
until it attains a very high temperature, and then allowed
gradually to cooL

There are several varieties of firebrick in general use, named
usually after the locality providing the fireclay from which they
are made.

Stourbridge Firebricks are made in a district about twenty miles Boutli-
west of Birmingham, which contains several varieties of fireclay.

The material naed for these firebricks is a black clay found in a thick
seam under the coal-measures.

The bricks produced are generally of a pale brownish colour, sometimes
reddish or yellow-gi-ey. They are frequently mottled with dark spots, which
are stated by Dr. Percy to be due to the presence of particles of iron pyrites.

** With Stourbridge clay it is customary to mix burnt ordinary day. For
common firebricks the proportions of the latter to the former are often as
much as two to one. This gives a brick capable of resisting the action of the
heat caused by a house fire, though it would not be sufficiently refractory for
resisting a furnace temperature. Fireclay being expensive, the inferior brick
is naturally cheaper, and is much used." ^

Kilmarnock and NewcoitU furnish firebricks somewhat similar to those
from Stourbridge.

Dincu Firebrich are made from a so-called fireclay found in Glamor-
ganshire.

It will be seen from the table of analyses on the previous page that tlie
so-called " clay " consists nearly entirely of silica. It is found in the state
of sand. About 1 per cent of lime is added, and enough water to make it
cohere. The bricks are then moulded by machinery under pressure, drieil,
and burnt in a close kiln.

The bricks made from this substance will bear a most intense heat, being
the only description that will resist the temperature (4000" to 6000* Fahr.)
of a regenerative furnace.'

They expand under heat, are porous, and will not stand rough usage.

The fractured surface of a Dinas firebrick "presents the appearance of
coarse inegular white particles of quartz, surrounded by a small quantity
of light brownish-yellow matter. The lime which is added exerts a fluz-

^ Abney's Notes on Chemistry of Building Maieridls,
' Dr. Siemens, Chemical Soeif4y, 7th May 186S.

124

NOTES ON BUILDING CONSTRUCTION.

ing action on the surfSace of the fragments of quartz, and so causes them
to agglutinate. . . . From their siliceous nature it is obvious that they
should not be exposed to the action of slags rich in metallic oxides." i

Ouimnuyda Firebricks^ made near Swansea, and Narherih Firtbrxeks^ from
Pembrokeshire, are of the same description as those from Dinas.

Lee Moor Firebricks are made from the refuse of china clay produced
by the disintegration of felspathic granite (see p. 16), found chiefly in Gom-
wslH and Devonshire granite.

A weU-known variety of these bricks is manufactured at Lee Moor, near
Flympton. They have a compact surface of a dull reddish-brown ; are veiy
hard and highly refractoiy.

JFindsor or Hedgerly FirAricks are made from the sandy slate-coloured
loam used for the manufacture of rubbers, and «re of a red colour when
burnt These bricks consist chiefly of sand ; they contain only 9 per cent
of alumina, and a laige proportion (4^ per cent) of oxide of iron. They
are unable, therefore, to resist vexy high temperatures.

The following Tablb shows the Crushing Strength, Weight
when diy, and ABSORFnYE Power of different classes of Fire-
bricks:—

Resistance to Compression, Weight, and Absorption op
Firebricks.

DncBipnov or Bbicx.

DiimnoiiB or Spbcixkn,
In Inches.

Ana
ezponed

to
cnuh-

tag.

Average

weight

under

which

briok

cxaeked.

Avenge

foroe

nqoind

tocnuh

bilok.

Weight
when
diy.

Per-

centsge
of water
abeorbed.

Antho-
iity.»

Length.

Brattdth.

ThicknMs.

Stourbridge firebrick .
Lee Moor do.
Newcastle da
Dinas do.
Welsh do. .

9-08
912
8-91
8*92
8-64

4-4

4-84
4*40
482
4-62

2-47
2-54
2*44
2-44
2-66

8q.ln.
89*9

89-6

89-2

88-7

86-8

Tone.
25-0

14-8

27-0

28-0

14-4

Tone.
60-9

64-9

46-6

49-0

68-8

Lbe.
7-2

7-7

6-9

9-6
4-9
9-9
9-8
6-2

L
L
L
L

TEERA COTTA.

Terra Cotta is a kind of earthenware which is rapidly coming
into use as a substitute for stone in the ornamental parts of
buildings.

* Percy's Metallurgy, p. 288.
" Mr. Baldwin Latham, Sanitary Engineering,

FIRECLA Y AND FIREBRICKS. 125

Many localities furmsh clay bam which terra cotta may be
made, as, for example, Tamworth, in StafiEbrdshire ; Watcombe,
in Devonshire; Poole, in Dorsetshire; Everton, in Surrey, and
other places in Northamptonshire and Cornwall

Making Terra. Cotta. — The great difficulty to be overcome
in making terra cotta is the uncertain shrinkage of the day.

To obviate this as much as possible, different clays are mixed
together, and a large proportion of ground glass, pottery, and, in
some cases, of sand, is added.

This mixture is ground into fine powder, thrown into water,
finely strained, pugged, kneaded, forced into plaster moulds smeared
with soft .soap, very carefully dried, gradually baked in a pottery
kiln, and slowly cooled.

The drying process requires to be conducted with extreme
care. If the blocks are subjected to draughts of cold air, if they
are of unequal thickness, or if the operation is conducted too
quickly, they wiU warp, twisty and become useless.

Natwre of Clay. — ^As before mentioned, the red clays contain
oxide of iron. If this is in considerable proportion (say from 8
to 10 per cent), it makes them very fusible and difficult to bum
successfully.

This fusibility is aggravated by the presence of lime, magnesia,
and other impurities, and the resulting terra cotta is not so hard
a^d durable as that from the more refractory white clays.

In some cases the white clay is used with an admixture of
oxide of iron just sufficient to make it bum to a good red colour.

Fireclays are used for the manufacture of terra cotta, in some
instances with very little preparation.

Terra cotta made from fireclays, when properly bumt^ is
excellent in texture, colour, and surface, but appears ragged and
porous directly the outer skin is removed. It manifestly suffers
for want of a small proportion of some flux, such as that afibrded
by the lime and alkalies in the mixed clays.

The mixed clajrs used for terra cotta contract from -^^ ^
of their linear dimensions in diying and baking.

The red clays shrink only about -^ lineaUy, while fireclays
shrink as much as ^. More than half of this shrinkage is id
drying, and the remainder in burning.

Blocks. — ^The blocks used for building purposes should average
from about 1 to 3 cubic feet in bulk, and no block should contain
more than 4 cubic feet

126 NOTES ON BUILDING CONSTRUCTION.

Such blocks are geneiallj made hollow, the thickness of the
shell of terra cotta being from 1 inch to 2 inches.

Large blocks should have a diaphragm, or partition of terra
cotta across them, to prevent their warping.

If required to bear considerable weight the blocks should be
filled with broken brick bedded in good mortar or cement.

Building Terra Cotta. — ^The blocks should be so shaped as
to form a good bond with tiie brickwork, or whatever material is
used for the backing.

The blocks are usually made from 12 inches to 18 inches
long, 6 inches to 15 inches high, and from 4^ to 9 inches thick
on the bed. These dimensions are suitable for bonding into
brick backing.

When the blocks are of the thicknesses above mentioned, the
joints are made square and flush as in ordinary ashlar work.

Advantages. — The advantages of terra cotta are as follows : —

Dv/rability. — ^If properly burnt, it is unaffected by the atmo-
sphere, or by acid fumes of any description.

Lightness. — If solid it weighs 122 lbs. per foot cube; but
if hollow, as generally used, it weighs only from 60 to 70 lbs.
per foot cube, or half the weight of the lightest building stones.

Strength. — Its resistance, when solid to compression, is nearly
•^ greater than that of Portland stona

Hardness. — ^Mr. Page found by experiment that it lost -^
inch in thickness, while York stone lost ^ inch with the same
amount of friction. It is, therefore, well adapted for floors.

Cast. — It is cheaper in London than the better descriptions of
building stone. It is so easily moulded into any shape, that for
intricate work, such as carvings, etc., it is only half the cost of
stone.

Disadvantages. — ^Terra cotta is subject to unequal shrinkage
in burning, which sometimes causes the pieces to be twisted.

When this is the case great care must be taken in fixing the
blocks, otherwise the long lines of a building, such as those of
the string-courses or cornices, which are intended to be straight,
are apt to be uneven, and the faces of blocks are often "in
winding."

Twisted and warped blocks are sometimes set right by chisel-
ling, but this should be avoided, for if the vitrified skin on the
surface be removed, the material will not be able to withstand
the attacks of the atmosphere, etc.

FIRECLA Y AND FIREBRICKS. \rj

Another drawback is the uncertainty of getting terra cotta
delivered as required, whereas a stone may be taken and fixed at
once, the carving being left, if necessary, to be completed after-
wards.

CoLOUiL — Terra cotta is made in several colours, depending
chiefly upon the amount of heat it has gone through.

White, pale grey, pale yellow, or straw colour indicate a want
of firing.

Eich yellow, pink, and buflf varieties are generally well burnt

A green hue is a sign of absorption of moisture, and is a sign
of bad material

A glazed surface can be given to terra cotta if required.

PoBOUS Tebba Cotta is made in America " of a mixture of
day and some combustible material — such as sawdust, charcoal,
cut straw, tan bark, eta When baked the combustible material
is consumed, leaving the terra cotta fall of small holes. It is
fireproof, of little weight, great tenacity, strong, can be cut
with edge tools, will hold nails driven in, and gives a good
siurface for plastering/' ^

Inferior Terra Cotta is " sometimes made by overlaying a
coarsely-prepared common body with a thin coating of a finer and
more expensive clay."

" Unless these two bodies have been most carefully tested and
assimilated in their contraction and expansion, they are sxire in
course of time to destroy one another ; that is, the inequality in
their shrinkage will cause hair cracks in the fine outer skin, which
will inevitably retain moisture, and cause the surface layer to
drop oflT in scales after the winter frosts."

"Another very reprehensible custom is that of coating over
the clay, just before it goes into the kiln, with a thin wash of
some ochreish paint, mixed with finely ground clay, which
produces a sort of artificial bloom, very pretty looking for the
first year or two after the work is executed, but sure to wear off
before long." *

Common window sills, etc., have been made of concrete covered
over with a skin of burnt clay to look like terra cotta — ^this skin
soon breaks away.

WluTt iLsed, — Terra cotta has been extensively used in Dulwich
College, in Messrs. Doulton's warehouses, Lambeth, in the Albert

1 Proceedings RLB.A. 1886, p. 129.
* B^Mtrts an SBBhibitian, 1876, p. 14.

128 NOTES ON BUILDING CONSTRUCTION.

Hall, in the new Constitutional Club, in the Natural History
Museum, and in several other of the new buildings near the South
Kensington Museum.

Stoneware is the name given to articles made bom the
plastic clays of the Lias formation, obtained chiefly in the south
of England.

The best comes from Poole, in Dorsetshire, or from the
vicinity of Teignmouth, in Devonshire. It contains about 76
parts silica and 24 of alumina^ with a very small proportion of
other ingredients.

This clay contains very little infusible matter. It is generally
mixed with a certain proportion of powdered stoneware, ground
and calcined flints, ground decomposed Cornish granite (see p.
16), or -sand, to prevent excessive shrinkage.

They are burnt in domed kilns like fireclay goods, but at
a very much higher temperature.

A fractured surface shows that this ware is thoroughly vitrified
throughout It is intensely hard, dense in texture, close in grain,
and rings well when struck.

This material is admirably adapted for all purposes where
strength and resistance to atmospheric, chemical, or other destroy-
ing influences are required.

Stoneware articles are often salt glazed (see p. 129), but the
material is in itself non-absorbent, and will resist the effect of
moisture even when unglazed.

PIPES AND MISCELLANEOUS CLAY WAEES.

Pipes and other articles made in clay are practically divided
under four heads.

1. Unglazed Eartlunware, made &om ordinary clays, similar to
tiiose used for common bricks and tiles.

Earthenware of this description is weak, porous, liable to the
attacks of frosty and is not adapted to resist the atmosphere or
other destroying agents.

2. Fireclay Ware^ made bom the fireclays of the coal-measures
(see p. 120).

This material has a very open grain, is porous, except where
protected by glazing ; and is weak when compared with terra cotta
or stoneware

PIPES AND MISCELLANEOUS CLA Y WARES, 129

Tt IB much used for common varieties of the dififerent articles
about to be described, especially in the localities where the fire-
clay is found ; but it is inferior to stoneware or to terra cotta
for nearly every purpose.

3. Stoneware is made, as before stated, from days of the lias forma-
tion, mixed with sand and ground potteiy, to prevent shrinkage.

The characteristics of this material have already been pointed
out (see p. 128).

Its strength, durability, imperviousness, and resistance to
destructive influences make it an admirable material for sanitaiy
ware, sewer pipes, ornamental works exposed to the atmosphere,
and for vessels to contain chemical compounds.

4. Terra Cotta is often used for pipes and other miscellaneous
articles.

Its composition, and the mode in which it is manufactured,
have already been described.

It is inferior to stoneware, inasmuch as it is more absorbent
and less dense in grain. It is burnt at the same heat as fireclay
goods, but is superior to them in strength and durability.

Glaaing. — ^It is often advisable to glaze the surface of articles
made in clay, sometimes for appearance, but more generally in
order to prptect portions exposed to the action of the atmosphere,
to sewage, or other destroying agents.

These glazes are either transparent — ^merely a film of glass —
or opaque^ like an enamel

.Transpabent Glazes of several kinds are known in the trade.
Two methods, adapted to the somewhat rough articles used by
the engineer and builder, will now be described.

Salt Glazing is efTected by throwing salt into the furnace when
the articles it contains are at a high temperature. The heat of
the fire volatilises the salt (chloride of sodiimi), the vapour being
in the presence of oxygen and silica is decomposed, the chlorine
goes ofif through the top of the furnace, the sodium combines
with the silica in the clay to form silicate of soda, which again
unites with the silicates of alumina, lime, or iron in the day, to
form a surface coating of glass.

This method of glazing has great advantages. The vapour of
the volatilised salt gets into every crevice, however small, and
coats it with an impenetrable film of glass.

It is used for stoneware, and also for articles made from fireclay.

Lead Glazing is carried out by dipping the artide to be glazed
RC. — m K

130 NOTES ON BUILDING CONSTRUCTION.

(after it has been once burnt) into a bath contaimng oxide oi
lead and tin — or borax -with kelp, sand, etc, ground to powder,
and stirred in water to a creamj consistence.

The particles of these dififerent materials adhere to the surface
of the article when it is dipped. It is then withdrawn and re-
burnt The high temperature of the furnace causes the particles
to run together and to form a film of glass over the whole surfaca

This method of glazing is used for terra cotta, and sometimes
for articles made from fireclay.

Lead glazing is also used for earthenware crocks, etc., which
are made out of inferior dajs such as would not stand the hi^
temperature required for salt glazing. A lead glaze will generally
chip off easily.

Opaqxte Glazes are required in cases where it is ^vished to
give (to the whole, or to any portion of an article) an appearance
superior to that presented by the ordinary burnt material

The article to be glazed is dipped before burning into a dip
formed of superior clay, very finely worked, dried, etc, and
brought to the colour required.

Thus the pans of water-closets are often made white inside,
and of a cream colour, or some other tint, outside.

Burning. — ^Terra cotta, stoneware, and fireclay ware, are all
burnt in domed kilns.

The heat is applied gradually, and after it has risen to its
height is kept up for a period varying from 24 to 72 hours,
according to the size of the kiln and of the articles in it The kiln
is then allowed to cool down gradually.

Terra cotta is burnt at a much lower temperature than stoneware.

In Older to protect articles of a delicate nature from direct contact with
the fire, which would discolour them, they are placed in laige fire-clay jars
called teggarSy or encloaed in a casing of fire-brick formed within the kiln, and
known as a muJU,

Pipes are made from clay, very finely ground, washed, sieved,
tempered, pugged, and forced by machinery through a mould,
or dod as it is called — dried, and baked in a circular kiln.

AoBioui/ruRAL DRAur PiPis are made of various sections, but the circular
and O shaped are those in most common use.

These pipes are sold in S-foot lengths, and of diameters vaxying by half
inches from 1 inch to 6 inches.

Collar$ are short pieces of pipe sometimes used to cover the joints between
each pair of lengths of the drain pipes, so as to give the ends of the pipes a
firm bed.

PIPES AND MISCELLANEOUS CLAY WARES.

131

They are 3 or 4 inches in length, and abont 1 inch greater in diameter
than the pipes they unite.

They are, however, generally omitted altogether.

Skwbr Pipes should be of a yitreons imperishable material, of sufficient
strength to resist fracture, having toughness enough to withstand shocks,
tenacious, hard, homogeneous, impervious, uniform in thickness, true in sec-
tion, perfectly straight longitudinally, or formed to the proper curve, uniformly
glazed both inside and outside, free from fire cracks and flaws of all kinds.

When struck they should ring clearly.

Porous substances are not so good as those that are vitreous throughout,
and pipes burned at a low temperature are inferior to those that have been
subjected to a considerable heat

Sewage pipes are made both from stoneware and fireclay. The former is
the stronger material, and is said better to resist the decomposing e£fect of
sewage and other substances having a chemical action.

Salt-glazed pipes only should be used ; if the glaze can be picked off it is
proof that the pipes are made out of a clay that would not stand a high tem-
perature ; in fact, that the pipes are not stoneware.

Fireclay pipes should be made thicker than those of the same diameter in
stoneware.

Different Fomu cf Sewer Pipes, — Several fonns of sewer pipes have been
devised, but only one or two of the most common need be noticed.

Socket Pipes. — ^Pipes intended to convey sewage are generally made ^th
sockets. Care should be taken that this socket
is in the same piece with the pipe, not formed
separately, as is sometimes the case.

Half Socket Pipes have a socket on the lower
lialf of the circular section only, so that a
broken length may at any time be taken out
and replaced, or a junction inserted.

The following Tabli gives the dimensions and thickness of stoneware,
fireclay, and other cky pi^, as laid down by Mr. Baldwin Latham : — ^

rig. 44.

BlOHCWAIlB.

FiRKLAT.

Otrxb
Clays.

AllPipbb.

Intenul
Dtametor.

Thickness.

Length in
work.

Thickness.

Length In
work.

Thickness.

Depth of
Socket

InchM.

9
10
12
15
18

Inches.

If
li
li

FMt.

2
2
2
2
2
2
2
2 to 8

Inches.

1
1
f

i
1
lA

n
14

Feet

2
2to8
2to8

Inches.

A 1
1

1
i

Inches.

Specification for Bideford Waterworks.— iTtimitfr.

132

NOTES ON BUILDING CONSTRUCTION.

Mr. Baldwin Latham states that he '^ has found in some cases that the
thickness given in the above Table for fireclay pipes is not sufficient." ^

Socket pipes maj readily be obtained as small as 2 inches in diameter ;
also pipes of 21, 24, and 30 inched in diameter, in 2^ or 3 feet lengths.

Bends are curved lengths of pipe which are made to varying radii, and of
2, 3, 4, 6, 9, 12, 15, and 18 indies bore. They should always be s^ments
of circles, and should form perfect curves when jointed together.

Tafeb Pipes (Fig. 45) are intended to form a con-
I nection between two pipes of different diameter.

JuNOTiONS for pipes are made in several different
Fig. 45. forms. They are usually in 2 feet lengths.

SingU Jwictions are those to form the joint when
one pipe enters the side of another. The junction may either be at right
angles to the pipe, as in Fig. 46, or joined to it by a gradual bend, as in Fig.
47. The latter is the best construction.

Fig. 46. Fig. 47.

Dovhle Junctunu are to form the joint where two pipes meet a third,
either at the aides as in Fig. 48, or at one end as in Fig. 49.

Fig. 48.

Mr. Baldwin Latham gives the following directions for forming bends and junctions : —
" The centre from which a branch on a main \b struck must be upon a line at right angles
to the centre line of the main pipe, the inside of the main pipe meeting the inside of the
branch at a tangent on a radius line fh)m which it is struck ; the ends of all curved pipes
must be in the direction of the radius of the curves with which they are described.*' '

Saddles and Chairs in earthenware are formed of such a shape as to make
a secure junction between the adjacent lengths of a sewer pipe, and yet to
enable the sewer to be examined at any time, and any obstruction to be
removed without breaking a pipe.

Lathim*8 Saniiary JSngineering, ' Specification for Bideford Waterworka

PIPES AND MISCELLANEOUS CLAY WARES.

"^11

Figa. 50, 51 show the jimctioiiB of Jenningfa improyed patent drain pipes.

Fig. 60.

Fig. 51.

The chair is shown at C in pontion supporting the end of a pipe ; another
length would be placed in the vacant half of the chair, and then the short
piece S placed between the two lengths over the chair. The bottom of the
short piece is flush with that of the lengths of pipe united by it

Some of the saddles are plain, as at P, which shows one in position. Others
have junctions attached, as at J.

Other saddle and chair junctions introduced by Mr. Jennings have no
short piece attached to the saddle. The
chair and saddle are rebated at each end,
of a depth equal to the thickness of the
adjacent lengths of pipes, which therefore
fit into the rebates, and have their inner
surfaces flush with those of the saddle and chair.

Fig. 52 shows one of these chairs. The saddle is exactly similar in
form, being made, however, with or without junctions, as in Fig. 51.

The objection to pipes with half sockets, saddles, etc., is that when the
sewer is more than half full they leak or overflow.

Opercular or Lidded Pipes were introduced by Messrs. Doulton.

They are similar in form to ordinary socket pipes, but are strengthened by
two libs ranning lengthways, shown at r r in Fig. 53, which is a section
of the pipe;

Fig. 52.

Fig. 58.

Fig. 64.

A longitudinal nick or furrow is made throughout the length of the pipe
along these flanges, so that by inserting a chisel the upper portion of the pipe
between r r may easily be removed.

Thus the whole length of the pipe may be opened up for inspection or for
removal of obstructions.

Capped Pipes have circular or oval holes in them, with loose covers, so
that they can be examined without being broken or taken up.

Stphoh Traps in stoneware may be obtained of almost any shape and

description, either with or without in-
lets for examination.

One form is shown in Fig. 55, with
the inlet dotted. This description may
be obtained of 2, 3, 4, 6^ 9^ and 18
inches bore.
Fig. 55.

134 NOTES ON BUILDING CONSTRUCTION

The position of inlet shown in Fig. 55 is the usual one, but a trap so
formed is liable to choke, and it is better to have the inlet at the upper end
of the pipe.

Tests for Sewer Pipes. — ^" The impermeability of a pipe may
be tested by tying a piece of bladder over one end, reversing
it, and filling with water. If it is not perfectly impervious, the
water will begin to ooze through the pores " of the pipe.

The absorption of water, ascertained by weighing a dry pipe,
inmiersing it for twenty-four hours, wiping dry, and reweighing,
was found by Mr. Baldwin Latham to vary from 429 to 6*89
per cent of the weight of the dry pipe. .

The power to resist chemical action may be tested by pulver-
ising a piece of the pipe and boiling it in hydrochloric acid, wash-
ing on filter, and noting loss in weight Dr. Millar has shown
that in stoneware pipes there should be no loss.

StanfarcCs FcUerU Joint is used in order to get a perfectly

close joint between the lengths of
socket pipes.

This is ensured by casting upon
the spigot and in the socket of each
pipe, rings of a durable material (a
mixture of coal-tar, sulphur, and
ground pipes), which, when put to-
gether, fit mechanically, so as to form
a water-tight joint without the aid of
«. r* cement

Fig. 66.

In putting such a joint together,
the surface is sometimes greased with Bussian tallow and resin.

MiBoeUaneoas Clay Wares. — The variety of articles used by
the engineer and builder — ^which are made from burnt or baked
clay — ^is endless.

A few of the more important may now be mentioned.

Perforated Air Bricks are made in stoneware and tern cotta. They are
pierced with different pattemsy and are moat
useful for ventilating courses, supplying air to
stores, etc.

They are better for thifl purpose than iron
putings, as they are cheaper, more durable, do
not stain the waUs with xnst, or require paint-

^°^* Fiff 67

The pattern shown is from Mr. Jennings' dr- °

cular. Tliey are made in all sizes^ from 9x3 inches up to 18 x 18 inches.

PIPES AND MISCELLANEOUS CLAY WARES.

135

Damp-pboof C0UB8B8 are made in stonewaxe (or sometimes in fireclay)
pierced with perforations of different patterns.

wmm

\*- 9.**.-

Fig. 68.

Fig. 59.

The slabs are generally 9 inches long. They vary from 9 inches to 18
inches in width, to suit different thicknesses of brick wall^ and their own
height or thickness varies from 1^ to S| inches.

A damp-proof coarse slab in stoneware, as made by Messrs. Donlton^ with
ribbed surfaces and tongue and groove joints, is shown in Fig. 58.
A thicker slab, as made by Mr. Jennings, is shown id Fig. 59.
The method in which these damp-proof courses are used is explained at
page 216, Part II.

BoNDDTQ BfiiOKa — ^These bricks, introduced by Mr. Jennings, are used for
uniting the opposite sides of hollow
waUs.

The original bricks were straight
A sketch of one is given in Fig. 61.
The improved bonding bricks are,
however, bent (see Fig. 60), so that
water endeavouring to pass from the outer to the inner
side of the wall would have to go up an incline.
An illustration of the use of these bricks is given at
page 216, Part U.

These bricks are made in four sizes, ranging from No. 4 to No. 7 ; their
dimensions being as follows : —

Fig. 61.

Parte of the

brick. See

Fig.flO.

No. 4.

No. 6.

No. 8.

No. 7.

Wall Faoinos are made of different patterns, in earthenware and in terra
ootta. Those patented by the Broomhall Ck)mpany are of an L shape, and
are used to form a superior facing to walls built of concrete.

Slbspsb Blocks, made in stoneware, are useful for carrying floors which
are close to the ground in damp situations.

136

NOTES ON BUILDING CONSTRUCTION

Fig. 62 shows a epedmen of one of these, as made by Mr. Jenningai
They are made for 9 inch and 4i inch walls^ or wall plates.

Fig. 62.

Fig. 68.

Jbig. 6i.

Chihnet-flub Pipes ^ are made in terra cotta, fireclay, etc

These pipes are intended for lining chimney flues^ instead of pargetting
them (see Part II. page 243).

They are frequently cylindrical, with plain butt joints, sometimes with
ordinary sockets, or with the sides of the sockets cut off, as in Fig. 63.

They are made of 9^ 10, or 12 inches in diameter^ and generally in 2-feet
lengths.

These pipes are sometimes oval, or of a section consisting of a rectangle
with the comers rounded, as in Fig. 64.

The oblong sections are manufactured by Messrs. Doulton and Co. in
three sizes : —

10 inches.

» „

6 H

Fig. 65.

CofMnid Smoke and Air Flues are made in the fonn shown in Fig. 65.

These pipes are intended to be built into chimney
breasts. The smoke ascends the flue S, while the foul
air is drawn off through the flues marked //.

The blocks containing these flues are made in differ-
ent forms and sizes. In some patterns the smoke flue
is circular, 12 inches in diameter, the whole block occu-
pying 18 X 14 inches. In others there is only one air
flue, and the whole block takes up only 14 x 9i inches
in plan.
Ohdcnbt Pots of every imaginable design are made in
terra cotta. Any attempt to illustrate them in detail would be useless.

Billings Chimney Tenninaltf with partitions similar to those described in
Part IL page 243, are made in terra cotta by Messrs. Doulton and Ca

Invert Blocks of stoneware for sewers have been mentioned in Part IL, and
their advantages described.

The best of these are provided with a projecting lip, as shown in Fig. 67,
which covers the joint between two adjacent blocks.

Sometimes two or three blocks are combined to fonn an invert^ as in
Fig. 66.

JuNonoN Blocks (Fig. 69) are intended to be built into brick sewers to
receive pipe drains.

^ Sc FefU-Hnin{^,

PIPES AND MISCELLANEOUS CLAY WAfiES.

137

Fig. 06.

Fig. 67.

They are made either direct as at A, or oblique as at jS, to suit the posi-
tion of the drain.

The blocks vary in pattern so as to fit drains of any size, placed at diffe-
rent angles of inclination.

Fig. 68.

Fig. 69.

SscniENTAL Sewebs are made in stoneware of pieces formed to the shape
of segments of the circle, and nnited by groove and tongue joints

OuUey Traps for streets and yards, Sewer Gas Interceptors, Traps, Sluice
Vdhes, Valve Traps, Channel Pipes for sewage, Conduits, and sanitary apparatus
of every form and variety, are made in stoneware, but any detailed description
of them is necessarily omitted here for want of space.

The same reason makes it necessary to exclude any description of the various
ornamental articles executed in terra cotta, such as dental, dog-tooth, and
moulded cornices, trusses, medallions, cornices, moulded arch blocks, lintels,
jambs, capitals, pier caps, parapet fittings, terminals, etc etc.

Stoneware is also made of every form and colour for wall decoration, both
external and internal

ijS NOTES ON BUILDING CONSTRUCTION.

TILEa

The tiles used in connection with buildings may be divided
into two great classes.

1. Common tiles of different shapes used for roofing and
paving.

2. Encaustic tiles used for decorative purposes.

Common Tiles are made out of somewhat the same material
as ordinary bricks, but they should be purer or stronger clays —
well worked so as to bear ** thwacking," or they will be liable to
lose shape in burning.

The day is weathered either by exposure to frost or sun —
allowed to mellow in pits — ^tempered — ^pugged, cleared from stones
— ^moulded, trimmed with a knife — ^thwacked (that is beaten when
half dry with a wooden bat to correct warping) and burned in a
domed kiln.

Common tiles are made in a great variety of shapes, for roofing,
paving, and other purposses.

Paving Tiles — for common purposes — ^are made in dilBferent
shapes, such as squares, hexagons, et&, and in sizes varying from
6x6 inches, to about 12 x 12 inches, and about 1 inch
thick

Flooring tiles are sometimes known as Quarries.

BooFma TnEa — Of these there are several different kinds, a few
of which will now be described.

Tile roof coverings are heavy ; moreover they are apt to absorb
water, and to keep the roof wet

To prevent this they should be glazed, which involves rebum-
ing and makes them expensive.

Many descriptions of roof tiles do not fit together very closely,
and therefore require pointing to make a tight root

TILES,

139

Plaxik T^kfB are flat^ either rectangular, or cat to Yaiions patterns. See
Kg. 7a

Fig. 70.

Each tile is pierced with
two holes near its upper edge,
through which small oak pegs
are driven, by which the tile
is hung on to battens or laths,
nailed apart at the proper
gauge, as described in Part IL

Sometimes the holes are
omitted, or two little pro-
jections at the back of the tile

are provided to take the place j^ ^.

of the oak pins. '^^ ^^•

Figs. 70 and 71 are from page 264, Rurt IL, where the method of laying
these tiles is described.

PantiUa^ are moulded flat, and afterwards bent to the form
shown in Fig. 72, over another mould.

Each tile has a $tuby projecting abont |-inch from the centre of
the back of the upper edge of the tile, by which it is hooked on to
the laths.

The method of laying these tiles is described at page S66,
Partn.

Fig. 72.

Dtmble Boll Tile$ are like two pantiles joined
together, side by side. They have three stubs on the
back.

Corrugated Tiles are similar to pantiles, but each
tile contains three or four corrugations, as in Fig. 73.

Fig. 78.

Improved CorrugaUd TiUi have flat pieces alternating between the cor-
rugations.

1 Sometimes called FUmiah Tiles.

140

NOTES ON BUILDING CONSTRUCTION

Taylat^s Patent Roojlng Tiles^ now known as the BroomhaU Company'$
Patent Boofing TtleSy form a handsome roof covering.

The form of the tiles is shown in Fig. 75. They are laid alternately as

Kg. 74.

Fig. 76.
form shown in Fig. 77, which is from page 266, Part IL

Fig. 75.

capping and channel tiles, as shown in
Fig. 76, in which T T are laid as channel
tiles, while U, being a tile of the same form
as the others, is reversed to fit over them
as a capping tile.

A description of the method of laying
these tiles has been given at page 266,
PartIL

Venetian or Italian Tiles are of the

Fig. 77.

The snow is rather apt to lodge upon these tiles, and when it thaws to pass
through the roof.

Wade and Cherrjfs Tiles. — ^These tiles are each shaped something like the
ace of spades, so that their form renders the amount of lap smaller than in
ordinary tiles.

c r

Pig. 78.

Fig. 79.

Fig. 80.

A flange, or raised rim, of dovetaUed or under^sut section is formed on the
top half of the uppermost side of each tile (Bee Figs. 79, 80}, and on the lower

TILES.

141

half of the undennost side (the latter is dotted in Fig. 78). The upper
flanges correspond to r r. Of course B in the figure hooks on to the lower
flanges b s. This holds them firm, and it is said to exclude wind and rain
and to render pointing unnecessary. •

Eid^e Tiles are made of various forms : Plain, as in Figs. 81, 82 ; with
a grooved roll to contain detached /w*r«, as in Fig. 70 ; or with a plain rolL

The various lengths may he joined hy pegs, holes for which are left in the
loUs, as in Fig. 7 1, or they may be made to lap, as in Fig, 82.

Fig. 81. ^^^^^ Fig. 82.

In some varieties fleurs or other ornaments are made in one piece with the
tile.

Other kinds, such for example as the Broomhall tiles above mentioned,
require special ridges.

Hip and ValUtf Tiles are made of special shapes, to fit the hips and valleys
of tiled roofs. Their form necessarily varies according to the pattern of tile
and the pitch of the roof to which they are to be fitted.

Wall Tiles. — Hal^s ffcmging Tiies are glazed of different colours and
fixed to walls by a nail in each tile driven into the joints of the brickwork,
and are used to cover walls where light is important, as in areas, or fur
cleanliness, as in dairies.

Encaustic Tiles are those in which the colours are produced
by substances mixed in with the clay — not printed on after the
tile is mada

Such tiles may be made from ordinary clays and marls carefully
prepared — sometimes mixed with finer clays, and also with different
colouring substances, such as manganese for black, cobalt for blue.

Those tiles which are ornamented by inlaid patterns of different
colours are made in the following manner : —

The clay used is first very carefully prepared — ^mixed with the
colouring matter, and " slipped" that is passed through fine muslin
or silk sieves ; boiled in the dip-kUn until it becomes plastic,
ivedged, that is cut up into pieces, which are dashed against one
another to drive out the air and consolidate them ; and aged, that
is kept for several months, during which fermentation goes on
and organic matters disappear. During this time the wedging
should be repeated at intervals. After this the clay is slapped,
that is, cut up by means of a wire into long pieces, which are
kept always in the same direction. This consolidates the mass
and preserves the grain.

Each tile generally consists of three layers : — ^The face, which
is a slab of very pure clay of the colour reqidred for the ground

142 NOTES ON BUILDING CONSTRUCTION

of the pattern ; the body, which is of coarser clay ; and the back,
to prevent warping, which is formed with a thin layer of day dif-
ferent from the body.

The clay for the face is cut into a pat about \ inch thick, and
as much laiger in area as will allow for contraction in burning.
It is then placed upon a plaster-of-Paiis slab, upon which the
form of the inlaid pattern is left in relief The face clay pressing
upon this receives an indentation corresponding to the form of the
pattern required.

It is then backed up with the body of coarser clay, and the
thin layer to form the back.

At this stage the maker's name is stamped on the back, and also
a few holes to make the cement adhere to the tile when it is set.

Slip day of the difTerent colours required, according to the
design, is then poured into the different parts of the indented
pattern on the face.

After this has become hard, the superfluous clay is carefully
scraped off, leaving it only in the parts originally indented so as
to form the pattern.

The raw clay tiles are then trimmed, carefully dried, baked
in ovens, protected from smoke, etc., by being arranged in large
fireclay jars called aeggars.

The burnt tiles may then, if required, be glazed by dipping them
into a mixture of powdered glass and water, and reheating.

Inferior Encavstic Tiles. — *' A class of pseudo-encaustic tiles is
now being largely made, in which the colour, which should be
burnt in along with the clay, is merely applied as a transfer
printed pattern on the surface.

''Such tiles are frequently coated in the glass oven with a
transparent fritted glaze, and serve for flower boxes, wall tiles,
and such like purposes.

** To give them the appearance of having true inlaid colours,
the edges of these tiles have frequently a little colour applied
to them to represent the depth of the insertion of the coloured
clay."i

Dry Tiles. — ^These tiles, each of which is of the same colour
throughout, are made by the dry process.

The day having been very carefrdly prepared is mixed with
the colouring matter, "dipped,*' dried, and reduced to fine powder.

It is then placed in a press and subjected to enormous pressure
> Report on Intamatioiial Exhibition 1871 ; b^ Gilbert Bedgraieb Eh*

TILES. 143

bom a steel die. This reduces the powder to a third of its btilk
and thoroughly consolidates it ; at the same time the pattern, if
any, is impressed upon the tile by means of the die.

They are then carefully dried in a hot room, glazed, and fired.

There are several places in which encaustic tiles are made,
but the most celebrated manufactory in the country is that of
Messrs. Minton, HoUins, & Co., at Stoke-upon-Trent ; the founder
of which, Mr. Herbert Minton, brought the art to its present state
of perfection.

There are other manufacturers at Stoke, Stafifordshire, at Poole
in Dorsetshire, also at Broseley, near Hereford.

Tesserw are tiles sometimes made by the dry process just
described, and are so accurate in form that they can be laid as
mosaic work in pavement without any rubbing or injury of the
face.

They are sometimes made out of moist day, and cut into
various shapes by wires.

Majolica Tiles have raised patterns, and their colour " applied
in the form of an enamel or coloured opaque glaza They have
not therefore the same amount of durability, and are only used
for walls and similar ornamental purposes."^

Mosaic Paving Slabs are made by arranging tesserae in the
pattern required Strips of wood are placed round the whole
so as to form a rough frame.

Portland cement is then run in over the backs of the tesserae,
and the whole strengthened and formed into a slab by two layers
of common tiles set in cement'

Uses. — Flat encaustic tiles made by either process may be used
for paving or wall decoration, but those with raised patterns
must of course be restricted to the latter purpose.

In some cases the tiles for wall decoration are put together in
panels before being glazed. A picture is painted upon the panel,
the tiles composing it are then separated, burnt at a high tem-
perature, and glazed.

Chemical Analysis^ — In order to make these Notes more complete, and
as a matter of interest to those who possess the necessaiy chemical Imowledge,
a description of the analysis of a brick earth or brick is appended.'

^ Report on the International Ezhihition, 1871 ; hy Gilhert Bedgrare, Esq.
' Gwilt*8 Bneifdopcedia,
* From NcUs on the Cfhemislry of Building MaUriaU^ hy Captain Ahnsy, B.IS.1
F.B.a

144 NOTES ON BUILDING CONSTRUCTION.

** The analysis of a brick or brick earth is conducted in a yery similar
manner to that of a lime or a cement (see p. 223).

*^ To find the constituents, a small portion of the finely powdered brick is
taken and treated with dilute HCl, and digested with it until nothing more is
• dissolved. The solution is then filtered and tested in the same manner as
directed when treating on cements^

" The insoluble residue, after being dried, is mixed with about three times
its bulk of a mixture of the carbonates of soda and potash, in the proportion
of 5^ parts of the sodium to 7 of the potassium carbonate, and placed in a
platinum crucible containing a little of the fluxing mixture at the bottom, and
heated over a strong flame. The mass will melt and a decomposition take
place, owing to the silicic add of the brick having, when heated, a stronger
affinity for the soda and potash of the fluxing mixture than for the bases
with which it was combined in the brick.

" The crucible should be allowed to remain over the flame till no more
bubbling is observed, caused by the escape of CO,, which will generally be
in about five or ten minutes ; it should then be carefully removed and
allowed to cool, and the contents as far as possible detached from the sides of
the crucible, and the whole placed in a dish with some dilute HCl which will
dissolve the fused mass. The crucible should be removed from the dish, and,
after washing it, the solution should be evaporated to complete dryness, re-
dissolved in acid, and the SiO,, which by the process of diylng has become
insoluble, be filtered out The examination of the solution should be pro-
ceeded with as the one originally obtained, after treating the brick with add.

^ The common constituents of bricks are

Silica. Iron.

Manganese. Alumina.

Lime. Magnesia.

Soluble Salts. Sulphur.

The sulphur may exist in the brick in one or two states, either as sulphuric
acid, or combined with iron as sulphide of iron. If contained in the add
state it may be detected by boiling some in water and adding barium chloride,
which produces a white precipitate insoluble in acids. As a sulphide it may
be detected by fusing a portion with a little of the fluxing mixture, detaching
the fused mass and moistening it on a silver plate or coin. The sulphide of
soda formed by the fusion will blacken or stain the silver.

*' QuANTiTATiVB ANALYSIS. — 25 grains are very carefully weighed out and
transferred to a porcelain dish into which dilute hydrochloric and nitric adds
are poured, and the whole heated ; the portion remaining undissolved is
filtered out, dried, and weighed. The nitric acid acts upon any sulphur
which the brick may contain and converts it into sulphuric acid."

Chapter HI.

LIMES, CEMENTS, MORTAR,
CONCRETE, PLASTERS, AND ASPHALTES.

LIMES AND CEMENTS.

THESE are hardly any materials used by the engineer,
architect, or builder, on whiph so much depends as upon
mortar and concrete.

There are difTerences of opinion on many points connected with
the preparation and use of these materials, and there is still
much prejudice existing in favour of exploded notions and of old-
fashioned ideas.

These prejudices are the more diflScult to overcome, because
the old-fashioned methods of preparing mortar and concrete were,
as a rule, less troublesome than those of more recent introduc-
tion.

In order to clear the way for a proper understanding of this
important subject^ it will be well, first, to explain the meaning of
some of the commonest terms used in connection with it.

Terms in Use. — ^The natural Lvtnea and Cements used for build-
ing are produced by the calcination of limestones or other cal-
careous minerals, the effect of which is to drive off the carbonic
acid and moisture they contain.

Calcination is heating to redness in air.

Quicklime or Caustic Zims is the resulting lime as left imme-
diately after calcination.

Slaking is the process of chemical combination of quicklime
with water. This gives rise to various phenomena which will be
more particularly described hereafter. (See p. 146.)

Slaked Lime is the substance remaining after slaking, and is
chemically known as the " hydrate of lime'* ^

^ Calcium hydrate. The ordinary chemical nomenclature has been adopted
throughout these Notes as being more familiar to readers generally than the new
nomenclature. The modem names are given in footnotes.

B. 0. — m L

146 NOTES ON BUILDING CONSTRUCTION.

Setting is the hardening of lime which has been mixed into a
paste with water.

This is quite a different thing from mere drying. During dry-
ing the water in the paste evaporates, but no setting action
takes place.

Eydratdidty. — Tiime or cement is scdd to be more or less
hydraulic, according to the extent to which paste or mortar made
from it will set imder water, or in positions where it is free from
access of air.

Limestones and other minerals from which limes and cements
are produced differ greatly in their composition, ranging from
pure carbonate of lime,^ such as white chalk or marble, to stones
containing from 10 to 30 per cent of clay, in addition to other
foreign constituents, such as magnesia, oxide of iron,^ etc.

As the properties of the resulting lime or cement depend very
greatly upon the composition of the stone from which it is pre-
pared, it will be instructive briefly to note the characteristics of
the most common constituents of such stones before proceeding
further; especially distinguishing those which produce hydrau-
licity from those which have not that effect

CONSTITUENTS OF LIMESTONE.

Constitaents of IiiiiiestoneB whioh do not produce Hydraulioity.
— Carbonate of Lime.^ — As already noticed, some limestones, such as chalk
and marble, consist entirely of this substance, and in all it plays an important
part.

When pare carbonate of lime is calcined, the carbonic add and water con-
tained in it are driven off, and *' quicklime *' results.^

Slaking, — If the quicklime is treated (either by sprinkling or dipping with
as much water as it will easily absorb, it almost immediately cracks, swells,
and falls into a bulky powder with a hissing crackling sound, slight ex-
plosions, and considerable evolution of heat and steam ; — this is the process
of ^^ slaking.** By it pure lime is increased in volume from 2 to 3^ times
its original bulk, — the variation depending both on the density of the original
carbonate and on the manner of conducting the process.

Air-slaking. — If the pure quicklime be exposed to the air, it will gradu-
ally absorb moisture, and fall into a powder with increase of volume, but
vdthout perceptible heating ; it is then said to be *' air-slaked." Some car-
bonic acid is also absorbed in ^ air-slaking."

Setting, — If a small pat be made of paste from the slaked lime and placed

^ Cdleiwn carbowite. ' Fernc oaeide.

* Called also *' anhydrous" or '* caustic" lime.

CONSTITUENTS OF LIMESTONE. 147

under water, it will slowly dissolve, nntil (if the quantity of water be suffi-
cient, or is changed often enough) it entirely disappears.

In air the surface of the pat will absorb carbonic add, which reconverts it
into a carbonate of lime. This action continually decreases, and practically
ceases after forming a surface crust less than half an inch thick — the in-
terior remaining pulpy or friable, according as the situation is damp or dry,
and undergoing no further change of any kind.

Sand, of an ordinary description (such as that from flint or grains of
quartz) occurring as an impurity in the limestone, has by itself no chemi-
cal action with the quicklime, when forming part of a limestone calcined
at the temperature oidinarily reached in a kiLn, but constitutes with it a
mere mechanical mixture ; forming what is called a *' Poor Lime," and
having the effects described at page 162.

Ck>n8titaentB of liimestone which produce Hydraulidty. — ^The sub-
stances above noticed give the lime no hydraulic properties whatever.

It is most important to understand distinctly what constituents are
necessaiy in a limestone to confer upon it the characteristic of hydrau-
lidty.

These will now be shortly referred to.

Clat is the most important constituent of those which produce hydraulidty
in limestones, indeed the great minority of hydraulic limes owe their pro-
perties to the day they contain.

The effects produced by the presence of clay in a limestone are as follows : —

a. It greatly modifies the slaking action. When a large proportion of day
is present, such action does not take place at all.

&. It confers the power of setting, and remaining insoluble under water, 01
in other podtions where the air has no access.

In order that the clay may properly fulfil its functions, it is necessary —

1. That the amount of clay should be properly proportioned to that of the
remaining constituents.

^e effects above mentioned are more marked as the proportion of clay is
greater, up to a certain limit when the excess of clay becomes injurious.)

2. That the stone should be calcined at the proper temperature.

fThis is a very important and veiy intricate portion of the subject The
same stone will give very different results according to the degree of calcina-
tion to which it is subjected.)

The nature of the changes undergone by the clay, and the evils caused by
over-burning or under-burning the stone, are explained at page 230.

These changes are of a somewhat complicated nature, and it will be suf-
fident at present to note the fact that after proper calcination of a limestone
containing clay, the result is a substance containing a proportion of free
quicklime together with compounds (formed by the clay and lime) which have
the property of becoming hard when formed into a paste, even if seduded
from the air or placed under water.

Soluble Silica. — There are several forms of sUica, such as sand, flint, etc.,
which, as already noticed, are useless in lime, for they are only in a state of
mechanical mixture with it. The silica must be in combination with other
substances and in a peculiar soluble state, or it will not combine with the
lime ; in such a state it is found in clay.

Unfortunately, in most analyses of limestones the soluble or usefully active
form of silica is not distingnidied from the sand, or silica in an inert state ;

148 NOTES ON BUILDING CONSTRUCTION.

this leads to some confuBion, and renders the analyses less useful than thej
would otherwise be.

Carbonate of Magnesia ^ combined with lime reduces the energy of the
slaking, and increases that of the setting processes ; when other substances are
present, its behaviour and combination with them are similar to those of lime.

When carbonate of magnesia is present in sufficient quantity (about 30 per
cent), it renders lime hydraulic independently of and in the absence of clay.

Alkalies and Metallic Oxides. — ^These if exposed to a great heat become
fused and quite inert ; but when subjected only to lower temperatures
sometimes tend to produce soluble silicates, and thus to cause hydraulicity.

Sulphates in small quantities tend to suppress the slaking action, and to
increase the rapidity of setting.

The introduction of these is the basis of a very important class of cements
which will be considered presently. (See p. 179.)

CLASSIFICATION OF LIMES AND CEMENTS.

The calcined limestone is divided, according to its action in slaking and
setting, into the following classes : —

1. Rich, Fat, or Pure Limes.

2. Poor Limes.

3. Hydraulic Lime&

J, r\ * ( Natural.

4. Cemento | ^^^^_

These classes merge gradually the one into the other, without sharp distinc-
tions, the difference between them depending upon the nature and amount of
the foreign constituents associated with the lime, and upon the degree of
calcination to which the stone has been subjected.

The physical characteristics of the raw stone are no index to the properties
of the lime or cement produced from it These properties may however be
inferred from the nature and proportions of the chemical constituents of the
stone. A general composition has been assigned to the materials yielding
each of the classes above mentioned, but it must be borne in mind that thib
is only an approximate indication of quality, and that the behaviour when
calcined and treated ydtV water is the only safe means of classification.

The following Table shows the composition of a number of limestones
and cement stones, chosen as characteristic examples, and intended to give
some idea of the varieties actually met with.

In comparing these analyses with others, it must be borne in mind that
these show the composition of the raw stone, or raw material from which the
lime or cement is produced. Analysis of the burnt lime or cement would in
each case have given a higher percentage of clay and sand, and the lime and
magnesia would not appear as carbonates. (The carbonic acid would have
been expelled during calcination.)

^ MajfM9i%wi earhonaJU,

> »i >y-u— . w^^ ■■■ ,m*^;. J pupiui .

CLASSIFICATION OF UMES AND CEMENTS.

149

TABLE

GIVING THE Composition of Various Limestones, Cement Stones, etc.,

BEFORE Calcination.

CoHPoeiTioM OF Raw Stomk ob Raw Material.

Nature
ofXJme

or
Cement
produced.

Iff

Description.

Carran Marble (see
p. 66)

White Chaik .

Bath OoUte (see p.
W)

Portland OoUte(«
p. 00)

Sillcifenms Oolite,
Chilmark Stone (see
P.«8)

Grey Chalk, Hailing
(see p. 155)

Roach Abbey, Dolo-
mite (see p. 59)

Bolsover, Dolomite
(see p. 59)

Carboniferous,
Aberthaw (see p.
155)

Orey Chalk, Sussex
(see p. 155)

Carbonate of Lime

and Carbonate

of Magnesia.

100 carb. lime

98 '6 earb. lime
-4 carb. magnesia

99-0

94-5 carb. lime
8*6 carb. magnesia

97 0

96*3 carb. lime
1*8 carb. magnesia

96 4

79*0 carb. lime
8 '7 carb. magnesia

82-7

92 carb. lime .

57 '5 carb. lime
89.4 carb. magnesia

90-9

51 'I carb. lime
40*2 carb. magnesia

91-8

80-2 carb. lime

88 carb. lime .

Clay, Sand, Iron,
etc

-2 iron, manganese
and phosphates
•8 silica and alumina

1-0

1*2 iron and alumina
1-2

'5 iron and alumina
1*2 silica

1-7

2*0 Iron and alumina
10-4 silica (nearly all
sand)

12^
8 clay

'7 iron and alumina
-8 8iUca

1*8 Iron snd all
3-6 silica

11*2 clay .

17 clay

Water
and
Loss.

1-8

1-9

4*2

1*6

8-8
2-6

Analyst or
Authority.

Vicat.
Schweitier (ReidX

Professors Daniel
and Wheatstone :
Commission on
Stone for Houses
of Parliament

Do.
Do.

coL Scott, as.

Professors Daniel
and Wheatstone ;
Commission on
Stone for Houses
of Parliament

Do.

Phillips (Captain
Smiths Yicat).

CoL Scott, RE.

ISO NOTES ON BUILDING CONSTRUCTION

Composition of Limestones, etc. — Continued,

OoMFMiTioH or Raw Btokb ob Raw Matsbiau^

Xatare
of Lime

or
Cement
produced.

Description.

Carbonate of Lime

and Carbonate

of Magnesia.

Clay, Sand, Iron,
etc.

Water

and

Loss.

Analyat or
Aathorlty.

Blue Lias, Lyme
Regis (Me p. 165)

Carboniferous,
Holywell, Wales
(Halkin Mountain
LimestoneX see p.
165

Arden, near Glas-
gow (see p. 156)

Heary English

Portland

8 White Chalk and
1 CUy dried, but
unJbunU (see p.
100)

Portland Cement,
good

Kimmeridge Clay

(Boulogne)
(Natural PortUnd)

urnbumt

Natire Magnesia
(Madras)

Dolomite, PortgyfU,
North Wales

Rosendale Cement
8ton«, Layer No.
9. Hiffh Falls. Ul-
ster, New Torii

70*2 carbi lime

71'56carb. lime
l-S5Garb.

17-8 silica and aln-

721»

68*0 carb. Ume
-8carb.

8*6 alumina
2-Siron.

•8 alkalies
90-1 silica

86-«

26-8 clay
2-4 iron
*6 chlorides

77* carb. lime

77-0

58 to 68 carb. lime

76'0 carb. lime
*8 carb. magnesia

28-8

2*7 alumina
3*5 iron
15*8 silica
1*0 alkalies

23*0.

77*4
90 carb.

21 to 24 silica
5 to 9 alumina
3 to 6 oxide iron
0*5 to 1*6 sulphuric

acid
9*2 Iron and alu-
mina
18*4 silica

22^

•5 silio

21*4 carb. lime
61*16 carb. magnesia

6*68 silica
2*071
876 iron

82 56

48*8 carb. Hme
20-0 carb. magnesia

69-8

16-41

20*7 silica and alu-

1-9 iron
2*0 sulphuric acid
4-2 alkaline chlo-
rides

28*8

25*69 iron and alu-

Medina Cement
Stone (see p. 158)

47*80 carb.]
47-80

1-50 sulphuric acid
24*50 siUca

5109

8*6

2*4

1*1

1*9

*61

Beid.

Mospratt

IngraoL

Beid.

Specification of
I'Admlniitration
des Pont et Chaus-

Oilmore.

Dr. Malcomson
(Oaptaln Smith's
Vicat)

Professor Gabatt
(Lipowitz).

Professor Boynton
(Oilmore).

Some varie-
ties contain
less cUy.
Average
about 12-5
percent.

Cnrrie ft
Co.'s cir-
cular

Ingram.

' For analyses of the burnt Portland cement see p. 227

CLASSIFICATION OF LIMES AND CEMENTS,

151

Composition of Limestonks, etc. — Continued.

GoMPOUTioBr or Baw Btobtb or Saw Matebial.^

Natan
of Lime

Oement

pnMlnoed.

Daseription.

CarbooAte of Lime
and Carbonate
of

Clay, Sand, Iron,
etc.

Water
and

Analyttor
Authority.

Bomaa Cement Stone
ftom Calderwood
(Seotlaiidi Me p.
169

Medina Cement
Stone ftom Porte-
month, Ide of
Wight (see p. 168)

64*0 carb. lime
14*2 carb. magneeia

68*9

46*82 earbi lime
*60carb.

Cement
Stone ftom Bou-
logne Septaria

Oement
Stone ftom Sheppy
Septaria

Boeeadale Cement
Stone, Layer No.
16. High Falls,
New Torli

46-82

61*6 carb. lime

61*6

66-7 oaitu lime
•6 carb. magneeia

66-2

46*0 carb. lime
17*8 carb. magneeia

68-8

8*4 alumina
13*31 iion
8*8 tUlca
2*6 phosphates

281

14*16 iron and alu-
mina
170 sulphuric acid
37'«6 8iUca

63 60

4*8 alumina
16*0 sUlea
91>lron

28-8

6*6 alumina
6*8 iron
1*9 1
18-OsiUca

82*6

80-0 silica and alu-
mina
1*8 Iron.

*2 sulphuric acid
4*1 alkaline chlo-
rides

86-6

8-7

9^6

1*80

Professor Bnmy
(Gilmore).

tths Vicat).

Professor Beyntoii
(OilmoreX

Sough Tegts. — A few rough tests may be applied to a limestone to see if it
is likely to fnmish a hydraulic lime or cement

Such a stone will generally have an earthy texture, and will weather to a
brown surface.

Acid will not cause upon it so great an effervescence as upon purer lime-
stones.

When breathed upon or moistened a clayey odour is emitted from the
stone.

The best plan, however, is to bum a little of the stone in a small experi-
mental kiln, to judge by the slaking, and by the behaviour of pats made from
the paste.

For analyses of the burnt Boman cement see p. 241.

152 NOTES ON BUILDING CONSTRUCTION

LIMES.

Bioh or IVit Limes are those calcined from pure, or very nearly
pure, carbonate of lime, not containing sufficient foreign con-
stituents to have any appreciable effect upon either the slaking oi
setting actions.

The phenomena attendant upon these actions and the charac-
teristics of the resulting paste exactly resemble those described
for pure carbonate of lime (see p. 146), and need not be repeated.

Uses. — The solubility and want of setting power of fat lime
render it unsuitable for making mortar, except for the waUs of out-
houses and for other similar positions. It is nevertheless fre-
quently used for the mortar in structures of a much more imposing
character.

It is however better than hydraulic limes for sanitary purposes
(being purer), and is very useful for plastering and for white-
washing. It is also extensively employed in the manufacture
of artificial hydraulic limes and cements.

Precaution in Using. — ^Fat lime requires to be mixed with a
great deal of sand to prevent excessive shrinkage, but this addi-
tion does not materially injure it, as it attains no strength worth
mentioning under any circumstances.

The only setting that takes place in it is the formation of a
thin surface crust, bearing a small proportion to the whole bulk ;
mortar made from such lime may therefore be left and re-worked
repeatedly without injury.

Stainsd Fat Limbs. — Some of the lime which finds its way into the
Tjondon market, under the assumed names of Dorking, Hailing, and Mers-
tham, is merely fat lime tinged with iron sufficiently to give it the buff colour
characteristic of the hydraulic lime made out of the grey chalk from the
localities above mentioned (see p. 155).

Of course, this stained lime makes mortar of the same inferior descrip-
tion as would be obtained from a common fat white lime, and has no
hydraulic properties whaterer.

Poor Limes are those containing from 60 to 90 per cent of car-
bonate of lime, together with useless inert impurities, such as sand,
which have no chemical action whatever upon the lime, and there-
fore do not impart to it any degree of hydraulicity.

These limes slake sluggishly and imperfectly, the action only
commences after an interval of from a few minutes to more than
an hour after they are wetted, less water is required for the pro-

LIMES, 153

cess, and it is attended with less iieat and increase of voliime
than in the case of the fat limes.

If they contain a large proportion of impurities, or if they are
over-burnt, they cannot be depended upon to slake perfectly
unless first reduced to powder.

The resulting slaked lime is seldom completely pulverised — is
only partially soluble in water, leaving a residue composed of the
usdess impurities, and without consistence.

The paste formed from the slaked lime is more incoherent, and
shrinks less in drying, but behaves in other respects like that
made from fat Ume — ^in fact, it is like a fat lime mortar contain-
ing a certain proportion of sand.

Mortar made from poor lime is less economical than that from
fat lime, owing to the former increasing less in slaking, bearing
less sand (as the lime already contains some in the form of
impurities), and requiring a more troublesome manipulation than
the latter. It is in no way superior as regards setting, and
should therefore only be used when no better can be had.

Hydraulio I«imeo are those containing, after calcination, enough
quicklime to develope more or less the slaking action, together
with sufficient of such foreign constituents as combine chemi-
cally with lime and water to confer an appreciable power of
setting without drying or access of air.

Their powers of setting vaiy considerably. The best of the
class set and attain their full strength when kept immersed in
water.

They are produced by the moderate calcination of stones con-
taining from 73 to 92 per cent of calcium carbonate, combined
with a mixture of foreign constituents of a nature to produce
hydraulicity.

Different substances have this effect, as already mentioned (see
p. 147), but in the great majority of natural hydraulic limes com-
monly used for making mortar, the constituent which confers
hydraulicity is day}

The phenomena connected with the slaking of limes varies
greatly according to their composition. With none is it so
violent as with the pure carbonate of lime (see p. 146), and the
more clay the limes contain the less energy do they display, until
we arrive at those containing as much as 30 per cent of day,

^ In some varieties, as before mentioned, a portion of the carbonate of lime is re*
placed by carbonate of magnesia, which increases the rapidity of setting.

154

NOTES ON BUILDING CONSTRUCTION.

when hardly any effect at all is produced by wetting the calcined
linie> unless it is first ground to powder.

The setting properties of hydraulic lime also differ very con-
siderably in proportion to the amount they contain of the clay or
other constituent, which gives the lime its power of setting with-
out drying or the access of 8ur.

This led to their being subdivided by Yicat into three classes,
as shown in the following Table : —

CLASSIFICATION OF HYDRAULIC LIMES.

If ame of Class.

usocisled with
Carbonate of Ume

only, or with

Carbonate of Lime

and Carbonate of

Magnesia.

BahATioor in sUiklng alter
being wetted.

Behaviour in setting
onder Water.

Feebly
Hydraalic

5 to 12 p. c

Pauses a few minutes,
then slakes with de-
crepitation, develop-
ment of heat, crack-
ing, and ebullition of
vapour.

Firm in 15 to 20 days.
In 12 months as hard
as soap— dissolves with
^eat difficulty, and
in frequently renewed
water.

Ordinarily
Hydraulic

15 to 20 p. c

Shows no sign of slaking
for an hour, or perhaps
several hours — finallv
cracks all over, with
slight fumes, develop-
ment of heat, but no
decrepitation.

Resists the pressure of
the finger in 6 or 8
days, and in 12 months
as hard as soft stone.

Eminently
Hydraulic

20 to 30 p. c.

Very difficult to slake—
commences after long
and uncertain periods
— very slight develop-
ment of heat, sensible
only to touch — ^very
often no cracking, or
powder produced.

Firm in 20 hours — ^hard
in 2 to 4 days— very
hard in a month — in 6
months can be worked
like a hard limestone,
and has a similar frac-
ture.

Varieties of Idme in Common Uae. — Fat Limbs. — ^White chalk, marble,
the Oolitic limestones, and shells, when calcined, furiush the fat limes in
ordinary use. A great variety of fkt limes is found in England, Scotland, and
Ireland.

Oysters and other shells require burning at a high temperature. They
contain gelatine, which is converted into charcoal, and bums with difficulty ;
the resalt is a tendency to produce a badly slaking lime.

LIMES. 155

Htdraulio Limes. — Grey CkaU Lime (called " stone lime " in London) it
of a feebly hydranlic character.

It is obtained from the lower chalk beds in the South of England, the
present supplies coming from Hailing, Dorking, Lewes, Petersfield, Mers-
tham, etc.

This lime is usually of a light buff colour, and slakes very freely. When
used with two parts of sand in brickwork, a good sample should sensibly
resist the finger-nail at a month old.

Lias Lime varies greatly iu its properties according to the locality of the
beds irom which it is procured, some being only moderately hydranlic, and
others eminently so.

The raw stone ia of a dark blue colour (hence the lime is called *^ blue
lias "), and the burnt lime a pale grey.

It slakes very sluggishly, and should set well in wet situations (according
to its composition) in from one or two to several days.

This lime is sold both in lump and ground. The latter is, as a rule, the
best, as the softer stones, containing more day, are selected for grinding,
but it may be adulterated with sand, or be air-slaked (see p. 202).

The lime is ground to nearly the same fineness as Portland cement (see p.
162), and sold in sacks, or, for export, in casks.

Mr. Beid says that limestones which approach nearest to the analysis given
in the Table, p. 150, *' should have the preference.**

Lias lime is procured chiefly from the Midland and South-western counties —
the best known being that from Barrow-on-Soar, in Leicestershire ; frt)ni
Watchet, in Somersetshire ; Lyme Regis, in Dorset ; Whitby, in Yorkshire ;
and Rugby, in Warwickshire.

The Carioniferoue Limestones yield very valuable hydraulic limes, among
which may be mentioned the Hdikin Mountain limestone, from Holywell, in
Flintshire ; the Aberthaw lime, found near Cardiff ; lime found near Berwick,
in Northumberland, etc.

The Aideu lime, found in this formation near Glasgow, is of an eminently
hydraulic character, and has been much used for docks and other important
work. It partakes rather of the character of a Roman cement, and will not
stand a large proportion of sand.

The Milton or Hurlett lime, and the Kilbride lime, from the same neigh-
bourhood, are of a similar description.

Hydraulic lime is found also in Fifeshire, at Dunbar, etc etc.

I%e Magnesian Limestones^ found in Durham, Yorkshire, Derbyshire, Don-
caster, and Notts (see p. 57), also furnish hydraulic limes, which are sometimes
of a powerful character.

In Ireland the calp limestone yields a hydraulic lime, but it is very vari-
able in quality.^ A good hydraulic lime is obtained from the Oillogue quarry
in the carboniferous formation near Limerick.

The lias has not been met with to any extent in Ireland, and is usually
imported.

Artifioial Hydraulic Lime may be made by moderately cal-
cining an intimate mixture of fat lime with as much clay as will
give the mixture a composition like that of a good natural hydraulic
limestone, of which the product should be a successful imitation.

A soft material like chalk may be ground and mixed with

1 Wilkinson's Pradieal Oeology qf Ireland,

156 NOTES ON BUILDING CONSTRUCTION.

the clay in the raw state. Compact limestone, on the other hand,
is more commonly burnt and slaked in the first instance (as
being the most economical way of reducing it to powder), then
mixed with the clay and burnt a second time.

lime so treated is called ''twice kilned" lime.

The mixture may be made by violently agitating the materials
together in water by machinery, or by grinding them together in
a dry state, afterwards adding water to form them into a paste.

The paste in either case is moulded into bricks, which are dried,
calcined, and otherwise treated like ordinary lime.

Artificial hydraulic limes are not much manufactured or used
in this country.

CEMENTS.

The cements used in building and engineering works are cal-
careous substances, similar in many respects to the best hydraulic
limes, but possessing hydraulic properties to a far greater degree.

They may be divided into two classes —

1. Natural Cements.

2. Artificial Cements.

They are distinguished from limestones by not slaking or
breaking up when mixed with water after calcination.

Cements are used chiefly in foundations in wet places; in
subaqueous work of all kinds; for important structures, where
great strength is required, such as dock walls and lighthouses ,
also for making coucrete and cement mortar.

The more exposed parts of ordinary structures, such as the copings
of walls, are frequently built in cement, also the tops of chimneys.

Cements are also used in the walls of cesspits, the joints of
drains, etc. ; for protecting the outer faces of walls and buildings
from the weather ; for thin walls where extra strength is required ;
for pointing, filleting, and many minor purposes.

NATURAL CEMENTS.

Natural cements are burnt direct from stones containing from
20 to 40 per cent of clay, the remainder consisting chiefly of
carbonate of lime alone, or of carbonate of lime mixed with
carbonate of magnesia.

Carbonate of Magnesia by itself, when calcined, yields anhy-
drous magnesia, which does not slake like quicklime^ but if
powdered and made into paste sets through its whole mass.

NATURAL CEMENTS. 157

permanently expanding, bnt not breaking up. It is soluble in water,
but not so readily as lima

Cement Stones or Nodules are frequently found in thin
strata^ amongst those of hydraulic limestone. They are usually
brown or fawn-coloured, of compact texture, and with an earthy
fracture.

Those met with in this country generally contain a large pro-
portion of clay (about 30 or 32 per cent), are burnt at a low
temperature, and yield a quick-setting cement of no great ultimate
strength.

These stones will not bear much heat without fusing, as they
contain a large proportion of iron (see p. 236).

Stones containing a lower proportion of clay (about 22 per
cent) are strongly bumt^ and yield a heavy slow-setting cement.

The natural cement found at Boulogne (see Table, p. 151) is of
this character, and a similar description has been met with at
^^^7 ; b^^ slow-setting natural cements are rare in this country.

More than 40 per cent of clay injures the cement. If the
stone is haU clay, it should be used as a " pozzuolana" (see p. 196);
if there is more than two-thirds clay, it will not set under water.

SkJcing and Setting.-^-JjVJsi'p^ of burnt cement stones are hardly
aflfected by water; when ground to powder and wetted, they
produce a paste which, without any preliminary slaking action,
sets under water in from five minutes to as many hours, and
acquires within a year a strength varying from that of soft brick
to that of the stronger kinds of stone ; the differences in setting
powers and strength depending upon the composition of the
stone.

The shrinkage of cements setting in air is very slight^ the paste
being much denser than that made from lime, in consequence of
the absence of the expansion caused by slaking.

Boman Cement (originally called Parker's Cement) is made
by calcining nodules found in the London day. These con-
tain from 30 to 45 per cent of clay ; before being burnt they
have a fine close grain, pasty appearance, and greasy surface
when broken.

The burning is conducted at a low temperature and requires
great care.

The colour of the calcined stone is generally a rich brown, and
is no guide to the quality of the cement

WeigJU and Strength, — Good Eoman cement should not weigh
more than 75 lbs. per bushel, and should set very quickly (within

X58 NOTES ON BUILDING CONSTRUCTION.

about 15 minutes of being gauged into paste), but attains no
great ultimate strength (see Table, p. 159).

Specifications should mention a miniTnuTn weight for these and
similar cements, for a heavy cement is likely to be over-burnt, and
moreover a stale cement will have become heavier by absorption
of carbonic acid from the air.

The little strength possessed by Boman cement rapidly dimin-
ishes on the addition of sand.

1 or \\ part of sand to one of cement is the greatest propor-
tion that should be added.

Storing, — Boman cement is sold in a ground state, and kept in
casks, which must be kept carefully closed and dry, otherwise the
cement will absorb carbonic acid and becx>me inert. For the
same reason it is important to examine this cement carefully
before using it.

Uses. — It should be mixed in very small quantities and used at once,
and on no account beaten up again after the setting has commenced.

The properties of Boman cement make it valuable for tem-
porarily pointing joints in work to be done and set between tides,
and for other purposes where quick setting is desirable, and no
great ultimate strength is required.

It is also used for external rendering or stucco, but is liable to
efflorescence on the surface, which presents an unsightly appear-
ance (see p. 238).

Market Forms. — Boman cement is nsually sold in casks ; sometimes, if it
is to be used at once, in sacks.

The inside dimensions of the casks are 2 feet 4 inches high, 1 foot 4^
inches diameter at middle, 1 foot 3) inches diameter at ends.

Each cask nsually contains 3^ trade bushels^ of 70 lbs. each — t.e. 246 Iba

The sacks measure 3 feet 7 inches by 2 feet, and contain 3 trade busheLi
— i.«. 210 lbs.

Medina Cement is made from the septaria found in Hampshire and the
Isle of Wight, and from those dredged up out of the bed of the Solent

It sets very rapidly, is of a light brown colour, and resembles Boman cement
in its characteristics, but is stronger for the first three months (see Table, p. 159).

It is sold in casks containing 3^ trade bushels of 68 lbs. each, or sacks
containing 3 bushels.

Harwich and Sheppt Cements are similar materials made from nodules
found in the London clay at Harwich and Sheppy.

^ There are two kinds of bushel used in connection with cements : — (1) The "striked
hushelf" being a measure containing 1 '28 cubic feet, lightly filled, and struck smooth at
the top with a straight edge (see p. 16S) — 21 of these bushels go to a cubic yard ; (2)
The trade bushd^ which is a given weight established by practice, and varying for each
cement. The weights of trade bushels of different kinds of cement are given at p. 256.

Unless cement is ordered by weight, there is likely to be some confusion between the
two kinds of bushel above mentioned. It is desirable where possible to order cement by
the tun net.

ARTIFICIAL CEMENTS,

159

Whitbt, Mulgravb's, or Atkinson's Cement is made from the septaria
of the Whitby shale beds of the Lias formations in Yorkshire. It is some-
thing like Portland cement in colour, takes slightly longer to set than Roman
cement, and absorbs more moisture, but resembles it in its charactenstics
generally.

Caldbrwood Cement is a variety of Roman cement of a dark colour from
nodules found in Scotland.

East Kilbride in Lanarkshire furnishes a very similar cement.

The following Table, compiled from different sets of experiments by Mr. Grant, ^ shows
the strength of two different samples of Roman cement, and of one of Medina cement,
and also the weakening effect of sand when added to one of the former : —

ROXAH CXVBNT.

Medina

Cbmbmt.

Neat

immerBedin
Water.

Sample A.

Neat.

Sample K

1 Cement

(B)
isknd.

1 Cement

(B)
8 Sand.

7 Days .
14 „ .
21 „ .

1 Month
3 Months
6 „ .
9 » .

13 „ .

2 Years.

202

178

186-5

260-8

822-6

472-7

4711

643-1

546-3

120-5
169-9
165-2
358-2
220-4
252-6
251-5
268-6

47-6
65-6
74-2
81-2
121-9
814-8

7-0
42-8
46-9
41-9
91-75

100
19-2
17-4

211-0
808-4
298-0
806-0
448-8
412-4
467-2
476-9
276-0

N.B.— The sectional area of the briquette was 2^ sqoare inches.

ARTIFICIAL CEMENTS.

Hydraulic cement is made artificially by a process similar to
that already described for artificial hydraulic limes (see p. 155),
a higher proportion of clay being added to make the mixture
resemble the composition of a natural cement stone.

The twice-kilned lime is not however used, but the raw lime-
stone or chalk is if necessary crushed by machinery before mixing.

The cements usually manufactured are of a heavy slow-setting
character, and require to be calcined at a high temperature, which
produces incipient vitrification. As it is impossible to maintain
a perfectly uniform temperature all through the mass, the result
is a mixture of products of different degrees of calcination, includ-
ing half-raw under-burnt portions of light yellow cement^ and
dense heavy clinker (see p. 181).

A judicious selection of them for grinding, and more especially
the rejection of the under-burnt portions, is essential to the pro-
duction of good and uniform cement.

* Min. Proceedings Civil Engineers, vols. xxr. and xxxil

l6o NOTES ON BUILDING CONSTRUCTION

As the best of the cements are burnt to the state of clinkers
the subsequent breaking and grinding are tedious and costly opera-
tions. Fine grinding is however most essential to properly
develope the strength of the cement when used, as it commonly
is, with sand.

Portland Cement is so called from a fancied resemblance in its
colour to Portland stone.

It is by far the most valuable of all the cements, and is made
by intimately mixing and calcining together substances of different
kinds, so as to obtain a material containing, as a general rule, when
burnt some 58 to 63 per cent of lime combined with about 22
per cent of soluble silica — 7 to 12 per cent of alumina — and
small percentages of oxide of iron, magnesia, etc. (see p. 241).^

The materials used may be either chalk and clay-7— which are
mixed by the wet process — or limestone and clay or shale mixed
by the dry process.

Manufacture from Chalk and Olat. — The cement best known in thia
country is made on the banks of the Thames and Medway, from chalk and
day mixed by the wet process.

The proportion of chalk and day mixed together depends upon the com-
position of the chalk before burning. The result required is to obtain a
mixture containing before burning some 23 to 26 per cent of clay.^

With white chalk (which itself contains no clay) 3 volumes of dialk
are mixed with 1 volume of alluvial day or mud from the lower Thames
or Medway.

If the chalk itself contains clay, the proportion of clay added is modified
accordingly.

For example, with grey chalk, 4 parts of chalk are used to 1 of clay.

The chalk and clay are mixed in water to the condition of a creamy
liquid, which is called *' slurry," the fine particles in suspension are allowed
to settle in large tanks, reservoirs, or '* backs," for several weeks, and when
the deposit becomes nearly solid, the water is run off, the residue is dug out,
sometimes pugged, dried on iron plates over coking ovens, or over the flues
from the kiln, burnt in intermittent kilns (see p. 189), at a very high tem-
perature, and then ground to a fine powder.

This method of manufacture is of course applicable only when the mate-
rials to be mixed can easily be liquefied in water.

The above is the wet process as ordinarily practised on the Thames and Medway,
bat in very modem works modifications have been introduced, some of which may be
mentioned.

Under the patents of Messrs. I. C. Johnson h, Co. of Oreenhithe the undermentioned
processes have been adopted at theh* various works, and some of them have been intro-
duced at other works.

Tlie chalk and clay are mixed with much less water (only about 10 per cent) to the
consistency of batter pudding. The slurry thus formed is passed through gratings into
a pit, whence it is lifted by buckets fixed to the circumference of a vertical revolving
wheel, and passed through millstones which f^^nd it to a minute degree of fineness.

^ For very light quick-setting pemcnts the proportion of lime is considerably l^sa
(see p. 241).

' 28 or even 30 per cent of clay may be used for light quick-setting cements used
for stuccoing.

PORTLAND CEMENT, i6i

The mixtnre is then pumped np and spread ov«r the floor of a large arched chamber
which branches ont from the kiln at a height of about 15 feet above the flre ban.
The top of the kiln is dosed, so that the waste heat and gases have to pass through this
chamber and over the snrlsice of the slurry,' Which is tiius quickly and thoroughly dried.
It is then burnt in the usual manner. ...

It will be seen that by this system this hacki are rendered unnecessary. This is a
great advantage, for they take up much room ; moreover, when slurry is' allowed to sub-
side in a deep back the heavier particles have a tendency to separate from the other,
so that the resulting material is not uniform in composition ; and lastly, in using this
system, any slurry found by analysis to be defective can more easily be dealt with than
it can in the large mass contaioed in a reservoir.

The method of drying the slurry is effective and' also economicaL It utilises the
whole heat Irom the Idln, a large proportion of which in ordinary kilns escapes at the top.

Ranaome** sy«teff» ponsists in burning the dried slurry in a revolving iron chamber lined
with fire-brick, and fed with waste-gases on the same system as in a regenerative furnace
(see p. 74). By this process it is produced in the form of a coarse powder, thoroughly
burnt through, in tiie course of about half an hour, instead of spending seven days in a
kiln. Among the advantages claimed for this system are, economy in space, ftiel, grinding,
and time, and improvement in quality by the exclusion of the ftiel ftom the cement.^

MAnnFAOTURK FROM LiMESTOiiss AND Clat OB Shalb.— lu some parts of the country
the denser limestones are used in the absence of chalk for the manufSeuiture of PorUand
cement : hard shales have also often to be used instead of clay.

Thus the Warwickshire (Rugby and Stockton), Somersetshire (Bridgwater), Dorset
(Poole and Wareham), Portland cements are made from Lias limestone and clay, and in
Cheshire (Doveholes) the limestones of the Carboniferous formation are used lot the same
purpoee.

When dense limestones are used for the manufacture of Portland cement, they must
be crushed by machinery. The shale or clay is roughly burnt to ballast (see p. 198),
the two are then mixed in the proper proportion (according to their composition) to give
the percentage of clay and lime required — and are ground to a fine powder.

This powder is passed into the pug-mill of a brick -making machine — thoroughly
mixed — slightiy moistened, and then moulded semi-dry into bricks. These bricks are
then dried upon hot plates to drive off any remaining moisture — burnt in kilns as here-
inafter described — and then ground to powder.

The process of manufacture just described is adapted for hard limestones and shaly
clays, which cannot be reduced to liquid and thus mixed together. The dry process is
stated by Mr. Beid to be very eflBcient and economical. He says, moreover, ''The
carbonate of lime is in so finely comminuted a state, and so accurately blended with the
silica and alumina, that no injurious development fsom this source can possibly arise, at
all events in the direction of the cracking or blowing danger."

Hie plant required for a Portland cement manufactory is so extensive that it can
hardly ever be worth while for an engineer or builder to manufacture for himselfl This
branch of the subject will, therefore, not be pursued further; but any one who is
interested in it wQl find full details of the processes of manufacture, with much other
usefdl information, in Mr. Beid's woib : A PmcUcal TreoHm on the Manufacture of
Portland Cement; The Practical Manufacture of Portland Cement, translated fh>m
Idpowitz ; and The Science and Art of the Manufacture of Portland Cement; also in
a paper by General Scott and- Mr. Bedgrave, in the Minutes of Ms Proceedinge of Civil
JSngineert, vol. Ixii p. 67.

PORTLAKD CbmIbnt MADB Fiioil: Slao. — Ordinary blast fkirhaoe slag (see p. 259) contains
nearly the satne constituents as Portland cement, but not in the same proportions — ^the
proportion of lime being too smaU. Mr. Ransoms runs the molten slag into water, so that
it forms a sort of sand^ grinds this with the required extra proportion of lime in the form
of chalk, and then by burning the mixture in a revolving kiln produces good Portland
cement. The writer has no experience of this material, but it is said to attain the same
strength as ordinary Portland cement, and in a shorter time.^ The process is, of course,
useful only in blast-furnace districts, for it would not pay to transport slag to other places
for the purpose.

''Great caution is necessary in adopting a cement of this nature, more especially
when it is recollected that blast-furnace slags differ materially in their composition.
... It wbuld a|)pearj hdweVer, that when care is taken to see that the constituents

^ Engineer, 4th March 1887.
B. C. ^m M

i62 NOTES ON BUILDING CONSTRUCTION.

of the cement exist in suitable proportions, a very serviceable article is capable of being
produced." ^

Portland cement differs very considerably in its characteristics and action.

It can be mann&ctored more cheaply when under-burnt, because then a
greater bulk of cement is produced with a given quantity of material^ and it
requires less fuel and less grinding; it also sets more quickly, but never
arrives at the same ultimate strength as a properly burnt cement Under-
burnt cement contains^ moreover, an excess of free quicklime, which is apt
to slake in the work and cause great mischief This may be remedied by
exposing the cement^ and allowing these partLcles to become (Ur-daked.

Tests op Quality. — A very slight diflference in the manufac-
ture may make a great difiference in the character of the material,
and rigid testing is necessary in order to secure the best cement

Before using Portland cement for important work, the under-
mentioned points should be inquired into : —

Fineness of OrU. — ^The cement should be ground to a fine
powder.

This can be roughly tested by rubbing it between the fingers,
or, accurately, by passing it through a sieve with meshes of known
size.

With regard to the exact degree of fineness that is advan-
tageous, there is some difTerence of opinion.

There seems, however, to be no doubt that properly burnt
cement, when ground extremely fine, is, as compared with one
coarsely ground, much stronger when used with sand, and also
safer, for there are none of the coarse particles which exist in
well burnt and coarsely ground cements, especially when they
have any tendency to excess of lime.

A heavy well burnt cement is diflBcult to grind properly, and
it will often contain a considerable proportion of coarse particles
which ought to be separated and reground.

The experiments by Messrs Grant, Golson, Mann, and others
show that when used neat {ije, without admixture of sand) a
coarse-grained cement is stronger than one finely ground.

When mixed with sand, however, as it generally is in actual
use, the finely groimd cement makes stronger mortar than the
other, the difference in its favour being greater as the proportion
of sand in the mortar is greater.

A lightly burnt cement is easily ground fine, and '' at 7 or even 28 days
may appear to be superior to heavy, which is with difficulty ground as fine as

1 Denf s CaiUw LeOwrtB,

PORTLAND CEMENT. 163

the lightly burnt, but in the long run the heavy, if not too coarsely ground,
wUl Burpass the lightly burnt, and if the heavily burnt were as finely ground
as the light it would be a great deal stronger from the beginning, the time
of setting being of course the same. Fine cement, as it takes more sand, goes
fiuiher than coarse, it is also much safer when it verges on the blowing point
from excess of lime." ^

Grinding is better than sifting, **• Heavy clinker ground fine will when
tested give higher results than lighter cement of equal fineness obtained by
sifting."!

Mr. Mann, in his experiments on the adhesive strength of cement^ found
that with cement sifted through a sieve having 176 meshes to the lineal inch,
— i,e, 80,976 to the square inch, the so-called '* coarse " grains stopped even
by this fine mesh influenced the cement as follows : —

Adhedye itrength after 7
days ; in lb«. per iq. inch.

The fine particles only 91

Ditto with 25 per cent of the coarse grains . .63
Ditto with 75 per cent of coarse grains . .26
Coarse grains only 8

Mr. Mann, says that this fine sieve was found to '' afiford more definite and
reliable results than those having larger meshes."

The experiments of the late Mr. Qrant, Mr. Mann, and others, have shown
that the larger grains in a coarsely ground cement, besides being in many
cases a source of danger, are almost usdess, sometimes quite useless, as cement,
being more or less inert, so that even if safe they play no other part than
that of additional sand.

Mr. Qrant found that ^ coarser cement than would pass through the sieve
of 2580 to the square inch, was at least no better than sand, and that when
it contained free lime it was a source of weakness if not of danger." ^

There is no general consensus of opinions or practice among engineers
with regard to the degree of fineness which it is best actually to require in
specifications for Portland cement.

At first the cement used for the Metropolitan Main Drainage Works ^as
specified to be ground '* extremely fine," but the exact size of mesh it should
pass is not fully determined.

In 1876 Mr. Mann said, ''l-50th inch square (2500 holes per square
inch) is as fine a mesh as can be conveniently used in practice, smaller ones
clogging very easily ; on the other hand, cement reduced to this fineness has
a very appreciable superiority with sand, as compared with even slightly
coarser samples." *

In the second series of very elaborate and useful experiments made by the
late Mr. Grant, the resident engineer of the Metropolitan Main Drainage
Works, the cement tested had all been passed through a sieve of only 400
holes to the square inch, the weight of the sifted cement being 110*56 lbs.
per bushel.

» Grant, M.P,LC.E.y vol. Ixii. p. 102.

» M,P,LC,E., vol. IxU, p. 243.

* Captain Innes, R.E., J2.j^. Corps Papm^ vol. xxL p. 4.

r64 NOTES ON BUILDING CONSTRUCTION.

Of late yton, howeyer, manufactarers in Qennany and Austria have intro-
duced cements ground to a much greater degree of fineness

Cementfr are- eauily piocusable wiiiclL wilL entirely pan sieves* of 2A60
meriies to the inch (400 to the* square centimetre), leaving only 10 per oent
on sieves of 6806 meshes to the inch (900 to the square centimetre), and. it
has been stated that cement can be procured of which only 3- tO' Id pec oent
is rejected by a. sieve of 3S,000 meshes to the incL^

These German cements are not much, if at aU, used in engineering works
in England, but they are used by the manufiEu^urers of patent cement paving

and wimilftT wnftt^TJAln.

With regard to oidinaiy English cements,. Mr. Mann found, that of the
cement reoeived ftom nine makers, from 36 to 60 (average 46*6) per cent was
stopped by a sieve with 30,976 meshes per square inch, and with, eight
varieties Mr. Qrant found the residue to average 49*6 per cent

There seems to be no reason, except the extra cost, why all the cement
should not be ground to go through the finer mesh, but at present a per-
centage to be stopped is allowed in most specifications.

Experiments made by a friend of the writer's showed that a cement which
left 10 per cent core on a S600 mesh sieve, left 20 per cent on the 30,976
mesh sieve. A cement which left only 10 per cent core on the 30,976
mesh sieve cost about 4& a ton more for grinding than the other. It appears
therefore that to obtain 10 per cent more cement cost 4s., and that the extra
grinding is not economical, except for cements, which cost more than 4X)& a
ton delivered on the works, as they do sometimes abroad.

Where fineness of grit is alluded to in specifications, as it' alWays should
be, 2600 meshes to the square inch is frequently specified, though the
Metropolitan Board of Works and a few engineers specify that not more than
10 per cent by weight shall be rejected by a sieve of 6800 meshes to the
square inch, and there seems no doubt that this requirement, which is estimated
to add only i^.to the cost of the cement, is a very desirable one to enforce
until still finer grinding can be obtained.

Qreat care must be taken, however, that finely ground cement is not lightly
burnt, to prevent which the weight, or better still (see \\, 167) the specific
gravity, of the cement should be specified too.

Where cement is to be sent abroad, and' thus rendered expensive bythe
addition of freight^ or it seems especially desirable to have a- material' which
gives the rjMaEmwm strength with the minimum bulk.

The table (page 169) shows the degree of fineness and' other particulan
specified by various public departments and on various works.

Qkuge of Wirt of Smes* — It is a cmioiis thing that thooc^ many enginetn specify
the number of meshes to the square inch in the sieves to be used, very few mention the
gauge of the wire of which the sieves are to be made, althoogh it is manifest that the
size of the orifice of the mesh in the sieve mnst depend upon the thickness of the wire ;
two- sieves with- the same number of meshes to the inch, but of difftrent gauges of wire,
must paMuoements quite dlArent as to -fineness*.

It is therefon neoesMury to state the gauge of the wire to be used, and asiuniformity
in this IB desirable, the author has obtained flrom Messrs. Currie and Ck>. of Leith a
list of gauges appropriate for sieves of the meshes stated below.

These are shown in the second column of the following table— the gauges shown in the
third column are those used by Messrs. Adie in making sieves for the Metropolitan
Board of Works.

i M.RLCE, 1880, vol. bdL p. 242.

PORTLAND CEMENT.

i6s

QaogeofWira.

Gauge of Wire.

BWO.

BWQ.

...

tq. inch.

400 .

900 .

1,«00 .

-2,500 .

8,600 .

«,800 .

14,400 .

.82,090 .

Weight — This particular is generally carefully ascertained.
It used to be considered that a good weight per bushel was a
sign of thorough burning, but it is now resJised that the weight
is greatly influenced by the degree of fineness to which the cement
is ground, upon the degree to which it has been aerated, and
upon the way in which the measure is filled.

The weight is, however, generally specified in connection with
the degree of fineness required.

The weight of the Portland cement in the market varies from
95 lbs. to about 120 lbs. per striked bushel

The heavier cements are slow-setting, but as a general Tule,^
they ultimately have a jgreater tensile strength than those of small
specific gravity.

A heavy cement is likely to be thoroughly burnt throughout,
but care must be taken to ascertain that its weight is not caused
by its containing a large proportion of coarse unground particles.

In some cases a heavy cement contains a large proportion of
over-burnt particles, and unless these are most carefully ground to a
fine powder, they slake very slowly, frequently not till they have
been used in the work, in which case they cause serious injury.

In very heavy cements there is some danger of an excess of
lime, which, if left in a free state, that is uncombined with the
silicic add of the clay, is liable to cause disintegration in the work.
It also renders the cement unfit for the joints of sewers,* or for
any position where it would be liable to the attacks of chemical
agents, which would destroy the carbonate of lima

Ab above mentioned, the weight of a given balk of cement depends to a
great extent upon the fineness of its grit ; a coarse cement is heavier than
one equally well burnt which is finely ground.

^ The experiments of Messrs. Grant, Colson, and Mann show that this rule does cot
Always hold good.
' Mr. Baldwin Latham, Min, Pfoc Ifut, Civ, Eng,, vol. xxzii p. 68.

i66

NOTES ON BUILDING CONSTRUCTION

The weight depends also upon the amount of aeration the cement has leoeired,
sometimes after weighing one bushel it will be found that the next bushel
weighs 1 lb. or 1^ lbs. less. In testing the weight of large quantities, there-
fore, the sample bushels should be taken from different parts of the heap.

Lastly, the weight depends upon the method in which the measure is filled
—one sample must not be more tightly packed than another.

To ensure this the cement should be poured into the measure as described
at p. 168.

The effect of fine grinding upon weight is shown in the following results,
obtained by Messrs. Currie and Co. of LeitL The figures will, however, vary
considerably with different cements.

Meiihes per sqoue
inch of Steve.

PBXoentage retained
by sieve.

Welffht of Cement
per Dushel in lbs.

Weight of Cement per
cabic foot in lbs.

2,500

8,600

5,500

14,400

82,000

10
10
10
10
10

115
112
109
104
98

90
87
85
81
76

It is evident from the above that the weight test ought never to be used
without the sieve test or it would be a direct incentive to coarse grinding.

On the other hand, to use the sieve test only would lead to being supplied
with light easily ground cements of no great tensile strength.

The practical difficulty, however, of accurately comparing the weights of
cements makes the weight test unreliable, and engineers therefore sometimes
require the cement to be of a given specific gravity, which cannot vary
with the different degrees of fineness of grit.

The weight of the Portland cement originally used on the Metropolitan Main
Drainage Works was specified to be at least 110 Iba per striked busheL

The cement actually supplied averaged 114*15 lbs. per bushel in weight.

The cement for the later series of experiments by Mr. Grant was specified
to weigh 112 lbs. per striked bushel. It weighed 113*2 lbs., including
the coarser particles, but only that portion of it was used which passed through
a mesh of 400 holes to the inch, and weighed 110*56 lbs. per bushel, as above
stated.

In a few eases a cement weighing 123 lbs. per bushel was experimented
upon. It does not seem desirable, as a rule, to specify a weight for cement
of more than from 110 to 115 lbs. per bushel. Mr. Qrant recommends that
when a weight is specified it should not be more than 112 lbs. a busheL

The weight is generally stated in lbs. per bushel; 21 bushels (each con-
taining 1*283 cubic foot) make a cubic yard. Sometimes it is stated in lbs.
per cubic foot

A very heavy and strong cement is required in important
engineering works; but for ordinary purposes of building great
tensile strength is not of the first importance, and in some cases,
e.g, for rendering walls, a lighter and more quickly-setting cement
may be used with advantage.

PORTLAND CEMENT. 167

Sptdfc OratiUy, — Mr. Mann found ^ that the specific graylty of cement Bupplied by the
best English manafacturera slightly exceeded 3*0.

The particles rejected by a sieve of 2900 meshes to the square inch had a specific gpravity
firom 3*08 to 3*13, and the fine particles passed by that sieve a specific gravity of from
2*97 to 8'06, but In some cases the coarse and fine particles of the same cement had the
same specific gravity.

In an inferior cement he found the specific gravity 2*80, and that of the finely sifted
portion only 2*55.

Grant's ezi)eriments ' show the specific gra^ty of differently burnt cements to be as
follows : —

Dght burnt ..... 3*130

Hard ...... 3134

Medium,, 8-131

Mr. Orant^s specification for specific gravity is " not less than 3*1.'*

The apparatus described in the next paragraph is recommended by Mr. Grant for
ascertaining the specific gravity of cement.

Keai^9 Speeijie OraxrUy BaiUe, — This bottle consists of two bulbs, the lower somewhat
exceeding the upper in capacity. The exact capacity of the lower bulb is of no im-
portance. On the neck between the bulbs is a file mark h, on the neck of the upper bulb
is a similar mark a.

The capacity of the upper bulb between the marks a and h must be
accurately determined, and may conveniently be either 500 or 1000
grains in water measure at 60" Fahr.

In ascertaining the specific gravity of a solid in small fragments —
small shot, for example — ^the following is the mode of procedure : fill
the bottle with distilled water up to the mark 6, accurately counter-
poise the bottle so filled in a balance, drop the substance (of which
the specific gravity is to be taken) carefally and gradually Into the
bottle until the water rises i^m 6 to a. Ascertain exactly the weight
of the material so added. If the capacity of the upper bulb be 1000
grains of water, the weight of the materiid required to raise the water
firom 6 to a is its specific gravity ; if the capacity of the bulb be 500
grains of water, the weight of the substance added must be multiplied
by 2, which will give the specific gravity.

The principle of the apparatus is very simple ; the capacity of the
upper bulb is an exact measure of distilled water, and when the water
is raised from ft to a by dropping a solid into the bottle, the bulk of
that solid equivalent to the given volume of distilled water is ascer-
tained and the relation between the weights of the two is given by the
weights of the substances added, which is either the specific gravity
direct, if the capacity of the bulb is 1000 gprains, or it can be ascertained pig. ggo.
by multiplying the weight of the solid by the number which represents
the part of 1000 represented by the capacity of the bulb, etc

If the solid be soluble in water, any convenient liquid can be used in the place of water
in making the experiment, the only thing necessary being carefully to counterpoise the
bottle filled with the liquid up to 6 in this manner. Petroleum, oil, turpentine, or any
liquid suitable to the nature of the material to be tested, may be used, all other things
remaining the same.

The only precautions to be observed are that the air, which is apt to cling somewhat to
the solid matter when dropped into the liquid, is carefdlly removed, and that if a very
volatile liquid be used in the place of water the bottle should be stopped or oorked to
prevent evaporation.*

Method of Weighing. — In order that the cement may be
accurately weighed, great care must be taken in filling the
measure.

* M.I.CE., vol. Ixii. p. 224. > M.LC.K, vol. Ldi. p. 180.

' Taken verbatim from Appendix iv. p. 129, M,LC.£., vol. IziL (Oimnt).

i68 NOTES ON BUILDING CONSTRUCTION.

Thifl may be done by allowing the dry cement to nm down a board ot
shoot, inclined at an aogle of 45°, into the measure, any superfluity being
carefully struck off with a light straight-edge^

A vessel with holes in it is sometimes used for filing instead of the shoot
An accurate method is to fill the measure through a sieve of about -^ inch
mesh held a short distance above it, or the cement may be poured through a
hopper placed about two feet above the measure. A drawing of the hopper
is sometimes supplied in connection with the specification.

CoLOUE. — ^This point should be examined, though it is not of
very great importance. Bad cement may be of a good colour.

Good Portland cement, as received from the manufacturers, should be of
a grey or greenish-grey colour.

A brown, or earthy colour, indicates an excess of day, and shows that
the cement is inferior — ^likely to shrink and disintegrate.

A coarse bluish-grey powder is probably overlimed and likely to blow.

The colour may best be observc^l by rubbing the cement on the hand or
on a piece of white paper.

Test for Tensile Strength. — This is the most important test
in most cases, and it should be made with the aid of a proper
machine, as hereinafter described (see p. 182).

Seven Bayi TeA, — The tensile strength of Portland cement, as required by
the original specification for the Metropolitan Main Drainage Works, was 400
lbs. on the briquette area of 2^ inches after six days' immersion.

Shortly after this the specified breaking weight was raised to 600 lbs. per
area of 2^ square inches.

The average strength of the cement supplied under this specification
during five years was 806 '63 lbs. on the briquette area.

The standard breaking weight specified on these works was afterwards
raised to 787 lbs. on the briquette area, or 350 lbs. per square inch after
seven days' immersion, the specification being as follows : —

"llie whole of the cement shall be Pbrtland cement of the very best quality, gronnd
extremely fine, weighing not leas than 112 lbs. to the striked bushel, and capable of
maintaining a breaking weight of 350 lbs. per square inch seven days after being made
in a mould and immersed in water during Uie interval of seven days."

The rigid testing on these and other engineering works has raised the
tensile strength of the best cement mauufactiu^ since that date.

The breaking weights specified on the works mentioned below are shown
in the following Table (page 169).

The tensile strength of Portland has been increased of late years,
besides which improvements in the methods of testing, and the increased
care with which they are carried out, cause higher results to be shown with
cements similar to those of former years.

Cements can be obtained which will stand a tensile stress of 660 lbs.
per square inch, even higher.

PORTLAND CEMENT.

169

9r,

fi«

o .—

-<
>•

'iffSi

|a§=

^Ig*

^11

►.
^

o
in

Ill

SO p 00

'^ "O '^

:^l

rl WCO

<o o

I-* f-H 00

Si-

lii

ill

Q
H
PS

-<
^

lit

000

kO o 10

o 00
^ Sao

i>o NOTES ON BUILDING CONSTRUCTION.

There is, however, great danger in raising this test too high. A cement
having great tensile strength after a short interval of setting can only be
obtained by using a maximum amount of lime in the manufacture, and an
excess of lime in the cement may cause it to expand in the work months
or even years after it is used.

It is better, therefore, to require a moderate tensile strength, such as from
300 to 350 lbs. per square inch.

Thirty Days* TesL — It will be noticed that most of the tests above mentioned an ap-
plied seven days after the cement ia ganged and formed into a briquette.

It has, however, often been suggested that, especially in the case of a heavy slow-
setting cement, seven days is too short a period for its properties AiUy to develop, and
a period of thkty days has been suggested as one which would give the cement a fairer
trial.

There would be a practical disadvantage In having to keep a consignment of cement
thirty days before it is accepted or rejected, otherwise the longer period might be prefer-
able. If it were adopted, of course a far higher tensile test would be necessary.

Mr. Mann found the increase in strength, in samples kept under water thirty days, to
be about 20 per cent as compared with those kept only seven days.

Mr. Grant says that cement required to bear 850 lbs. per square inch after seven days
should bear 450 lbs. after thirty days.

It has also been suggested that as the cement has generally to be used in the form of
mortar, it should be mixed with sand before being tested. Such, however, is not Che
common practice in this country.

Testing tmih Sand. — For many years Portland cement was always tested neat, %.e,
without admixture of sand, and this practice is still almost universal among engineers.

It has, however, frequently been pointed out by Mr. Qrant, Mr. Colson, and others,
that as Portland cement is nearly always used with a mixture of sand, it would be better
to test it, as far as possible, under the condition in which it is used in practice, as it is
thus that its probable behaviour when in use can best be ascertained.

The Germans have for some time made their tests on briquettes of 1 Portland cement
and 8 sand after twenty-eight days' setting.

It is found that the testing of neat cement forms but little guide to their behaviour
when mixed with sand, thus, ''coarsely ground cement will, as a rule, give somewhat
higher results when tested neat than finely ground, but when mixed with sand, say in
the proportion of 1 to 8, the superiority of the finely ground cement becomes apparent"^

Sand, however, retards the hardening, and it is found that briquettes formed of 1
Portland cement to 8 sand must be left at least twenty-eight days before being tested.

The length of time required for this test with sand renders it very difficult, indeed
almost impossible, to carry out on ordinary works for want of storage room — and it has
also other disadvantages.

It is impossible to compare tests made with mixtures of cement and sand, unless the
sand is always of exactly uniform composition and quality as regards size, sharjmess, and
surface of gprains, degree of dampness, eta, and sand so uniform in quality woulid be
very difficult to obtain.

The practical difficulties involved in testing cement mixed with sand have prevented it
from being universally adopted ; there can be no doubt, however, that for large works
where ample storage exists and sand of uniform quality can be ensured, more informa-
tion about the future behaviour of the cement can be obtained by this test than by
testing the cement neat

Teshno bt Comfrbssiov. — ^Again it has been pointed out that cement when in actual
use is generally subjected to compression — ^very rarely to tension — and that it would be
more useful to test its resistance to a compression than to a tensile stress.

The apparatus for testing cement by compression is, however, cumbersome and ex-
pensive, and tests of compressive strength are never specified by engineers.

Many experiments have, nevertheless, been made on the resistance of Portland cement
to compression. Mr. Grant found the measure of the *' compressive strength to be about
twenty times that of the tensile strength,"' but Herr Bauschinger considers that "there
is no fixed relation between the crushing and tensile strength of cement"'

» Grant, M.P.I.C.E. 1880, vol. Ixii. p. 104.
» M.P.I.O.E., YoL Ixii. pp. 108, 208.

PORTLAND CEMENT.

171

ADHB8IVE Stbehoth. — ^Yet another objection is made to the method of testing hitherto
and still adopted by most engineers.

It is pointed out that, as the principal ftmction of cement is to produce adherence
between portions of the materials used, its capacity to do this should be ascertained,
that the strength of its adherence to the materials should .be tested ; i.& its adhesive
strength, not merely its cohesive strength, that is, the strength with which its own
particles cohere.

Bfr. Mann has made a great many valuable experiments on the cohesive strength of
cement forming it as a joint between two pieces of limestone and finding what weight
was necessary to tear tbem apart

The following table gives the results of some of his experiments, and he points out that
it tends to show that under the ordinary cohesive tensile test a i^ly go<>d cement may
be rejected. For example, in experiment No. 9 the cement had a very low cohesive
strength after twenty -eight days — only 809 lbs. per square inch — which might have
caused its rejection, whereas its adhesive strength — 110 lbs. per square inch — was greater
than any of those tried with it.

Ck)MPABi80N of Adhksive and Cohesive Stbenoth.^

Average strengths in lbs.

No.

DncRipnoN.

per square inch.

Adhesive.

Cohesive.

Ordinary cement. Age 7 days

582

>t If }» ...

836

Fine cement sifted through sieve, ) . ^ t .i-„-
80,976 meshes to square inch j ^^ ' "^^^

428

»» )» *t

845

500

„ Age 28 days

105

500

If >f

109

887

428

)

110

809

1 f f f 1

820

He found also that " with one or two exceptions, the quick-setting cements manifested
a greater development of adhesive strength tiian the slow, while, in the case of cohesive
strength, quick-setting seems generally to produce an opposite efifect." '

In the experiments tabulated below, Mr. Mann shows very clearly that the adhesive
strength of a very finely ground cement is much greater than that of one coarsely ground.'

Comparative Cehentitiotts Stbenoths of Sifted and Unsifted Ceicents.'

AVERAGBB IV LBS. FEB SqUARX InCH.

Age 7 days.

Age 28 days.

Age 13 weeks.

Cement with coarse particles re-
moved by sieve with 80,976
meshes to square inch .

Ordinary cement, as received from
the manufacturers .

78
57

116
98

In the next Table Mr. Mann shows the strength of adhesion of Portland cement to
various materials.

1 M,P,LC,K, vol. Ixxi. p. 262. • M.P.LCK, vol. bm. p. 262.

> M.P.LC.K, vol. Ixxi. p. 260.

172

NOTES ON BUILDING CONSTRUCTION.

Strength of Adhesion of Portland Cement to Various Materials.^

In lbs. per square inch.

Matbbial.

AVKIUOK Adhbbitb STRBvara.

Remark*.

7 days.

28 days.

18 wk8.

emntltt

Bridgwater brick .

Ordiziaiy tsement.

»! >»

...

Sifted through No. 176 sieve.

Slate (sawn) .

...

Ordinary cement

Portland stonu

Sifted through No. 176 sieTQ.

...

Ordinary. FngmentB torn out tirsur-

fsAA

»i »»

...

uKie.
Sifted through No. 176 sieve. Png-
ments torn out of surfiuse.

Ground plate glass

...

102

113

Ordinary cement.

i» n

...

145

...

Sifted through No. 176 sieve.

Plate iron .

6*8

..•

Ordinary.

^>» , »i

...

Sifl»d through No. 176 sieve.

Sandstone

...

Ordinary. Fragments torn out of sur-

Polished marble

...

Ordinary cement

it »»

...

Sifted through No. 176 sieve.

Polished plate glass

Ordinary cement

if f>

...

Sifted through No. 176 sieve.

Granite (chiseUed)

...

Ordinary.

»t >t

168

...

Sifted through No. 176 sieve.

Limestone (sawn) .

Ordinary cement

a it

116

...

Sifted through No. 176 sieve.

i^.B.— No. 176 sieve was made of silk and had 80,976 meshes per square inch.

The Bkiquette. — The tensile stress that a cement will bear
depends greatly upon the manner in which the test is made, the
form of briquette, the method in which the cement is gauged, the
amount of water used, etc. eta

Method ofmaJdng BriqtieUea. — The briquettes, whether of neat cement or of oement
and sand, are made in brass moulds of the form shown in Fig. 86.

The following directions are taken chiefly from Mr. Grant's papers, the circulars of
Messrs. Ourrie and Sons, Messrs. Oibbs and Co., and Mr. Faj|ja.

Briquettei of Neat Cement, — Supposing the briquettes are to be made of neat cement,
and of the 1-inch square section, the procedure would be as follows : —

The cement from the different casks or sacks should be turned well over, samples from
different parts of the heap should be mixed, and if hot should be spread out, especially
in hot weather, so as to become thoroughly cool, and water should be carefully added,
noting the proportion required to bring the mixture into such a condition that repeated
pats with the trowel will bring the moisture up to the surface.

Two cakes of about 2 or 3 inches diameter and ^-inch thickness should be made, and
the time noted in minutes that they take to set sufficiently to resist the finger nail.

''If after two hours the cake is soft enough to take ths impression of a finger nail, it
may be considered slow-setting."*

If the cement should be slow-setting, all the briquettes may be made at once, but if
quick -setting, only three or four at a time, and if very quick only one should be made
at a time.

The moulds should be cleaned with a greasy cloth, and a number of pieces of thin
blotting-paper each rather larger than a mould are then placed upon a marble, glass, or
slate slab, and on these the moulds are placed.

Then about 4 lbs. cement, or enough for ten briquettes, are weighed and placed upon
the non-absorbent slab in a heap ; in the centre of this a hole is made, into which from

Af.RLC.R, vol. bud. p. 266.

' Grant, M.RLC.K, vol. Ixii. p. 104.

PORTLAND CEMENT. 173

B graduated glass is gradually poured the quantity of water previously determined, the
mixture being worked with a trowel until it becomes a short, harsh paste, the water is
then discontind^, but the working with the trowel continued until the paste becomes
pat and smooth.

With this paste the bxus moulds an filled as quickly and solidly as possible, a small
trowel being used, and the mortar beaten or lightly rammed and gently shaken until all
the air has been driven out of it and the mortar has become elastic. ThA surplus should
be cut off level, and the surlhoe left smooth.

The whole operations of making the paste and filling the moulds untU the briquettes are
placed on one side diould not tidke more than five minutes. The quicker it is done,
provided it is done properly, the better, for it is most important that the cement should
be at rest before the setting action commences.

When the moulds have been filled they should be numbered' and laid aside, in some
place where they will be secure against shaking or vibration in a wet damp atmosphere, or
covered with a damp cloth till they have set sufSciently to be taken out of t^e moulds.

This will probably be in less than twenty-four hours, the time varying according to
the rate of setting of the cement, but it must be done with great care to avoid flaws, and
not too soon, or the briquettes will lose their shape and be difficult to fit into the clips
of the machine:

The briquettes- Aould then be placed upon "sheets of gUwr or on slabi^ and laid in a
flat box having a^ cover lined, with several layers of linen, woollen, or cotton cloth, kept
damp. In this box they are kept until they have hardened sufficiently to be put into
waters This will vary ftom one or two hours to a day or more, but for uniformity,
unless in the case of specially slow-setting cements, briquettes of neat cement may be kept
for twenty-four hours before being transftrred from this box to the shallow tanks in
which tiiey are to rentain until the moment of testing.

*' The numbers on the neat cement briquettea may be made with a sharp point or with
a strong penciL

''The water in the testing room should be kept at a temperature as nearly uniform as
possible, say from 60° to 70* Fahr., but if the boxes in which the briquettes be kept
are covered, moderate changes of temperature will not materially affect the results."^

Briquettea of CemaU and Sand are made in a similar manner. About 1 lb. of cement
and 3 lbs. caxeftilly washed standard sand will make ten of the 1-inch briquettes.
The proportions of water required will be from 8 to 10 per cent, and the mixture roust
be beaten into the mould with a spatola^ or light wooden mallet, so as to be as solid as
possible.

The briquettes are treated like those made with neat cement^ except that they should
not be removed fnm. the moulds until at least forty-eight hours after they are made, and
should be kept in the boxes another forty-eight hours before they are numbered.

Nalwre and Proportion of Water in Cement Mortar, — No more water should be used
tiian is necessary to make the cement- fit- for use, an excess produces porosity and retards
the process of hardening.

Orant's experiments show that with 19 per cent of water, making the briquettes into a
stiff paste, they stood from 28 to 40 per cent more tensile stress than when 25 per cent of
water was used, making the cement of the consistency of stiff grout'

9 oz. of water to 40 oz. of cement, or about 22 per cent, is recommended by Messrs.
Gibbs and Co.

With hot or quick-setting cements neat more water will be required than with cool or
alow-eetting cements.''

With mixtures of 1 cement and 8 sand, about 11 to 12 per* cent may be used fof those
which set in leas than thirty minutes, and 10 per cent for those that take longer.

Briquettes mixed with salt water are rather stronger than those with i^h water,
but salt water ahould not be used in cement intended for building or rendering the walls
of houses to be inhabited, because it tends to keep them damp. Dfrty water would of
course injure the cement by introducing impurities which would prevent proper adhesion,
and hot water should not be used except for experiments- to niakethe'Cementset more
quickly.

Shape of Briquette, — The cement to be tested is formed into a briqpette
shaped in one of the forms shown in section in Figs. 83 to 86.

■ ■ ™ ■ ■ ■■ ■ I ■ »■— — a^—^ nil I fcnaiiii . .

» Orant, MP.LC.K, vol. IxiL p. 124.
* Qraat, M,P.LC.E. 1880, toL Izii p. 158.

174

NOTES ON BUILDING CONSTRUCTION

The briquette is placed in the clips of a testing machine (see p. 182), and
broken by slow tension. Each of the figures shows the briquette in the clips
ready to be attached to the machines.

There is no doubt that the shape of the briquette has an important
influence upon its strength.

The transition from the thicker parts of the briquette to the minimum or
breaking section should be gradual---all angles avoided — the shoulders should
be so shaped that the bearing of the clips upon them is imiform — ^the clips
hung so that the stress shall pass through their central points.

The form first used in this country is shown in Fig. 83 ; the principal
angles were afterwards rounded off as shown in Fig. 84, which is not a
good form, for it generally breaks as shown by the dotted line, and not at
the minimum section.

Whenever the clips bear upon a considerable part of the surfiEu^e of the bri-
quette, as in Figs. 83, 84, it is very difficult to prevent them from pressing more
at one point than another, and thus causing want of imiformity in the stress.

To avoid this the clips are sometimes done away with, and the briquette
is suspended by pins with knife-edges passed through holes in its ends, as in
Figs. 85, Z6, which represent one of the forms used by Mr. Grant in his
experiments.

The last form adopted by the Board of Works is shown in Figs. 86, 86a.
The change of form in the briquette is very gradual ; the clips are rounded so

Fig. 84. Fig. 85. Fig. 85a.

Fig. 86.

Fig. 86a.

Fig. 88.

as to bear on it at only four points, are hung on knife-edges We, and have
loose joints at BB, so that the stress may pass through their centre points.
This fonn of briquette seems to be the best that has been introduced.

It will be understood that the briquettes shown in the figures are all 1^
inch X 1^ inch =2^ square inches, at the waist or part intended to be
broken. This is clearly seen in Figs. 85, 85a. In many cases the weakest
section of the briquette is made only 1 x I square inch (see p. 183), and
briquettes of this size are said to give a higher resistance per square inch than
the larger ones. In testing, the mean of six briquettes should be taken.

Tests for Coolness. — In some cases cement which appears
perfectly good in every way has a tendency to crack and swell,
when placed under water. This action, which is commonly
known as " blowing," is caused by the cement being under-burnt,

PORTLAND CEMENT. 175

by its containing an excess of lime, or by its not being properly
" cool," that is, free from unslaked particles.

In order to detect this tendency to blow, the briquette placed
under water should be carefully watched.

If it is inclined to blow, it will show signs of expansion after
a day or two under water; in extreme cases the samples will
entirely break up, but a few cracks about the edges are the
commonest indications.

Pats should also be made about 3 inches in diameter and \ inch thick,
gauged in neat cement with thin edges, and placed upon pieces of glass or
other non-porous material

One is placed under water and watched ; if twenty-four hours after its
immersion there are no fine cracks round the edges, the cement may be con-
sidered safe.

With slow-setting cements surface cracks commencing at the centre are
merely the result of the surface drying too rapidly.^

The other pat is left in the air, and should remain of a dark grey colour.
If it is yellow or ochrey, the cement contains too much clay, and it is likely
to be deficient in tensile strength.

Additional Tests for Portland Cement. — Besides the ordinary
tests above mentioned, the following rough tests will give an in-
dication as to some important qualities of the cement before using it.

1. A bottle is filled with paste made from the neat cement If, after the
cement has been set some days, the bottle remains uncracked, it may be con-
sidered that the cement is not too hot

If the cement has shrunk within the bottle it is probably under-burnt ;
the flhrinkage can be detected by pouring in a little coloured water.

2. Another test is to fill a piece of glass tubing with neat cement paste,
and to note whether there is any shrinkage.

8. A rough method of ascertaining whether the cement is cool enough for
use, is by plunging the bare arm into the cement.

If it feels hot the cement has not been sufficiently weathered, and requires
further turning over.

Hardenino and Setttno. — It is important to know how long a cement
takes to harden and set This is generally roughly ascertained by the im-
pression of the finger nail upon the cakes of cement, as described on page 172,
but as a rule no means are used for ascertaining this in a more accurate
manner.

TifM for SeUinff, — It is extremely difficult to define the time reqtured for the
setting of different classes of cements, samples from the same lot may take fire minntes
or fire honra to set, according to its age, temperatnre, the quantity of water used, etc.
As a rough guide, however, tiie following times for setting may be taken under normal
oiroumstanoes : —

Quick Setting Gements . . . .15 minutes

Slow M >» • • • • 2 hours

Very Slow w tt • • • .6 hours

» Grant M.F.IC.K. vol. IxiL

176

NOTES ON BUILDING CONSTRUCTION

Fig. 87.

VloaCa NeedU ApparatuB, — Y\!g. 87 shows an apparatus, invented by M. Vicat, for
ascertaining the time of hardening and setting of cements. It is taken firom Messrs.
Currie's circular, together with the following directions for its nse.

*'To ose this apparatus, gauge 14 oz. of neat cement
with the requisite quantity of water, mix quickly into
a stiff paste, and with this fill the circular brass mould
resting on the ^ass plate, and which has a height of 4
centimetres and a diameter of 8 centimetres. The
moment at which the needle having 1 sq. millimetre sec-
tion and 300 grammes* weight is not able to penetrate
completely to the bottom of the paste, marks the com-
mencement of hardening. The interval from the time
of gauging till the beginning of the hardening process
U the Hme the cement should be worked and uaed^ if the
Mrength of the toork is to eorreepond to the quality of
the cement. As soon as the paste has become so hai^
that the needle does not leave an observable impression,
it is set, and is the time that should be noted as tetUng
time.

"The same apparatus may be used for aJBcertaining
the correct consistency of cement ; only the point of 1
sq. millimetre is replaced by a cylinder of 1 centimetre
in diameter. The circular mould is filled as quickly as
possible, and the piston immediately let down gently
into the paste. The consistency of the paste may be
, considered correct when the piston sticks at a height of
about 6 millimetres firom the bottom of the mould. In
this manner the exact- quantity of water required may
be ascertained.'*

STomNG.-=^I^ortrand cement is generally received in sacks in this
country, in casks abroad; these should at once be emptied, the cement
spread out for a month or so on a wooden or concrete floor, to a depth
not exceeding 3 or 4 feet, in a large weather-tight room, and occasioil-
ally turned over, so that it may become th<»oughly air-^aked and
cooled. (See tests- for' coolness, p. 174.) During the time it is
thus exposed the cement if fresh will increase considerably- iii bulk.*

Sometimes cement which it tested when new wbuld crack or
'' blow,'' will be found after this cooling, to have lost* the tendency
to do so.

This air-slaking or "cooling" is of the very great^tj importdttce,
particularly with cements which, on account of their very high
tensile resistance, may be suspected of containing an access of lime»

Strength. -^The strength of Portland cement varies, as has
already been mentioned, according to its original composition as
regards the percentage of chalk and clay used in its mcuiufacture,
with the degree of burning to which it has been subjected, tod
according to the fineness to which it has been ground.

The strength of gauged Portland cement rapidly inoteases with

age, the breaking weight on a sectional area of 2^ square inches

' In some moist climates abroad cement wonid be deadened by tbis treatment, so
tbat when sending cement to such climates it should be thoroughly cooled before it
is packed into the casks.

PORTLAND CEMENT,

177

beiDg as shown in the second column of the following Table for
neat cement weighing 112 lbs. per bushel.^

The strength of Portland cement mortar decreases as the
proportion of sand is greater, which will be seen bj the remaining
columns of the Table.

Age and time
Immeised.

Pbofortiok or Clean Pit Sakd to

IObhbmt.

Neat
Cement

Itol

Stol

8tol

4tol

6tOl

1 Week . .

445-0

152-0

64-5

44-5

22-0

1 Month. .

679-9

826-5

166-5

91-5

71-5

49-0

8 Months .

877-9

549-6

451-9

805-8

158-0

128-5

6 Months .

978-7

689-2

497-9

304-0

275-6

218-8

9 Months .

995-9

718-7

594-4

888-6

1 12 Months. .

10757

795'9

607-5

424-4

817-6

215-6

The following Table ^ shows the strength of Portland cement at dififerent
periods of time with different degrees of fineness and with different propor-
tions of sand.

TABLE' showing the Cement coarsely ground and sifted through a fine sieve

neat and mixed with sand.

The German mould used = 5 square centimetres in section.

Aos OF
BuQUKin.

Nkat.

Thau ov Sand.

Fiv« OF Sakd.

10*2 per cent
resldae on a
sleye of 2680
meehea per
■qoare inch.

Sifted 8o as
topaaaaU
through aieye
of 82,267
meahes per
square Inch.

10*8 per cent
left on sieve

of 2680
meshes per
square inch.

All passed

through sieye

of 82,287

meshes per

10*2 per cent
left on sieve

of 2680
meshes per
square inch.

All passed

through sieve

of 82,267

meshes per

square ipch.

Weeks.

Lbe.i>er
■qoare incb.
358
588
585
701

Lbe. per
square inch.
846
880
469
495

Lbe. per

square inch.

171

206

282

Lbs. per
square inch.
252
380
858
897

Lbs. per

square inch.

118

166

Lbe. per
square inch.
186
208
223
272

Refmaxla. — This Table shows (1) that the coarsely ground cement broke at a higher
point when used neat than when finely ground or sifted, but at a much lower point when
mixed with sand ; (2) that at 25 weeks with 3 of sand the gain was equal to 41 per cent,
and with 5 of sand equal to 64 per cent ; (8) that the strength of the fine cement with
5 of sand was equal to a greater strain than that of coarse with 8 of sand, especially at
the earlier stages. The proportion remaining on a sieve of 5000 per square centimetre
(82,257 per sq. inch) was 49*5 per cent— J. O.

The resistance of Portland cement to crushing after nine months
is greater than that of most building materials, being 3 tons per
square inch.

^ Grant's Experiments.
» From M.P.LaS^ toL IxiL p. 149 (Grant).

B. C. — III

178

NOTES ON BUILDING CONSTRUCTION.

04 wA

"sl

"2 -^

«i

^ ^

as «>

■tf ^

«M OQ

.5 rH

S.g

'^ i

jf^

•«■•

1s|

3lg
III

Sol
5K"

5>J

■sBpu

11^

^rH0i|00^»O«0a0OC9

<^Al0^eOO<01r-lfH

dOO'^'^eOCIO'lp-lr-l

Or-teo^o-^i-iooaiooa*

kOiOOOOOOOCItoC4eOC4

. A 00 00 oo

• f-< -^ <o O

CO ©I i-li-l

. a» O «D «-4

• ko CO ^«^«
•-^eo « i-i

. O) 00 r-t
• 00 00 QO
•©1 i-l i-l

.00-* 00

. "^ CO »>• "^
' 00 C4 i-H rH

:SS;

. -^ O 00 t<.
• GO Ok 00 <0
' ©IC4 i-lr-l

. 00 A 00 o

• t^t^ « 00

* <N t-H 1-H 1-H

. 00 P-l 0» to

. to <^ kO r-t

•t-HOO o «
• ©1 !-• rH

. 00 <« kO QO

• p-i PH 0» "H

• CO CO rH i-<

.00 to COO

• 00 -^ ©) O
•« rH.-l

^»-l©«00'^»OtOOOO©l

«oaoo ©I

w <« 00 ©4 a>

0 ^OO<0CO©4

a JScoeo©^ CO

?° l-i^OO pJ'Oi'tO

•I!

to QP «-4 <
$©4 Ot«<

O fl rf©l<_ , _
P4 9 ^ <^00O»00

1^ ►^s'sfss

^ <0 O 00

Ma» loco

to 00^

^oo«4

j5rH©J^<0

h3 oTcf ocT

to<0C»

00 a» ^

_ to, rH 00

h3 O^oT rH*
©»i-l rH

00 ArH
^ 0> kO to

1-^ HiToo tC

oS pH rHOk
^ AOto

•J©f» V

^00 to
oJkO OOHH
^«0 »to

iJ oT O^lO

to"^ rH

rH Owa

-,'<♦» ©I -^H

M <0 CO «

CO GO Ob

A b« (O

_ 00^ ©^^lO

-( ©9<D©I

S i-llorH
-^ to kO O*
M»0©l©|

OOOO ©)

rH
P4

':5

SELENITIC CEMENT. 179

lAoMlt to InoreoM of Strength voith age. — ^Mr. Grant's experiments with a
cement weighing 123 lb& per bushel led him to the conclusion that it
attained its maximum strength after constant immersion for two years, and
that there is no reason to fear that a good cement ever deteriorates. The period
at which the rnftyimnm strength is attained varies, however, with the class of
cement — in the case of a light cement it would probably be much shorter.

Market Fomis.— Portland cement is sold in casks or in sacks for home
consumption, and in casks for export

The inside dimensions of the casks are sometimes as follows, but they
vary. Length, 27^ inches. Diameter at middle, 19 inches. Diameter at
ends, 16 inches.

Each cask usually contains 400 lbs. (net).

Those for export should be well hooped and nailed, and lined with stout
brown paper.

The sacks measure 22 inches x 38 inches, and each usually contains 2
trade bushels or 200 lbs. of cement, but sometimes is filled so as to contain 2 cwt.

Good Portland cement is slow-setting as compared with the
cements made from most natural cement stones, but surpasses
them in ultimate strength ; and is more extensively used than any
other, for all kinds of work for which cement is suitable. It is
particularly weU adapted for making concrete.

Scott's FrooesBes. — General Scott's two processes depend upon an in-
timate admixture with the lime of a small quantity of a sulphate, usually
sulphate of lime,^ before, or at the same time that, the water is added.

All limes are improved by them, and converted into a kind of cement, the
slaking action being suppressed, and the lime setting without expansion, thus
forming a denser and harder mortar.

The quickness of setting is greatly increased by these processes for all
limes, and their ultimate strength is also improved.

Scott's Cembnt is prepared by passing the ftimes of bnining snlphur through lumps
of qtiicklime placed on gratings, and nieed almost to a red heat, by which about 5 per
cent of it is turned into a sulphate.

The calcined stone, if properly burnt, will be found to have lost all power of slaking ;
upon being ground it becomes a fine homogeneous powder, of a tint sindlar to that of tibe
unslaked lime from which it is prepared.

Good Scott's cement should be finely ground, and contain not less than 10 per cent of
soluble silica ; it should weigh fully 60 lbs. per striked bushel, and when mixed with two
parts of sand should be strong enough to come out of the mould in twenty-four hours.
After being left for seven days in a dry place, the weight required to break it should be
not less than 66 lbs. per square inch.

This material was coming into considerable use some years ago for making mortar, but
especially for plastering. It is not now in the market, having been superseded by selenitic
cement, in which the same qualities and characteristics are obtained by a mudi simpler
process of manufacture. It has, however, been described here, as there is sometimes a
confusion between the two.

Selenitio Cement,^ sometimes known as selenitic lime, w also an inven-
tion of General Scott's.

This cement, like the other, contains a small proportion of sulphate of lime,

^ Calcium sulphate.

* So called from Selenitic, the scientific name for gypsum which is sulphate of lime»
and forms, when burnt and ground, plaster of Paris,

i8o NOTES ON BUILDING CONSTRUCTION

which is added in the form of plaster of Paris, mechanically mixed and
ground with lime. Lime may, however, be selenitised by adding a small
proportion of any sulphate, or by mixing it with sulphuric add.

The sulphate begins to take effect directly water is added. Its presence
arrests the slaking action, causes the cement to set much more quickly, and
enables it to be used with a much larger proportion of sand than ordinary
lime without loss of strength.

Nature of Lime, — This cement may be made from any lime possessing
hydraulic properties. The limes from the magnesian limestones are much
used for the purpose, also those from the grey chalk. But the best limes for
selenitising are those from the Lias formation and grey chalk.

Fvnene9s of Grit — The cement should be finely ground so as to pass through
a sieve of 900 meshes to the inch.

Proportion of Sulphate. — ^The quantity of sulphate the cement should contain
depends upon the quality and description of the lime used for its manufacture,
and varies from 4 to 7 per cent, the usual proportion being about 6 per cent.

When more than 7^ per cent of sulphate is required to stop the slaking
action, the lime may be considered not suitable for making selenitic cement.
In this case, however, the lime may be rendered suitable by mixing it with
one containing more clay.

JFhere used. — ^This cement has been used at the New Law Courts ; Orosvenor
Mansions ; Chesterfield Mansions, etc. ; and for plastering at the Alexandra
Palace, Manchester New Town Hall, and several of the principal new
buildings in London, and other lai^ towns.

Strength. — ^The Table on the opposite page is taken from a circular issued
by the Selenitic Cement Company.

It shows the comparative strength of selenitic and Portland cement, with
different proportions of sand, and also the increase of strength which accrues
to the lime when it is prepared by the selenitic process

Ordinary lime may he eelenitieed during the process of mixing it into mortar.
The method of doing this is described at p. 207.

Selbnitio Clat is a preparation of clay and sulphate of lime, which, when
added to a pure or nearly pure lime, confers upon it hydraulicity, and also
the quick-setting properties of selenitic cement.

Methods of artificially producing Hydraulicity. — In addition to the
manufacture of hydraulic limes and cements by the intimate mixture and
calcination of the necessary ingredients, hydraulic properties are sometimes
conferred upon mortars made from fat lime by adding to them such sub-
stances as are known to produce hydraulicity.

PozzuoLANA MORTAR& — These are formed by adding to ordinary fat lime
or feebly hydraulic mortars such a proportion of pozzuolana (see p. 196) as
will make good their deficiency in clay. This proportion depends upon the
composition of the lime in the mortar to be improved.

The success of pozzuolana mortar depends upon the intimate mixture of the
ingredients, which should be reduced to a fine powder, and ground in a mill
for 20 to 30 minutes.

Qood pozzuolana mortar behaves like that made from eminently hydraulic
lime.

Alkaline Silicates, produced by boiling flints in an alkali, may be added
to mortar in the form of a thin syrup.

They are found to greatly quicken the setting of £at lime mortars, making

SELENITIC CEMENT.

i8i

•3

4
i

Sj*s

III
III

«t! 8

•-Hi-H(N p-irli-li-H 04<N(N(yi i-lfH i-l01,-i«CN

OftCOO «Or^C0Q0 • 'oQOOi*© • • • • '^OOO"^

OC004 GOQOQOO COeOCOCO OOdCOO)

-^««o ti<eoiOiocoooo&oa.^'^aii-Hti<aiOo;o»ooo

oco;o co;ocoeo^coor^OdQOOd(yi'«i*Oda)'^oiQOio

CO -^ h*
?o o ^

i-H CO w

CO «

CD r^

CO ^

OS o
to ^
« I-l

CO o

r^^ CM

r^coiocoi^iooioco^coio
r^coocoOi-«i>»cooo&coon

i-i(N(N CTCMf-ii-i<N«COCO

CO lO ^ CO CO o

•^eO'^eocoio^coeocoiO'^eocoiO'^cQ

^1 =

V WW

a a

cq pq

5 s-^

I82

NOTES ON BUILDING CONSTRUCTION

them to resemble hydraulic limes and cements in this respect, according to
the quantity used, but they do not materially inciease their strength.

Means for testing Tensile Strength of Cement. — It has already
been mentioned that the tensile strength of Portland cement for
important works should always be tested by direct experiment

There are several different machines by means of which this
test can be accurately applied.

A few of these will now be described^

Adie'a Testing Maohines were among the first adopted for this purpose,
and are still widely known and extensively used.

Fig. 88. Adu's No, 1 CcTnenl- Testing Machine,

Adie's No. 1 Machine. — This machine, by means of a straight lever,
applies a known strain to a briquette of cement (see p. 172), until the latter
breaks across at the narrow central part, the area of which is accurately known.

Fig. 88 gives an elevation of the machine.

Fig. 88a is a split mould for the briquette. It is arranged to divide longi-
tudinally into two parts, so that the briquette may easily be
liberated without the aid of a press. Split moulds are sometimes
hinged at one end.

These figures and the following instructions are from the
circular of the maker (Mr. Adie, 16 Pall Mall).

Maker* 8 Instructions. — To set up the machine, drop the spindle R into
its place in the table, then put iJie pillar Q in position and insert the Yia. 88a.
notched plate in groove of spindle, bolting down Q so that the beam when gpi^'^oyXd,
strained [by putting a moulded brick of cement into the clips B and C, ^
and then tightening by means of the wheel R] may take its position freely in the centre
of fork H. The wire oord passes twice round pulley at H, and once round that at G,
and should never be very tight. When the cement is set, open the mould eareftally, un-
doing both screws simultaneously, and treat the briquette as described at p. 172.

TESTING CEMENTS.

183

Insert the brick in the ciips B and 0, then tnrn the wheel R till the beam at H rises
to the pulley [t.«. well above the zero line], and roll the weight D gently along until the
fracture takes place.

The weight N should not be in its place, except when testing below 800 lbs., when the
top row of figures is used.

If the weight D is not sufficient to break the brick, roll it back and hang on the extra
weight in a notch in the beam near H.

7%0 ffj^eed, with whicb the weight is bronght to bear upon the briquette, or
at which it is increased, materially afifects the result. When the weight is
moved rapidly the resulting tensile strength, as shown by the machine, is
higher than when the weight is wound slowly.

Adie's Cement Tester with Automatic Register. — In order to arrange
for a uniform speed, Mr. Adie has added an automatic regulator to his machine,
which is shown in Fig. ZZK

Fig. 886. CemtnX Tester^ with PaiaU AuUmuUic Jtegulaior,

Patentee's Imtructions. — To make use of this regulator, fix the brass tube to the
floor, vertically underneath the pulley marked No. 2 in the drawing above, and fill the
tube with clean water. Attach the long cord to the left side of the vernier E, pass it
downwards over No. 4 round No. 3 and then upwards round No. 2, and down again to
the eye at 3. Attach the short cord to the right side of E, pass it under the pulley at H
and twice round it, then along over No. 5 and hang on the weight W.

Put the brick into its place and make all arrangements before actually putting on the
strain. Screw up R, lifting the point of the beam well above the zero line on the pillar
H, so as to free the check K, and while the weight D is travelling observe that the check
IB not allowed to touch the rachet wheel ; screw up R more if necessary to allow for any
slip or springing of the clips. The catch stops the rolling weight when the fracture takes
place, and the result is shown in lbs. on the scale.

To commence another test take oflf the weight W, before gently letting down the piston,
at the same time easing back the weight D by the hand.

Adie*s Na 2 Testing MACHiins. — Fig. 89 is a smaller machine by Mr. Adie for testing
briquettes having a central section of 1 indh square. It can also be used as a weighing
machine.

This figure, slightly modified, and the following instructions, are from the maker's circular.

PcUentee's InstructUma. — If the standard ▲ be not in its place when received firom the
manufacturer, bolt it down to the stand, so that the beam when strained (by putting a
moulded bride of cement into the dips B and 0 and then tightening by means of Uie

1 84

NOTES ON BUILDING CONSTRUCTION

wheel underneath at d) may take its position freely in the centre of fork s. Wind the
pord once round the pulley at a, and twice round that at B. Mix the cement to be tested
with as little water as possible, consistent with perfect homogeneity, and having kid the
mould on a flat surface, or on the iron plate supplied for the purpose, fill it with the

cement asdescribed, and scrape
the top flush. When set, take
the briquette out of the mould
carefully, and place it on the
flat plate in water for seven
days, it will then be ready for
testing. To eflect this, place
it in the clips, turn the wheel
at D till they clasp the brick
with sufficient force to raise
the end of the beam nearly up
to the pulley above.

(a) For strains frx>m 0 to
130 lbs., using the bottom
row of figures, hang the trans-
ferable weight F in the notch
at the end of the beam (as
shown in the drawing), and
roll the vernier weight g along,
taking about one minute to
travel the length of the beam.
(6) From 90 to 200 lbs., using the middle row of figures, remove F from the machine,
and roll o forward as before. ^

(c) Above 150 lbs., using the top row of figures, hang on F in the notch under o, and
roll o (carrying F with it) forward as before.

To use as a weighing machine, remove the sliding block carrying D and c ; take out
the top clip B, and hang on the scale pan instead. A hook passing through a hole in the
stand can be supplied with one-tenth bushel measure to weigh the cement if required.

Micbaelis's Double Iiever Cement Testing Apparatus, Figs. 90 and 90a. —
Makers Directions, — This apparatus consists of a japanned cast iron column, wliicli

Fig. 89. Adies No, 2 CetnerU Testiiig Machine,

Fig. 90. Fig. 90a.

Michaelis'a Double Lever CeTneiU Testing Apparatus,

TESTING CEMENTS.

185

carries two levers, the combined leverage of which is 1 to 50 : that of the longer, being 1
to 10, and that of the shorter, 1 to 5.

Each lever has three hardened steel knife edges acting upon hardened steel concave
bearings, so that an extremely accurate balance is obtained.

The ^ort arm of the upper lever is provided with a movable counterpoise, to secure
the correct position of the levers, which is indicated by a mark on the upright catch at
the top of the colunm. At the extremity of the long arm is suspended a small brass
frame to carry the shot bucket.

On the lower lever, near its fulcrum, is suspended the upper damp or clip for holding
the briquettes. The lower clamp is fixed to the base of the column and adjusted by
means of a screw.

To make a test, the cement briquette is taken out of the water, dried and put into the
cl&mps, which must be accurately applied to the sides of the briquette, and the screw
applied until the upper edge of the long lever is opposite the mark on the upright catch,
f^e shot is then poured from the self-acting shot-run into the bucket suspended from
the long lever until the briquette breaks, when the supply of shot is instantly cut off.
The breaking strain per square inch is thus exactly fifty times the weight of the bucket
and shot ; but to avoid all calculation and possible risk of error, a Salter spring balance
with a special dial is supplied, upon which the bucket and shot are weighed and the exact
breaking strain of the briquette at once shown.

Miohele'B liaohine. — Fig. 91 is a sketch taken from the illustrated advertisement of
the machine.

A briquette of neat cement having been made as before described, and immersed in
water for the specified number of days, is placed in the clips V L, as shown.

The handle H is then tpmed ; it is fitted with a pinion which works in the rack R.
The end of the rack being drawn down by the motion of the pinion, draws down the
clip L, and brings a stress upon the briquette, which in its turn draws down V and the
short arm S of a bent lever.

Fig. 91. Michde*a Cement Testing Machine,

The long arm L of this lever carries two weights, WW ; as the short arm S is drawn
down, these weights are lifted.

While they rise, the leverage with which they act increases with their horizontal dis-
tance from the fulcrum F. When the stress produced is sufficient to overcome the
resistance of the briquette it breaks across.

The nuts n which secure the clips prevent the weights WW from fEdling back more
than about half an inch.

The stress applied is measured along the graduated arc A. The pointer p is carried
up with the long arm of the lever as it rises, but remains when the weights fall, to show
the point to which they rise.

These machines are made to test up to 1500 lbs. on the briquette.

i86

NOTES ON BUILDING CONSTRUCTION.

Fig. 92. Faya's Testing Machine,

Faija's TestinK Machine is shown in Fig. 92, firom the patentee's circular.
The ordinary-sized machine adapted to briquettes of 1 square inch section will test finom
1 to 1000 lbs.
The machine is 14 inches high, 14 inches long, by 3 inches wide, and weighs less than

80 lbs. A special gearing pre-
vents the strain from being put
on too quickly.

Patentee* s Inttrudions. — On
receiving the machine, clean off
all old oil and relubricate,
attach the balance weight W to
the short end of the lever.

To USB THE Maohinb. — See
that the quadrant A is in the
XX)8ition ^own in sketch, so
that the chain B to the dial C
is slack, and the lever D free
and balanced.

Turn the wheel £ from right
.__ to left, until the lower clip F
can be raised into contact with
the upper clip G.

Insert the briquette to be
tested in the clips, taking care that it is put in true and evenly, and so that the pull
on it and the clips is true and vertical ; then turn the wheel E from left to right, which
will bring down the lower clip F, and secure the briquette firmly in the clips. (It is
generally advisable to put such a strain on the briquette by turning wheel E that about
100 lbs. is indicated on the diaL) When in this position there should be about half an
inch between the under side of knife edge H, and the buffer or recoil spring I.

Having seen that the pinion K
is in gear with the wheel L, turn
the handle M until the briquette
breaks. The loose pointer will
show on the dial the strain in lbs.
at which the briquette broke.

To Return to Zero. — Throw
the pinion K out of gear with the
wheel L by removing the pin and
pushing it to the left ; turn the
wheel L frx>m left to right until
the quadrant A has returned to
its normal position with the chain
B slack ; put the loose pointer
back to zero ; release the lower
clip F by turning wheel E from
right to left ; remove the broken
briquette, and insert the next that
is to be broken.

Beid and Bailey*! Oement
Tester is shown in elevation in
Fig. 93, which is taken frx>m the
makers' circular.^

The briquette having been in-
serted in the clips c c holds down
the short arm of a straight lever.
The long arm has a graduated
measure attached to its end ; this
is gradually weighted by water
running from the cistern above.
When the briquette breaks, the fall of the long arm of the lever draws down A, and shuts
off the supply cock. The weight required to rupture the briquette is indicated by the

Fig. 93. Jteid and Bailey's Cement Tester.

^ Messrs. Bailey and Co., Salford.

TESTING CEMENTS.

187

Fig. 93a.

amount of water in the meaanre. Mr. Reid states that this machine is reliable and
accurate. The weight is ai)plied very gradually and without tremulous vibration, and is
recorded automatically by the machine itself.

Bailey's Table Pattern Cement Tetter.
— Another of Messrs. Bailey and Co.'s cement
testers is shown in Fig. 93a, which explains itself.
It takes sections of 1 inch square, and is some-
times fitted with an automatic arrangement for
pouring the shot into the can.

Thurston's Testing MaoMne. — In order to
avoid the difficulty of getting the stress fairly dis-
tributed over the area to be fractured, which always
occurs in tensile tests, cement has been tested by
twisting.

Professor Thurston's machine used for testing
metals by torsion has, in America, been applied
to cements.

This machine has not, however, been adopted in
this country, and it need not therefore be de-
scribed.

Simple Tests without Machines. — ^A tank of water suspended from the specimen
may be used as a good simple method of testing the tensile strength. The weight in lbs.
at different depths can be marked inside the tank.

The following specification has been used where there is no testing machine available.

'* The cement is to be made into small blocks 1 inch square, and 8 inches long, after
being made, these blocks are to be immersed in water for seven days, and then tested by
being placed on two supports 6 inches apart, when they must stand the transverse strain
produced by a weight of 75 lbs. placed in the centre." ^

Chemical Testa — ^The importance of having a chemical test for Portland
cement, in addition to the tests already mentioned, has lately been strongly
urged, in consequence of failures arising from an excess of magnesia which has
slaked and expanded in the work, causing rupture ; an excess of lime may
have the same effect, or cause weakness ; ^ more than 2 per cent of magnesia,
or 1^ per cent of sulphuric acid, is said to be injurious to Portland cement.

Adulterations in Portland Cement — It is stated in the circulars of some
cement manufacturers that iron slag is used for the adulteration of Portland
cement If this is suspected, the only way to avoid it is to refuse to take
cement from any manufacturer who has slag on his premises.

Slag has been refused both for cement making and as an a^regate for
concrete, for fear that the lime that it contains should disintegrate after use
in the work.

This is doubtless a wise precaution. Slag properly treated by being burnt
with lime is, however, sometimes used as the basis of a good Portland cement,
as described at p. 161.

^ Messrs. D. B. Stevenson. M.P,LC,E., vol. Ixxxvii. p. 229.
« M.P.LC.R, vol. Ixxxvii p. 163.

t88 yOTES ON BUILDING CONSTRUCTION

LIME AND CEMENT BURNING.

Limestone is calcined (bunt into lime) in " clamps " or in '* kilns " of
different forms.

Clamps consist merely of heaps composed of alternate layers of limestone
and coal, having a fire-hole below, and covered with clay or sods to prevent
the escape of heat

This is a very wasteful method of burning, and should only be used where
limestone and ^el are abundant

Very similar arrangements for burning lime are in some parts of the
country called Sow KUns.

Lime Eilna are divided into two classes, Tunnel Kilns and Flare Kilns.

Tunnel KUne are those in which the fuel and stone are placed in alternate
layers.

Flare Kilns have the fuel below, so that the flame only reaches the stone
in the kiln above.

Either form of kiln may be worked on the continuous or on the inter-
mittent system.

The Continuous system is that in which the lime is gradually removed from
the bottom of the kiln in small portions, fresh limestone being added at the
top to make up for the burnt lime removed at the bottom.

The Intermittent system consists in burning and discharging a whole kiln-
ful at a time. After the stone is well burnt through, the kiln is allowed tc
cool down, and the burnt lime is removed. The empty kiln is then re-
charged, and the operation repeated.

The continuous system is most generally applied to tunnel kilns.

The lime so produced is likely to be unequally burnt, but the process is a
cheaper one.

By the intermittent system, in which the whole kilnful is burnt at once,
the lime is more uniformly calcined throughout

Tunnel Kilns, called also OoNnHUons, " Runnino,'* << Pkrpktual,** or
" Dbaw-Kilnb,"

A kiln of this class is shaped internally either like a cylinder, an inverted
cone, or a pair of vertical cones base to base. It is lined with firebrick, and
has an opening below, generally protected from the weather by a shed.

At the lower extiemity of the cone is a grating, upon which is placed a
layer of brushwood, and then alternate layers of coal and moistened stone,
reaching to the top, the largest pieces being in the middle, where they will
get most heat

As the lime becomes burnt it is withdrawn through the grating, and fresh
stone and fuel are added at the top.

This kiln is economical in fuel, requiring only about i the weight of the
lime produced, but the lime is not equally well burnt throughout, and it
requires great experience to manage the kiln properly.

Fig. 94 is a section of the form of kiln frequently erected as a temporary
arrangement to bum lime during the progress of large works.

The kiln may be built of either bricks, stone, or concrete, or sunk into the
ground.

UME AND CEMENT BURNING.

189

Fig. 94.

When concrete or very rough masonry is used, bonding timbers are built
in, or iron bars are fixed externally to bind the
structure together.

The interior is lined with firebricks, a hollow
space being left behind the lining.

The fuel and broken stone are thrown in at the
top of the kiln, and lie in alternate layers, the
thickness of each layer of stone being from six
to eight times that of the fuel.

At the lower end of the kiln lies the wood for
kindling the fire, resting upon a grate of loose
bars, which can be drawn out one at a time.

Tlie fire having been lighted at the bottom
below the grating, the heat passes through the
layers ; those nearest the bottom are burnt first, and are withdrawn through
the grating by removiug one or more of its bars.

As the burnt lime is taken out at the bottom, the bulk of the contents of
the kiln slide down, and the space thus left at the top is filled with fresh
layers of fuel and stone.

It is convenient to have a shed in front of the drawhole, to secure the
freshly burnt lime from the weather.

The size of the kiln varies according to the supply required. A kiln of
the form shown in Fig. 94, 16 feet high, 4 feet wide at the bottom, and 9
feet at the top, will hold '* about 25 tons of limestone, and will bum sufficient
lime to keep twenty bricklayers constantly supplied with mortar."^

Fig. 95 shows in section a form of kiln lai^ely used in the Midland
counties for burning Lias
lime.

The conical mound on
the top. is composed of
layers of fuel and stone,
plastered over with clay.

'' Care is taken that
the day plastering cover-
ing the conical mound
does not give too much
vent in any one part to
the products of combus-
tion, lest too strong a
draught should be set up
toward such orifice, and cause overbuming of the lime in its course.

^ The fuel is made to bum in a smouldering fashion throughout its operation.

*^ At the opening of the drawhole, in order to ignite the contents of the
kiln, a few large pieces of coal are built up.

'* The fuel layers vary from 6 to 3 inches in thickness, those at the bottom
being the thickest. The layers of mineral vary from 10 inches at the bottom
to 18 inches at the top."^

Slare Kilns, called also Intebiottent Kilns, are generally in the form of

^ Hiirs Ledurei on Machinery.

* Cooke's Aide Mimoire,

I90

NOTES ON BUILDING CONSTRUCTION

a cylinder, surmounted in most cases by a conical vault The broken limestone
rests upon arches, roughly formed from large pieces of the same material

Fig. 96. Plan.

Fig. 97. Section.

These rough arches must be carefully built, and the heat applied gradually
so as not to split the stones.

The fire is lighted below, only the flame being in contact with the stone,
thus producing much cleaner lime than that obtained by the methods in
which they are mixed together.

Such a kiln is more easily managed than the kinds which are worked con-
tinuously, and the lime produced is more uniform in quality. The necessity
of letting the fire out after each charge is burnt is a great inconvenience, and
also causes waste of fuel

For the same kind of lime this kiln requires about f {jLe. nearly double)
as much coal as does the tunnel kiln. Moreover, the intermittent kiln
requires relining every twelve months, which is a source of great expense.

Fig. 96 is the plan, and Fig. 97 a section of a pair of flare kilns, such as
are used for burning grey chalk into lime. L is the hole through which the
lower part of the kiln is loaded, I that for the higher levels. The draw-
holes D D open into a central passage P.

In the section the kiln to the right is shown as loaded, the other as empty.
The rough arches of limestone are shown in the former. The fire bars for
the fuel are shown in plan and section, the spaces C C are packed with
broken chalk, c c with chalk dust. The firebrick lining is hatched with broken
lines, the ordinary brickwork with continued and broken lines alternately.

LIME AND CEMENT BURNING.
Fig. 98 is the section of a simpler flare kiln in common use.

191

Pig. 98.

Portland Cement EilnB {Common Form), — ^Fig. 99 is the section, and
Fig. 100 an elevation, of a form of kiln commonly used for burning Port-
land cement in the Medway district

J\'fr

f ^

■ If

^-■/ ii
■"■'■-■■ '^\

WS4

lii^^fW^

Fig. 99. Section.

Fig. 100. Elevation.

It is worked upon the intermittent system j the coke and sluny are, how-
ever, packed in alternate layers 6 and 4 inches deep.

Such kilns hold about thirty tons. Their contents are burnt in forty-eight
hours, and are drawn about once every four days.

The kiln is lined with firebrick, sometimes only up to the line a, but
better throughout, and loaded at the holes H H H.

The firebrick lining should be detached from the mass of the brickwork, so
as to be free to expand and contract under the great changes of temperature
to which it is subjected.

The inside should be painted over with wet stuff from the bach each time
before the kiln is charged. This will greatly increase its durability.

In some forms of this kiln the top has a wider opening, and the short
vertical neck or chimney is frequently omitted.

193

NOTES ON BUILDING CONSTRUCTION.

The description of kiln used varies in different places. A modification of
Hoffmann's kiln aimUar to that used for bricks may be economically adopted
where a large continuous supply of cement is required year after year.

The time required to bum a kiln varies according to the proportion of the
materials, the position of the kiln, eta

The contents are burnt at a high temperature, but the amount of firing
depends upon the proportions of the mixture. If the lime be in excess it can
hardly be overbumt, but if there be too much clay it will fall into dust

The Michele-Johnson Kiln is a modification of the kiln mentioned at p. 161.

The arched chamber there referred to as branching out from the kiln has
a very thin arch over it Above this the cool slurry is spread for a prelimi-
nary drying before it is forced through the openings of the arch and spread
over the floor of the chamber ; there it is further dried by the hot air and
gases from the kiln, which pass through the chamber on their way to the
chimney.

"Roman Cement Kilns. — ^Fig. loi is a plan and Fig. 102 a cross section

Fig. 101. Plan.

Fig. 102. SecHan.

of the kiln used for burning Roman cement It is worked on the constant
system. The stone is packed in strata separated at' intervals of from 6 to 9
inches by thin layers of fuel The cone in the centre guides the burnt cement
to the drawholes D D where it is taken out

General "Reniarlca cm Burning. — Gradual heating is necessary in burning
lime or cement stone. If the heat be su&denly applied, the carbonic acid and
moisture will be driven out with such violence as to blow the stone to pieces.

Appearance of the Burning Stone, — As long as the burning is incomplete,
and any carbonic acid is left in the stone, it will remain of a dull red colour.
When the carbonic add is all expelled, the stone in the kiln becomes pecu-
liarly bright, which is a sign that the calcination is complete, and that the
lime may be withdrawn.

The Temperature at which a lime or cement should be burnt depends upon
its composition.

A pure or fat lime requires only heat enough to drive off the carbonic acid
and moisture.

UME AND CEMENT BURNING. 193

Limes containing clay require a somewhat greater heat, in order that the
silicates and aluminates may be formed which give the hydraulic properties
required.

A great deal depends, however, upon the composition of the clay.

A large proportion of iron and alumioi^ (especially of iron) as compared
with the silicic acid, greatly facilitates the action which takes place iu calcin-
ation, and the prepared mortar also sets more quickly.

Qreat care must be taken, however, that the heat is not sufficient to fuse
the particles of the lime or cement.

Thus Roman cements, in which the quantity of iron and alumina together
nearly equals the silicic acid, are burnt with little fuel at a low temperature.

Portland cement, on the other hand, in which the iron and alumina are
less than half the silicic acid, is burnt at very high temperatures. There is
very little danger of fusing the particles, and the heat may with advantage be
Taised to a point just short of vitrification.^

I%« Size of the Lumps into which the lime or cement stone ia broken greatly
influences the burning operation.

The denser the stone and the higher the temperature at which it is to be
burnt, the smaller must be the pieces into which it is broken.

Pure or fat limestones are broken into pieces containing from one to two
cubic feet

Hydraulic limestones into pieces containing about a quarter of a cubic foot

Roman cement stones and others of the same quick-eetting class are broken
into pieces containing one or two cubic inches^

The Quantity of Fuel is of course influenced partly by the form of kiln, but
chiefly by the nature of the stone and by the temperature at which it is to be
burnt

Thus, for the calcination of pure dense limestones about } to ^ their weight
of coal is required.

For hydraulic limestones about i to I their weight

For Roman and other quick-setting cements aotut t to iV of the weight of
stone.

For Portland cement about ^ the weight of the dried slurry.

Portland Cbment Clinkjsk. — The clinker of good Portland cement, when
properly burut, is of a dark greenisMlack colour, differing in density accord-
ing to the amount of fuel used.

It is almost impossible to bum the contents of any kiln quite uniformly
throughout, and the clinker will be found differing in colour accordingly.

It should not be clinkered into large masses — should rattle well as it
comes out of the kiln — should be honeycombed in texture and nearly free
from dust

Some will be found of a bright yellow colour, and of light specific gravity.
This will set very quickly, and it should be picked out.

Some, again, will be of a pink or dirty white colour, but more or less heavy
according to the heat to which it' has been subjected. Clinker of this kind
has been imperfectly burnt, and must be again passed through the kiln. It
is a dangerous substance to use.

Dense glazed black clinker indicates excess of lime, and will also yield

^ General Scott in RE. Papert^ vol zi
B. C. — III

194 NOTES ON BIMLDING CONSTRUCTION

dangerous cement inclined to blow ; dark Uiu clinker, a sluggiBh cement ?
and a hnywn clinker with much dust, a weak cement^

Dangerous Iiimes and Cements. — Sometimes, from defects in the pro-
cess of calcination of a stone which should produce an eminently hydraulic
lime or cement, compounds result which are of a most dangeroas character.

These are caused either by oyer-buming or under-burning.

OverAmnU, — In the former case, a hard and heavy substance is produced,
burnt almost to a clinker, which slakes with very great difficulty, and after a
considerable lapse of time.

This can only be remedied by screening out the hard portions and grinding
them to a fine powder ; otherwise any larger particles that may be left will
slake after the mortar has been laid in the work, and may do great damage to
the masonry.

UfideT'bwnU. — ^When, on the other hand, the stone has been under-burnt,
a somewhat similar result occurs, but from a different cause.

The substance produced consists partly of a perfect cement or hydraulic
lime, and partly of free quicklime. The latter is prevented, by the setting
action of the cement, from slaking at once, but does so eventually, and with
the same disastrous consequences as occur with over-burnt lime.

This dangerous action may, however, be got rid of by free exposure of the
lime or cement, so as to air-slake the caustic portions, or by frequently re-
working the mortar, or by adding a proportion of soluble silicates, which
anticipate and prevent the slaking action* The latter is, however, seldom if
ever done in practice.

Dead-burnt liime is lime that has been imperfectly calcined and will not
slake with water.

This may be caused by under burning, so that only part of the carbonic
add is expelled, the resulting substance being a compound of quicklime and
carbonate of lime, which refuses to slake.

Hydraulic lime may be rendered '^ dead " by over-burning ; the silicates
are partially fused and coat the stone, so that the evolution of the carbonic
add is prevented * (see p. 234).

Flare-burnt Lime is lime burnt in flare kilns, in which it is kept cleaner
than in tunnel kilns owing to its not being in contact with the fuel

^ Certain varieties of overclayed cements yield a deep broDze-coloared clinker
which, as it cools on comiDg from the kiln, disintegrates spontaneously into a fine
flakey greyish powder which produces an inert cement,^M,P,LC,E,, vol. IxiL p. 81.

" Dent.

SAAD AND SUBSTITUTES FOR SAND, 195

SAND AND SUBSTITUTES FOR SAND.

Sand is known as " argillaceous," " siliceous," or " calcareous,"
according to its composition.

It is procured from pits, shores of rivers, sea-shores, or by
grinding sandstones.

It is chiefly used for mortar concrete and plaster. The qualities it
should possess for those purposes are pointed out at page 198.

Pit Sand has an angular grain, and a porous, rough surface, which makes
it good for mortar, but it often contains clay and similar impurities.

River Sand is not so sharp or angular in its grit, the grains having been
rounded and polished by attrition.

It is commonly fine and white, and therefore suited for plastering.

Sea Sand also is deficient in sharpness and grit from the same cause.
It contains alkaline salts, which attract moisture and cause permanent damp
and efflorescence.

Screening. — When sand contains lumps or stones it should be " screened,"
or, if required of great fineness, passed through a sieve.

Washinq. — Sand found to contain impurities^ such as clay, loam, etc.,
which unfit it for almost every purpose, should be washed by being well
stirred in a wooden trough having a current of water flowing through it which
carries off the impurities. It is sometimes washed by machinery, such as an
Archimedean screw revolving and carrying up the sand, while a stream of
water flows down through it

Examination of Sand. — Clean sand should leave no stain when rubbed
between the moist hands. Salts can be detected by the taste, and the size and
sharpness of the grains can be judged of by the eye.

Size of Grit. — Where this is specified, as it is in connection with the
cement and sand test for Portland cement (see p. 162), it is generally re-
quired that the sand should pass through a sieve of 400 meshes to the square
inch and be retained by one of 900 meshes.

Substitutes for Sand. — Burnt Clat is sometimes used as a substitute
for sand in mortar.

It is prepared by piling moistened clay over a bonfire of coals and wood.
As the clay becomes burnt and the fire breaks through, fresh layers of day
and coal, " breeze," or ashes, are piled on, and the heap may be kept burning
until a sufficient supply has been obtained.

The clay should be stiff. Care must be taken that it is thoroughly burnt
Raw or half-burnt pieces would seriously injure mortar.

Crushed Stone. — Sand is sometimes very economically obtained by grind-
ing the refuse '* spalls " left after working the stones for walling. It is generally
clean if carefully collected, but the sharpness of its grit depends upon the
nature of the stone from which it is procured*^

1 Hr. Kinniple's experiments show that mortar of 1 Portland cement and 1 crushed
sandstone ii 55 per cent stronger than that of 1 Portland cement 1 pit sand. —
M.P.LCE,^ vol. Ixiv. p. 880. Expenments by a friend of the writer's showed

196 NOTES ON BUILDING CONSTRUCTION

ScoRTiS from ironworks, old bricks, Clinker from brick kilns, and Cinders
from coal, make capital substitutes for sand when they are quite clean and
properly used. Wood Cinders are too alkaline. Cru^ed Slag from furnaces
may be dangerous if it contains lime.

POZZUOLANAS, btc.

PozzuoLANA is a name given to several substances which somewhat re-
semble each other ; including the Puzzaolana proper, also Trass, Arkies,
Psammites, etc.

These are clayey earths containing 80 to 90 per cent of day, with a little
lime, and small quantities of magnesia, potash, soda, oxide of iron,^ or man-
ganese.

When finely powdered in their raw state without being calcined, they may
with great advantage be added to fat lime paste.

In consequence of the amount of clay they contain they confer hydraulic
properties upon the lime to a very considerable degree.

The Italian pozzuolana may with advantage be used with fat lime and
sand in the following proportions : — ^

1 2 Pozzuolana well pulverised.
6 Quartzose sand well washed.
9 Rich lime recently slaked.

Natural Posiuolana is a naturally-bumt earth of volcanic origin, found
at Pozzuoli, near Vesuvius, and in other parts of southern Europe.

It is found in the form of powder more or less coarse in grain, of a brown
colour, sometimes passing into red, grey, yellow, and white.

Trass is also a naturally-burnt argillaceous earth, found on the sites of ex-
tinct volcanoes, chiefly near Andemach on the Rhine.

It occurs in lumps of a greyish colour and earthy appearance, is used in
the same way a}s poasuolana, and confers hydraulic properties upon fat limes.

Ar^nes are natural mixtures of sand and clay. They appear not to have
been subjected to heat, but they confer hydraulic properties upon fat lime,
probably because they contain a large proportion of soluble silica.

Pbammitbs may be considered as " very feeble pozzuolanas in the crude state,
and acquire but a slight increase of hydraulic energy by any degree of cal-
cination.

*' £ven their feeble powers, however, confer upon them this advantage,
that for mortars not absolutely immersed in water when green, and when
there is ample time for their properties to develop themselves before sub-
mersion, they can be employed in larger proportions than any species of sand
wholly inert would admit of." «

Disintegrated Granite, Schists, and Basalt furnish sand having the
same characteristics as the Psammites.

Artificial Pozzuolanas are prepared from clays of suitable composition
by a slight calcination.

Pounded bricks or tiles possess the properties of pozzuolana in some degree

mortar of 1 Portland cement and 2 cmshed limestone to be 60 per cent stronger than
that of 1 Portland cement and 2 sand.

'* Briquettes made from crushed syenite from which the impalpable powder had
been removed were 18 per cent stronger than those in which it had not been n-
moved."— Jf.P./.a-R, vol. IxxxviL p. 203.

* Ferric oxide, * ' Gillmore.

MORTAR. 197

MORTAR

OrdiTvary Mortar is composed of lime and sand mixed into a
paste with water.

When cement is substituted for the lime, the mixture is called
Cement Mortar,

Uses. — The use of mortar in brickwork or masonry is to bind
together the bricks or stones, to afford them a soft resting-place,
which prevents their inequalities from bearing upon one another,
and thus to cause an equal distribution of pressure over the beds.
It also fills up the spaces between the bricks or stones and
renders the wall weather-tight

It is also used in concrete (see page 210) as a matrix for
broken stones or other bodies to be amalgamated into one solid
mass ; for plastering, and other purposes.

The quality of mortar depends upon the description of materials
used in its manufacture, their treatment, proportions, and method
of mixing. These particulars will now be considered.

Description of Lime or Cement to be used in Mortar. — Fat
Limes should only be allowed for inferior or temporary work.

On account of their being cheap and easy to manipulate, they
are often used in positions for which they are entirely unfit.

Mortar made from fat lime is not suitable for damp situations
or for thick walls. In either case it remains constantly moist ;
when placed in positions where it is able to dry it becomes friable,
and in any case is miserably weak.

Even the economy of fat lime mortar is in many cases doubt-
ful ; for walls built with it are injured by frost, require constant
repointing, and perhaps before many years rebuilding.

M. Vicat says of fat limes : — " Their use ought for ever to be
prohibited, at least in works of any importance."

Sir Charles Pasley adds with regard to fat lime mortar that
" when wet it is a pulp or paste, and when dry it is a litUe better
than dust."

JSvils of Fat Lime Mortar, — If a pure or feebly hydraulic
lime mortar is used in massive brickwork or masonry, it is only
the outer edges of the joints that are affected by the carbonic acid
in the air. A small portion of the exterior of the joints sets, but
the mortar in the inside of the wall remains soft. The result of
this is that a heavy pressure is thrown upon the outer edges of

198 NOTES ON BUILDING CONSTRUCTION

the bricks or stones, and they become " flushed," that is, chipped
off. In some cases, from the same cause, the headers of brickwork
are broken, so that the face of the wall becomes detached, and
liable to fall away.

Again, these weak mortars retain or imbibe moisture, which,
when it freezes, throws off the outer crust. Pointing is then
resorted to. If this is done with the same sort of mortar, the
same result ensues, and in an aggravated degree, for as the opera-
tion is repeated, the joint becomes wider. In the end it will
often be found that more has been expended in patching up work
done with bad mortar than would have sufficed to provide good
mortar at the first

Hydraulic Lime or Cement should, therefore, always be used
in mortar for work of any importance. In subaqueous construc-
tions it is, of course, absolutely necessary.

If there is any choice, the class of hydraulic lime used will
depend upon the situation and nature of the work to be
done.

For ordinary buildings, not very much exposed, slightly
hydraulic limes will suffice to form a moderately strong joint, and
to withstand the weather.

For damp situations, such as foundations in moist earth, a more
powerful hydraulic lime should be prepared.

For masonry under water an eminently hydraulic lime or
cement mortar will be necessary. K the work be required to set
very quickly, Soman cement, or a cement of that class, would be
used ; whereas, if quick setting be not necessary, but great ulti-
mate strength is required, a heavy Portland cement should be
adopted.

Cement is also generally used for copings, plinths, arches, and
other important parts in ordinary house-building.

Description of Sand to be used in Mortar. — Sand is used in
mortar to save expense and to prevent excessive shrinkaga

Ordinary sands are not in any way chemically acted upon by
the lime, but are simply in a state of mechanical mixture with
it ; with hydraulic limes and cements the effect of sand is to
weaken the mortar.

When fat Ume is used, however, the porous structure, caused
by the sand, enables the carbonic acid of the air to penetrate
farther, and to act upon a larger portion of the joint.

Moreover, the particles of fat lime adhere better to the stirfacee

MORTAR. 199

of the grains of sand than they do to one another ; therefore the
sand is in two ways a source of strength in fat lime mortar.

It is of the utmost importance that the sand used for mortar
should be perfectly clean, free from clay or other impurities which
will prevent the lime from adhering to it

Sand for this purpose should have a sharp angular grit, the
grains not being rounded, their surfaces should not be polished,
but rough, so that the lime may adhere to them.

It has been found that, speaking generally, the size of the
grains of sand does not influence the strength of the mortar.

Mr. Mann's experiments tend, however, to show that in
samples four weeks old Portland cement mortar made with fine
sand was weaker than that made with coarse sand.

Very fine sand is objectionable for mortar, as it prevents the
air from penetrating, which is necessary in order that the mortar
may set

Although coarse irregular-grained sand may make the best
mortar, when very thin joints are used finer sand is sometimes
necessary.

Calcareous sands, on the whole, give stronger mortars than
siliceous ones.

Sea sand contains salts, which are apt, by attracting moisture,
to cause permanent damp and efflorescence.

This moisture will effectually prevent a fat lime from setting,
or rather drying, but would tend to increase the strength of a
hydraulic liine or cement (see page 235).

Great care must be taken to exclude all organic animal matter
from the sand, or substitutes for sand, that may be used in mor-
tar for building or plastering the walls of dwellings, otherwise they
will putrefy, and render the walls and ceilings sources of unwhole-
some emanations.

Substitutes for Sakd in Mortar. — ^Any of the substances
mentioned at page 195 may be used as substitutes for sand in
mortar, some of them with advantage, as there pointed out

Smiths' ashes and coal dust are used to make the hlack mortar
used for pointing, slating, and for some kinds of rubble masonry.

The Description of Water to be used in Mortar. — The water
used for mixing mortar should be firee from mud, clay, or other
impurities.

Salt Water is objectionable in some situations, as it causes
damp and effloresceuca

200 NOTES ON BUILDING CONSTRUCTION,

Salt Water is objectionable in some situations, as it causes
damp and efSorescence.

The salts it contains attract moisture, which improves the
strength of hydraulic limes and cements by preventing them from
drying too quickly, but is fatal to a pure lime for the reasons
given above.

Dirty water, and water containing organic matter, are of course
objectionable for the same reasons as dirty sand.

Mr. Dyce Cay gives a table of ezperiments made with 8 oz. fresh water to 36 oz. neat
Portland cement, and 7 oz. sea water to 86 oz. Portland cement, which seems to show, as
far as experiments with neat cement could show it, that " roughly speaking the salt water
briquettes are as strong in a week as the fresh water ones are in a fortnight, and as strong
in a fortnight as the fresh water ones are in a month." ^

Strenfi^h of Mortar as compared with Brioka in a Wall. — Lime is
much more expensive than sand. It is, therefore, a source of economy to
add as much sand as is possible without unduly deteriorating the strength
of the mortar.

So long as the joints of masonry or brickwork are weaker than the stones
or bricks, the strength of the wall will increase in proportion as the strength
of the mortar increases, until they are nearly equal in power of resistance.

The mortar need not be quite equal in strength to the bricks, because in a
bonded wall the fracture is constrained to follow a longer path than when the
work is put together without breaking joint.

The object, then, is to produce such an equality of resistance as will com-
pel the fracture to follow a straight line, ue, to break the material of the
wall straight across rather than to follow the joints.

This cannot always be done, with a due regard to economy, where the wall
is built with very hard stone, but it can be done with the generality of
nhckfl.

In some cases a stronger mortar, no doubt, adds to the strength of the
walL For example, when the bricks are very bad, they will sometimes
weather out on the (ace, leaving a honeycomb of mortar joints.

Again, unusually strong mortar is required sometimes for the voussoirs of
arches — ^to prevent sliding — for the lower joints of chimneys and waUs,
etc. etc

As a role, however, it can hardly be economical to make the strength of
the mortar joints greater than that of the bricks or stones they unite.

Proportion of Ingredients. — In considering the proportion of
sand to be mixed with different limes and cements it is necessary
to bear in mind that the strength of the joint formed by the
mortar will have an influence upon that of the wall

The following Table shows how different limes and cements are
weakened by the addition of various proportions of sand : —

' Af.RI.C.E., vol. Ixii. p. 212.

MORTAR.

20I

TABLE

Showing the effect of different Proportions of Saud in Mortars
made from varioas CsMBNTa

Natubs of Matbaial.

Portland Cement

Medina .
Roman .
Atkinson's
Scott's Cement
Lobs Lime

Age
when
tried.

11 days

PaoPOBTioar or Cbmbht ob Limb axd Babb^

la
Neat

10.
18.

Ic.

28.

88.

48.

6 8.1

Bbbakiko Weight in lbs. upoh Abka or 10 Ibcbbl

Bricks
broke
first

504

483

808

420

400

852

278

201

149

400

279

178

154

149

...

885

175

292

286

808

828

281

119

124

288

88
78

194
42

The above fignres are from experiments made for General Scott by tearing
asunder bricks united by the different kinds of mortar, and set in air. The
sectional area torn asunder being 4x2^ = 10 inches in each case.

The Table at page 168 gives fuller particulars as to the loss of strength
caused by adding sand to Portland cement

The proportion of the ingredients in mortar is generally speci-
fied thus : — " 1 quicklime to 2 (or more) of sand," meaning that
1 measure of quicklime in lump ^ is to be mixed with 2 measures
(or more) of sand.

Now, the quantities of sand put at different times into a
measure vary a little, according to the amount of moisture the
material contains ; but so little that practically it makes no differ-
ence, and this mode of measuring sand is very convenient and
sufficiently accurate.

With the lime, however, many conditions have to be fulfilled
in order to make it certain that the same quantity always fills
the same measure.

The specific gravity of the calcined stone, the size of the
lumps, the nature of the burning, the freshness of the lime, all

1 Portland cement mortar made with 8 parts of sand to 1 of cement may advan-
tageously be used in preference to lime mortar (see p. 208).
* The pieces of caldned stone are called ** lump-lime," or in the North '* lime-shells."

202

NOTES ON BUILDING CONSTRUCTION

cause the actual quantity contained in a given measure to differ
considerably.

In order to avoid this uncertainty it has been proposed that
the weight of lime for a given quantity of sand should be
specified

Practically, however, this has not been carried out to any great
extent, and the bulk of lime to be used is generally specified as well
as that of the sand.

The following proportions are given by General Scott for mor-
tar in brickwork built with ordinary London stock bricks.

Parts by Measure.

Fat limes

QuickUme. SuuL
1 3

Feebly hydraulic limes .
Hydraulic limes (such as Lias) .
Roman cement

1 2i

1 2

1 1 or U

Medina „

1 2

Atkinson's „

1 2

Portland „

1 6

Scott's „ . .

1 4

Selenitic „ .

(see p. 179).

'* The proportions here recommended apply only to works above
the surface of the ground, or free from the action of a body of
water."

* For hydi^ulic purposes and foundations 1 sand to 1 quick-
lime is as much as should be admitted. With cement mortar 2
sand may be used with 1 cement, unless actually in contact with
water, when 1 part of sand should be the limit allowed." ^

Preparation and Mixing. — ^The quicklime and sand having
been procured, and their proportions decided, the preparation of
the ingredients commences.

Slaking. — ^A convenient quantity of the quicklime is measiired
out on to a wooden or stone floor under cover, and water enough
to slake it is sprinkled over it.

The heap of lime is then covered over with the exact quantity
of sand required to be mixed with the mortar ; this keeps in the
heat and moisture, and renders the slaking more rapid and
thorough.

In a short time — ^varying according to the nature of the lime
— it will be found thoroughly slaked to a dry powder.

In nearly all limes, however, there will be found overburnt

^ General Scott in KE. Corps Papers^ vol. zL

MORTAR. 2C3

refractory particles, and these should be carefiilly removed by
screening — especially in the case of hydraulic limes ; for if they
get into the mortar and are used, they may slake at some future
time, and by their expansion destroy the work.

Quantity slaked and Time required. — The fat limes may be
slaked in any convenient quantity, whether required for imme-
diate use or not. Plenty of water may be used in slaking without
fear of injuring them, and they will be found ready for use in two
or three hours.

Hydraulic limes should be left (after being wetted and covered
up) for a period varying from twelve to forty-eight hours, accord-
ing to the extent of the hydraulic properties they possess; the
greater these are, the longer will they be in slaking. Care should
be taken not to use too much water, as it absorbs the heat and
checks the slaking process. Only so much should be slaked at
once as can be worked off within the next eight or ten days.

With strong hydraulic limes, or with others that are known to
contcdn overbumt particles, it is eulvisable to slake the lime
separately, and to screen out all dangerous lumps, etc., before
adding the sand, or the safest plan is to have the lime ground
before using it.

Ground Lime. — ^When lime is purchased ready ground there
is sometimes danger of its having become air-slaked, by which
wear and tear of machinery in grinding is saved at the expense
of loss of energy on the part of the lime.

At the same time, if unadulterated and fresh, ground lime is
likely to be of good quality for the reasons stated at p. 155.

Quantity of Water used. — ^The quantity of water required for
slaking varies with the pureness and freshness of the lime, and is
generally between one-third and one-half of its bulk.

A pure lime requires more water than one with hydraulic pro-
perties, as it evolves more heat and expands more in slaking.

A recently-burnt lime requires more water than one that has
been allowed to get stale.

Mixing. — ^The great object in mixing is to thoroughly incor-
porate the ingredients, so that no two grains of dry sand should
lie together without an intervening layer or film of lime or
cement.

On extensive works a mortar-mill is universally adopted for
mixing the ingredients, and, indeed, is absolutely necessary for
the intimate incorporation of large quantities.

204 NOTES ON BUILDING CONSTRUCTION

A few dififerent forms of mortar-mill are shown and described at
page 223 et seq.

The heap of slaked lime covered with sand» above described,
(p. 202; is roughly turned over and shovelled into the revolving
pan of the mortar-mill, enough water being added to bring the
mixture to the consistency of thick honey.

When the ingredients are thoroughly mixed and ground to-
gether, the mortar is shovelled out of the pan on to a " banker " or
platform to keep it from the dirty ground, whence it is taken
away by the labourers in their hods.

A good deal has been said regarding the number of revolutions
that should be given to the pan. Nothing seems to have been
settled upon this point except that the mortar should be thoroughly
mixed, yet not kept so long in the mill as to be ground to
pap. About twenty minutes is a good time for running each
charge of about f of a cubic yard.

On very small works the mixing is effected by hand or
in a pug-mill. It is evident, however, that such a mixture
must be very incomplete unless a gi*eat deal of time is devoted
to it.

Before hydraulic lime is mixed in this manner it is absolutely
necessary that it should first be ground to a fine powder, and
with any description of lime the smallest refractory unslaked
particles should be carefully screened out

Mortar, when made with cement, should be mixed dry, the
ingredients being carefully turned over together two or three
times before the water is added. By this process a very
thorough incorporation of the materials can be effected.

Quantities mixed. — If a hydraulic mortar is allowed to com-
mence to set and is then disturbed, it is greatly injured. Care
should be taken, therefore, to mix it only so long as is required
for thorough reduction and incorporation of the ingredients, and
only to prepare so much as can be used within a few hours.
With fat limes it matters little whether large or small quantities
of mortar are made at once, because they set very slowly.

Very quick-setting cements must be used immediately they are
mixed.

Btdk of Mortar produced, — The bulk of mortar produced in
proportion to that of the ingredients differs greatly according to
the nature of the lime or cement and the quantity and descrip*
tion of the sand added to it

MORTAR,

205

The more hydraulic limes produce a smaller amount of mortar
because they expand less in slaking.

The following Table shows the bulk of mortar found by experi-
ment to be produced from a few of the most common ingredients
in ordinary use. It must be regarded only as a guide to the
approximate quantities. The actual bulk would vary according
to the freshness of the lime and the coarseness of the sand.

Mortar made from given Quantitiea of Lues and Cement and Sand.

Deacriptlon.

Quick-
lime or
Cement.

Sand.

Water.

Mortar
made.

Remarks.

Cub. ft.

Gallons.

Cub. ft.

White chalk lime in
lump

Do. do. .

Portland atone lime in
lump

S
3

8
7}

2A
8!

The (quantity of water
mentioned includes that
required for both slak-
ing and mixing.

Grey chalk lime in lump

Do. do.

Stone lime (Plymouth,^
• in lump

Lias (Eeynsham)^ in
lump

Lias (Warwickshire) in
lump

Do. do. ground

24*

Lias (Keynsham) ^ do.

Do. do. do.

Lias (Lyme Regis) do.

Arden lime ground

Roman cement * .

Portland cement '

Do.«

Do.« . .

Do.«

' Deduced from Cooke's Aide MSmoire,

" Deduced from Grant's Experiments, Af.LP.C.E,, vol. xxv. The quantities varied
according to the ampunt of water used ; the Table shows the average.

Where authorities are not given, the quantities stated have been derived from
experiments made for this work.

2o6 NOTES ON BUILDING CONSTRUCTION

The results of further experiments, giving the same kind of
information, will be found in Hurst's Swrveyor's Handbook,

The use of Sugar in Mortar. — It was pointed out many years
ago ^ that the bad qualities of rich limes " may be in some degree
corrected by the use of a comparatively small quantity of the
coarsest sugar dissolved in the water with which they are worked
up," and that sugar was extensively used in the East for common
mortars made of calcined shells, which when well prepared " re-
sist the action of the weather for centuries." A recent discussion
on the subject has led to expeiiments being made to ascertain the
effect of sugar on Portland cement ; and it was found that the
addition of from ^ per cent to 2 per cent of pure sugar to
DyckerhofiTs German Portland cement increased its strength after
three months considerably. The sugar is said to " retard the set-
ting," and thus permit the chemical changes in the cement to
take place more perfectly. More than 2 per cent of sugar made
the cement useless.^

Selenitic Mortar is generally made by mixing selenitic cement
and sand. It was at one time made by mixing a small propor-
tion of calcium sulphate with ordinary Ume and sand.

The licenses issued by the patentees render it necessary
that selenitic cement should be used. The proportion of sulphate
required to develop the characteristics of the material is added
to the cement before it is sold, and the process of mixing the
mortar is carried on under the following rules, which are taken
from the circular of the patentees : —

Selenitic Mortar made with Selbnitised Limb or Selenttic Cement.
N,B, — One bushel^ of prepared selenitic lime requires about six gallons
of water (two full-sized pails).

If 'prepared in a Morta/r Mill — Ist, Pour into the pan of the edge-runner
four full-sized pails of water.

2<2, Gradually add to the water in the pan 2 bushels of prepared selenitic
lime, and grind to the consistency of creamy paste, and in no case should it
be thinner.

3d, Throw into the pan 10 or 12 bushels of clean sharp sand, burnt day,
ballast, or broken bricks, which must be well ground till thoroughly incorpo-
rated. If necessary, water can be added to this in grinding, which is pre-
ferable to adding an excess of water to the prepared lime before adding the
sand.

When the mortar-mill cannot be used, an ordinary plasterei^s tub (con-
taining about 30 or 40 gallons) or trough, with outlet or sluice, may be
substituted.

^ Vicat on Cements (Smith), published in 1837. ^ Sngmeering, 1888, p. 102.
' A striked bushel = 1.28 cubic foot (see page 158).

MORTAR, 207

If prepared in a Plaalerer's TvJb. — Isty Pour into the tub 4 full-sized pails
of water.

2(2, Oradually add to the water in the tub 2 bushels of prepared selenitic
lime, which must be kept well-stirred until thoroughly mixed with the water
to the consistency of creamy paste, and in no case should it be thinner.

3(2, Measure out 10 or 12 bushels of clean sharp sand or burnt clay
ballast, and form a ring, into which pour the selenitic lime from the tub,
adding water as necessary. This should be turned over two or three times,
and well mixed with the larry or mortar hook.

Both the above mixtures are suitable for bricklayers' mortar or for first
coat of plastering on brickwork (see p. 246).

N,B, — The Selenitic Cement Company recommend that the workman
intrusted with the making up of the selenitic mortar be supplied with suitable
measures for his lime and sand, to ensure that the proportions stated in the
circulars be adhered to. The want of this frequently leads to unsatisfactory
results

A box measuring inside 13^ inches by 13^ inches by 13^ inches would
contain about 1 bushel, and would be useful for measuring the lime, and
should be kept dry for that purpose ; and a box without a bottom, measuring
inside 36 inches by 18 inches by 18 inches would contain about 6^ bushels,
and would be very useful for measuring the sand.

Increase or decrease the quantities given proportionately with the require-
ments. The prepared selenitic lime must be kept perfectly dry until made
into mortar for use.

N,R — It is of the utmost importance that the mode here indicated of pre-
paring the mortar, concrete, etc, should be observed — viz. First well stirring
the prepared selenitic cement in the water before mixing it with the sand,
ballast, or other ingredient, otherwise the cement will slake and spoiL

Selenitic Mortar made with Ordinary Lime. — ^A few years
ago persons using selenitic mortar were permitted to add the sul-
phate of lime for themselves, and where selenitic cement is not
procurable the process might still be useful.

It is conducted as follows :

Three pints of plaster of Paris are stirred in 2 gallons of water. After
the mixture is complete it is poured into the pan of a mortar mill ; then
4 gallons of water are added, and the mill revolved three or four times, so
as to ensure thorough mixing.

A bushel of finely-ground unslaked lime is now added ; the mixing is
continued tiU the whole becomes a creamy paste, and then 6 bushels of
sand are gradually introduced, the whole being thoroughly mixecL

No more is mixed than will be required during the day.

If the mortar gets heated or sets too slowly, a little more plaster of Paris
should be added, but not more than ^ pint extra per bushel of lime.

When the lime used in this last-described process is deficient in hydraulic
properties, a proportion of selenitic clay should be added so as to bring the
total amount of clay in the prepared lime up to about 20 per cent. Any
lime requiring more than 7^ per cent of plaster of Paris added to stop slaking
with heat will require selenitic clay.

It will be seen that the addition of the plaster of Paris, clay, etc., requires

208

NOTES ON BUILDING CONSTRUCTION,

considerable skill and judgment, and the simpler process is to use the selenitic
cement, in which the necessary additions have already been carefully made by
the patentees.

The following Table, from the patentees' circular, shows the strength of
selenitic cement mortar with different proportions of sand as compared with
mortars made with other cements.

TABLE

Showing the relative Breaking Weights in lbs. of Briquettes having a
sectional area at the neck of two and a quarter square inches.

Nature of Lime
or Cement

Age In

Days

when

fractured.

Composition

or Mortar.

Saand

tol

cement

or lime.

4 sand

tol

cement

or lime.

6 sand

tol

cement

or lime

6tMind

tol

cement

or lime.

Brbakimq Tensile 6trrb8 om
2^ Square Imches.

Portland cement .

167

...

206

149

113-5

White chalk lime .

164

67-5

Do. (Selenitic) .

161

72-3

Burham lime (Selea-
! itic)

Do. do.

165

234

161

256

340

170

210
260

Good Medwavgrey
V lime, sold by
Messrs. Lee.

Halkin lime (Selen-
itic)

128-6

197

111

Good hydraulic lime.

Dolgoch lime (Selen-
itic)

155

156-5

157

206-5

Very hydraulic lime

Mixture of Iiime and Cement. — Bad lime is much improved by mixing Portland
cement with it

General Gilmore says : — " Lime paste may be added to a cement paste in much larger
quantities than is usually practised iu important works without any cousiderable loss of
tensile strength or hardness.

" There is no material diminution of strength until the volume of lime paste Vccomes
nearly equal to that of the cement paste, and it may be used within that limit without
apprehension under the most unfavourable circumstances in which mortars can be placed."

Portland Cement Mortar with large proportion of Sand. — Mortar
composed of 1 Portland cement, 8 sand, and 1 of slaked fat lime is much
better and generally cheaper than 1 of grey lime to 2 sand — the slaked lime
slightly weakens the mortar, but is necessary to prevent it from working
'* short" Loam is sometimes used instead of the slaked lime, but it weakens
tbe mortar still more. This mortar is greatly preferable to that made from
lime when frost is to be feared.

The following was used in the outer wall of the Albert Hall : —

1 Portland cement
1 grey lime (Burham).
6 clean pit sand.

MORTAR 209

The lime was slaked for twenty-four hours, then mixed with sand for ten
minutes. The cement was then added, and the whole ground for one minute.
Such a mixture must be used at once.

Grout is a very thin liquid mortar sometimes poured over
courses of masonry or brickwork in order that it may pene-
trate into empty joints left in consequence of bad workmanship.

It may also be necessary in deep and narrow joints between
large stonea

It is deficient in strength, and should not be used where it oan
be avoided.

FreoautionB in using Mortar. — Fat lime mortars, unless im-
proved by adding pozzuolana and similar substances, are so wanting
in strength that any precautions in using them are of but little
avail

In using hydraulic limes and cements it should be remembered
that the presence of moisture favours the continuance of the for-
mation of the silicates, etc, commenced in the kiln, and that the
setting action of mortars so composed is prematurely stopped if
they are allowed to dry too quickly.

It is, therefore, of the utmost importance, especially in hot
weather, that the bricks or stones to be imbedded in the mortar
should be thoroughly soaked, so that they cannot absorb the
moisture from the mortar ; and also in order to remove the dust
on their surfaces, which would otherwise prevent the mortar
from adhering.

Mortar should be used as stiff as it can be spread ; the joints
should be all well filled ; grout should never be used except with
large blocks or in other cases where from the position or form of
the joint it cannot be filled by mortar of proper consistency.

In frosty weather the freezing and expansion of the water
in the mortar disintegrates it and destroys any work in which it
may be laid.

Mortar should always be placed for the use of the builder on a
small platform or " banker," or in a tub, to keep it from the dirt.

Cement mortars have, of course, peculiarities depending upon
the nature of the different cements. These have been noticed in
treating of those substances.

B. c. — III

210 NOTES ON BUILDING CONSTRUCTION.

CONCKETK

Concrete is an artificial compound, generally made by mixing
lime or cement with sand, water, and some hard material, such as
broken stone, gravel, burnt day, bits of brick, slag, eta etc.

These ingredients should be thoroughly mixed so as to form a
close conglomerate free from voids.

The lime, or cement, sand, and water, combine to form a lime
or cement mortar in which the hard material is imbedded, so that
the result is a species of very rough rubble masonry.

The broken material is sometimes for convenience called the
aggregate, and the mortar in which it is encased the matrix.

The strength and other qualities of concrete depend chiefly
upon the matrix. They are, however, influenced also by the
aggregate, and it will be well to make a few remarks upon these
two parts of the material separately before proceeding further.

The Matrix, as before stated, is the lime or cement mortar in
which the hard broken material, or aggregate, is imbedded.

The lime, or cement, sand, and water, Bhould be so proportioned that the
mortar resulting from their mixture is the best that can be made from the
materials available. As a rule it should be better than the mortar used for
walling, especially if the concrete is to be used in important positions. The
reason for this is, that in concrete, the mortar receives less assistance, from
the form and arrangement of the bodies it cements together, than it does in
masonry or brickwork.

In some cases the mortar is mixed separately, just as if it were to be used
in building brickwork or masonry, and then added to the hard materiaL

More generally, however, the ingredients are mixed together in a dry
state, and sprinkled while they are being mixed.

For further remarks on the subject of mixing, see p. 214.

The Aggregate is generally composed of any hard material
that can be procured near at hand, or in the most economical
manner.

Almost any hard substance may be used when broken up. Among these
may be mentioned broken stone, bits of brick, of earthenware, burnt clay,
bteeze, and shingle. If there is any choice, preference should be given to
fragments of a somewhat porous nature, such as pieces of brick or limestone,
rather than to those with smooth surfaces, such as flints or shingle, as the for-
mer offer rough surfaces to which the cementing material will readily adhere.
When weight in the concrete is undesirable, a light porous material such as

CONCRETE. 211

breeie^ may be used, but when great weight ia an advantage, as in the
works of a bieakwater or sea wall, the aggregate may be of the heavieet
material that can be procured.

Any aggregate of a very absorbent nature shonld be thoroughly wetted,
especially if it is used in connection with a slow-setting lime or cement, other-
wise the aggregate will suck all the moisture out of the matrix, and greatly
reduce its strength,

S^pe. — Many engineers prefer aggregates composed of angular fragments
rather than those consisting of rounded pieces, t.g. broken stone rather
than shingle. The reason for this is that the angular fragments are sup-
posed to fit into one another, and slightly aid the coherence of the mortar
or cement by forming a sort of honnd^ while the round stones of the shingle
are simply held together by the tenacity of the matrix. Moreover, the
angular stones are cemented together by their sides, the rounded stones only
at the spots where they touch one another, and angular stones are as a rule
rougher and the cement adheres better to their surface.

/Suse. — The aggregate is generally broken so as to pass through a 1^ or 2
inch mesh. Very large blocks cause straight joints in the mass of the
material, which should be avoided if the cement is to bear a transverse stress
or to carry any considerable weight

Of the aggregates in common use, hroJuta Ifrid^ breezej or coke from gasworks
if clean, and burnt clay if almost vitrified throughout, all make very good
concrete. Oravd and haUoMt are also good if angular and clean. Shingle
is too round and smooth to be a perfect aggregate. Broken etone varies ; some
kinds are harder, rougher on the surface, and therefore better, than others.
Flints are generally too round, or, when broken, smooth and splintery. Chalk
is sometimes used; and the harder varieties make good concrete in positions
where they are safe from moisture and frost.

Slag from iron furnaces is sometimes too glassy to make good concrete, but
when the surface is porous it is one of the best aggregates that can be used.
It Ib hard, strong, and heavy, and the iron in it combines chemically with
the matrix, making it much harder than it would otherwise be. Some slag,
however, contains Ume which may be dangerous (see p. 161).

The results of experiments as to the relative value of some of these aggre-
gates are given at p. 222.

The materials for concrete may be broken by hand, except when large
quantities are required, in which case a Blake's stone-crusher is generally
employed.

The size of the pieces of which the aggregate is fonned influ-
ences the content of the void spaces between them, and therefore
the quantity of lime and sand that must be used.

Unless the mortar is of such a description that it will attain
a greater hardness than the aggregate, the object should be for
the concrete to contain as much broken material and as little
mortar as possible.

' Concrete made of breeze is also used when it is required to receive nafls, as in
lintels, or to be proof against fire.

10|

da
do.

9 do.

6 do.

212 NOTES ON BUILDING CONSTRUCTION.

The following Table shows the amount of voids in a cubic
yard of stone broken to diflferent sizes, and in other materials : —

1 Cnbio Yard contains
YoidB amoanting to
Stone broken to 2^inch gauge • 10 cubic feet

Do. 2 da

Da 1^ da

Shingle
Sand
Thames ballast (which contains the necessary

sand) . . . 4^ do.

A mixture of stones of different sizes reduces the amount of
voids, and is often desirable.

The contents of the voids in any aggregrate may be ascertained
by filling a water-tight box of known dimensions, with the mate-
rial thoroughly wetted so as not to absorb, and measuring the
quantity of water poured in so as to fill up all the interstices ; or
by weighing a cubic foot of the aggregate and comparing its
weight with that of a cubic foot of the solid stone from which it
is broken.

Packing, — In building walls, or other masses of concrete, large
pieces of stone, old bricks, chalk, eta, are often packed in for the
sake of economy.

Care should be taken that the lumps thus inserted do not
touch one another. They should be so far apart, and clear of the
face, that the concrete may be well rammed around them.

Where chalk or lumps of absorbent material are used, care
must be taken that they are not exposed so as to absorb wet or
moisture, otherwise they will be liable to the attacks of frost, and
may become a source of destruction to the walL

Proportion of Ingredients. — ^The materials to form concrete
for ordinary work are generally mixed together in a dry state,
the proportion of each being determined by custom, rule of thumb,
or experience.

In former days, when lime concrete was more used, a common
mixture was

1 quicklime. Or ^ quicklime.

8 sand. 7 Thames ballast (which contains

5 or 6 gravel, broken stone, or brick. sand and shingle).

The same proportions were for some time blindly adhered to,
irrespectively of the nature of the materials used.
• The best proportions for the ingredients of a cubic yard of

CONCRETE. 213

concrete to be made with any given materials may, however,
always be arrived at by ascertaining the contents of the voids in
a cubic yard of the aggregate (without sand), and adding to the
latter such materials as will make mortar of the best quality and
in sufficient quantity to perfectly fill those voids. Where the
concrete is not required to be of the best quality, as for example
in the backing of heavy walls, the mortar may be made poorer
accordingly.

If the aggregate contain sand (as in the case of gravel or
ballast), the sand should be screened out of the sample before
the voids are measured, and the amount of sand thus screened
out will be deducted firom that required for the mortar which is
to form the matrix of the concrete.

In practice a little more mortar than is actually required to fill
the voids is provided, in order to compensate for imperfect mixing
and waste.

Thus, sappoedng the aggregate available for making concrete to be clean
shingle containing 9 cubic feet of voids per cubic yard, a first-rate concrete
can be made by adding to each cnbic yard of aggr^ate 4 cubic feet of
Portland cement and 8 cubic feet of sand, which will miJLe 10} cubic feet of
8 to 1 Portland cement mortar (see p. 205), or a little more than sufficient
to fill the 9 cubic feet of voids in the shingle.

Again, if the aggregate were ballast, itself containing 4^ cubic feet of sand
in each cubic yard, and 4^ cubic feet of voids besides, it would be necessary
to add to each cubic yard 4 cubic feet of Portland cement as before, but only
3^ cubic feet of sand, because there are already 4^ cubic feet of sand in the
aggr^ate, making 8 cubic feet of sand altogether, which, with the 4 cubic feet
of Portland cement, will make 10| cubic feet of 2 to 1 Portland cement
mortar, or more than sufficient to fill the 9 cubic feet of voids that there are
in the ballast without the sand.

If the concrete is not required to be of the first quality, as for example in
the backing of heavy walls, the mortar may be made poorer accordingly.

Thus, to make a poorer concrete, with clean shingle for the aggregate, to each
cubic yard may be added 12 cubic feet of sand and only 2 cubic feet of
Portland cement, making 6 to 1 mortar (or mortar of 6 sand to 1 cement) ip
more than sufficient quantity to fill the voids.

The chief point to be considered is the quality of the mortar in the
concrete. This should be airanged as above described so as to be good enough
for the work in which it Ib to be used, and sufficient in quantity to thoroughly
fill the voids of the aggregate, with a little to spare in case of imperfect

Till Ting,

It is a curious thing that engineers have not agreed upon any short way
of describing concrete so as to indicate at once its proportions and quality.

As recently as in November 1886 Mr. Hayter said at the Institute of Civil
Engineers : — ^

1 M.KLC.E.y vol. Ixxxvii. p. 161.

214 NOTES ON BUILDING CONSTRUCTION.

'^In describing concretes it was customary to say tbat thej wen
mixtures consisting of so many parts of gravel or shingle and sand to 1
part of cement But in Mr. Hayter's experience two concretes so described
might mean admixtures of two different strengths. Thus, assuming a concrete
that might be called a 6 to 1 mixture. In specifiying such one engineer
might say the concrete was to consist of 1 part Portland cement and 6 parts
of gravel or sand of approved quality. Another engineer might say that the
concrete was to consist of 1 part Portland cement^ 4 parts of gravel or shingle
without any sand, and 2 parts of sand.''

He pointed out that these two concretes, though both called 6 to 1
concretes, were very different, for in the first there is 1 part of Portland
cement to 6 of gravel containing sand, whereas in the second, after the sand
is mixed with the shingle, it merely fills the interstices, and the concrete is
composed of 1 part Portland cement to 4 of shingle containing sand in its
interstices (see p. 213).

The present practice as to briefly describing concrete differs and is often
very misleading. It is necessary, therefore, to be very careful in specifications
to state exactly how much of each ingredient^ shingle or stone, sand and
cement is required.

It has been stated that concrete can be made equally good without sand,
but sand is a necessary ingredient in all cases where the concrete is required
to be waterproof, and it is also desirable on account of strength. Recent
experiments have shown that with different aggregates — the proportion of
cement, etc., being the same — the concrete made wiUi sand was far stronger
both as re£^u:ds transverse and tensile stress and crushing than that without
sand.

Concrete is much used for paving, being made with the very
best Portland cement into slabs, and then laid like ordinary stone
flags.

For this purpose it is preferable to use an aggregate, such as
shingle or granite, much harder than the matrix, and to use very
little sand in the latter.

As the matrix becomes worn away, the pebbles of the aggregate
project slightly, making the surface slightly rough, and therefore
less slippery, and at the same time the matrix is protected from
further wear.

Mudng. — As before mentioned, the materials are generally
mixed in a dry state, not upon the bare ground, but upon a clean
timber or stone platform. The proportions decided upon are
measured out either roughly by barrow-loads, or in a more precise
manner by means of boxes made of sizes to suit the relative
proportions of the ingredients to be used.

Such boxes, in which the quantities to be mixed together can
be accurately gauged, should always be used in mixing cement or
other concretes intended for important work.

CONCRETE.

2IS

Table showing the Proportions of the Concrete used in various works.

Whxbb usbd.

Pbopobtiovb.

Fob what ubcd.

1. Peterhead Breakwater

1 Portland cement .
6 sand, shinffle, and broken
stone, wiUi granite rub-

Concrete blocks.

ble incorporated therein

Do,

1 Portland cement .
6 sand, shingle, and broken
stones

Cement in bags.

1 Portland cement .
4 sand and shingle

Concrete joggles.

2. Newhaven Harbour .

1 Portland cement .

2 sand

5 shincle

1 Portland cement .

Western sea-walL

8. Wicklow Harbour .

In breakwater.

7 navel and sand
1 Portland cement .

4. Colombo Breakwater

In ordinary rings of

8 stone
2 sand

cylinder foundations.

4 stone and sand

In cutting rings of ditto.

1 Portland cement .

2 sharp sea sand

4 hana-broken stone (3}")

Blocks.

2 machine-crushed (1^")

screened stone

5. Greenock Harbour .

2 Portland cement .

Facing to quay wall.

7 sand and ballast

PUui/Ui coTicreU behind
sheet piling.

1 Portland cement .

Backing to quay wall.

6 sand and ballast

FlasUc concrete.

8 aranite chips

1 Portland cement .

Dock walls—

2 sand

For faced to 10 inches

4 slag

thick.

1 Portland cement .

For backing of dock

12 gravel

walk.

7. Cork Harbour Forti-

1 Portland cement .

The bulk of the sand )

fications

8 broken stone and sand

that of the broken
stone.

Do.

1 Portland cement .

Under water, more cement

4 to 6 of broken stone and

to make up for scour.

sand

8. Metropolitan Main
Drainage Works

1 Portland cement .

h\ ballast

I Portland cement .

For roofe, floors, etc.

9. For ordinaiy build-

6 sravel

1 Portland cement .

For walls.

ings
Da

8 flravel

1 Portland cement .

6 gravel

For floors, roofs, etc.

L Sir John Goode. 2. M,P.LC.E., voL IxxxvII. p. 99. 8. P. 118. 4. M.P.LCS,, vol. Ixxxvii. p.
18«. 5. M.PJ,C.E,, vol. Ixxxvll. pp. 66, 67. 6. M.P.LCE., voL IriL ^ 94. 7. ILK. Corjn Papen,
voL sL & M.P.LCB., vol. zzv. 9. Suiiding Nswt,

2i6 NOTES ON BUILDING CONSTRUCTION.

Tho measured materials are then heaped up together, and
turned over at least twice, better three times^ so as to be most
thoroughly incorporated.

The dry mixture should then be sprinkled, not drenched, the
water being added gradually through a rose^ no more being used
than is necessary to mix the whole yery thoroughly. If too
much water be added, it is apt to wash the lime or cement away ;
at the same time due allowance must be made where the water is
liable to soak away or to evaporate quickly.

The moist mixture should then again be turned over twice or
three times.

When lime is lued it ahonld be in a fine powder.

If a ftnt lime (which is almost useless for oonerete in most positions), it should he
slaked and screened.

If a hydranlic lime, it should be finely gronnd, or, in the absence of machinery for
grinding, it should be carefully slaked, and all unslaked particles csieftilly removed by
passing it through a sieve or fine screen.

The lime is often used fresh firom the kiln, piled on to the other ingredients during the
mixing. This is apt to leave unslaked portions in the lime, and is a dangerous practice.

When Portland cement is used for concrete, it must be thoroughly cooled before
mixing. Cements of the Roman class should be ftesh.

Iiaying. — Concrete should, after thorough mixing, be rapidly
wheeled to the place where it is to be laid, gently tipped (not
from a height) into position, and carefully and steadily rammed
in layers about 12 inches thick.

For large masses a somewhat slow-setting cement should be
used, and the layers should follow one another so that each is
laid before the last has had time to set This leads to a thorough
key being formed between the layers, by which horizontal joints
are avoided.

It is essential that the layers should be horizontal ; if not, the
water trickling off will carry the cement with it.

When circumstances require that each layer should be allowed
to set separately, it should be carefully prepared to receive the
one that is to rest upon it

A common practice, which in former years was much insisted upon, is to tip the con-
crete, after mixing, from a height of 10 feet, or more, into the trench where it is to be
deposited.

This process is now considered objectionable, on the ground that the heavy and light
portions separate while falling, and that the ooncrete is therefore not uniform throughout
its mass.

Wooden shoots or steeply-inclined troughs are therefore sometimes used, down which
the ooncrete is shot from the plaoe where it is mixed to the site where it is to be used.
Such shoots are also objectionable, because the larger stones have a tendency to separate
from the soft portions of the ooncrete.

Its surface should be carefully swept clean, made rough by

CONCRETE. 217

means of a pick, washed and covered with a thin coating of
cement

This is especially necessary if it has been rammed, for in that
case the finer stuff in the concrete works to the top, and also a
thin milky exudation, which will, unless removed, prevent the
next layer from adhering.

The joints between the layers are the most important points to be
attended to in concrete. When the proper precautions have not been taken,
they are found to be sources of weakness, like veins in rocks, and the mass
can easily be split with wedges.^

When there is not time to allow each layer to set before the concreting is
continued, it is better to ram it as quickly as possible, and, before it is set,
to add the layers above it

Anything ib better than to allow the layers to be disturbed by ramming,
by walking over them, or in any other way, after they have commenced
to set

Concrete made with a very quickHsetting cement should therefore not be
used for large masses, and if used, not rammed at alL

When concrete has to be laid under water, care must be taken that it is
protected during its passage down to the site of deposit, so that the water
does not reach it until it is laid.

This protection is afforded sometimes by shoots, by boxes, or by specially
contrived iron " skips," which can be opened from above when they have
reached the spot where the concrete is to be deposited, so as to leave it there.
Sometimes the concrete is filled into bags and deposited without removing
the bags.

Concrete is also made into blocks varying in size from 2 to 200 tons.
These are allowed to set on shore, and are deposited, the smaller ones in the
same way as blocks of stone, those of enormous size by special arrangements
which cannot here be described.

PUutie OonoreU* is a oame that has been given to concrete that has been mixed with
a very snudl proportion of water, allowed to set for from 2 to 5 hoars, aooording to the
state of the weather, and a little quick-setting cement — such as Roman, Medina, or
Orchard — added to it just before it is placed in skips and deposited nnder water.
(Concrete deposited in this condition is said to resist the action of the sea and to nnite
with that previonsly in poeition better than concrete deposited in the ordinary liquid
condition. On the other hand, it is said that the disturbance of the concrete after it has
commenced setting prevents it from, ever attaining a proper hardness. The material has
not at present been sufficiently used for any decided opinion to be given with regard to
its merits.

The Cementing Material to be need fbr Oonorete. — It is hardly
necessary to say that when there is a choice the strength and quality of the
cementing material should be in proportion to the importance of the part the
concrete has to play.

Thus fat lime concretes would be objectionable almost anywhere except as
filling in the spandrils of arches.

JLE. Corps Papers, vol xxii. « Jif»PJ.C.K, vol. Ixxxvii. p. 66.

ii8 NOTES ON BUILDING CONSTRUCTION

Hydraolie lime, or cement, Ib advisable for concrete in nearly all aitua*
tiona

Eminently hydraulic limea should be used for concrete foundations in
damp ground, and in the absence of cement for subaqueous work of any kind.

Portland cem^it concretes are adapted for all positions, especially for
work under water, or where great strength is required ; also in situations
where the concrete has to take the place of stone, as in facing to walls, copings
eta etc.

For work to be executed between tides, where the concrete is required to
set quickly but not to attain any great ultimate strength, Roman or Medina
cement may be used with advantage.

When, for the sake of its strength, Portland cement concrete is necessarily
used under water, it must be protected by canvas covering or other means
from any action which would wash it away before it had time to set

When concrete is likely to be exposed to great heat, as in fire-proof floors,
gypsum has been used as a matrix (see p. 249).

Bulk of Concrete produced. — ^The bulk of concrete obtained
from a mixture of proper proportions of cement, sand, and aggre-
gate, varies considerably according to the nature and proportions
of the materials and method of treatment ; but it will in general
be a little more than the cubic content of the aggregate before
mixing, as the other substances, if in proper proportion, should
nearly fit into and disappear in its voids.

The following examples show how the bulk of concrete produced varies
according to circumstances : —

Concrete of 1 Portland cement ^ to 6 shingle (or broken stone) and 2 sand.

27 cubic feet shingle or broken stone, \ ...

Q ™ J I Make one

9 „ sand, \. k* wi

4i „ Portland cement (3j bushels), ( ^ f

26 gaUons water, ) ^^^^^^

Concrete of 1 Portland cement to 6 broken brick and 2 sand.

30 cubic feet broken brick 2 " mesh, \ ...

10 sand, I "^*°"*

6 Portland cement, ( 'T''' ^

12 gaUone water, ) of concrete.

Concrete of 1 Portland cement to 7 Thames ballast ^ (consisting of
2 stone 1 sand).
33 cubic feet ballast, \ Make one

4} cubic feet Portland cement (3^ bushels), V cubic yard
30 gallons water, ) of concrete.

Concrete of 1 Portland cement to 12 gravel, used at Chatham dockyard.
32i cubic feet gravel (before shrinkage), \ Made one

24 n Portland cement, > cubic yard of

50 gallons water, j concrete in $U%.

1 Hmst

CONCRETE. 219

Cbncrele of 1 Portland cement to 8 stone and sand, used at
Cork Harbour works.
27 cubic feet stone broken to 1^-inch gauge, | Made one
9 „ sand, > cubic yard of

4^ », Portland cement, ) concrete in ntu.

In some concrete landings made with breeze from gasworks and
Portland cement

29 cubic feet breeze broken to } guage, ( ^^^.^ ya^ of

8 ^ Portland cement, ( concrete ui «hi.

Concrete used at Portland Breakwater Fort, stone used in two sizes and

mortar mixed separately.

14 cubic feet stones broken to 3i-inch guage, . «, ,

-. , ,f 6-«6 » \ Make one

5 " «nd, ^ " (cubic yard

« " "D J? J i. I of concrete

5 „ Portland cement, I . ^^

23^ gallons water, ^

After being rammed the concrete is compressed into about
nine-tenths of the volume it occupies when first mada

Selenitio Conorete. — Concrete may be made with selenitic cement mortar
as the matrix.

Portland cement is sometimes added in small quantities to the selenitic
cement.

" From a series of experiments made on behalf of the patentees, it appears
that a mixture of one part of Portland, four parts of selenitic cement, and
twenty-five parts of sand, was if anything superior to the same Portland
used with four parts of sand." ^

The patentees' directions for preparing the concrete are as follow : —

For Concrete, — 4 fbll-Bized pails of water ; 2 bushels of prepared selenitic lime ; 2
boBheU of dean sand.

These ingredients are to be mixed as before in the edge-nmner or tnb^ and then tuned
over two or three times on the ganging-floor, to ensure thorough mixing with 12 or 14
bushels of ballast When the tub \a used the sand wiU be first mixed dry with the ballast,
and the lime poured into it firom the tab and thoroughly mixed on the gauglng-floor.
An addition of one-sixth of best Portland cement will be found to improve the setting.

Expansion ov Concretb. — Concrete, when made with hot lime or
cement, swells to an extent amounting to from one-eighth to three-eighths
of an inch per foot of its linear dimensiona

This is owing to the imperfect slaking or cooling of the lime or cement

It is probable that when such expansion takes place there is a slight dis-
integration throughout the mass of concrete, and that its coherence is destroyed.

It has been ascertained by experiment that when lime or cement is care-
fully slaked the concrete practically does not expand at all, and concrete
should be so carefully prepared that no expansion will take place.

In masses of concrete, thin in proportion to their area — such as concrete

> Building News, 80th January 1874.

220 NOTES ON BUILDING CONSTRUCTION.

laid in iUu instead of paving — cracka are aore to occur unleas the ana is
divided into portiona by the introduction of laths so aa to break up the 8ur£EU»
by dry open joints at intervala.

The expansion which occurs in concrete made with hot lime or cement
has been taken advantage of in undarpvMwiig walls that have settled in parts ;
hot concrete forced tightly into openings made below the faulty portions,
expanda and separates, filling the opening, and lifting the superincumbent work
into its proper position.

Usee of Concrete.^ — Concrete has long been used for the foundationa of
structures of all kinds^ and for filling in the spandrils of arches or the hearting
and backs of walls.

Of late years, as the material has improved, it has been employed for many
other purposes, a few only of which can now be mentioned.

The walls of ordinary houses, as well as the more massive waUs of engineer-
ing siructures, are now frequently built in concrete, either in continuous
mass or in blocks.

Ooncrete is also used for walls in the form of slabs fitted into timber
quartering ; and in hollow blocks, something like those of terra cotta (see p.
126), filled in with inferior material

This material is also adapted for arches, for stairs, for flooring of different
kinds (see Part IL ; p. 37 IX And even for roofk

It can easily be made in slabs well fitted for paving (see p. 76), and by the
use of wooden moulds can readily be cast in the form of window sills, lintels,
drestdngs of all kinds, steps, etc, and can even be used for troughs and cisterns.

Drain pipes and segments of sewers are also sometimes made of concrete. It
was thought that the adds in sewers might act upon the cement^ but this has
been found practically not to be the case.

The different methods of building monolithic walla^ of making blocks^ and
of casting concrete into different forms, cannot here be entered upon.

Bdon is a name given by some writers to any concrete made with hydraulic
lime or cement

By others a distinction is made between the two, cimcreU being the name
given when the materials are all mixed together at once, and hAon when the
mortar is made separately.

Practically, however, l^e word '^ concrete " covers any form of artificial con-
glomerate, except artificial stones, which receive distinct names under various
patents (see p. 74).

Coignefs BAon AgglomM is a description of concrete made from a mixture
of Portland cement and lime, to which is added a large proportion of sand, no
gravel or broken stone being used.

The ingredients are moistened with a minimum quantity of water and
pugged in a special mill ; after which the mixture ia thrown into a framework
of the shape the concrete is intended to assume, and nunmed in layers about
6 inches deep.

This material has been laigdy used in making the Paris sewers^ and also
occasionally in this country.

Some experiments made to contrast Coignet's Bdton with Portland cement
concrete showed the former to be a weaker material than the other.i

T.P,I.C,E., vol. xxxii. Grant's Experiments.

CONCRETE.

22t

Rock Concrete Tubex with rebated end joints are made at the Bourne Valley Works
from the best Portland cement with carefnlly selected aggregates. These are filled into
iron moulds by machiaery under heavy percussive action. They are used chiefly as a sub-
stitute for brick sewers of firom 21 to 86 inches diameter, and are found superior to them in
every way.'

Experiments on the Rbsistancb of Conobete to Compression.

The following particnlars are extracted from the accounts of the weU-known
experiments by Mr. J. Qrant.'

Strenfi^h of Concrete. — Concrete blocks 1 2 inches cube, made of Port-
land cement, weighing 110*56 lbs. per bushel This cement (neat) broke
under a tensile stress of 427 lbs. per square inch after seven days' immersion
in water.

The blocks were made in layers 1 inch thick, and compressed by ramming,
or in a hydraulic press.

They were kept twelve months before being tested — ^half of them in air,
the others in water.

CBU8BED AT ToWS.

Composition of
Concrete.

Blocks kept in
Air.

Blocks kept in
Water.

Cement Ballast.

Tons.

1 to 1

107*

170*

1 ,. 2

149

160

1 ,. 8

113

115

1 „ 4

103

108

1 » 5

1 » 6

1 „ 7

1 » 8

1 ., 9

1 „ 10

* Exceptional.

These experiments showed that the blocks made with the larger proportions
of cement are the stronger, the strength being nearly in proportion to the quan-
tity of cement.

Further experiments showed that compressed blocks were "apparently

^ Manufacturers' Circular.
' Proceedings InsUttUe OivU Engineers, yoL xxzii Table 1, Appendix.

asa

NOTES ON BUILDING CONSTRUCTION

stronger than uncompressed blocks in lai^ger proportion than their difference
in density.*'

The relative strength of the concrete cnbes made with different kinds of
aggregate is shown in the following Table.

Several different proportions between the aggregate and cement were tried,
but the following relate to cubes containing eight parts of the aggregate to one
of cement.

Blocks 1 S inches cube (compressed), 8 Aggr^te to 1 Cement^

MnterUl for
Aggregate.

Crothsd

AT Tom.

Blocki In Air.

Blocks in Water.

Ballast .

Portland stone

110

126

Gravel .

Pottery .

118

SUg . . .

Flints .

108

117

Glass .

These experiments showed that the concrete of pottery or broken stone was
stronger than that of gravel, probably because in the latter case a good deal
of the cement is taken up in binding the partieles of sand together ; partly
because the gravel was wanting in angularity.

Tar Ck>norete is made of broken stones and tar.

About 1 2 gallons tar are used per cubic yard concrete.

If the tar is too thin, pitch is added to bring it to the proper consistency.

Adding 4 to 1 bushel of dried and pounded chalk, or dead lime, dried clay,
brick dust, or pounded cinders, etc., to every 1 2 gallons tar, tends to harden
the mass.

The materials should be heated, or, at all events, be made perfectly dry,
before admixture with the tar.'

Mineral tar or bitumen is better for the purpose than coal tar. The former
contains an oil which in coal tar is veiy volatile — escapes, and leaves the tar
brittle.

Iron Ck>norete is composed of cast-iron turnings, asphalte, bitumen, and
pitch.

Qas tar is sometimes substituted for the asphalte.

This material has been tried as a backing for armour plates iii iron for-
tifications.

Concrete consisting of 1 part iron borings to 34 of gravel (Ly bulk) was used with
success at the Stranraer Pier.'

Lead Concrete, made of broken bricks immersed in lead, has also been
used in iron forts.

1 M.P.LC,E. vol. xxxii. Table 5, Appendix. ' Hnnct > Stevenson On Ha/rboun,

MORTAR AND CONCRETE MIXING MACHINERY. 223

MORTAR-MIXIKG AND CONCEETE-MIXING
MACHINEEY.

Mortar-mixing Maohinee. — Mortar-Mill driven by Steam Power, — ^A full
description of the different machines in use for mixing mortar would be out
of place in these Notes, but a glance at one or two of the commonest forms
may be useful.

The mortar-mill in ordinary use on large works is shown in Fig. 103.

A cast-iron pan, P, about 6 or 7 feet in diameter is made to revolye by

■-pT^if^*''''

Fig. 103. Mortar-MUl,

machinery under a pair of heavy cast-iron rollers filled with concrete, and
weighing from 1 to 3 tons the pair.

The ingredients of the mortar are thrown into the pan while it is revplving ;
plates of iron, marked k in the figure, are fixed in suitable positions to
guide the material, so that it may all come under the rollers.

The pan has a loose bottom of cast iron, formed in segments, which can be
removed and replaced as they wear out

Machines of this description are generally driven by a small portable
engine, a 4-hor8e power engine being required for a 6-feet pan, and in pro-
portion for other sizes. The band from the engine is passed over the driving-
wheel D, and thus turns the spur-gearing which moves the pan.

These mills are made in different sizes, the pans varying in diameter from
5 to 10 feet ; the rollers from 2 feet 8 inches to 3 feet 6 inches.

A mill with a 7-feet pan will turn out about 1 J cubic yard of ordinary
lime and sand mortar per hour ; if^ however, the mortar is made with burnt

224

NOTES ON BUILDING CONSTRUCTION

ballast, or brick robbish, which requires grinding as well as mixing, only about
I cubic yard per hour will be turned out.

Fortdble Mortar-Mill. — For smaller works, and those which are scattered
— as, for instance, along a line of railway — a portable mortar-mill may be
used (see Fig. 104).

This machine somewhat resembles the one last described, but is mounted
on wheels, and carries a small three horse-power engine with it

The pan of this machine is sometimes 6 feet, sometimes 6 feet in diameter ;
the rollers 2 feet 8 inches or 3 feet in diameter.

Fig. 104. PortahU Mortar-Mill

Such a machine will mix enough mortar to keep ten or twelve bricklayers
at work.

Fig. 105. Horse Mortar-Mill,

Hone Mortar-Mill — A special mill, made by Messrs. Huxliam and Brown of
Exeter, to be worked by horse-power, is phown on Fig. 105.

MORTAR AND CONCRETE MIXING MACHINERY^ 225

Hani Mortar-MUL — For still smaller works hand mortar-mills may be
used of the forms shown in Fig. 106.

The ingredients of the mortar are poared into the hopper H, and find their
way into the cylinder C, which contains a series of blades fixed on a central
shaft, and made to revolve by means of the handle.

Fig. 106. Hand Mortar-Mill.

It is stated that by the aid of this machine one boy can keep eight men at
work, and that one man using it can keep twenty men at work.

Ck>norete-niixing Machines. — Concrete can be thoroughly well mixed by
hand in small quantities ; but when large quantities have to be dealt with,

it is difficult, without good
organisation, discipline, and
very close superintendence,
to ensure the thorough in-
corporation upon which the
quality of the material so
much depends.

In most cases the use of
machinery is a cheap as well
as an efficient way of mixing
large quantities.

Several arrangements have
been devised at different
times, suited to the peculiar
circumstances of particular
works, but it is proposed to
describe in these Notes only
two or three forms that are commonly used, and one or other of which
would be applicable in ordinary cases.

B. B. — UI Q

Fig. 107. Inclined Cylinder Concrete- Mixer.

226

NOTES ON BUILDING CONSTRUCTION

Inclined Cylinder Machine. — A simple form of concrete-mixer consists in
an inclined hollow iron cylinder mounted as shown in Fig. 107.

The ingredients of the concrete are filled in by the aid of a hopper throngh
a door at either end, and the cylinder is made to rotate, the band of the
engine being passed round the driving-wheel D.

The eccentric motion of the cylinder causes its contents to be rolled over
and over, thrown from side to side, and end to end of the cylinder, and thus
thoroughly mixed.

A modification of this machine was used at the Dover Harbour works.

This machine is made in four sizes, containing respectively J, i, f , and 1
cubic yard.

Fig. 107 is taken from the circular of a manufacturer, Mr. H. Sykes, of 66
Bankside, London.

Messent^s Patent Concrete-Mixer. — ^The following description of this machine
and the illustration Fig. 108, are taken from the circular of the makers, Messrs.
Stothert and Pitt of Bath.

** It consists of a closed box or chamber. A, revolving on an axle, and of such a
form as, when half filled with the materials for making concrete, to cause them
to be turned over sideways, as well as endways, four times in each revolution

Fig. X08, Mt^ejit's Ooncret^-Jifi^^

The dotted lines show diflbrent positions of the hopper, and also the mixer after a quarter revolntion.

of the chamber, so that, in from six to twelve revolutions (the number neces-
sary being varied according to the weight and nature of the materials), a more

MORTAR AND CONCRETE MIXING MACHINES 227

perfect mixture is effected than can poeaibly be produced by hand, or (except
in a much longer time) by any other machine."

'' The mixer is worked by hand or steam power, and is mounted on a trolly
of the ordinary railway gauge, and travelled by the same handles that are
used for turning it The travelling gear can, however, be disengaged when
the machine has to be taken a long distance by horse or locomotive.

^ For filling concrete into a trench, or the hearting of a pier, the machine is
supported over the opening, on two balks of timber ; a waggon containing the
gravel (and cement in bags) follows on the same line. The hopper H, shown
in the figure, suspended from a davit, is made to contain the proper measure
of gravel for a charge, whilst the bags contain the proper quantity of cement,
and a cistern near at hand (filled by a flexible hose) the proper quantity of
water. Two men standing on the waggon (the sides of which are generally
raised so that it contains about twice the quantity of an ordinary earth waggon)
are able to fill the hopper, in the time employed by four men to give the
mixer the requisite number of turns. For counting these, a tell-tale is pro-
vided, which indicates when the proper number of turns is completed ; the
mixer is then stopped with the door downwards. The door fastening is released,
and the charge of concrete falls into its place, the discharge being instantaneous.
The opening of the mixer is then turned upwards as in the figure, the door is
opened (through the dotted arc, as shown), the hopper, suspended from the
davit, is brought over the opening and at once discharged into it, and the
water is run in from the cistern at the same time. The door, which closes
water-tight, is then shut, and the mixing resumed, the hopper being mean-
time refilled for the next charge.

^ For making concrete blocks, the hand mixer is mounted on a light travel-
ling frame, capable of being moved from one mould to another, and the
materials filled into a large tray, holding from 10 to 15 tonR, are lifted on
to a raised portion of the travelling frame by the steam travelling crane
provided for lifting the concrete blocks.

^ With the hand-mixer above described, a gang of six men, with a boy for
attending to the water cistern, can make from 30 to 40 cubic yards of concrete
blocks, and a larger quantity of concrete in bulk in a trench in a day, of better
quality and at a cheaper rate than can be done by shovel mixing ; and when
tiie mixers are turned by steam, as at Aberdeen, etc, twice the above quantities
are made.

^' The mode of applying steam-power varies with the locality and the quan-
tity of work to be done.

" The great advantages of this mixer over others, are its portable shape and
self-contained arrangements, which enable it to be easily moved and used in
different parts of a work, dispensing with mixing platform and measures ; its
economy, and above all, the ra]Md and perfect amalgamation of materials
effected by it, producing, for a certainty, with moderate supervision, concrete
of superior strength and quality."

The machine just described was invented by Mi; Messent, the engineer
of the Tyne Pier works, Tynemouth.

It has been extensively used on the Tyne at the new breakwaterjB ; at the
harbour works, Aberdeen ; at the Surrey Commercial Docks, London ; for the
Sulina works at the mouth of the Danube ; for the Alexandria Dock works
at Kurrachee, etc. eta

Le Meturier^t Concrete Machine is shown in plan and elevation in Figs. 109^-^

228

NOTES ON BUILDING CONSTRUCTION.

no. These figures, and the folio wmg description of the machine, are ^m
the circular of the makers, Messra James Taylor and Co., Birkenhead.

'* The figures show the machine ready for working. It may be driven by an
ordinary 5 horse-power portable engine. AA are hoppers to contain each
about 2 cubic feet, into which the ballast is shovelled, or material from stone
crusher (if used) is delivered.

" These hoppers revolve as on a turn-table, and in course of revolution the
sand and cement are added.

'^ When a hopper arrives at B the door is opened, and its contents delivered
on to the elevator band, the arrangement of which speaks for itself.

'^ The supply of water is added as the materials are delivered from the ele-
vator into the revolving mixing cylinder at C.

^^ The mixer is a plain cylinder of wrought iron, with some dividing plates

miXiNO CYLlNOe^

Fig. 110. Plan.

in it, and is slightly inclined In travelling through it the concrete becomes
thoroughly mixed, and is delivered at D either into a shoot leading direct to
its destination, or into barrows for wheeling it away.

"When barrows are employed a short swivelling shoot is used, transferable
from one to the other, so tiiat the delivery is continuous.

** In case of interruption there is a clutch by which the mixer may be
thrown out of gear.

" It will be seen from the drawing that the whole apparatus is portable in
two parts; one the turn-table of hoppers, which is constructed on a bogie, and
the other the mixer and elevator, the latter being hinged to the frame at E,
so that the end F may be raised clear of the ground, and retained so by the
clip at O.

" For following up straight work the end F of elevator may be suspended
to the bogie under the hopper turn-table, and the whole moved as one
machine on baulks of timber.

" In addition to the advantages of simplicity, portability, and efficiency,
there is economy, as this machinery will easily produce 150 cubic yards of

MORTAR AND CONCRETE MIXING MACHINES. 229

very superior concrete at a cost of fourpence per yard, including engine
power.

^' It will tlius be noted that the moderate prime cost is very small in pro-
portion to the advantages.''

This machine has been extensively used in the new dock works at Birken-
head, and also at Hull.

The Carey-Laiham Conctete-Mixing Machine consists of an arrangement
of buckets like those of a dredger. These deliver the sand and ballast into

Fig. 110a.

a mixing cylinder, where they are met by a continuous supply of cement —
the whole are mixed first dry by revolving blocks until they reach the
middle of the cylinder, where the water is added through a perforated shaft,
and the mixing is completed with the materiaLs in a wet state.

The quantity of sand in proportion to the ballast is regulated by the
arrangement of the buckets, that of cement by an archimedean screw. The
machine thus measures as well as mixes the materials. It is made in various
sizes to deliver from 5 to 70 cubic yards per hour.

The fig. and part of the above description is from the makers' circular.

Ridley's Concrete-Mixer has a fixed inclined cylinder, with a central shaft
carrying longitudinal shelves, which lift the materials as the shaft revolves,
and mix them together.

SUme^fe Conerete^Mixer is an inclined open iron trough having a shaft
passing through its centre, with projecting blades which revolve and mix the
materials.

Americcm Concrete-Mixer, — ^This machine consists of a long box or shoot
divided verticaUy into compartments separated from one another by doors.

230 NOTES ON BUILDING CONSTRUCTION.

The ingredienta are placed in the uppennoet compartment, and the doors
being opened by long levers worked from the top of the shoot, the materials
&11 gradually- from one compartment to the other ontil they wdf^ the bottom
of the shoot thoroughly mixed.

The advantage of this arrangement is that the lower end of the shoot may
be placed at the point where the concrete is to be deposited, so that any
further handling of the concrete after mixing it is unnecessary.

This machine is not used in England, and therefore no illustration of it is
given.

ON THE ACTION OF FOREIGN CONSTITUENTS IN
LIMESTONES AND CEMENTS.

The following is an attempt to convey some information with regard to the
peculiarities connected with the burning, setting, etc, of limes, cements, and
mortars of different clas8e&

The subject is one almost too intricate for a treatise of such an elementary
character as this, in which much chemical knowledge cannot be presupposed.
Nevertheless it is touched upon, for without some idea of the principles
involved, all dealing with these important materials must be conducted
entirely by rule of thumb, or guess work.

A very slight acquaintance, however, with the changes that take place
during the different operations will enable the student more easily to remem-
ber, and more intelligently to avail himself of, the several characteristicB of
different limes and cements.

Pare or Fat LlmeB* — From the experiments made with limes of which
the composition \& accurately kuown, it is evident that the differences in their
slaking and setting properties are due to the nature and proportion of the
foreign constituents they contain. These are chiefly clay and magnesia.
Pure or fat limes contain none of these foreign constituents.

Calcination. — Pure carbonate of lime^ contains nothing but lime, car-
bonic acid, and water. When it is calcined the carbonic acid and water are
driven off by the heat, and pure quicklime remains.

Slaking. — Such a quicklime, when slaked, shows very violent action, great
heat is evolved, the mass is greatly swollen, and thoroughly disint^:rated.

Settinq. — The residue left after slaking is soluble in water, and has
within itself no constituent which will enable it to solidify, except to a very
slight extent It is therefore constantly soft when in a moist situation, and
will dissolve under water.

Such portions of it6 surface, however, as are exposed will imbibe carbonic
acid from the air, and will be reconverted into a crust of carbonate of lime,
as before described (p. 147)i

Mortar hadb froh Fat Lihe. — It has before been pointed out that the
addition of sand improves the setting of fat limes —

1. Because the porous structure caused by the presence of the sand enables
the carbonic acid of the air to penetrate farther, and thus to reconvert a
greater depth of the lime into carbonate.

^ Caleium earbonate.

LIMES (5* CEMENTS: ACTION OF CONSTITUENTS. 231

2. Because the particles of lime adhere more firmly to particles of sand
than to one another.

It has been stated also that pore silica in the shape of sand acts merely
mechanically^ and enters into no chemical combination with the lima

For all practical purposes this is true^ but experiments have shown that in
the course of several years some such action does take place to a very slight
degree.

In Petzholt's experiments (described by General Gilmore) he found —

1. That in mortar one hundred years old there was more soluble silica
than in the original lime.

2. That in mortar three hundred years old there was three times as much
soluble silica as in the mortar one himdred years old.

Now, it is a well-known chemical fact that silica does dissolve in alka-
line water, though with extreme slowness ; and in this case, no doubt, in the
course of a hundred years, a small portion of silica had been so dissolved,
and thus enabled to attack the lime.

On the other hand, General Scott mentions a case in which fat lime mortar
from a wall five years old was found to be set only on the exterior, and to be
in a friable pulpy state inside. Also another case of fieit lime mortar fifty
years old, which was so soft that it could be beaten up with a trowel

On the whole we may allow that in fiat lime mortar made with siliceous
sand a minute proportion of silicate is formed in the course of many years.
However, the time required to develop this action ifl so very long that the
fact is of no practical importance to the engineer or builder.

The hardening of lime does not depend merely upon the chemical effect of
the combinations which result in the formation of the carbonate, and to a
slight degree of the silicate.

It is also caused partly by the crystallisation of the hydrate of lima The
water in fresh mortar contains lime in solution. As llie mortar dries the
water evaporates, and leaves crystals of lime deposited upon the adjacent
particles of lime or sand. These crystals attach themselves firmly to the
particles, and will withstand a considerable tensile force.

In the same way, wherever the air can penetrate the carbonic acid con-
tained in it combines with the lime, and deposits crystals of carbonate of lime.

As before mentioned, the formation of ^cates in a fat lime mortar, if it
ever occurs, is so slow as to be of no practical value.

The uselessness of fat lime mortar for good work is shown by the following
extracts from some of the greatest authorities on the subject : —

Sir Charles Pasley says that '* chalk-lime mortar when wet is a pulp or
paste, and when dry it is little better than dust"

Vicat says, ^^ Their use should for ever be prohibited in works of any im-
portance."

General Freussart says, *' Where good hydraulic lime is to be had, no other
kind should be used for any purpose whatever.^

General Scott, in a paper on the subject, says ^ In the foregoing remarks
the worthlessness of pure or fat lime mortars for all constructions, and espe-
cially for such as involve the use of heavy masonry, or which will remain
damp for any length of time, has been insisted on ; and it has been explained
that their unfitness for thick and damp walls results from their not contain-
ing within themselves any property by which solidification can be brought
about."

232 NOTES ON BUILDING CONSTRUCTION

Hydranlio Iiimes and Cexnenta oontainixi^ Clay. — ^Witli a lime
containing clay the action is different from that of a pure lime, and not quite
8o simple.

Before attempting to explain this action it will clear the ground to make
a few remarks regarding the nature and composition of clay. Some of the
information now about to be given ha8> however, been anticipated in the
chapter on Bricks.

Clay is a compound of silica and alumina with water, chemically known
as *' hydrated silicate of alumina."

Silica and alumina alone, or in the preeenoe of each other, are infusible,
except at extremely high temperatures.

The presence of iron, however, causes the mixture (silica, alumina, and
iron) to fuse at a comparatively low temperature.

The same effect is produced to a still greater degree by potash, soda, and
chlorides of potassium and sodium.

Many clays naturally contain iron and also the alkalies above men-
tioned.

Lime is also an infusible substance. When burnt with clay the lime is
attacked by the alumina as well as by the silica of the clay, and both silicate
of lime and aluminate of lime are formed.

Calgimation. — ^When a limestone containing clay is burnt, the carbonic
acid from the carbonate of lime and the water from the clay are partially or
wholly driven off, and the ingredients are re-arranged in a new set of com-
pounds, the exact nature of which varies both with the original composition
of the stone, and with the degree to which it is burnt In general terms it
may be said that these compounds consist of quicklime mixed with silicate
of lime and aluminate of lime.

The silicate of lime is formed at a comparatively early stage in the burn-
ing, but it is only at the higher temperatures that the alumina and lime enter
into combination to form aluminate of lime.

When the burning has been carried to the proper point, these substances
are left in a condition in which they wiU combine with one another and with
a proportion of water (when made into a paste with the latter). During this
combination they form a new set of compounds, and eventually yield a hard
substance insoluble in water.

" When Portland cement is thoroughly well made, hardly any causticity
can be detected by the tests owing to the silicates which have formed
round the particles of quicklime.'' ^

The limit of temperature to which the burning should be carried varies for
different stones, and can only be found out experimentally.

The proportion of clay contained by the limestone, also the composition of
the clay, both affect the question of the degree of burning, and it will be well
to consider these points separately.

Proportion of Clay. — Effect in Sknet burnt at a moderate temperaiure, —
If the stone contain a large proportien of day and is burnt at a moderate
temperature, the silidc add in the clay attacks the lime, forming calcium
silicate. The alumina in the clay does not combine with the lime as long as
the temperature is moderata

If there be suffident clay present, the whole of the lime is so converted

1 Scott and Redgrave ; M.LC.JS., vol. Ixil p. 78.

LIMES ^ CEMENTS: ACTION OR CONSTITUENTS. 233

into fiilicate of lime, and the result ib a quick-setting cement like those of the
Roman dasa.

If there is only a rnnM amount of clay (that is, not sufficient to provide
the necessary amount of silica for the conversion of all the lime into silicate),
some of the lime will he left uncombined — %,e. in a quick state. This
uncombined lime will slake upon the addition of water.

The slaking action will, however, be sluggish as regards the mass of the
stone, for it is impeded by the presence of the clay.

Such a state of things exists in hydraulic limes ; in these the greater part
of the compound body has been converted into a silicate of lime ; but there,
is sufficient uncombined quicklime remaining to develop a slaking action.
This action, however, is in most cases feeble, and sometimes almost suppressed,
in consequence of the bulk of quicklime being so small in comparison with
that of the masa

Effect in Cejnenie burnt at a high temperaJbire. — ^When, however, the calcina-
tion is carried to a further stage, and the stone is burnt at a very high
temperature, not only is the carbonic acid driven off and some of the lime
converted into mlicate of lime, but a further combination takes place — ^the
alumina of the clay combines with the lime, forming aiuminate of lime, and
at the same time a further eUicaie of Ivme is formed. In addition to these
combinations, there are others of an intricate character which result in the
formation of double silicates of lime and alumina.

The aluminate of lime was found by M. Fr^my to set readily, when
powdered and wetted, without access of air, and also to be capable of cement-
ing together inert particles such as those of sand.

The double silicates of lime and alumina also have the property of setting
when hydrated — i,e. when mixed with as much water as they will take up.

When Portland cement is raised to the very high temperature necessary for
the proper burning of that material, the whole of the lime in the mixture
is converted into either silicate or aluminate — ^the entire mass is composed of
either one or the other of these compounds, and the result is great strength.

In an uvderbumt Portland cement, however, the aluminate is not formed,
some of the lime is left free ; the resulting cement is quick-setting, but weak
and apt to ^^blow,*' the uncombined particles of lime slaking either when
they are wetted, or after a considerable lapse of time.

Composition of Clay. — If the clay contains a large proportion of iron
and alumina (especially of iron) as compared with the silica, the calcination
must be at a comparatively low temperature, or the particles will be
fused.

In the Roman, Medina, and Atkinson's cements the quantity of iron and
alumina together nearly equals the silica. These are therefore burnt at a
low temperature.

When, however, the iron and alumina are in comparatively small propor-
tion compared with the silica, the mixture can be burnt at a very high
temperature without danger of fiisioiL This is the case with Portland cement.

The presence of potash or soda in conjunction with the alumina produces
the same effect as the presence of iron, but to a greater degree. If material
containing them be exposed to a high degree of calcination, it will fuse into
glass or slag.

The same relation holds good between the composition of the clay in
hydraulic limestones and the temperature at which they are burnt

234 NOTES ON BUILDING CONSTRUCTION

^ The larger the amount of the iron and alamina present, the more readily
will the lime and the clay, when the limestone is raised to a red heat, pass
successively from that condition in which the lime retains all its own proper
energy for water, to that in which the lime and day prefer, in partnership
as it were, to enter into combination with it in a gradual and quiet manner,
and to that in which the formation of the silicates is completed without the
intervention of water, and the resulting vitrified compounds show themselves
quite indifferent to it^ or are only affected by it after having been submitted
to its action for some time." ^

Effbots oausbd bt different Deorbbs of Oaloination. — ^It has already
been pointed out that the temperature at which the calcination is affected
greatly influences the nature of the hydraulic lime or cement produced.

As a general rule slight calcination produces the quickest-setting cements,
and prolonged calcination those which have the greatest strength.

Hydraulic Limeriones, — ^When a stone yielding hydraulic lime is subjected
to too high a temperature, the effect will be to partly fuse the particles^
which prevents them from absorbing water and slaking at once. They thus
form either a totally inert substance, or one which slakes after a lapse of
some considerable time^

Hydraulic limestones should therefore be burnt at a moderate temperature.

Cement Stones cantoMiing a emaU amount of Clay, — ^With a stone containing
the smallest quantity of clay required to form a cement, a slight calcination
will not carry the combination far enough to form a strong cement, and
the result will probably be either a hydraulic lime which slakes on the
addition of water and sets afterwards, or a mixture of quicklime and quick-
setting cement, the latter of which sets first, and is then broken up by the
slaking of the lime.

A high degree of calcination produces a cement of great strength ; the best
Portland cement is therefore produced by burning at a high temperature.

If, however, the calcination be carried to &r, the extreme heat will vitrify
the cement, and make it almost entirely inert

Cement Stones containing a large proportion of Clay, — Stones containing
much clay give, on the other hand, the best result with a slight caldnaHony
many indeed at a point short of the expulsion of the carbonic acid. A
higher degree of heat, sufficient to make the whole of the lime caustic,
sometimes gives a mixture of lime and cement like that produced by under-
burning a slow-setting cement, or it may give a slow-setting cement

The point of vitrification is reached much sooner in such a stone, especially
if the clay contain much soda, potash, or iron.

Roman cement and others of the same class are produced firom stones con-
taining a large proportion of clay and of iron, and are therefore burnt at a
low temperature.

The foregoing is only a general sketch of the results of the burning process,
to which there are many exceptions caused by peculiarities of composition.

Some stones yield — 1, a cement ; 2, an intermediate lime ; 3, a cement ;
4, an inert substance ; 5, a cement ; and 6, an inert substance again, in the order
given, and at progressive increasing degrees of calcination.

Slakinq. — This action also is influenced by the proportion of clay con-
tained in the lime.

^ General Scott ; RE, Corps Papers, voL xi.

UMES ^ CEMENTS: ACTION OF CONSTITUENTS. 235

If the barnt stone contains so small a proportion of clay that the silicates
and aluminates cannot combine with all the lime, a certain proportion of quick-
lime is left in an oncombined or free condition. This canses a modified slak-
ing action, more or less marked in proportion to the amount of free lime that
is present. <

In proportion as the amount of clay increases, and therefore in proportion
as the free quicklime diminishes, t,g, in hydraulic and eminently hydraulic
limes, this slaking action is more^and moro suppressed.

Finally, in the. case of cements, where the quantity of uncombined lime is
reduced to a mindmum, the slaking action entirely disappears, and the setting
process begins immediately upon tiie addition of water.

SiBTTiNa.— r-We see, then, that after the processes of burning and slaking
hydraulic limes containing clay, there is left within them a mixture of pure
lime and silicates, or of pure lime, silicates, and aluminates, ready to combine, if
a proper communication is provided to bring them into contact.

When the lime is placed under water, this is effected, for the water at once
commences to disseminate and in some degree to dissolve the particles of pure
lime ; these mingle with the silicates (many of which are also partially soluble),
and combine with them, one by one, by slow degrees, to form a new set of
hydrated silicates.

It is evident, then, that the water acts by enabling the particles of alumina
and silica to get at the particles of lime, and thus to attack them ; whereas
if the particles remained in a dry state, they would lie within a short distance
of one another, without ever combining.

A certain proportion of the water also plays another part, by itself combining
with the silicates and aluminates to form hydrated compounds, which set by
ciystallising, and pass into the solid state.

This explains why mortars of hydraulic limes should not be allowed to dry
too quickly. The dissemination and dissolution of the particles is thereby
stopped, and the setting process impeded.

A properly burnt lime, containing sufficient day, when saturated with
moisture after calcination, or when quite immersed, is therefore in a favour-
able condition for forming the hard and insoluble compound above mentioned ;
in fact its composition adapts it for setting under water.

Even in the case of fat limes the presence of moisture for a certain time is
useful, for it enables them more readily to absorb carbonic acid from the air.
In hot countries it is necessary that work in which they are used should
be kept moist for some time, otherwise the mortar will be in a granular
crumbly state, it will not readily absorb carbonic acid, and the lime will not
enter the crystalline condition which is essential for proper setting.

Frcfp(yriiim of Clay.-^To give a perfect result there must be sufficient day
to combine with aUthe lime in the mixture ; otherwise some of the lime,
having nothing to xombine with, remains pure and soluble, and reduces the
average setting property of the whole.

This occurs in those hydraulic limes which contain from 8 to 15 per cent
of silica. When all this silica haa entered into combination, there is still
some quicklime left (more or less in inverse proportion to the amoimt of clay).
This remaining lime develops the slaking action as before explained, and im-
pedes the action of setting.

On tiie other hand,- there must not be too much day, or, after the lime is
turned into silicate, tiiere will be a surplus of free clay left — having in itsdf

236

NOTES ON BUILDING CONSTRUCTION.

no hardening property, and which will decrease the strength of the resulting
cement

The proportions required to produce a cement vary, however, within toler-
ably wide limits (22 to 36 per cent in the raw material); as a general rule,
the quicker-setting cements are produced from stones containing most clay.

Composition of Clay, — Those days which contain a large proportion of iron
and alumina cause the lime in which they occur to set with greater rapidity
than do ordinary clays. ^' Clays deficient in iron and alumina, and in which
the silica is present in the shape of finely divided quartos, are apt to form in-
soluble silicates of lime at a high temperature owing to the want of suitable
bases to combine with the silica, which also renders them unfit for making
Portland cement Such clays also when calcined at too low a temperature
yield hardly any soluble silicates, form therefore no protection to, and seem
in no way to prevent the hydration of the lime, and produce a material devoid
of hydraulic properties."^

The foUovdng Tablb sums up approximately, and in a concise form, the

Proportion of

CUy before

buming.

Gomposition of
CUy.

Degree of

Setting
Properties.

Ezunples of the

Clau.

0 to 8 p. c

...

Very low.

Absorb car-
bonic acid from
air.

Fat limes.

8 to 18 p. c.

Various. Those
with most iron
and alumina
set most quickly

Moderate.

Moderately
quick settmg.
No great
strength.

Lias and other
hydraulic limes

20 to 80 p. c.

Iron and alu-
mina. Silicic
acid.

Very high.

Sets slowly.
Very strong.

Portland
cement

Do.

Bxtreme.

Become inert

Do. over-burnt

28 to 55 p. c.

Iron and alu-
mina. Silicic
acid.

Low.

Sets very
quickly.
^0 great
strength.

Roman cement
and others of
that class (see
p 158).

Do.

High.

Become inert

Do. over-burnt

mutual relations of the proportion of clay, composition of clay, degree of
calcination, and setting properties in different classes of limes and cements.
We have considered the eflfect of clay in conferring hydraulic properties

1 Scott and Redgrave; M.LCE,, vol. Ixii. p. 80.

LIMES ^ CEMENTS: ACTION OF CONSTITUENTS 237

upon limes, which it does by presenting silica in a state fit for combination,
but clay is not the only substance which has this e£fect

PozznoLANA, etc. — Ab before noticed, the presence of several other forms
of soluble silica and pozzuolana will also answer the purpose in a greater or
less degree.

The general nature of the reactions that take place in the setting of limes
containing these substances are much the same, and produce effects similar
to those already described.

It has been recommended that mortar made with substances of this kind
should be allowed to remain in paste for some time before use. The reason
for this is that in consequence of the clay and lime not having been burnt
together, none of the silicates have been formed, as they are in ordinary
hydraulic limes burnt in the kiln. Every facility should therefore be given
to the silica to attack the lime through the intervention of the water (see
p. 221), and thus to form silicates, before the mortar is used.

Carbonate of MAom&siA. — Carbonate of magnesia is a substance very
similar to carbonate of lime ; it loses its carbonic acid in burning, combines
with silica, etc., and behaves generally in the same way, with one important
exception, viz. that the calcined magnesia will not slake on the addition of
water, but combines with it graduaUy and quietly, and sets to some extent in
doing so. When silica is present it combines with the magnesia, and with
the lime, forming a double silicate of lime and magnesia, which is of greater
strength than either silicate of lime or silicate of magnesia separately.

Besides this, the magnesia and lime, even without the intervention of the
silica^ will combine and harden under water.

The hydraulic mortar that is produced from magnesian limestones and
dolomites (see p. 59) owes its properties to the different combinations above
mentioned.

Several failures that have recently occurred in Portland cement after use
have been attributed to an excess of magnesia in the cement

As this has caused considerable mistrust of the material, the following
remarks on the subject by Mr. Dent will be valuable : —

« When the lime \b aasociated with magnesia, the magnesia should be regarded as to
some extent taking the place of the lime, and the quantity of the lime should be pro-
portionately diminished.

'* A well prepared Portland cement, such as is made on the Thames or the Medway,
should not contain any appreciable quantity of magnesia, say about 1 per cent. Although
any laige proportion of magnesia in Portland cement cannot be considered desirable,
yet it must not be forgotten that magnesia is capable of fonning hydrates of great
permanence and hardness, and that some very good hydraulic cements contain as much
as 8 per cent of magnesia, such, for example, as the well known Bosendale cement of the
United States of America.

" There can be little doubt but that the assertions that have been frequently made as
regards the tendency of cements containing magnesia to disintegrate, may sometimes
have arisen from overlooking the ISftct that the results observed might be due to excess
of basic constituents in the cement In a recent statement put forward as to the
injurious action of magnesia, the cement referred to contained 72 per cent of lime and
magnesia, and it could scarcely be regarded as extraordinary that such a cement should
prove a complete failure since it is well known that such a proportion as 72 per cent of
lime would render Portland cement so unsafe as to cause it to be condemned.** ^

It should be mentioned, moreover, that in the cases of failure which have occurred the
magnesia has been found by analysis after the cement has been for some time under sea-

* Dent's Camior Lectures, 1887.

238 NOTES ON BUILDING CONSTRUCTION

water, and that it may not have been In the cement when originally deposited, but
introdnced by the chemical action of the sea-water upon the nncombined lime existing
in the cement If this is so, the best safeguard against the evil would be extreme care to
avoid overlimed cements, and to cool and serate the cements thoroaghly before nse
(see p. 176).
With regard to the action of sea- water upon cement, Mr. Dent says : —
" From a recent report of Professor Brazier on the cause of the failure of some cement
used in the construction of a graving dock in Aberdeen harbour, it would appear that the
reaction which takes place between the magnesium chloride contained in sea- water and
lime may, under certain conditions, be sufficient to cause the disintegration of some
descriptions of Portland cement, the lime in the cement being dissolved."

SaLPHATE& — Lime cun also be made to unite with water by the presence
of a small quantity of any sulphates, and the employment of Uiis property
by a suitable process will considerably increase its setting power.

The setting of lime thus treated is essentially distinct from that produced
by combination with silica, inasmuch as it depends on combination with
water only (which becomes solid) and the resulting substance (which is simply
hydrate of lime) is entirely soluble in water, though with more difficulty
than the ordinary slake lime, owing to its superior density.

Sulphate of magnesia ^ (commonly known as Epsom salts) is very soluble
in water.

EFFLOEESCENCE ON" WALLS.

The surfaces of walls are often covered with an efflorescence of an
unsightly character.

This efflorescence is formed by a process known as saltpetreing. It shows
itself chiefly in the case of newly built walls, but also in those parts of older
walls which are exposed to damp. It varies somewhat in appearance and also
in chemical composition, and is most apparent in dry weather.

Appearance, — It is generally white in colour and crystalline in structure ;
the crystals presenting the appearance of very fine fibres or needles, or
looking like a thin coating of snow or white sugar.

Composition. — Chemical analysis has shown that these crystals vary con-
siderably in composition. They often consist of sulphate of magnesia, also
of sulphate of lime ; of carbonate, sulphate, or nitrate of soda ; of chlorides
of soda and potash, and carbonate of potash.

Causes. — Efflorescence is attributable sometimes to the bricks or stones of
a wall, sometimes to the mortar. Dampness is favourable to its formation.
Cold as low as the freezing point stops it

In bricks burnt with coal fires, or made from clay containing iron pyrites
(bisulphide of iron), the sulphur from the fuel converts the lime or magnesia
in the clay into sulphates. When the bricks are wet these dissolve ; when dry,
they evaporate, leaving crystals on the surface. The sulphate of magnesia is
generaUy found in much greater quantity than the sulphate of lime, as it is
far more soluble in water.

Many limestones contain magnesia (see p. 149) ; these are acted upon during
calcination by the sulphur in the fuel ; sulphates are formed, which find their
way into the mortar and produce effects similar to those above mentioned.

Again, the sulphur acids evolved from ordinary house fires attack the

1 Magnesium sulphate.

EFFLORESCENCE ON WALLS. 239

magnesia and lime in the mortar joints of the chimney ; these dissolye and
evaporate on the 8ai£ace.

The formation of chlorides is nearly snre to take place if sea sand or sea
water be used, or in bricks made from day which has been covered by salt
vrater.

In some sitoations the formation of the nitrates has been attributed to the
absorption of ammonia from the air.

The potassium and sodium salts are supposed in many cases to be derived
partly from the limestone used for the mortar, and partly from the fuel
employed in burning the lime.

DUadvantaga. — ^Not only does the efflorescence present a disagreeable
appearance, but it causes damp patches on the surface of the wall, it will
eat through any coat of paint that has been applied after the efflorescence
has once commenced, and will even detach small fragments of the materials
composing the walL

Remediei, — Prevention in this case is better than any attempt at cure.

The best plan is to avoid all the materials above mentioned as likely to
give rise to efflorescence.

In the case of bricks, day containing pyrites or much magnesia should
not be used ; special bricks may be burnt with coke or wood.

As regards. mortar, the use of limestones containing magnesia to any great
extent may generally be avoided.

If, however, it does occur in spite of all precautions, the following remedies
may be tried : —

In the case of ashlar-work : — 1. The suxfiEu^e may be covered with a wash
of powdered stone, sand, and water, which is afterwards cleaned off.

This fills up the pores of the stone, and temporarily stops the efflorescence.
When the wash is removed the saltpetreing will recommence, but in a weaker
degree than before.^

2. Painting the surface is sometimes efficadous if it is done before the
efflorescence commencea

The mortar before use may be treated to prevent it from causing efflores>
cence —

1. By mixing with it any animal fatty matter. General Gillmore recom-
mends 8 to 12 lbs. of fatty matter, 100 Ibe. quicklime, and 300 cement
powder.

2. Potash salts may be rendered harmless by adding hydrofluoeilidc add.*

ANALYSIS OP LIMES AND CEMENTS.

The strictly chemical view of this subject is beyond the scope of these
Notes ; but in order to render them more complete, the following directions*
for testing and analysing a lime or cement are added, in the hope that th^
may be useful to such readers as may have the chemical knowledge neces-
sary to understand them and put them into practice.

Chemioal Test. — '^ A useful chemical test for the amount of hydraulidty
is made as follows : — A small portion of the lime or cement (about as much as

^ Bu'nell On Limet and Cements.

* OiUmore On Lifnet and Cements.

* From Notes an the ChefmiMtry of Building Materials^ by Captam Abney, R.E.,

p.R.a

240 NOTES ON BUILDING CONSTRUCTION

can be piled upon a sixpenny piece) is placed in a test-tube, and suffident
H^O added to cover it, and finally about 1^ drachm of HCL. It is then
warmed over a gas jet or spirit lamp. If much soluble silicic acid be present
it will form a thick jelly, whilst if poor or if it have become inert, it will be
only partially gelatinis^, and perhaps remain liquid. Taking a cement
which is known to be rich in silica, and comparing it with the one which is
to be tested, a very fair estimation of its hydraulicity can be made. Limes
which contain much magnesia are apt to part with their silica in an amorpboas
powdery form, yielding only a slightly gelatinous appearance. This should
be noted, and a sample not rejected if the ^edpitaUd silica be sufficiently
large in amount If the cement or lime effervesce wry strongly on the appli-
cation of the HCl, there is a strong suspicion that it has absorbed too much
carbonic add, and has thereby weakened its setting and lasting properties."

Chemical Analysis. — ^^'The chemical analysis of a lime or cement is
one which is easily performed, and requires but little apparatus.

'' About 30 grains of the cement should be powdered in a mortar and placed
in a small porcelain dish, and about 2 drachms of H,0 and the same quantity
of HCl added to it, and the dish placed on the sand bath ; a brisk effer-
vescence being noted, shows the presence of carbonic acid. The powder, after
stirring with a glass rod, will begin to dissolve, and after five minutes' boiling
a residue will be left which is plainly unattackable by the acid. This must
be filtered out, and noted as irisoluble reMue, consisting most probably of
sand. After filtering and washing out the dish the liquid is evaporat^ to
dryness. When the dish is sufficiently cool, a little strong HCl is poured on
the mass, and then hot water, and the whole again boiled. It will now be
found that a white residue Ib left undissolved. This is silicie acidy which
must, be filtered out

** A small portion of the liquid is poured into a test-tube, and a little H^
added. Should there be no pp*, the absence of Qroup IL may be inferred.^
Another portion is treated with NH4CI+NH4HO ; this will be found to yield,
in almost all cases, a reddish gelatinous pp\ Such being the case, the same
re-agents must be added to the whole remaining portion of the liquid which
should be transferred to a glass beaker. The pp^ must next be filtered out,
and well washed with warm H,0, and the filtrate (a) left for further
examination.

*' The pp^ being dissolved off the filter by passing a few drops of strong HCl
through it, and the solution being diluted with a little water, EHO is added
in excess. A red gelatinous pp^ at once becomes apparent This is filtered
out and tested for iron by (NH4)jS. Blackening shows the presence of iron.
The filtered solution is now treated with NH^Cl, and should a white gelati-
nous pp^ be formed after standing, alumina is present Solution (a) is next
examined, — a small portion of it may be tested with ammonium hydro-
sulphate, usually without any result : but should a pp^ be produced, it will
indicate Mn or Zn, or both ; the remaining portion is treated with (NH4),C0t ;
a dense white pp^ will be at once formed, this must be filtered out, and the
solution (13) put away for subsequent examination. The pp^ is then treated

* Group II. consists of metals, in solutions of which HCl gives no precipitate, but
Ha + HjS give precipitates— the metals are Hg. Cu. Bi. Cd. As. Sb. Sn. The metals
of this group are but seldom met with in lines or cements ; should any be present,
recourse must be had to the tables.

ANALYSES OF CEMENTS.

241

with a very little dilate HCl, which dissolves it To a portion of its solution
a little CSaSO^ is added ; a pp^ on boiling indicates the presence of Ba or Sr,
while a pp* caused by (NHJiC/)4+NH4H0 — ^in a fresh portion of the solution
— shows the presence of lime,

" Solution \p) is next treated with a few drops of NH^HO and Na^HPO^, and
left standing an hour ; a pp^ being then visible gives evidence of magnesia,

** About 100 grains of the cement should be boiled in water to extract any
soluble salts, and the filtered solution evaporated down to small bulk ; none
of the soluble salts of the metals of groups ii., iii., and iv. would be likely to
occur in a lime or cement, and consequently the metals of these groups need
not be looked for. A small quantity of lime will, however, be taken up by
the water. A funall quantity of ammonia, and ammonium oxalate, and an
excess of ammonia, must be added to the solution to precipitate it, after
which the filtered solution should be evaporated to dryness. The residue
should then be strongly ignited to drive off the excess of ammonium oxalate,
and should there still be a residue it will probably consist of alkaline chlorides
present in the cement To confirm this result, redissolve the residue in
water and test a portion for chlorine with silver nitrate, which should pro-
duce a white curdy precipitate, insoluble in boiling nitric acid.

" Finally, if any soluble sulphate be present it will have been taken up by the
HjO ; therefore, a fresh portion of the solution should be tested with barium
chloride, which will produce a white precipitate if any sulphuric acid be present.

*' A further search for acids is unnecessary, no one of any importance or of
any value could be found, as any such would have been traced in the ex-
amination for metals. The qualitative examination of a lime or cement
usually gives the following as present : —

'^ Carbonic Acid. Alumina.

Insoluble Residue. Lime
Silicic Acid. Magnesia.

Ferric Oxide.

Alkalies.
Chlorine.
Sulphuric Acid (trace).'

The following Table gives analyses of a few cements (made by a friend of the writer^s)
taken from actual specimens of fair quality met with in practice : —

POBTLAKD CkMEMT.

BOMAN CeMEST.

MCDIHA

Heavy

slow-

setting.

Light
quick-
setting.!

Average

good
cement

Specimen 1.

Specimen 8.

Clay unacted upon »

•3

4-4

Traces.

7-9

5-8

Soluble SUica .

22-8

20-6

22-0

160

17-2

190

Oxide of Iron» .
Soluble Alumina

8-2
7-2

8-5

10-9

8-5

8-0

. 22-2

1 21-5

• 16-6

Sulphuric Acid

1-4

2-4

1-0

Lime

63 0

500

62-0

41-2

46-1

49-8

Magneaia .

•6

•2

1-0

1-6

Alkalies .

1-8

1-6

1-5

Carbonic Acid .

...

6-0

Traces.

' 9*2

[ 67

■ 9-8

Moisture and loss

1-5

1-0

1 This cement evidently oontaina too little lim

' Ferric 0:

dda

B. C. — III

242 NOTES ON BUILDING CONSTRUCTION.

PLASTEES, Exa

Materials used by PlaBterers. — ^A great variety of compori'
tions are used by plasterers, some of which will be describecL

Among the most important of these are cements of varions
kinds. Many of these are used also for building purposes, and
have ahready been considered. Others are very deficient in strength
and weathering properties, and axe suitable only for covering the
surfaces of internal walls. These wiU now be described.

In addition to these there are several mixtures made up of
lime, sand, and other materials, distinguished by various names,
and also used for covering surfaces of walls.

The description of these was, to a slight extent, necessarily
anticipated in Part IL, but will here be repeated.

Materials used by the plasterer in common with other trades,
such as size, laths, etc., will be described in Chapter IX.

Cements, etc, used as Plasters. — Gtpsuic — ^The bans of most plasten
Ib a native hydrated sulphate of lime occurring as a soft stone, usually of a
more or less crystalline texture, and varying in colour from white through
shades of brown and grey to black. White and light shades are the com-
monest in England, where it is found in Derbyshire, Nottinghamshire,
Cheshire, and Westmoreland. It is also found in great abundance in the
neighbourhood of Paris.

The very fine-grained pure white varieties are termed '' alabaster/' or, when
transparent, '^ selenites.**

The raw stone is prepared either by simple calcination, or by calcination
and combination with various salts of the alkalies.

Plaster of Paris is produced by the gentle calcination of gypsum to a
point short of the expulsion of the whole of the moisture. The raw stone is
sometimes ground in the first instance and calcined in iron vessels.

Paste made from it sets in a few minutes, and attains its full strength in
an hour or two.

At the time of setting it expands in volume, which makes it valuable for
filling up holes and other defects in ordinary work.

It is also added to various compositions in order to make them haiden
more rapidly.

Plaster of Paris is used for making ornaments for ceilings, eta, which axe
cast by forcing it, in a pasty state, into wax or gutta-percha moulds.

Where it is plentiful, as in the neighbourhood of Paris, it is used in aU
parts of house-construction where it will be free from exposure to the
weather, for which exposure it is unfit, as it is very soluble in water.

There are three qualities of plaster of Paris in the market — ^the "wper/In^,"
^^Jme" and *^ coarse;" the two former being whiter and smoother in grain
than the last The superfine is sold in casks, and the other qualities in casks
or sacks. Both casks and sacks contain 2 cwt

Portland Cbment is much used by plasterers for external rendering (see
page 404, Part IL)

PLASTERS, ETC.

243

As before mentioned, the lighter varieties of Portland cement, weighing
from 95 to 105 lbs. per bushel, are those best adapted for this purpose.
They set more quickly, and thus save expense not only in their first cost, but
also in the labour that is bestowed upon them by the plasterer.

Rohan Cbmbnt, and others of the same class, described at page 157, are
used for external rendering, as mentioned at page 405, Part 11.

Eksnb'b CxMisirr is a plaster produced by recalcining plaster of Paris after
soaking it in a saturated solution of aluuL

One pound of alum is dissolved in a gallon of water, and in this solution
are soaked 84 lbs. calcined plaster of Paris in small lumps ; these lumps are
exposed eight days to the air, and then recalcined at a dull red heat.

The addition of half-Hrpound of copperas gives the cement a cream colour,
and is said to make it better capable of resisting the action of the weather.

This cement is harder than the other varieties made from plaster of Paris,
and is consequently used for floors, skirtings, columns, pilasters, etc. ; it is
also frequently painted to imitate marble.

Keene's cement is made in two qualities, the coarse and the superfine :
the former is white, and capable of receiving a high polish ; the latter is not
so white, or able to take so good a polish, but sets hard. The superfine
quality is sold in casks containing 3^ bushels, and the coarse in casks of the
same size, and in sacks containing 3 bushela

Pabian Ckmbnt, sometimes called Keating*s Cement, is said to be produced
by mixing calcined and powdered gypeum with a strong solution of borax,
then recalcining, grinding, and mixing with a solution of alum.

There are two qualities of Parian cement in the market — the '* superfine "
and the " eoaree,*^ They are sold in casks and sacks of the same sizes as those
used for Keene's cement

** Parian is said to work freer than either Keene's or Martin's cement, and
is therefore preferable for large surfaces^ which have to be hand-floated before
trowelling ; but the two latter cements are fatter, and produce sharper arrises
and mouldings." ^

As Keene's and Parian cement are not nsed for mortar, their tensile strength is of no
praotioal importance. When allowed to set In air their strength was found by Mr. Grant
to be as follows per sectional area of 2} inches : —

Keene.

PotUb.

Seven days .
Fourteen days
Three months

Iba.
5460

586*8

720-5

Ite.
642-3

«71-2

853-7

Mabtin's OxMiSNT is made in a similar way to Parian—carbonate of potash
(pearl-ash) being used instead of borax, and hydrochloric add being some-
times added.

It is made in three diiferent qualities — coarse, fims, and superfine — the coarser
kinds being of a reddish-white colour, and the finer pure white. It is said
to cover more surface in proportion to its bulk than any other similar
material.^

^ Seddon.

" Papworth.

244 NOTES ON BUILDING CONSTRUCTION

Robinson's Ceuent is made from alabaster (sulphate of lime) found in the
Inglewood Forest near Carlisle. It has somewhat similar properties to
Keene's and Parian cements, and can be used for similar purposes — ^for
decorations, plastering, etc.

Metallic Cement " has a metallic lustre, is suitable for outside work,
and is intended to dispense with colouring or painting, but is not much
used.*'!

One variety is made by mixing ground slag from copper-smelting works
with ordinary cement stone.

PortUind. Cement Sttuxo is a mixture of Portland cement and chalk. It is of a
good colour and close texture ; weaker than Portland cement, but not so
liable to crack.

Lieu Cement is produced from Lias shales containing a large proportion of
soluble silica. It resembles Lias Ume in appearance ; sets in eight or ten
minutes, and is used for lining water-tanks, or other piirposes for which a
light quick-setting cement ia required.

John's Stucco Cement is used as a wash or paint, and when mixed with
three parts of sand as a stucco. It is said to adhere well, to be hard when
set and impervious to wet, and to be fit for mouldings or castinga^'

Uses. — The Keene's, Parian, and similar " cements " or plasters
are largely used for the best class of internal plastering, and, as
they set very quickly, they can be painted within a few hours,
which is a great advantage.

They are capable of receiving a very high polish, to obtain
which the surface is rubbed down with gritstones of varioaa
degrees of coarseness ; afterwards stopped or paid over with semi-
liquid neat cement which fills up the pores ; rubbed again with
snake-stone, and finished with putty powder.

The plasters should not be used in situations much exposed to
the weather, on account of their solubility. This consideration,
combined with their cost, and the moderate strength they attain
even under favourable circumstances, makes them unsuitable for
most engineering works.

Mastics are a species of cements consisting of brick, burnt clay, or lime-
stone powdered, mixed with oil and litharge, or some other drier.

In former years they were much used for covering external mouldings, etc
They were applied in a thin coat with great care, and looked well, but
required painting periodically to compensate for the evaporation of the oiL

Several varieties were used on the Continent, but that best known in Eng-
land was called HamelirCs Mastic

This material, however, was expensive, and has been superseded by Port-
land cement

The MatexialB used in Ordinary Plastering are laid on in
successive coats, which diflfer from one another in composition.
In all of them the lime used should be most thoroughly slaked,
^ Seddon. * Papworth.

PLASTERS, ETC, 245

or it will throw out blisters after being spread. For this reason
the "stuff" is generally made long before it is required, and left
for weeks to cool.

Pure or fat limes are generally used for the sake of economy,
and for safety. Hydraulic limes would require special attention
to prevent them from blowing. Moreover, the surface of plaster
made with fat lime is more absorbent, and less liable to encourage
condensation, than that of plaster made with hydraulic lime.

Salt water and sea-sand should not be used, as the salts they
contain would cause permanent dampness and efflorescence.

Hair. — The hair used by the plasterer in order to make his
'' coarse stuff" hang together is obtained from the tanner's yard.

It should be long, sound, free from grease and dirt, thoroughly
separated, beaten up, or switched with a lath, so as to separate the
hairs, and dried.

It is classed a<x;ording to quality as Nos. 1, 2, and 3, the last
being the best. A bushel weighs from 14 to 15 lbs.

White hair is selected for some work, but as it should all be
thoroughly covered by the coats subsequent to that in which it
occurs, its colour is not of importance.

Coarse Stuff is a rough mortar containing 1 or 1^ part of
sand to 1 of slaked lime by measure.

This is thoroughly mixed with long sound ox hair (free from
grease or dirt, and well switched, or immersed in water to sepa-
rate the hairs) in the proportion of 1 lb. hair to 2 cubic feet of
the stuff for the best work, and 1 to 3 for ordinary work.

The sand is generally heaped round in a circular dish form ;
the lime, previously mixed with water to a creamy consistence,
is poured into the middla The hair is then added, and well
worked in throughout the mass with a rake, and the mixture is
left for several weeks to " cool," ijt. to become thoroughly slaked.

" If mixed in a mill the hair should only be put in at the last
moment, or it will get broken and torn into short pieces.

'' If there is sufficient hair in coarse stuff for ceilings, it should,
when taken up on a slate or trowel, hang down from the edges
without dropping off.

" For walls the hair may be rather less than in top stuff for
ceilings."^

Fine Stuff is pure lime slaked to paste with a small quantity
of water, and afterwards diluted with water till it is of the coii-

^ Beddon.

246 NOTES ON BUILDING CONSTRUCTION.

aistence of cream. It is then allowed to settle ; the water rising
to the top is allowed to run off, and that in the mass to evapo-
rate until the whole has become thick enough for use. For some
purposes a small quantity of hair is added.

Plasterer's Putty is pure lime dissolved in wiater, and then
run through a fine sieve. It is very similar to fine stuff, but pre-
pared in a more careful manner, and is always used without hair.

Gauged Stuff, alao called " PiUty and Plaster" contains from
J to ^ plasterer's putty, the remainder being plaster of Paris.

The last-named ingredient causes the mixture to set very
rapidly, and it must be mixed in small quantities, not more being
prepared at a time than can be used in half an hour.

The proportion of plaster used depends upon the nature and
position of the work, the time available for setting, the state of the
weather, etc., more being required in proportion as the weather is
damp. An excess of plaster causes the coating to crack.

It is used for finishing walls and for cornices. In the latter
the putty and plaster should be in equal proportions.

Selenitic Flatter is made with selenitised lime, otherwise known ai
selenitic cement

This material has been described at page 179.

The method of mixing the material for the first coat of plastering on
brickwork is exactly similar to the process as carried out for mixing mortar.

This process has been described at pages 206, 207 ; and also at page 407,
Part XL, and need not therefore be repeated.

For plastering on lath work and other coats the following directions of the
patentees should be rigidly followed.

They have already been given in Part XL, but are here repeated to make
these Notes more complete in themselves.

«^or Plastering on Lath fVork. — To the same quantitiesof water and prepared
lime, as given, add only 6 or 8 bushels of clean sharp sand and 2 hods of
well-haired lime putty ; the hair being previously well hooked into the lime
putty. When the mill is used, the haired putty should only be ground suffi-
ciently to ensure mixing. XiOnger grinding destroys the hair.

" Lime putty should be run a short time before being used, to guard against
blisters, which will sometimes occur.

^ N,B. — This nuxture will be found to answer equally well for ceilings as for
partitions Xf the sand is very sharp, use only 6 bushels of sand for covering
the lath, and when sufficiently set, follow with 8 bushels of sand for floating
(or straightening).

" Settiiig Coat and TroweUsd Stucco. — ^For common setting (or finishing coat
of plastering), the ordinary practice of using chalk lime putty and washed
sand is recommended. But if a hard selenitic face is required, care must be
taken that the prepared selenitic lime be first passed through a 24 by 24
mesh sieve, to avoid the possibility of blistering, and used in the folloM-ing
proportions : — 4 pails of water ; 2 bushels of prepared selenitic lime (pre-

PLASTERS, ETC. 247

viously sifted throngh a 24 by 24 mesh sieve) ; 2 hods of chalk lime putty ;
3 bushels of fine washed sand.

'* This should be treated as trowelled stucco ; first well hand-floating the
surface, and then well trowelling. A very hard su2face is then produced.

•* Selenitic Clay Finieh. — 6 pails of water ; 1 bushel of prepared selenitic
lime ; 3 bushels of prepared selenitic clay ; 2 bushels of fine washed sand ; 1
hod of chalk lime putty.

''This mixture, well hand-floated to a fair face, and then well trowelled, will
produce a finished surface equal to Parian or Eeene's cement, and will be
found suitable for hospital walls, public schools, etc Being non-absorbent,
it is readily washed.

''The use of ground selenitic day improves the mortar, and renders it more
hydraulic

" When the selenitic clay is used, 2 bushels may be added to 1 bushel of
prepared selenitic lime, the proportion of sand, ballast, etc, being the same as
for prepared selenitic lime. Tlie use of selenitic clay effects a considerable
saving, as it is much cheaper than lime.

*^Fcr Outiide PUutering uf«e 6 or 8 bushels only of clean sand, and for finish-
ing rovjgh dveco face use 4 or 5 bushels only of fine washed sand, to the pro-
portions of lime and water given."

Bough Cast is composed of washed gravel mixed with hot
hydraulic lime and water. It is applied in a semi-fluid state, as
described at page 409, Part II.

Stuooo. — This term is very loosely applied to various substances which
differ considerably from one another. These may be classed as follows : —
1. Compounds of hydraulic lime, formerly much used for external covering to
walls. 2. Mixtures of lime, plaster, and other materials for forming smooth
surfaces on internal walls, chiefly those intended to be painted. 3. All
sorts of calcareous cements and plasters used for covering walls.

These latter have been described under their several heads.

Coioiov Stucco consists of three parts clean sharp sand to one part of
hydraulic lime.

It was much used at one time as an external covering for outside walls,
but has to a great extent been superseded by cements of recent introduction.

The method of applying this and the other compositions mentioned below
is described at p. 406, Part II.

Trowelled Stucco is used for surfaces intended to be painted, and is com-
posed of two-thirds fine stuff (without hair) and one-third very fine clean sand.

Bastard Stucco is of the same composition as trowelled stucco, with
the addition of a Httle hair.

Rough Stucco contains a larger proportion of sand, which should, more-
over, be of a coarser grit The surface is roughened as described at page 406,
Part n., to give it an appearance like that of stone.

Artifioial Marbles may be produced by skilful workmen by
working colours in with almost any of the white cements or rathex
plasters mentioned at pages 242, 243.

Certain processes for imitating marbles are, however, known by

248 NOTES ON BUILDING CONSTRUCTION.

distinctive names, and one or two of the more important of these
will now be briefly noticed.

SoAGLiOLA is a coating applied to walls, columnB, etc., to imitate marble. It
is made of plaster of Paris, mixed with various colouring matters dissolved in
glue or isinglass ; also with fragments of alabaster or coloured cement inteF-
spersed through the body of the plaster.

The method of applying and finishing this material is described at page
410, Part II.

Marezzo Marble is also a kind of plaster made to imitate marble.

A sheet of plate-glass is first procured, upon which are placed threads of
floss silk, which have been dipped into the veining colours previously mixed
to a semi-fluid state with plaster of Paris. Upon the experience and skill of
the workman in placing Uiis coloured silk the success of the material pro-
duced depends. When the various tints and shades required have been put
on the glass, the body colour of the marble to be imitated is put on by hand.
At this stage the silk is withdrawn, and leaves behind sufficient of the
colouring matter with which it was saturated to form the veinings and
markings of the marble. Dry plaster of Paris is now sprinkled over to take
up the excess of moisture, and to give the plaster the proper consistence. A
canvas backing is applied to strengthen the thin coat of plaster, which ** is
followed by cement to any desired thickness ; the slab is then removed from
the glass and polished.

^ Imitation marble of this description is employed for pilasters and other
ornamental work, and is now used by Mr. George Jennings in the manufac-
ture of a variety of articles.**

'* The basis of Marezzo marble, as well as of Scagliola, being plaster of Paris,
neither of them is capable of bearing exposure to the weather." ^

"^ The Artifieial Marble now manufactured in London is made on the same
principle as the Marezzo, but differs from it in the character of the cement
used. A less expensive table is also substituted for the plate glass, and the
canvas backing is altogether omitted." ^

Other artificial marbles are described at page 76.

Enriohments. — ^The plasterer requires a great variety of
mouldings, ornaments, pateras, flowers, and other enrichments for
the decoration of his work.

These may be made either in plaster of Paris composition or
in papier-mach4.

Plaster Ornaments are cast either in wax or in plaster, the latter process
being used chiefly for large ornaments which have an undercut pattern.

The ornament is in either case first modelled in clay and well oiled.

In making wax moulds, the wax is melted, mixed with rosin, and poured
in upon the model, arrangement having been made to prevent its escape ;
the whole is then steeped in water, and the wax becomes detached in one

ASS.

When plaster is used as the material for the mould, it is laid on to the

> Dent.

PLASTERS, ETC. 249

model in plastic pieces fitted together, and then the whole, when diy, ia
immersed in boiled linseed oiL

In casting, the plaster in a semi-fluid state is dabbed with a brush into the
mould.

Composition Ornaments are made with a mixture of whiting, glue, water,
oil, and resin.

The oil and resin are melted together and added to the glue, which has
been dissolved in welter separately. This mixture is then poured upon
pounded whiting, well mixed, and kneaded up with it to the consistency of
dough.

When used the material is wanned to make it soft, and is forced into box-
wood moulds carved to the patterns required.

Papier-Mach£ is a much lighter material for ornaments than either com-
position or plaster, and it is much used for the purpose.

Cuttings of paper are boiled down and beaten into a paste, mixed with
sixe, placed in a mould of metal or sulphur, and pressed by a counter-mould
at the back, so as to be reduced to a thickness of about \ inch, the inner
surface being parallel to the outer surface, and roughly formed to the same
pattern.

Papier-mach^ is sometimes made of sheets of paper glued together, and
forced into a metal mould to give the pattern required.

In some cases a composition of pulp of paper and rosin is first placed in
the mould. This adheres to the paper ornaments moulded as above described,
and takes the lines and arrises of the mould more sharply than the paper
alone would do.

Carton Pierre is a species of papier mache made with pulp of paper,
whiting, and size, pressed into plaster moulds.

Fibrous Plaster consists of a thin coating of plaster of Paris on a coarse
canvas backing stretched on a light framework, and formed into slabs.

This material has great advantages. Large surfaces can be quickly covered
without much preparation for fixing, as it is less than \ the weight of
plaster, and it can, if required, be painted at once.

Dennett's Fireproof Material. — The material used for
Dennett's patent fireproof construction is a concrete of broken
stone or brick imbedded in a matrix of plaster produced by
calcining gypsum at a strong red heat (see p. 372, Part IL) Being
fireproof, it is much used for theatres. It sets at about the same
rate as ordinary Portland cement, and attains a strength nearly
equal to that of the original gypsum.

250 NOTES ON BUILDING CONSTRUCTION.

ASPHALTES.

Asphaltes are combinations of bitumen and calcareous matter,
sometimes found in nature, sometimes artificially formed.

Natural asphaltes are superior to artificial imitations, probably
because in them the bitumen is more thoroughly incorporated
with the limestone or other calcareous matter.

The natural asphalte is generally ground, mixed with sand and
a further proportion of bitumen, and run into moulds. When
thus mi:!ced it is known as mastic.

In the preparation of mastic mineral pitch (bitumen) must be
used, not coal-tar pitch ; the latter is brittle, easily softened, and
weak.

UseSy Advantages and DiBadvantages. — Patent asphalte
(or mastic) is waterproof, fireproof, easily applied, and to some
extent elastic, it can therefore be used with advantage for many
purposes.

It is an admirable material for the damp-proof courses of waUa
(see Part II. p. 214), also as a waterproof layer over arches or
flat roofs, or for lining tanks. It is useful for floors that require
a very smooth surface, as in racket courts ; also for those that
have to resist water, as in wash-houses, and for skirtings of such
floors. When spread and brought to a smooth surface it wears
well in footpaths, makes substantial and almost noiseless carriage-
ways, but is very slippery in damp weather.

It is also used for the joints of pavements of stone and other
materials, and prevents the penetration of wet^ but makes such
pavements more noisy.

GharaoteristioB. — Good mastic should be proof against frost
and damp, tough not brittle, and uninflammable. It should
withstand a temperature of from 140** to 160** Fahr. without
softening to any appreciable extent, and should not become so
fluid as to run down below a temperature of 260** Fahr.^

Laying. — ^Any details regarding the laying of asphalte would
be out of place in these Notes, which relate to the characteristics
of materials, not to the manner of using them.

The following remarks are necessary, however, in order to
understand the peculiarities of the different kinds of asphalte
described below.

^ Deot.

ASP HALVES, 251

There are two principal methods by which asphaltes may be
applied to a surface : (1) by being melted, spread, and rubbed to a
smooth surface.

(2) By being ground to powder, spread, and consolidated by
ramming.

Of these methods the first is the more convenient in many
positions, but asphaltes laid as compressed powder appear to be
the most durable imder considerable wear, as in carriage-ways.^

In all cases asphalte should be laid on a good base of concrete
or other solid material

Wheu the stuface is at a slope exceeding about i^r, the asphalte is apt to
ran if exposed to the sun, unless a good key can be obtained.

For steep inclinations and for vertical work (such as the linings of tanks)
the face must be roughed, the joints well raked out and filled with asphalte,
the whole surface &ee from moisture and warmed ; the asphalte is then applied
in successive thin coatings. Where the moisture cannot be got rid of, it is
necessary to build the face of the wall with asphalte joints, to which the
covering asphalte adheres. Plates of asphalte are sometimes used.

'^ Minute holes are noticeable in compressed asphaltes shortly after they are
laid, which seem after a time to dose up or disappear, while others opea
The cause of these has not been satisfactorily explained." '

VarietieB in the Market. — There are several different asphaltes
in the market. A few of them wiU now be described.

Besrssel Asphalte. known also as Claridg^s Patent AtphalU, is made from
a bituminous rock found at Pyrimont Sejssel, in the Jura mountains.

It is a limestone saturated with bitumen, and contains about 90 to 92 per
cent carbonate of lime and 10 to 8 per cent of bitumen.

This material is ground, mixed with grit and with heated mineral tar
until the mass has thoroughly amalgamated and become reduced to a mastic.
It is then run into moulds to form blocks.

These blocks are 18 inches square, 6 inches deep, and weigh about 125
lbs. each ; countersunk on two sides with the words PYRIMONT AND
SEYSSEL as the trade mark.

The asphalte is imported in this form by the Pyrimont Seyssel Asphalte
Company, from whose circular most of the following information is obtained : —

QaALiriEa — ^There are three qualities in the market —

1. Fine, without grit, used for magazine floors and as a cement for very
close joints in brickwork.

2. Fine-gritted, for covering roofs and arches, lining tanks, as a cement for
brickwork, and for running the joints of stones.

3. Coarse-gritted, containing more and laiger grit ; used for pavements and
floorings where great strength is required, as gun-shed floors, tun-room floors,
margins of stall floors, etc. In gateways for heavy carriage trafiic small
pieces of granite chippings, etc, are introduced.

^ Report of Engineer, City of London, 1871. ' Clark on Roads.

2 52 NOTES ON BUILDING CONSTRUCTION.

MixiKO. — The blocks of asphalte aie broken up into pieces of not more
than 1 lb. weight each, and melted in iron caldrons heated by wood or peak

Coal is objectionable on account of the smoke it creates ; coke injures the
material and destroys the caldron.

The following directions are from the circular of the company : —

" The fire having been lighted in the caldron, put into the boiler 2 lbs. of
mineral tar, to which add 56 lbs. of asphalte, broken into pieces of not more
than 1 lb. each. Mix the asphalte and tar together with the stirrer, till the
former becomes soft, and then place the lid on the caldron, keeping up a good
fire. In a quarter of an hour repeat the stirring, and add 56 lbs. more
asphalte, in similar sized pieces, distributed over the surface of that in the
caldron. Again cover the caldron for ten minutes, after which keep the con-
tents constantly stirred, adding by degrees asphalte in the proportion of 112
lb& to 1 lb. of tar, until the caldron is full and the whole is thoroughly
melted.^ When fit for use the a^halte will emit jets of light smoke and
freely drop from the stirrer."

The asphalte is removed from the cauldron in ladles, poured over the con-
crete foundation, or other place where it is to be applied, brought to a smooth
surface with wooden rubbers, and finished, either with a mixture of slate-dust
and silver sand in equal parts, or roughened by grit stamped in while the
asphalte is soft

Val de Travers Asphalte is from a rock found at Neuchatel in
Switzerland.

It is said to be richer in bitumen than the asphalte from Seyssel, contain-
ing from 11 to 12 per cent, and sometimes as much as 20 per cent

The material is laid in two different ways— either in powder, compressed, by
ramming, into a solid condition, or by melting and spreading, as in the case
of Seyssel asphalte.

Hot Compressed Princess, — The natural rock having been ground to powder,
is subjected to great heat in a revolving boiler. The boiler may be on the
spot, or the powder may be brought in a hot state in closed iron carts.

A foundation of Portland cement concrete having been formed, its surface
is spread over with the powder, which is then compressed by means of hot iron
rammers into one homogeneous layer without joints, and impervious to
moisture.

Carriage-ways are generally laid by this method.

Liquid Process. — The material used is composed of Val de Travers rock,
mixed with a large quantity of clean grit about the size of a split pea.

The asphalte is melted in boilers as above described, a small quantity of
bitumen being gradually added.

^ Practice, however, best regulates the quantity of tar to properly flax the asphalte^
In exposed situations, particularly on the coast during cold and other unfavourable
weather, a stroog fire is necessary to be kept up, and at such times the asphalte work
is longer in execution. On this account the tar is more quickly consumed^ and a
small quantity will have to be added. A somewhat laiiger proportion of tar is also
necessary in the application of asphalte to brickwork, and also in running the joints
of stones. In warm climates an excess of tar must be 'avoided. From the first
lighting of a caldron about 3} hours wiU be occupied before the entire mass with
which it is to be filled will become melted. The subsequent operation will occupy
about half an hour less time.

ASPHALTES, 253

It is carried in ladles from the caldrons to the concrete foundation pre-
pared for it, and spread in a liquid state over the surface and allowed to
cool.

About 18 parts asphalte and 2 parts grit are used for roofs, linings, tanks,
etc.

About 16 parts asphalte and 2 parts grit for flooring, footways, stalls,
etc. etc.

Bather more bitumen is added in the roofs than the floors, but the amount
depends, of course, upon circumstances.

Limner Asphalte is obtained from Limner, near Hanover.

The asphalte is broken up and mixed with clean grit, together with a
small quantity of bitumen.

The mixture is melted in caldrons, and laid in two thicknesses, the lower
stratum having coarser grit in it than the other.

Brunswick Book Aspbaite is obtained from mines at Vorwohle, in
Brunswick, Germany.

Kontrotier Asphalte is a French production, and is laid in compressed
powder. Maatlo Asphalte comes from Spain, and is laid in small blocks.

There are several other so-called asphaltes in which the natural substance
is mixed with various ingredients.

Among these may be mentioned the following : —

Bamett's Idquid Asphalte is made from natural or artificial asphaltes,
mixed with powdered oxide of iron and & small proportion of mineral tar.

The materials are melted and laid, as before described, on a concrete
foundation.

Trinidad Asphalte is a mixture of Trinidad pitch, broken stone, chalk,
and other ingredients, and is laid hot, in the form of powder.

Patent British Asphalte is a mixture of quicklime, pitch, sawdust, and
ground iron slag, heated and laid in a semi-liquid state.

Injferior Asphaltes are also made with coal-tar pitch boiled with chalk
and sand.

Pitch plays an important part in asphaltes, and it will be well to distin-
guish between the different varieties.

Mineral Pitch, or bitumen, is the constituent that makes asphalte so
valuable.

In fact, strictly speaking, solid bitumen is asphalte ; the rock asphalte,
generally known by engineers as asphalte, is merely stone saturated with
asphalte.

It used to be found in large quantities on the Dead Sea {JjOicm a«p^2it(M),
and thus obtained the name of Bifwawa of Judea.

Natural bitumen is found also in the island of Trinidad.

Bitumen contains an oil which in coal tar is very volatile, and escapes,
leaving the tar brittle.

Coal tar is very brittle at the freezing point, and softens at 115* (Fahr.),
whereas true bitumen is tough at 20*, and will not soften at 170* (Fahr.)

Goal Tar PrtCH is the residue obtained by distilling coal tar.

This material is sometimes used instead of bitumen for mixing with
asphalte.

It is, however, brittle, softens more under heat, is easily crushed, and it
altogether inferior.

254 NOTES ON BUILDING CONSTRUCTION.

WHITENING AND COLOURING.

Whitewash is made from pure white lime mixed with water.

It is used for common walls and ceilings, '' especially where, for sanitaiy
reasons, a frequent fresh application is considered preferable to any coating
which would last better. It readily comes off when rubbed, wiU not stand
rain, nor adhere well to very smooth or non-porous surfjEices. It is cheap, and
where used for sanitary reasons should be made up of hot lime and applied
at once, under which conditions it also adheres better." ^

Whitewash is improved by adding 1 lb. of pure tallow (free from salt) to
every bushel of lime.

The process is generally described as lime whiting.

The following is a meUiod recommended for making whitewash for outside
work.

'' Take a dean water-tight barrel, and put into it half a bushel of lime.
Slake it by pouring water over it boiling hot, and in sufficient quantity to
cover it 5 inches deep, and stir it briskly till thoroughly slaked. When the
slaking has been effected, dissolve it in water, and add 2 lb. sulphate of zinc
and 1 of common salt ; these will cause the wash to harden, and prevent its
cracking." ^

CoiiMON Colouring is prepared by adding earthy pigments to the mizturee
used for lime whiting.

The following proportions ^ may be used per bushel of Ume ; more or less
according to the tint required : —

Oeom Colour, — 4 to 6 lbs. of ochre.

Fawn Colowr. — 6 to 8 lbs. umber ; 2 lb& Indian red ; 2 lbs. lampblack.

Buff or Stone Colour, — 6 to 8 lbs. raw umber, and 3 or 4 lbs. lampblacL

Whiting is made by reducing pure white chalk to a fine powder.

It is mixed with water and size, and used for whitening ceilings and inude
walls. It will not stand the weather.

'* The best method of mixing it is in the proportion of 6 lbs. whiting to 1
quart of double size (see p. 449), the whiting to be first covered with oold
water for six hours, then mixed with the size and left in a cold place till it
becomes like jelly, in which condition it is ready to ^ute with water,
and use."

" It will take 1 lb. jelly to every 6 superficial yards." ^

Whiting is made in three qualities — common^ town, and gilders. It is sold
by weight in casks containing from 2 to 10 cwts.,in sacks containing 2 cwts.,
in firkins (very small casks), in bulk, and in smaU baUs.

DiSTBiiPER is the name for all colouring mixed with water and size.

White Distemper is a mixture of whiting and size.

The best way of mixing is as follows : — ^Take 6 lbs. of the best whiting
and soak it in soft water sufficient to cover it for several hours. Pour off
the water, and stir the whiting into a smooth paste, strain the material, and
add 1 quart of size in the state of weak jelly ; mix carefully, not breaking
the lumps of jeUy, then strain through muslin before using ; leave in a

> Seddon. * Bora.

WHITENING AND COLOURING,

255

cold place, and the material will become a jelly^ which is dilated with water
when required for use.

Sometimes about half a tablespoonful of blue black is mixed in before the
size is added.

It is sometimes directed that the size should be used hot, but in that case
it does not work so smoothly as when used in the condition of cold jelly,
out on the contrary drags and becomes crumpled, thus causing a rough
surface.

When the white is required to be very bright and clean, potato starch is
used instead of the size.

Coloured Distemper is tinted with the same pigments as are used for coloured
paints (see page 422), whiting being used as a basis instead of white lead or
zinc white.

In mixing the tints the whiting is first prepared, then the colouring pig-
ment, the latter being intixxiuced sparingly, size is then added, and the
mixture is strained.

The colours are classed as " Common," " Superior," and " Delicate," in the
same way as described at page 422.

Quantity of Katerials used for Plastering, etc. — The quantity of
materials required for plastering, rendering, etc, depends upon the nature of
the materials used, the degree of roughness of the walls, and other circum-
stances. Information on this subject will be found in the BuildeiV Price-
books, Hurst's Surveyor's Pochet-Book^ eta The following Table was carefully
compiled from practical observation for Colonel Seddon's Notes on the Building
Trades, etc —

TABLE of the Quantitt of Materials used in Plastering, Kenderino, etc.

10 Tarda Superficial.

cube.

Feet
cube.

Lb*.

Oal-
I0D8.

BdilL

Bundles

Render float and
trowel, 1 Portland
cement, 2 sand

Render one coat,
and set with fine
stuff

...

Render float, and
set with fine stuff

Lath, plaster, and
set with fine stuff

...

Lath, plaster, float,
and set with fine
stuff

...

356

NOTES ON BUILDING CONSTRUCTION.

WEIGHT OF LIMES, CEMENTS, etc.

The weights of various limes and cements are given approximately below.
The precise weight varies, of course, according to degree of freshness, size of
lumps, fineness of grinding, etc.

Quicklime in Small Lumps (Fresb).

White chalk lime .

Grey „ „ (Hailing)

Portland stone lime

Blue lias ,, „ (various)

Weight per Foot Cahe
in Lbs.

39
44

47
58 to 70

Quicklime, Ground (Fresh).

Blue Lias lime (various)

Grey chalk lime

Aiden » ti • •

Weight per Foot Weight per Striked
Cube in Lbs. Bushel in Lbs.!

49 to 68
48
68

68 to 87
55
87

CncBirn, etc.

Weight per

Foot Cube

in Lbs.

Weight per

Trade Bushel

inLbs.i

Weight per

Striked Bushel

in Lbs.

Portland

74 to 1014

100

95 to 180

Roman ....

60 to 624

77 to 80

Medina ....

Keene's ....

Parian ....

Plaster of Paris

Sold by weight

Whiting ....

Do.

1 See page 158.

Chapteb IV.
METALS.

THE metals used by the engineer and builder are iron, oopper,
lead, zinc, tin, and some of their alloys.

Ores. — These metals are not found to any great extent in the
pure metallic state, but chiefly in the form of oxides, carbonates,
or sulphides, called " ores."

Dressing. — The ores are broken up, and separated from the
earthy matters adhering to them, by stamping or crushing in
mills, and by washing in a stream, which carries away the lighter
impurities, leaving the ore, which is then said to be " dressed."

Qdcination and Roasting. — The next step is, as a rule, to roast
the ore in heaps or in Idlns, in order to drive off the moisture and
carbonic acid, and to fit it for smelting.

Smelting. — The ore is mixed with a substance called a " flux,"
selected in consequence of its tendency to combine with the par-
ticular impurities of the ore. The mixture is then thrown into a
furnace and subjected to intense heat, upon which the metal
sinks down in a fluid state, while the impurities combine with
the flux, and run off in a light and fusible slag.

IRON.

Froduotion. — Ores. — Iron ores are generally carbonates,
hydrates, or oxides of the metal, the latter being the best

British iron is obtained from ores found in several strata, but
chiefly in those of the coal-bearing or carboniferous series, in
which they are most conveniently interspersed with the fuel
(coal) and the flux (limestone) necessary for their reduction.

The following are the principal British iron ores : —

Clay Ironstone Ib a carbonate of iron of clay-like appearance. This is a rery im-
pnre on, containing not only clay, but pyrites and snlphnr, and producing in some caseit

B. C. — m S

258 NOTES ON BUILDING CONSTRUCTION

as little M 20 per cent of iron. However, on account of the large qnantitiee in which it
is found, and in consequence of its being near ooal and limestone, it is the most important
iron ore worked in Great Britain.

It occurs chiefly in the coal measures of Derbyshire, Staffordshire, Shropshire, York-
shire, Warwickshbie, and South Wales ; also in the Lias formations of Yorkshire (Cleve-
land). The ores vary greatly in quality, having a yield of iron which ranges from 20 to
40 per cent.

Blackbamd is clay ironstone darkened by from 10 to 25 per cent of bituminous and
carbonaceous matter, which makes it cheaper to smelt. It is found chiefly in Lanark-
shire and Ayrshire, where it yields about 40 per cent of iron ; also in Staffordshire, Dur-
ham, North Wales, where the yield varies oonsiderably, being generally less than in
Scotland.

Red RcBmaiUe is an oxide of iron found in many forms, often in globular or kidney-
shaped masses of red colour.

This is the richest British iron ore, the chief impurity being silica ; it yields from 50
to 60 per cent of iron.

This ore is found in the carboniferous limestone of Cumberland (Cleator Moor, White-
haven), Lancashire (Ulverston), and in Glamorganshire.

Some of these ores are greatly in demand for making Bessemer steel.

Brown ffcenuUiie is also an oxide of iron (hydrated), and of a brown colour. It con-
tains some 60 per cent of iron, and is found in Gloucestershire (Forest of Dean),
Cumberland (Alston Moor), in Durham, Devonshire, Northamptonshire, and on the
Continent

Magnetic Iron Ore is seldom found in this country. A little occurs in Devonshire,
but it exists in lai^e quantities in Sweden and Norway.

Spathic Ore is a crystallised carbonate of iron, generally mixed with lime, found in
Durham (Weardale), Devonshire (Exmoor), and Somersetshire (Brendon Hills). It yields
about 87 per cent of iron.

Such of these ores as are rich in manganese are used for the manufacture of Spieg
eleisen (see p. 290).

Foreign Ores which cannot be described in detail are much used in connection with
those of home production.

Iron ores are not sufficiently valuable to pay for their being washed and
dressed.

Those tliat occur in large masses, such as clay ironstone, are roasted to
drive off the carbonic acid, and to render them more easy to break up.

Smelting. — The extraction of the metal from the ore is
effected in a large upright furnace lined with firebrick.
Into this furnace a strong blast of air is forced.
In former years the air for the blast was supplied at its ordi-
nary temperature. This is still done in some few instances, the
process being called the ''cold blast I* and the resulring material cold-
blast iron.

Some years ago the hot-blast process was introduced. In this
the air is raised to a temperature of some 800** or 900® Fahr.
(sometimes to 1 200* or 1400*) before being forced into the furnace.
By this a very great saving of fuel i9 effected, and a greater heat
obtained. Moreover, calcining may sometimes be dispensed with,
coal may be used instead of coke, and altogether the process is far
more economical

The object of smelting is to free the metal firom its combina-
tions, and to get (as far as possible) all impurities out of the ore
in the form of a fusible slag.

IRON. 259

To effect this a fivx is added of a nature suited to combine
with the impurities or " gangue " in the ore.

If the gangue is chiefly clay, as it often is in this countryj
limestone is added as a flux. If the gangue is chiefly quartz, an
argillaceous iron ore and limestone are added. If the gangue
itself is limestone, clay or clayey ores are added.

The furnace is filled to a certain height with fueL When this
is burning, ore mixed with flux is introduced from the top, and
then layers of fuel and ore, with flux, alternately.

When the furnace is fully heated, the molten iron sinks to the
bottom, being covered by the lighter and more fusible impurities
in the form of " dag''

A furnace once lighted is not allowed to go out until it requires
thorough repair, but is continually replenished with fuel and ore
at the top.

When a considerable quantity of molten iron has collected, the
furnace is tapped, and the iron is run into a long channel formed
in sand, having branches on each side, caUed the sow and her
pigs — Whence the bars produced are called " pig-iron."

CompartUive Advantagu of Hoi and Cold Blast Iron, — The very high tem-
perature produced by the hot blast enables many of the impurities in the ore
to be reduced to a molten state, and ran out with the metal.

If this is taken advantage of, the impurities are retained in the resulting
metal, instead of being got rid of in the smelting process, and a very weak
inferior iron is produced.

It is evident, then, that the hot blast may be used to produce a very
inferior material, and this for some time brought it into disrepute.

Many specifications still direct that cold-blast iron is to be used.

It has, however, been shown by experience that the temperature of the
blast has, in itself, but little effect upon the iron produced, and that, with the
same care in the selection of materials and conduct of the process, iron may
be produced by the hot blast of as good quality, and as reliable, as that from
a cold-blast furnace.

After a great many experiments on the relative strength of hot-blast and
cold-blast iron, Sir William Fairbaim came to the following conclusion :-

" From the eridenoe here bronght forwmrd it is rendered ezoeedingly probable that the
introduction of a heated bUst in the manufacture of cast irons has iignred the softer
irons, while it has fireqnently mollified and improved those of a harder nature ; and con-
sidering the small deterioration that the irons of quality No. 2 ^ have sustained, and the
apparent benefit to thoee of No. 8, together with the great saving efifected by the heated
blast, there seems some reason for the process becoming general, as it has done." *

There are but few cold-blast furnaces now in the countiy. Among them
may be mentioned those at the celebrated Lowmoor and Bowling works ; also
some at Blsanavon in South Wales.

^ 8m jmtut 249. * /ron Mofnufadytre, etc., by Sir AVilliam Fairbaira.

26o NOTES ON BUILDING CONSTRUCTION.

PIG-IBON.

Pig-iron ia the name given to the rough bars of onpuiified cast
iron run from the blast furnace.

In this form it is sold to the founder or to the iron manufacturer.

By them it is subjected to various processes, which will here-
after be described.

Bifforent Materials produoed from Fig-iron. — The result of
these processes is the production of materials which, though origin-
ally from the same ore, and still of nearly the same chemical
composition, differ very widely in their mechanical properties and
characteristics.

These materials may be divided into three general classes . —
Cast iron.
Wrought iron,
and SteeL

The different processes required for the production of these
three classes of material, and those connected with the conversion
of the metals generally into the forms suited for the market — such
as pigs or ingots, plates and sheets, bars of different sections, etc —
will be very lightly touched upon.

Though every engineer ought to know something of the pro-
cesses of manufacture, it matters very little to him how the
iron he uses is made, for he can generally test it to see if it
is good.

Foreign Substances in Pig-iron. — ^Pig-iron always contains
foreign substances, among which are

Carbon, Silicon, Sulphur, Phosphorus, and Manganese, besides
many others in smaller proportion.

Of these foreign bodies that which plays by far the most
important part is carbon.

The great differences (which will presently be pointed out) that
exi&t between

Cast iron.
Steel,

Wrought iron,
depend chiefly upon the amount of carbon they respectively
contain.

The other substances may generally be regarded as impurities.

PIG-IRON. 261

Each, however, when present, plays an important part (see pp.
262, 263), and in some cases their presence is beneficial

With regard to the influence of carbon. Dr. Percy makes the
following remarks : —

" Of all the compoondB of iron none are to be compared with those of carbon in prac-
tical importance. . . . When carbon is absent, or only present in very small quantity,
we hare vfroc^hi tron, which is comparatively aoft, malleable, ductile, weldable, easUy
forgeable, and very tenacious, bat not fusible except at temperatures rarely attain-
able in funiaces, and not susceptible of tempering like steeL When present in certain
proportions, the limits of which cannot be exactly prescribed, we have the various kinds
of stetl, which are highly elastic, malleable, duxstile, forgeable, weldable, and capable of
receiving very different degrees of hardness by tempering, even so as to cut wrought iron
with facility, and fusible in furnaces. And lastly, when present in greater proportion
than in steel, we have catt iron, which is hard, comparatively brittle, and readily fusible,
but not forgeable or weldable. The differences between these three well-known sorts of
iron essentially depend upon differences in tbe proportion of carbon, though — as we shall
learn hereafter— other elements may and do often concur in modifying, in a striking
degree, the facilities of this wonderful metaL " ^

It is very important for the proper understanding of this sub-
ject that the student should, from the outset, bear in mind the
fact that

C<i8t Iron contains a large percentage of carbon (about 2*0 to
6*0 per cent).

Sted contains a small percentage of carbon (about *15 to
1*8 per cent).

Wrought Iron, when perfectly pure, is quite free from carbon.
Practically, however, it contains a small quantity — not exceeding
0*25 per cent

Between these main classes there ajre several gradations, merg-
ing gradually one into the other, and to which no definite limits
(as to percentage of carbon) can be assigned.

There are also several varieties of each class, varying according
as the percentage of carbon varies within the limits of that class.

These minor distinctions will presently be referred to, but at
present it wUl be only necessary to remember that the three
great divisions — cast iron, steel, and wrought iron — differ chiefly
according to the proportion of carbon they contain.

Ths Effbot of Cabbon upon Cast Iron. — There aie numy varietiee of
pig-iron, which themBelvee also differ pretty much according to the proportion
of carbon contained by them.

These differencee depend upon the quantity of fuel used in the reduction
of the ore, the heat at which the reduction was effected, and other particulars.

Before proceeding to consider the different varieties, it is necessary to
understand that there are two distinct forms in which carbon occurs in cast
iron.

* Percy's Uetallwrffy, V- 102.

262 NOTES ON BUILDING CONSTRUCTION,

1, In the state of Mechanical Mixture, — In this state the carbon is visible
in the shape of little black specks interspersed throughout the mass, which
give the iron containing them a dark-grey colour.

These little black specks are particles of free carbon, otherwise known as
graphite or plumbago.

2. In the state of Chemical Combination, — ^The carbon in this state is not
visible, and can be detected only by analysis.

The properties of cast iron depend not upon the absolute amount of carbon
it contains, but upon the eonditicn in which that carbon exists.

The varieties containing a large proportion of free carbon are of a dark-grey
colour, are soft, and run freely into moulds.

When the carbon is all, or nearly all, in chemical combination with the
iron, there are no black specks ; the metal is white, very hard, brittle, and
forms, when fused, a somewhat pasty mass, which will not freely fill a mould.

The former of these classes merges gradually into the latter, and between
them there are several gradations. Some varieties contain both free and com-
bined carbon.

White cast iron sometimes contains as much carbon as the grey varieties
(about 4 per cent), but of this very nearly all is in a state of chemical combi-
nation, whereas in the grey iron a very large proportion of it is free, in the
shape of distinct specks of plumbago, only about 1 per cent being in chemical
combination with the iron.

Impurities in Pig-iron. — The impurities mentioned below are originally derired
either from the ore or fuel, and unless dimiuated in subsequent processes, they will iigore
the respective metals produced in the manner stated.

Silicon is, next to carbon, the most common constituent of pig-iron. It is deriTed
from the ore and from the fuel. A good deal of it is got rid of in the slag produced
by smelting, and also during the refining and puddling processes.

In many respects silicon resembles carbon, and it affects east iron in nearly the sama
way.

Wrought Iron is rendered by it hard and brittle. To obtain good wrought iron the
silicon must be removed as far as possible by repeatedly heating and working the ivon.

SteeL — ^-^-^ part makes it cool and solidify without bubbling and agitation; more
makes it brittle. ^ per cent makes it unfoigeable.

Phosphorus is very readily taken up by the iron during the smelting process, and it
one of the worst impurities it can contain.

Coat Iron is hardened by it, but is made more readily fusible. Its tenacity is reduced.

Wrought Iron is injured by it in proportion to the quantity present

^V per cent does not reduce the strength of wrought iron ; and improves its capadty
for welding.

^ per cent makes it harder, but not weaker.

^ per cent makes it *'cold short " (see p. 275).

^ decidedly cold short.

i per cent makes it very brittle, and unfit for any but special purposes.

Steel is injured by a very minute proportion.

-^ per cent makes it unfit for the best cutlery.

-^ per cent makes it cold short, and useless for tool-making of any kind.

Makoakisb nearly always exists in east iron. It tends to produce the white variety,
in which a large proportion is generally to be found.

In Wrought Iron and Steel it counteracts red shortness, probably by encouraging
the departure of the sulphur and silicon (see p. 806).

Its presence is essential in the manufacture of Bessemer Steel, and fai some other
processes.

SULPHUB is derived from the pyrites in the ore and coal.

In Oast Iron it tends to produce the mottled and white varieties.

In Wrought Iron A to VS per cent produces red shortness.

in Steel more than -^ per cent unfits it for forging; but makei it more fluid, and htVxt
for casting. xV ?^^ ^^^ produces red shortness.

PIG'IRON. 263

Oomnt hu the following e£Eecte :—

In Ccai Iron ^ per cent does no harm.

In Wrought Iron tI^ per cent reduces tenacity. ^*q per cent makes it red short

In Steel -^ per cent midces it red short 2 per cent makes it brittle.

Aebbvio is not a very frequent impurity in iron.

In Coii Iron a smaller proportion is said to be good for chilled castings.

In Wrought Iron it causes red shortness.

Among the impurities met with more rarely, or in smaller quantities, are

Tin, which makes wrought iron cold short

TmroffrBN, which imparts hardness and elasticity to cast steel, and renders it more
capable of retaining magnetism.

A2ITIM011T, which makes wrought iron both hot and cold short

Titanium, which tends to produce mottled cast iron. The so-called "titanic steel "
contains no traces of titanium. The good qualities attributed to it must arise from
tome indirect action ^

Classifloation of Pig-iron. — ^The di£ferent varieties of pig-iron
are sometimes classed under three general heads.

Bessemer Pig. — A distinct variety of pig-iron made from hsematite ores
for conyersion by the Bessemer process (see p. 304). It should be as free as
possible from sulphur, phosphorus, or copper ; but a small percentage of
manganese and of silicon improves it for ihe purpose.

Foundry Pig, including all pigs having a fracture of a grej colour, con-
taining a considerable proportion of free carbon, and being therefore adapted
for the use of the ironfounder.

This iron is produced when the furnace is at a high temperature and pro>
perly provided with fueL

Forge Pig, consisting of those pigs which are almost free from uncombined
or graphitic carbon, and are therefore unfit for superior castings, being useful
only for conversion into wrought iron.

This description of iron occurs when the temperature is low, or the fuel
insufficient, also when there is much sulphur in the ore or fuel.

Forge iron is generally run from the blast furnace into iron moulds
(instead of sand), by which it is kept free from the impurities of the sand,
and also chilled, and thus rendered brittle and easy to break up for further
treatment

The pig-iron of commerce is more carefully divided into six or
sometimes eight varieties.

The exact classification varies at different works.

The following is condensed from one given in Wilkie's Manu-
facture of Iron in Great Britain, and quoted by Mr. Matheson in
his Works in Iran : —

No. 1. — The fracture of this quality of pig is of a dark-grey colour, with
high metallic lustre ; the crystab are large, many of them shining Hke par-
ticles of freshly cut lead.

This iron is of the best description, and the highest in price. The amount
of carbon it contains is from 3 to 5 per cent, which makes it fusible and
specially fitted for foundry work.

No. 2 is intermediate in quality between Noe. 1 and 3.

No. 3 contains much less carbon than No. I. The crystals shown in a

^ Bauerman's Metallurgy.

264 NOTES ON BUILDING CONSTRUCTION.

fracture of this iron are smaller and closer than in No. 1, hat are laiget and
brighter in the centre than nearer the edges of the fracture.

The colour is a lighter grey than that of No. 1, with less lustre.

No. 4 or Bright — ^This iron has a light-grey fracture, and but little lustre,
i¥ith very minute crystals of even sixe over the whole fracture. It is not
fusible enough for foundry purposes, but it is used in the manufjEU^ture of
wrought iron.

It is the cheapest of the grey irons.

When inferior in quali^, and nearly passing into the variety called
mottled, there is usually a thin coat or ^list" of white iron round the
exterior edges of the fracture.

No, 6, Mottled is intermediate between Na 4 and white iron, the fracture
being a dull dirty white, with pale greyish specks, and with a white " list "
at the edges. It is fit only for the manufacture of wrought iron.

No, 6, White, — This is the worsts most crude, hard, and brittle of the pig-
irons, the fracture being metallic white, with but little lustre, not granulated,
but having a radiating crystalline appearance. This iron is largely used in
the manufacture of inferior bar iron.

Cinder Iron is an inferior material obtained from the slag of the puddling
furnace, technically called '' cinder."

This cinder contains a large proportion of iron ; but also the phosphorus
and sulphur which have been extracted in making the better iron.

Such iron can only be extracted by the hot blast, and has done a great deal
to discredit the material produced by that process.

It is, however, very fusible, and therefore valuable to mix with other irons,
and is useful in itself for castings which do not require much strength.

Mine Iron is a name given to iron smelted from the ore only, without
admixture of slag.

When iron is specified as " hot-blast — all-mine," it means that no dnder-
iron or slag has been used in its production.

CAST lEON.

Cast Iron is obtained by remelting the foundry pig-iron of
commerce, and running it into moulds of the shape required as
hereinafter described.

In some cases the metal is run into the moulds direct from the
blast furnace, but in superior work it is generally specified that
the cast iron is to be of the " second melting ; ^ that is, from pigs
remelted in a cupola

The cupola is somewhat similar to a small blast furnace, and
acts in the same way. A little limestone is added as a flux,
which combines with some of the impurities left in the pigs> and
removes them in the form of slag.

There are several varieties of cast iron — made from the differ-

CAST IRON. 265

ent qualities of pig-iion — and they are classified by engineers
in a somewhat similar manner.

Grey Cast Iron is made from foundry pigs Kos. 1, 2, 3 of
the classification at page 263, and is itself generally divided into
three classes according to the nature of the pigs from which it is
mada

No. 1 is of a dark-grey colour, caused by the profusion of
specks of graphitic carbon throughout its mass ; it melts into a
very fluid state, which adapts it for very fine sharp delicate castings
not requiring much strength.

It is, however, not so strong as the other varieties of cast iron,
and is very soft, yielding readily to a chiseL

When broken it gives out a somewhat dull leaden sound, and
shows a large, dark, bright grain.

No. 2 contains less free carbon than No. 1, is therefore lighter
in colour, closer in the grain, and more difficult to melt ; but
being harder when cold is better for machinery, girders, castings
to carry weight, or in any position where strength and durability
are reqidred.

No. 3 is of a lighter grey, with less lustre, and contains still
less carbon than No. 2. It is therefore harder and more brittle,
and is employed in heavy castings.

White Cast Iron is made from forge pigs ; it contains very little
free carbon ; is of a silvery hue, extremely hard and brittle, and
is unfit for castings, except those of the very commonest kind,
such as sash weights.

White cast iron can be converted into the grey variety by
melting and slowly cooling it, and grey cast iron can be con-
verted into granular white cast iron by melting and suddenly
cooling it.

Mottled Cast Iron contains both the grey and white varieties,
which can easily be distinguished. The fractured surface is
either chiefly white with grey specks, or grey with white spots
and patches.

Orey cast iron may be distinguished from white cast iron by
treating the surface of a fracture with nitric acid. On grey iron
a black stain will be produced, on white iron a brown stain.

White and mottled cast iron are less subject to be destroyed
by rusting than the grey kind.

They are less soluble in acids, are hard, brittle, and not so
elastic as the softer kinds.

266 NOTES ON BUILDING CONSTRUCTION

Chilled Iron. — It is Bometimes advisable to produce a casting, some
parts of which are required to have the hardness of white iron, while others
are required to be of the toughest grey iron.

This efifect may be produced by placing in the mould over those parti
where a hard skin is required, pieces of cold iron of suitable shapes, thinly
coated with loam. Where these are touched by the molten metal its suzfaoe
is suddenly chilled and converted into white iron.

Thus the running surface of the wheel of a railway cairiage is chilled, and
covered with a hard skin of white iron, while the remainder of the wheel is
of tough grey iron.

Malleable Caat Iron is made by extracting a portion of the carbon from
ordinary cast iron in order to assimilate it to the composition of wrought iron,
and thus increase its toughness. This is generally done, in the case of very
small castings, by embedding them in powdered hssmatite ore, or in scales of
oxide of iron, and raising to a bright red heat in an annealing oven.

Malleable castings "^ may be easily wrought cold, but become very brittle
when heated, breaking to pieces under the hammer at an incipient white
heat ; at a higher temperature the kernel of unaltered cast iron melts, so that
articles that have been subjected to the process cannot be united by welding,
but may be brazed without difficulty.**

Mr. Elinnear Clark states that the tensile strength of annealed malleable
cast iron is *' guaranteed by manufacturers to 25 tons per square inch," and
that it 'Ms capable of supporting a tensile stress of 10 tons per square inch
without distortion." ^

Castings treated by this process, though they have not the peculiar fibrous
structure characteristic of wrought iron, become to a certain extent malleable,
and can be hammered or bent when cold without fracture.

They are specially suitable for intricate forms which could not be foiged in
wrought iron without much difficulty and expense.

The depth to which the casting is e£fected by this process depends upon the
time during w^hich it is exposed. Pieces about half an inch thick are ren-
dered malleable throughout ; thicker pieces have merely a skin of wrought
iron, the interior remaining unaltered.

This process is applied to the manufacture of buckles, gun-locks, snuffers,
pokers, tongs, etc ; and on a larger scale it has been used for toothed wheels
of machinery, screw propellers, and other purposes where a certain amount of
toughness is required combined with intricate forms.

Mr. Matheson recommends that malleable iron castings should be used for
the shoes and connecting pieces in roof structures.'

Toaghened Oast Iron is produced by adding to the cast iron and melting tmongst .
it from ^ to I of its weight of wrought iron scrap.

Dbsoriftions of Pig-Iron for Castings. — Qreat experience is required in
order to know exactly what descriptions of pig-iron to choose in order to
make castings for any particular purpose.

Mixtures of pigs classed under different numbers, and even selections from
different localities and makers, are recommended for large and important
castings.

1 Clark's TabkM. * Mathesoo.

CASTING. 267

Sir William Fairbftim racommandB ^ the following miztore as being of '* great valne in
castings, sach as girders for bridges, beams for buildhigs, etc, where rigidity and strength
are nqnired : —

Low Moor, Yorkshire, No. 8, 80 per cent

Blaina, or Yorkshire, Ko. 2, 25 „

Shropshire or Derbyshire, No. 8, 26 „

And good old scrap, 20

100

Many other recommendatioiu} as to different mixtures were made before
the Royal Commisaionets who reported on the employment of iron in railways

It is now, however, generally considered better by engineers to stipulate
that the iron shall stand certain tests, leaving the mixture to be used to the
judgment of the ironfounder.

Castdngs. — The description of the art of the ironfounder does
not come within the range of these Notes.

The few remarks which follow are intended only to give such
a general idea of the process of ironfounding as will enable the
student to understand the points to be observed in examining and
testing castings of different kinds.

Casting in Sand. — Castings, such as are used in building and
engineering works, are generally made by pouring molten iron
into sand, in which an impression of the article required has
been formed by means of a wooden pattern.

The sand is of a fine loamy character, free from oxides, and is
filled into iron frames or boxes, without tops or bottoms, called
"flasks^' made in two similar parts, one of which fits over the
other.

The "pattern" having been accurately formed in wood (a
little laiger than the required casting, so as to allow for contrac-
tion in cooling, see p. 343), is placed in the lower flask, and the
space round it is tightly filled with damp sand, the surface of the
pattern having been dusted with dry " parting sand.*'

The upper flask is then placed upon the lower one, and in its
turn fiUed with damp sand rammed round the pattern.

The box is then opened, the pattern taken out, and the halves
carefully put together again without disarranging the sand, an
orifice being left for the fluid metal, which is poured through
it, into the space, in the sand, previously occupied by the pattern.
* In order to prevent the met^ from being chilled (see page 266)
by contact with the sand, the inside of the mould is painted with
a blacking made of charred oak, which evolves gases under the

^ Applicaiion of Iron to B wilding I'urposes, p. 85.

268 NOTES ON BUILDING CONSTRUCTION.

action of the hot iron, and prevents too dose a contact between
the metal and sand.

The sand is also pierced with holes to allow of the escape of
the air, and of gases evolved when the metal is poured in. If
these are allowed to force their way through the metal, they will
cause it to be unsound and full of flaws.

The passages through which the molten iron is poured into the
mould should be so arranged that the metal runs together fix)m
different parts at the same time. If one portion gets partially
cool before the adjacent metal flows against it, there will be a
clear division when they meet, the iron will not be run into one
mass, but will form what is called a cold shtU.

The above is the simplest form of the process.

When a casting is to be hollow, a pattern of its inner surface, called a
**core^* is formed in sand, or other material, so that the metal may flow
round it

This leads to arrangements in the pattern which are somewhat complicated,
and which cannot here be fully described.

The core for a pipe consists of a hollow metal tube, having its surface full
of holes. This is wound round with straw bands, and the whole is covered
with loam tamed and smoothed to the form of the inside of the pipe.

The strength of a casting is increased if it be run with a head or superin-
cumbent column of metal, which by its weight compresses the metal below,
making it more compact and &ee from babbles, scorisa, etc These rise into
the head, which is afterwards cut ofL

For the same reason pipes and columns are generaUy specified to be cast
vertically, that is when the mould is standing on end. This position has
another advantage, which is that the metal is more likely to be of uniform
density and thickness all round, than if the pipe or column is run in a hori-
zontal position.

In the latter case the core is very apt to be a little out of the centre, so as
to cause the tube to be of unequal thickness.

In casting a lai^e number of pipes of the same size iron patterns are used, as they are
more durable than wooden ones, and draw cleaner from the sand. Socket pipes should
be cast with their sockets downwards, the spigot end being made longer than required for
the finished pipe, so that the scoriae, hubbies, etc., rising into it may be cut off. Pipes
of very small diameters are generally cast in an inclined position.^

Casting in Loam. — Large pipes and cylinders are cast in a somewhat dif-
ferent way.

A hollow vertical core of somewhat leas diameter than the interior of the
proposed cylinder is formed either in metal or brickwork.

The outer surface of this la plastered with a thick coating of loam (which
we may call A), smoothed and scraped to the exact internal diameter of the
cylinder (by means of a rotating vertical template of wood), and covered with

Huraber.

CASTING.

269

^' partisg mixture." Over this is spread a layer of loam (B) thicker than the
proposed casting, the outer surface of £ is struck with the template to the
form of the exterior of the proposed casting, and dusted with parting
mixture.

This surface is then covered with a third thick covering of loam (C) backed up
with brickwork y forming a cope built upon a ring resting on the floor, so that
it can be removed.

The outer brick cope^ with C attached to it, is then temporarily lifted away
upon the ring. The coating (B) is cleared out, and the cope is replaced so
that the distance between its inner surfiFice and the outer surface of A is equal
to the thickness of the casting.

The metal is then run in between C and A« When cool C and A can be
broken up, and the casting extracted.

The core, etc, have to be well dried in ovens before the metal is run. B
is often dispensed with, and the inner surface of C struck with the template.

Form of Castings. — The shape given to castings should be very ca^fully
considered.

All changes of form should be gradual. Sharp comers or angles are a
source of weakness. This is attributed to the manner in which the crystals
composing the iron arrange themselves in cooling. They place themselves at
right angles to the surfaces forming the comer, so that between the two sets
of crystals there is a diagonal line of weakness. All angles, therefore, both
external and internal, should be rounded o£

There should be no great or abrapt differences in the bulk of the adjacent
parts of the same casting, or the snudler portions will cool and contract more
quickly than the larger parts.

When the different parts of the casting cool at different times, each acts
upon the other. The parts which cool first resist the contraction of the
others, while those which contract last compress the portions already cooL

Thus the casting is under stress before it is called upon to bear any
load.

The amount of this stress cannot be calculated, and it is therefore a source
of danger in using the casting.

In some cases it is so great as to fracture the casting before it is loaded
at all.

Thus in cast-iron girders whose section has been improperly designed, as
shown in Fig. iii, the web being very thin would cool and contract
first. The subsequent contraction of the thick flanges would be resisted by
the already cold and rigid web. The flanges would therefore be kept by

e|j«.

Fig. 111.

the web in a state of tension, and the
web would be kept in a state of com- *?'
pression, the amount of which is un-
known ; moreover, the aharp angles
between the flanges and the web would ^'i
also be a source of weakness. I

When the girder is properly designed, I
as in Fig. 112, the change of thick- j^
ness is gradual, and the unequal contrac- -y'
tion does not occur. (See Part L p.
168.)

'^4

Fig. 112.

270

NOTES ON BUILDING CONSTRUCTION

Fig. 113.

In a castriron girder of omameDtal character such as that in Fig. 113,
with an open web and moderately thin flanges, the
flanges and verticals contract first, then the subsequent
contraction of the diagonals brings them into tension,
and they are very liable to break across, being resisted
by the outer flanges.

On the other hand, if the diagonals contract
first, they prevent the flanges from contracting,
and cause a rupture in them by throwing them into
tension.

The internal stress, produced by unequal cooling in the different parts of a
casting, sometimes causes it to break up spontaneously several days after it
has been run.

A case is mentioned by Mr. Anderson,' which actually occurred in practice.

The casting was of the form shown in Fig. 114. It was duly delivered
by the maker without any apparent flaw, but
after lying by for a day or two it suddenly split
through the middle to within a few inches of
the outer edges. On inquiry, it was found that
the cooling of the mass had been hastened. The
outer edges cooled first ; the thicker inner portion
remained hot and prevented the outer edges from
contracting, so they became stretched. When the
interior became cooled it attempted to contract. Fig. 114.

but the outer edges being rigid cracked in the attempt

Castings should be covered up and allowed to cool as slowly as possible ;
they should remain in the sand until cooL If they are removed from the
moulds in a red-hot state, the metal is liable to injury from too rapid and
irregular cooling.

The unequal cooling and consequent injury caused by great and sudden
differences in the thickness of parts of a casting, are sometimee avoided by
uncovering the thick parts so that they may cool more quickly, or by cooling
them with water.

It is generally thought that molten cast iron expands slightly just at the
moment when it becomes solid, which causes it to force itself tightly into
all the comers of the mould, and take a sharp impression.

As molten iron cools down it shrinks about it in all its dimensions ; the
patterns must therefore be made proportionately larger.

The exact amount of contraction depends, however, upon the size and
thickness of the casting, and upon the quality of the iron. The amount of con-
traction differs considerably in other metals, and the patterns should vaiy in
size accordingly (see p. 357).

The patterns should also be slightly bevelled (about i inch to the foot),
so that they may be easily drawn out of the sand.

Superior castings should never be run direct from the furnace. The iipn
should be remelted in a cupola. This is called the second melting, and is
generally prescribed in specifications. It greatly improves the iron, and gives
an opportunity for mixing difi^erent descriptions which improve one another.

^ Proceedings Society of Arte.

CASTING. 271

Castings required to be tamed or bored^ and foand to be too hard, are
softened by being heated for several hours in sand, or in a mixture of coal
dust and bone ash, and then allowed to cool slowly.

Examination of Castings. — In examining castings, with a
view to ascertaining their quality and soundness, several points
should be attended to.

The edges should be struck with a light hammer. If the blow
make a slight impression, the iron is probably of good quality,
provided it be uniform throughout.

If fragments fly off and no sensible indentation be made, the
iron is hard and brittle.

Air bubbles are a common and dangerous source of weakness.
They should be searched for by tapping the surface of the casting
all over with the hammer. Bubbles, or flaws, fiUed in with sand
from the mould, or purposely stopped with loam, cause a dulness
in the sound which leads to their detection.

The metal of a casting should be free from sconse, bubbles, core
nails, or flaws of any kind.

The exterior surface should be smooth and clear. The edges
of the casting should be sharp and perfect.

An uneven or wavy surface indicates unequal shrinkage, caused
by want of uniformity in the texture of the iron.

The surface of a fracture examined before it has become rusty
should present a fine-grained texture, of an uniform bluish-grey
colour and high metallic lustre.

GoA-Iron Pipes should be straight, true in section, square on the ends and in
the sockets, the metal of equal thickness throughout. They should be proved
under a hydraulic pressure of four or five times the working head. The sockets
of small pipes should be e8X)ecially examined, to see if they are free from honey-
comb. The core nails are sometimes left in and hammered up. They are,
however, objectionable, as they render the pipe liable to break at the points
where they occur.^

Tests for Cast Ibon. — For small girders and other castings intended to
carry weight, it is usual to test a certain proportion of the number supplied
by loading them till they break, and noting the weight under which they give
way.

For large castings this system of testing would be too expensive. SmaU
bars are therefore cast from the same metal and at the same time as the cant-
ings, and these are tested to fracture by a weight applied at the centre.

Some engineers require that the test bar should be cast with the main
casting, and not broken from it until they have seen it.

The test bars are usually about 3 feet 6 inches long, 2 inches deep, and
1 inch wide, with a clear bearing of 3 feet

^ Hnmbor.

272 NOTES ON BUILDING CONSTRUCTION.

Tlie test weight varies, according to the opinion of the engineer^ from 16
to 35 cwt

It is important, however, to ascertain not only the weight that will break
the test bar, but also the amount of deflection that will occur before ^sctuie.

The reason for this is that a very hard iron will often bear a considerable
cross strain when it is steadily applied, though it would be so brittle as to be
unfit for any position in which it would be liable to slight vibration or shocks
of any kind.

With regard to this point Mr. Matheson says : —

*' A strength capable of enduring 25 cwt. on the test bar without fracture should be the
minimum quality allowed even for short and heavy columns ; but for other ]
toad of from 28 to 30 cwt., and a deflection of ^ inch, should be demanded.

" The deflection will vary from *3 to '5 inch.

" There is no difficulty in getting such iron, and higher qualities can be given if i
sary, breaking strains of 30 to 35 cwt. being obtainable with judicious mixtures of the
best kinds of iron ; and in testing such iron it will generally be found that some of the
ban will endure as much as 38 cwt." ^

Mr. Stoney points out " a singular fact that there is an ezcess of about 16 per cent in
the weight that a 2-inch by 1-inch test bar will support when cast on edge and proved
as cast, over that which it will support when proved with the underside as cast placed
at the top as proved, and 8 per cent over the weight which the same test bar will sup-
port if cast on its side or end, and proved on edge.

" Hence cast-iron girders should be cast with the tension flange downward in the sand. '*

Dr. Pole has pointed out that small cast bars do not give a fair indication
of the strength of larger castings run at the same time, for the reasons stated
at page 302, in the paragraph headed Size of SectUm,

The cast-iron sleepers for the Great Indian Peninsula Railway were tested
by a falling weight ; and test bars, of the ordinary form, cast at the same
time, were broken by cross strain ; others, having a central section one inch
square, were broken by tension.

WEOUGHT IRON.

Wrought Iron is, or should be (as before mentioned), very
nearly the pure metal, containing not more than about 0*15 per
cent of carbon.

It may, by a peculiar process, be procured direct from the ore,
but is generally obtained from the harder descriptions of pig-iron
by a succession of processes, the object of which is to get lid of
the carbon, and of the phosphorus, sUica, and other impurities,
which injure the iron and make it brittle.

In order to expel these foreign substances the finest qualities
of wrought iron are refined and then puddled : the inferior quali-
ties are puddled only.

Forge pig is generally used for the manufacture of wrought
iron, and can be converted at once by the puddling process.

Grey iron, however, contains graphite and silicon. The latter
makes it diflBcult to puddle, and it is often removed by the pro-
liminary process of refining described below.

^ Mathe8on*8 World in. Iron. • Stoney On Strains, p. 477.

WROUGHT IRON. 273

Refining consistB in keeping the pig-iron in a state of fusion on an open
hearth with coke, for about two hours, with a strong current of air directed
upon it It is at the same time well stirred, so that all parts of it axe brought
into contact with the air and oxidised.

The oxygen in the air deprives the cast iron of, part of its carbon, and at
the same time converts the sHicon into silica, which combines with some of the
oxide of iron to form a fusible slag, that runs ofL

The liquid iron, is then run into cast-iron moulds lined with loam, and kept
eool with water circulating below them, so that it is chilled and easily broken
up into what is technically known as ^plaU meiaU*

The resulting fine metid greatly resembles white cast iron in its eharacter-
istics, but the percentage of impurities will be found to have been consider-
ably reduced by the refining process.

PuDDLiNQ consists in melting the pig-iron in a reverberatory fiiraace, by
means of which the metal is subjected to the heat of the flame and a strong
current of air, and kept quite clear of the fueL

The molten metal is at the same time well mixed with oxidising substanoeSi
such as hflsmatite ore, oxide of iron, forge scales, etc., and sometimes with lime-
stone and common salt The oxygen in these combines with the remnant of
carbon left in the iron, and the silicon is also oxidised, passing off in slag.

As the carbon is removed the iron becomes less fusible, and clotty lumps
of pure iron appear, which are collected by the puddler and pressed together
with the tool until they are formed into puddU-Mlt weighing about | cwt
or more.

In order to reduce the labour in puddling, rotatory furnaces and other
ingenious inventions have been introduced of late years. These, however,
need not be further referred to.

Shinolxno. — ^The lumps or balls formed in the puddling furnace are at
once placed under a helve or a tilt-hammer, the blows of which force out
the cinder and consolidate and weld the partides of iron together, forming it
into what is called a hloom.

Inferior descriptions of iron generally have the slag removed by a squeezer,
a machine something like the jaws of an alligator, after which animal it is
sometimes named.

On many works the steam-hammer w used for this purpose, and it can be
made to do the work very effectually. It may, however, be used to produce
very inferior iron, because it can be adjusted to give the mass such very
light blows that the slag is not squeezed out, but left in the iron to its very
great detriment^

Rolling. — Directly after this the red-hot slab of iron, or '* bloom," is passed
between grooved rollers, which convert it into ptiddled hart about 3 or 4 inches
wide, f to 1 inch in thickness, and 10 or 12 feet long.

The puddled bars thus formed are wrought iron, but of the lowest class.
They possess hardly any of the characteristics of the higher qualities, and
require to be greatly improved by subscqutot processes of piling, reheating,
and rolling.

Before referring to these processes and to the different qualities of iron
produced by them, it wUl be well to glance at the effect of rolling upon the
structure and strength of the iron.

J—-

B. C. — m T

274 NOTES ON BUILDING CONSTRUCTION.

Effect of Bollinq Ibok. — ^All wrought iron, after fusion, or after having
been exposed to high temperatures sufficient to induce softening or pastinem,
which is the case when iron is reheated to a white heat, consLsts of- an aggrega-
tion of crystals of a cuhical form.

In the act of rolling, these crystals are elongated into fibres, which form
the mass of all good wrought iron.

Some authorities consider that when bar iron is subjected to oontinaed
▼ibiation, constantly repeated loads, shocks, or blows, its structure becomes
altered, and that it returns to a crystalline condition. On this point, however,
there is considerable doubt (see p. 260).

The chemical constitution of the iron as well as its mechanical structure is
altered during the process of rolling. When heated the surfSeu^ is exposed to
the oxidising influence of the atmosphere, the amount of carbon is consider-
ably reduced, and a large proportion of other impurities may be got rid of.

Some experiments made at Woolwich on Bessemer wrought iron showed
that this iron, when fused and run into a mould, had a tensile strength of
18 '4 12 tons per square inch, but when the same iron was rolled its
tensfle strength became 32-4 tons per square inch, by which it appears that
the operation of rolling has the effect of nearly doubling the strength of the
iron.

The effect of rolling is illustrated also by the example given at page 333.

Iron, however, will not bear to be rolled too often, for it appears from Bir
W. Fairbaim's experiments that it gains strength only up to the fifth reheat-
ing, and then its strength begins to fall off.

Professor Rankine says — "^ Qood bar iron has in general attained its maxi-
mum strength, and the desired size and figure should be given to it with the
least possible amount of reheating and working."

Diflbrent Qualities of Bar Iron. — The products of the roUing
process are classified as follows : —

Puddled Bars, also known as No. 1 or nmgh hart.

The puddled bar obtained by the processes above described is of a veiy
weak and inferior quality.

It has a coarse crystalline structure, and very small tensile strength (see
Table, p. 318), but is of a harder texture than the better kinds of bar iron
about to be mentioned.

In order to improve the quality of the material, the puddled b«r is cut up
into short lengths and subjected to the processes of piling, reheating, and
rolling.

The effect of these processes is — 1st, To drive out the slag ; 2d, To give
uniformity of structure, weak parts of one bar being brought alongside the
strong parts of other bars ; 3d, To produce a finished surface.

Some of the harder kinds of iron are, however, worked chiefly by the
hammer, the bar being passed through the rolls only at the last when it is
to receive its finished section.

Mbrchant Bar or Common Iron^ known also as No. 2, is produced by piling
up short lengths of puddled bars, raising them to a welding heat, and passing
them through roUers. This amalgamates them into a single bar, and give^
the iron a fibrous structure which greatly increases its strength.

This quality of bar is, however, still very inferior, being hard and brittle.

WROUGHT IRON. 275

It can be foiged only with difficulty, and is useful only for the commonest
purposes.

Best BaIi is produced by cutting up merchant bars, and repeating the pro-
cesses of piling, reheating, and rolling.

In some cases the top and bottom of the pile are made with bars that have
been twice rolled.

Best bar Ib fSar tougher and more easily worked than merchant bar, and is
generally used for ordinary good work.

Bbst Best and But Best Best iron bars are those which have respectively
been submitted to three and four repetitions of the processes of piling, weld-
ing, and rolling.

Scrap Bars are made from short pieces that are useful for no other pur-
pose welded and rolled together into a single bar.

When the scraps used are old pieces not thoroughly cleaned, the resulting
bar is of an inferior description.

If, however, the scraps used are of new and clean iron, such as the short
ends cut off fimshed rails, an iron of capital quality is produced, which is
known as best scrap or hegt best scrap.

Manufaoturb op T and I Iron. — In manufacturing iron of T, I, or other
sections, or rails, a pile of bars is formed, heated, and welded togetlier under a
steam hammer.

This is then rolled, in the roughing or cogging rolls, into a hloom of about
half or two-thirds the sectional area of the original pile.

The bloom is reheated, and rolled down in grooved finishing rollers, each
approaching more and more nearly to the section of the finished raiL

The rails are then cut to a length, straightened, and finished.

For rails which have to withstand traffic, the upper and lower sur&ces of
the piles are of superior or better-worked iron.

Wrought iron girden can be rolled with ease up to a depth of abont 10 inches. When
they are required of greater depth than this, the upper and lower portions are sometimes
rolled separately, and then united bj inserting a piece of iron containing more carbon,
and which is therefore more ftuible. This piece ia subjected to a fierce heat from blow-
pipes, and at the same time hammered on both sides, so as to weld the upper and lower
portions of the girder together.

Ck>ntraetion of Wrought Iron^ — " When a bar of wrought iron is heated
to redness and quenched in water it becomes permanently shorter than
before. This fact u well known to practical men, who sometimes avail them-
selves of it when a wrought-iron crank, etc, has been accidentally bored out
too large for its shaft ; by one or more heats it may be reduced so as to be a
goodfie^

Ck>ld Boiled IroxL — ^Wrought iron bars and plates, rolled cold under a
great pressure, acquire a polished surface, and have their tensile strength in-
creased, and their ductility reduced as shown in the Table, p. 319.

Defects in Wrought Iron. — Cold Short iron is very brittle
when cold, and cracks if bent double, though it may be worked at a
high temperature.

This defect generally appears in an iron produced from a poor
ore, or is caused by an excess of phosphorus.

* BozonHeaL

276 NOTES ON BUILDING CONSTRUCTION.

Sed Short or Hot Short iron cracks when bent or finished at
a red heat, but is sufficiently tenacious when cold. The defect is
generally caused by sidphur from the fuel. Red short iron,
though useless for welding and for many other purposes, is tougher,
when cold, than other iron, and is much used for tin plate.

Arsenic, copper, and several other impurities also produce red
shortness.

TESTS FOR WROUGHT IRON.

General Bemarks. — ^There are several ways in which the
quality of a piece of wrought iron may be ascertained.

It may be broken by direct slow tension, or by a falling weight,
the breaking stress, elongation, contraction of area, and other par-
ticulars being noted. In the absence of facilities for breaking it,
it may be subjected to certain rough tests which will be presently
described.

Where these tests cannot be applied, some idea may be formed
of the quality of the iron by the appearance of the fractured sur-
face.

Wrought iron is used in many structures in which it is liable
to receive sudden and often-repeated shocks. This is the case,
for example, in bridges, and to a certain extent in roofs. It must,
therefore, be able not only to resist a great tensile stress, but also
to withstand sudden concussion or continued vibration.

A very hard iron will withstand a very high tensile stress, but
is brittle, and will snap under a sudden strain.

A good ii'on must, therefore, not only possess great tensile
strength, but must be ductile, that is, able to stretch before it
gives way. This ductility may be measured either by the pro-
portion borne by the permanent elongation to the original length
of the iron, or by the amount of contraction of area of section
caused by the stretching.

A specimen of such iron when torn asunder by slow tension

Fig. 116.

TESTS FOR WROUGHT IRON. 277

•will not break ofif short as in Fig. 1 1 5/ but will draw out as
in Fig. 1 1 6/ not only becoming longer, but also being reduced
in diameter and sectional area at the centra The dotted lines in
Fig. 116 show the original size of the specimen.

In order that both strength and ductility may be secured, it
is now usual for engineers to require that the iron for bridges
and similar important work should fulfil at least two condi-
tions:—

(1) That it shall not break with a tensile stress less than a
certain specified amount

(2) That before breaking it shall elongate not less than a
named proportion of its original length ; or

That before breaking its sectional area shall be reduced (as a
consequence of its stretching) by not less than a certain named
proportion of its original area.

Of these two forms of the test for ductility, the measurement
of the elongation is generally simpler and more easily managed
than the measurement of the reduction of area.

With ordinary irons, as a rule, that specimen which has the
greatest tensile strength is the hardest^ and will contract least in
sectional area, or lengthen the least before breaking.

Iron can, however, be made which will possess both qualities
in a very high degree.

In addition to ascertaining the strength and ductility of the
iron, it is desirable to know how the iron will behave when
reheated and worked.

This Ib ascertained by bending or otherwise distorting the iron
when hot, as described at page 280, under the head of Forge
Tests.

Such tests are especially valuable when the uron is to be forged
into different shapes before use in the structures for which it is
intended.

Ma. Ktrkaldy's ExPSBniBNTS. — ^At one time it was thought that the
tensile stress required to break a piece of iron was all that was necessary to
be known in order to ascertain its quality.

The investigations of Mr. Eirkaldy founded upon an elaborate series of
experiments made by him on iron of every description and quality, led him,
however, to the following conclusions,^ among many others, some of which
will be referred to presently : —

From Kirkaldy'a ExperifnnUs on Iran and SUel.

278 NOTES ON BUILDING CONSTRUCTION.

" 1. Th« breaking stnin does not indicate the quality as hitherto aasnmed.

"2. A high breaking strain may be due to the iron being of superior quality, dense
fine, and moderately soft, or simply to its being very hard and unyielding.

" 8. A low breaking strain may be due to looseness and ooarseness in the texture, or
to extreme softness, though very dose and fine in quality.

"4. The contraction of area at fracture, preyiously overlooked, forms an essential
element in estimating the quality of specimens.

" 5. The respective merits of various specimens can be ooirectly ascertained by com-
paring the breaking strain /otn^Zy with the contraction of area.

"6. Inferior qiudities show a much greater variation in the bresking stnin than
superior.

"7. Oreater differences exist between small and large bars in coarse than in fine
varieties.

'' 8. The prevailing opinion of a rough bar being stronger than a tamed one is «ro-
neous.

" 9. Rolled bars are slightly hardened by being forged dowiu

" 10. The breaking strain and contraction of area of iron plates are greater in the
direction in which they are rolled than in a transverse direction." (The experiments
show the difference to be about 10 per cent)

Uniforhitt. — ^In chooeiiig iron for railway bridges and similar stmctores
it is not only important that the iron should be strong and toogh, but alao
that it should be uniftyim in quality.

Iron structures should be so proportioned that an equal stress shall
come upon every square inch of the section of every part It is of no advan-
tage that the iron* in one part should be so good as to enable it to take moie
than this working stress, when at the same time another part would give way
if the stress were applied.

DiVFBBBNT Mbthodb OF Tbstino.' — (1) Upon receiving a quantity of
iron for any work, pieces may be taken at random and tested to breaking in the
manner before described.

This is the best way of testing — all the particulars required to be known
with regard to the iron may be ascertained — and though some bad pieces may
escape detection, yet the general average of the whole, and the degree of uni-
formity which exists, is pretty well aziived at

In order that the iron may be uniform in ductility as well as in tensile
strength, it has been recommended that a ma/Bimwfn percentage of elongation
or contraction of area should be specified as well as a minimum. This, how-
ever, is not done, the minimum only being referred to in most spedficationflL

There are, however, other ways in which engineers endeavour to ascertain
the quality of a lot of iron by applying a tensile stress.

These may just be mentioned.

(2) Sometimes every piece to be used in the work is tested under a small
stress, any bars which appear to elongate more than the others, and sooner to
take a permanent set (see p. 329), being considered inferior. This test gives
no information regarding the ultimate strength of the iron. Moreover, Uiere
is danger of testing each piece beyond its limit of elasticity (see p. 329), and
thus doing it a permanent injury.

(3) In other cases it is specified that all bars shall be rejected the elonga-
tion of which exceeds a certain fixed proportion under a specified stress

This is a bad test of the quality of the iron, for the large elongation may
be due either to the iron being a good tough material, which stretches con-

I Unwin's Iron Bridges cmd Eoqfi,

TESTS FOR WROUGHT IRON.

279

sideiably long before breaking, or it may be due to the iron being of a weak
description and on the point of breaking.

Testing ICadhines. — The machines for accurately testing iron and steel
are too cumbrous and expensive for ordinary usa Engineers generally send
their specimens to be tested by Mr. Eirkaldy of Southwark, to other testers
of materials, or to one of the chain-testing establishments, such as those at
Birkenhead and Sunderland.

A description of Mr. Kirkaldy's admirable machinery for testing is given
in Spon's Dictionary of Engineering.

Tensile Tests Ibr Wrought IroxL — ^The Tables at page 318 give the
tensile strength, the contraction of area, and other particulars, with r^;ard to
several di£ferent descriptions of iron.

These particulars differ in nearly every case. It is not usual to make shades
of difference in the tests applied, so that they do not vary with each minute
difference in the description of iron that is to be used.

The foUowing Tables, showing the tests that are applied to the various
classes of iron by the different (Government departments, will therefore be
usefuL

India Office. — The following Table is extracted from one prepared for the
India Office by Mr. Eirkaldy : ^—

Scale of Tensile Tests fob Iron of Vakious Qualities

DUCUPTIOK.

■ClamG.

Bars, round or
square .

Bars, flat .

Angle and Tee or T

Plates, grain
lengthways

Plates, grain
crossways

Tona
27
26
25

24^

h28

6 ts

Percnt.
45
40
80

20^

12j

Class D.

Tons.
26
25
24

28^
20 J

^21}

Percnt.
85
80
22

15^

► 12

Class EL

ill

Ton*.
25
24
23

22-]
19j

Percnt
80
25
18

12^

Class F.

PIS I

Tons.
24
23
22

isj

5 ts

Percnt
25
20
15

^ 20
J 17

Class O.

Tons.
28
22
21

20^

17)

18i

Percnt
20
16
12

jsj

Ultimate Stress ]

Swedish Bass.

Contraction <

Soft *^-.- Contraction of ) -^ «-• «-«♦

22 ton.. area at fracture, r^ !«'«"*•

Comparing this Table with the Tables of strength given at page 318, it will
be seen that

The best Torkshire iron might be expected to stand the tests luder
Class a

^ Wray'i Theory of Construetion.

28o

NOTES ON BUILDING CONSTRUCTION

The Best Best irons of the market should stand the test under dass K
The ordinary Best iron of the market should stand those of Class Q.

A and B are reserved for special qualities of iron which might be required at inr
future time, and the Classes D to F would be for qualities intermediate between the othen.

Recent India Office spedflcations are summariBed as in the following TaUe^ which
shows the ultimate tensile stress per square inch, and the percentage of elongatian for each
description of iron.

B.B.

Stafford.

shire.

B.B.B.

Stafford.

shire.

Yorkshire.

Miscel.
laaeovs.

For Iron
Roofing.

Ig-

J**

li
1^

9 A

0 U

li
1^

Tons.

TOHB.

Tons.

Bars round and square .

Flatban
overs' wide.

Do. flat .

...

FUthan
under5'wid€.

Angle Iron

TorH „

Plate /^^"^^^^^^^y"

I graui crossways .

...

Sheet -('^^®°^^'^*y*
^'^^^^l gram crossways .

...

Admiralty. — ^The Admiralty Tests for iroli for ship- building may be
tabulated as follows : —

Tensile strain
peraq[aare Inch.
22 tons.
18 „

BB or Ist class plate iron and sheet } (grain lengthways)

. } (grain crossways)

! (grain lengthways)
(grain crossways)

I (grain lengthways)

21
18

20
17

iron i inch thick and above
Do. f boiler plate, do. do.

B or second class plate and sheet iron .

Angle, Bulb, T, Angle-bulb, Tee-bulb,
or other iron of ordinary fodu

All the above are in addition to the foxge
tests enumerated at page 281.

BB bar iron, moulding, sash bar, half ^ Do.

round, and segmental iron. Fire-bar |-and such forge tests, hot and cold, as may
iron J be deemed expedient.

Bough Tests for Wrought Iron. — ^There are several very useful tests
whicb may be applied to iron of different forms in addition to the tensile tests.

Forge Tests, — Plate iron may be bent either hot or cold, with or across the
grain. The bending is done upon a cast-iron rectangular slab, having the
comer slightly rounded off. The angle through which the plate should bend
without cracking depends upon the quality and thickness of the iron, and is
shown in the following tables, which, together with the tests following for

TESTS FOR WROUGHT IRON.

281

angle irons, etc., have been extracted from the Admiralty directions for test-
ing iron.

PLATE IRON.

Hot.

CoLa

THiCKHan.

1 inch thick
and under.

linch.

}incb.

iinch.

B B, grain lengthways .

„ crosswaya
B, grain lengthways
„ „ CTOSsways ....

126*
90*
90*
60*

16*

10*

26*

10*

20*

85*
16*
80*
10*

70*
80*
66*
20*

SHEET lEON.

Hot.

Cou>.

B B, grain lengthways .

„ „ crossways
B, grain lengthways
„ „ crossways ....

126*
90*
90*
60*

90*
40*
76*
80*

N,B.-IX should be noticed that the angle mentioned above in each case '^^^f}^
through which the plate is bent, commencing at the horizontal, not the angle between the
two sides of the plate after it is bent. ^ -„ 1

Different descriptions of iron may be tested as follows :—

COLD.

HOT.
AngU Irons
'HLkj be bent thus

Or thus
Or flattened thus

And end bent over thus

Notched and broken across to
show quality of the iron.

One flange cut off and bent cold,
thus

1 These are the tests nsed by the Admiralty.

282

NOTES ON BUILDING CONSTRUCTION.
Tee Irons

May be bent thus

Or thus

ffi

Tee huib iron may be tested like
Tee iron, and a/ngle InUb iron
like angle iron, after the bulb
in each case is cut off.

Bulb Iron

Cut off bulb, and bend
web thus

Chemnellron

Bent thus

(T^"^

Same as for angle irona.

The bulb may be notched on one
side, and broken cold to show
the quality of the iron.

Bulb notched on one side, and
broken to show quality of iron.

Flange cut off and bent cold as
for angle iron. One sample
notched, and broken cold, to
show quality of iron.

Rivets of good quality should double when cold without Bbowing any signs
of fracture. The heads " when hot should stand being hammered down to
less than -J-inch thickness without cracking at the edge. Rivets should also
stand having a punch of nearly their own diameter driven right through the
shank of the rivet when hot without cracking the iron round the hole." ^

Appearance of the Fractured Surface of Wrought Iron. — ^At one time it was
thought that a fibrous fracture was a sign of good tough wrought iron, but that
a crystalline fracture showed that the iron was bad, hard, and brittle.

Mr. Kirkaldy's experiments led him, however, to the following conclu-
sions.'

" 1. Whenever wrought iron breaks suddenly, a crystalline appearance is the inTiri-
able result ; when gradually, invariably tkfbrous appearance.

**2. Whether, on the one hand, it is finely or coarsely crystalline, or on the other,
the fibre be fine and close, or coarse and open, depends upon the quality of the iron.

'* 8. When there is a combination in the same bar or plate of two kinds — the one
harder or less ductile than the other — ^the appearance will be partly crystalline and partly
fibrous, the latter produced by the gradual drawing asunder action previous to and at the
time of rupture ; whilst in l^e former the iron breaks suddenly, without elongating at
time 01 rupture.

"4. When the proportion of the harder is considerably lesH than the softer, the for-
mer snaps suddenly, whilst the latter continues stretching ; but when nearly equal, or the
less ductile predominates, both portions break together, or almost at the same moment ;

' Graham Smith in Proceedings Liverpool Engineering Society, from ** Engineer.**
' Kirkaldy's Bx^aerimuinls on Wrought Iron and Steel.

DESCRIPTIONS OF WROUGHT IRON. 283

the one part, gndoAUj aniTing at its limit of endunnoa^ breaka with a flhitnis appear-
ance, whilit a greatly increased strain consequently coming on the remaining portion, it
suddenly gives way producing a crystalline appearance.

" 5. The relatiye qualities of Taiious irons may be pretty accurately Judged of by
comparing their fk-actures, provided they have all been treated in predsely tiie same way,
and all broken under the same sort of strains similarly applied.

"6. By varying either the shape^ the treatment, the kind of strain, or its application,
pieces out oflT the same bar will be made to present vastly different appearances in some
kinds of iron, whereas in others little or no difiSsrence will result"

It will be 8een then that the appearance of the fractnied snifiEuse of wrought
iron ia to a certain extent an indication of its quality, provided it be known
how the stress was applied which produced the fracture.

Good iron may be either crystalline or fibrous, according as the stress which
caused fiacture was sudden or gradual, but it should be remarked that bad
iron is never fibrous.

Small uniform crystals of a uniform size and colour, or fine close silky fibres,
indicate a good iron.

Coarse crystalB, blotches of colour caused by scoriaa or other impurities, loose
and open fibres, are signs of bad iron, and flaws in the fracture surface are
signs that the piling, welding, and rolling processes have been imperfectly
carried out

Fractures examined should be those of bars at least half-an-inch thick, or
they will become distorted and will not exhibit the characteristic peculiari-
ties to be seen in larger bars.

The fibres of wrought iron are readily exposed by immersing the specimen
for a few days in very weak hydrochloric or nitric acid, which eats away the
material between the fibres, leaving the latter exposed.

Test by means of Falling "Weight, or Impaot Test. — In testing iron for very im-
portant situations, where it will be subject to sudden shocks, it is well to subject it to
the tension produced by a weight falling from a height, so as to imitate as nearly as
possible the action of the force to which it will be subjected.

This is done in the case of bolts for fastening the thick iron plates of armour-plated forts.

These are tested by means of a ton weight falling through a distance of 30 feet The
testing apparatus is so arranged that the blow acts in the direction of the length of the
bolt This, it is found, will pull asunder a 8-inch bolt in six or seven blows. The
firacture is required to be " silky fibrous, not crystalline in any degree,*' and the contrac-
tion of area 40 per cent

Iron rails are also sometimes tested by a fSedling weight

DIFFERENT DESCEIPTIONS AND MAEKET FORMS OF
WROUGHT IRON, AND THEIR RELATIVE VALUR

DESCRIPTIONS OF WROUGHT IRON.

The following are the different kinds of wrought iron most generally known
in this country.

Swedi^ Iron is made from pure magnetic iron ore — chiefly from Danne-
moia — smelted with charcoal

It excels any iron made in this country with regard to tenacity and tough-
ness, but its great cost precludes it from use in engineering and building
structures.

Best YorJahire Iron — ^produced by certain well-known firms of long stand-

284 NOTES ON BUILDING CONSTRUCTION.

ing (see p. 299). This iron can be more thoroughly relied upon for strength,
toughness, and uniformity than any other made in this country. It is gener-
ally specified for important work intended to withstand an unusual stress, or
to resist sudden shocks, or changes of temperature.

Other Yorkshire manufactures — Staffordshire Iron, Scotch Iron, Cleveland
Iron, NewcasiU Iron, MiddUsborou^h Iron, Welsh Iron, etCw eta, are other
descriptions of bar and plate iron in the market They vary considerably in
quality ; some of them possess considerable strength and toughness, are only
half the cost of best Yorkshire iron, and are more generaUy used for ordi-
nary purposes.

These different varieties are generally distinguished by marks or brands,
which are described at p. 296. The qualities of the different kinds of iron are
further referred to in connection with the brands under which they are sold.

MARKET FORMS OF WROUGHT IRON,

Wrought Iron is prepared for the market in several convenient forms.

Ordinary Dimensions are those generally made and kept in stock. Every-
thing required of different dimensions from these must be paid for at a higher
price. The ordinary dimensions for each district are given in the list of
extras, p. 291.

The extras charged in South Staffordshire, also in the North of England,
Wales, and Scotland, are shown in the list at page 291, which is copied from
that compiled by Messrs. Boiling and Lowe, London.

Dead Lengths and Exact Dimensions are also chai^gea for extra, that is when
a bar must be the exact length specified within ^ inch, or when a plate must
be a special unusual length by a special unusual width in disproportion.

Iron of irregular or unusual figure or dimensions, or cut according to
sketches, is also charged extra.

"Bar Iron includes simple sections — around, square, or flat

H ^ ' I Ordinary dimensions are generally from ^ inch to 3 inches
^ ^^1 diameter, or sides, increasing by t^ of an inch each size.

If under ^ an inch diameter, they are classed as rods ; or if under A inch
diameter, as wire.

i^HB Flat Bars. — The ordinary dimensions are generally from 1 foot by ^
of an inch to 6 inches by 1 inch, the width increasing i of an inch and the
thickness increasing i^ of an inch (at the same time) in the various sizes.

Bars of these sections may be readily obtained of to 22 feet in length with-
out extra charge.

^ Half round, ^^ OvaZ, ^^ Convex, stm^ Half -oval, # Hexagon^

w Octagon, and ^^^ Tyre iron, are other sections which are useful for dif-
ferent purposes, but which need not be more fully described.

Bar iron is classified as to quality in the manner described at p. 274.

Uses. — Best Forkshire Bar Iron is used for locomotives, and in superior
shipbuilding, also for bolts and fastenings of very important structures.

Best Best Bar Iron of other descriptions is used for all very important work
where the expense of Lowmoor, Bowling, or other best Yorkshire irons ex-
cludes their use.

MARKET FORMS OF WROUGHT IRON. 285

Beat Stafordtkire Bar Iron is used for ordinary work in bridges and roofs.

Common Bar Iron is used where the iron requires hardly any foiging, and
is not expected to offer much resistance. It suffices for hurdles, standards,
and, in faict, ordinary work.

Angle and T IronB. — Iron of these sections is most useful in a great
many building and engineering structures, such as roo&, girders, bridges, etc.
etc.

The sections are made of a great variety of dimensions. Iron merchants
generally publish lists showing those that they keep in stock.

• The sides a h^h c are sometimes equal, as in Fig. 117; sometimes unequal,
as in Fig. 118.

These forms of iron are obtainable in lengths up to about 40 feet.

It will be seen that extras are charged for the smaller sized angle and T
irons, also for sections exceeding 8 united inches, that is sections in which the
sum of the length of the sides, or of the length of both and stem, is more
than 8 inches.

Extras are also charged for sections haying an obtuse or an acute angle, as
in Figs. 121, 122 ; or '^ round-backed," as in Fig. 123.

Angle irons cannot well be rolled of a thickness less than i of the width
of one side. On the other hand, if they are very thick, there is a consider-
able percentage of loss of metal in the rivet holes.

They should have sides or flanges of equal thickness — ^holding up the full
thickness to the ends of the flanges, not feather-edged.

Channel Iron, known also as half H iron, is a form fre-
quently used in lattice girder bridges and simila^ structures.

The united indies in channel iron consist of the width added to
twice the height ^«- ^2*-

Boiled Girder Iron, known also as Boiled Joist IroUy Beam Irony I Iron^
or H Iron.

This is one of the most useful sections of iron for fireproof and
other floors, parts of bridges, roofs, etc, and is rolled in depths of
from 3 to 20 inches.

An endless variety of sections is kept by different makers who
generally publish full-size sections of their iron joists, showing the
weight per foot run of each joist, and the distributed load that it p. .or
will support

Misoellaneous Sections. — Besides the above-mentioned there are a great
many forms of wrought iron, some of which are in common use, others re-
quired only for special purposes.

A few of these will now be briefly mentioned. Their sections are shown
below.

I T LL L

Fig8.12e. 127. 128. 129. 180. 181.

►n, / Iron,

286 NOTES ON BUILDING CONSTRUCTION.

Bulb Beam (Fig. 126) is chiefly naed for shipbuilding.

BuJh Tee Beam or Deck Beam (Fig. 127) is also used for ships, and some-
times for roofs.

Btdb Angle (Figs. 128, 129) also for ships.

Square Boot (Fig. 130), used for riveted structures in which the feather
edge would cause an empty space.

Double Angle or Z Sections (Fig. 131), used for riveted structures instead of
a flat and two angle irons.

Bail Bars. — These are made of various sections ; some of them may be
illustrated, but need not be described.

Figs. 182. 188. 184. 186. 185a.

Double-headed Bail (Fig. 132). — Formerly a section in common use, but
now mostly found on British lines only.

Vignolee or Flat-boUom^d Bail (Fig. 133), used especially on Continental
lines, in India, and the Colonies.

Bridge Bail (Fig. 134), used mainly by the Great Western Bailway Com-
pany for the broad-gauge traffic.

Tram Bail (Figs. 135 and 135a), are only two of the many forms of sec-
tions used for tramways in streets.

Sash and Fancy Jron.^>This class includes a great variety of forms of iron

Figs. 186. 187. 188. 189. 140. 141. 142. 148.

«u^ han^ such as those in Figs. 136 to 138 ; Beading Iron^ for ornamental
work, as in Figs. 139 to 141 ; Cross Iron (Fig. 142), for struts ; Quadraid
Iron (Fig. 143), for building up parts of structures ; and other sections useful
for different purposes.

Market Sections. — Before ordering L, T, U iron, joists, or iron of the
various other sections, it is well to ascertain the dimensions of the usual sec-
tions kept in stock by the merchants, or for which the works have rolls. Iran
merchants give their customers printed lists of all such sections, and selections
should be made from them. If sections of tmusual form and dimensions are
called for, extra expense and delay are occasioned.

The lists include almost every variety that can possibly be required ; for
example, in those of Messrs. Boiling and Lowe.

Angle irons are shown from } inch x | inch x ^ inch thick up to 8 inches
X 8 inch x | inch thick.

T irons from 1^ inch table x | inch stem x | inch thick, up to 12 inch table
X 3^ inch stem x J inch thick.

U irons from $ inch wide x | high x A thick, to 12 inches wide x 4 inches
high X ^ inch thick.

Z iron from 2| inches high x 1 inch wide x \ inchthick^to 20 inches high
X 11^ inches wide x 1^ inch thick.

MARKET FORMS OF WROUGHT IRON. 287

Bi^et Iron, Chain Iron, Horse-shoe Iron, 19'ail Iron, arc special
qualities maTmfactnred for the purposes indicated by their lespectiye namea

Plate Iron is made in thicknesses between \ inch and 1 incL

The different thicknesses vary iVth inch each in succession.

When beyond f inch thick the plates are generally of ordinary quality,
unless specified ''best" or '^best best"

Extras, — Large or heavy plates are more expensive because they require
more care and labour in manufacture.

The extras charged upon plates vary slightly in the different districts, as
will be seen by the list of extras.

Thus, in Staffordshire, an extra is charged if the plate is more than 15 feet
long or 4 feet wide, or if it contains more than 30 square feet sui£eu», or
weighs more than 4 cwt In the North of England many of these extras are
given up, and a proportion (say 10 per cent) of an order for plates, weighing
as much even as 10 cwts. per plate, wiU be rolled without extra charge.

Plates less than \ inch thick are charged extra in the Cleveland district

nBB& — Common plates are used for shipbuilding, and called '' ship platea"

Best plates, also for shipbuilding where more tensile strength is required,
and for girder work.

Best best plates, for the better class of shipbuilding, such as men-of-war, also
for boilers of engines.

Treble best plates are used in boilers of superior construction, and first-class
work generally.

Chabooal Platb is produced by a peculiar process of refining with charcoal
instead of coke.

It is very tough and strong, and can be bent either way, with or against
the grain, and is used chiefly for the manufacture of utensils which are
stamped out of it

Tin Plates are coke or charcoal iron plates coated with tin.

Ternb Plate is the same plate coated with an amalgam of lead instead of
tin, and wears a less brilliant look, but suffices for lining packing-cases, eta

Mallet's Buckled Plates. — ^These are plates of any shape in plan, arched
from the edgep towards the centre ; the arch has a very slight rise, and forms
a dome or groined surface, according as the plate is round or square.

Such plates wiU bear a very great weight, and are applicable to fireproof
floors, bridges, and several other purposes.

Flitch Plates are made in widths up to 18 inches for use in flitch girders
(see p. 278, Part IL) They are generally of common iron, as they require no
bending or smithing, nothing but a few holee punched.

Sheet Iron Is so called when the material is of a thickness equal to or less
than No. 4 EW.Q. — i,«. -239 inch ; above that thickness the material is
called plate iron.

It is generally of superior quality and higher price (as there are so many
more sheets to the ton, and consequently extra labour in rolling, etc., than in
plate iron) and its thickness is specified in terms of the Birmingham wire
gauge (B.W.G.)

The following table ahows the classification of aheet iron as to thickneas:^

388

NOTES ON BUILDING CONSTRUCTION

Name of aoM.

B.W. Gauge.

Thickneee.

Prom

From

Singles

'289

•085

Doables

•085

•020

LatteDB

•020

•016

Sheet iron is not mucli required for engineering purposes, bnt in many places
it is used for roofing churches, houses, sheds, etc.

Chmigated Sheet Iron is made by passing sheets between grooved rollers,
which force and bend them into a series of parallel waves or corrugations.
These enormously increase the stiffness and strength of the sheets, and adapt
them for several purposes for which the flat sheets would be too weak.

The sheets must be of good quality to stand the process, or they will cracL

The sheets are in sizes, generally about 6 feet by 3 feet 2 inches, or 8 feet
by 3 feet 2 inches, before corrugation ; with corrugations 5 inches apart, which
reduce the width from 3 feet 2 inches to 2 feet 6 inches.

The thicknesses and weights are as follows : —

Birmingham

Wire Gauge.

RW.G.

Thickneaa
in inchea.

Weight

Width

of
Flutea.

Ueea.

No. 16 .

•066

880

5 in.

Where great strength is required.

„ 17 . .

•056

820

>»

■V

» 18 .

•049

280

n 19 .

•042

252

)

„ 20 .

•086

224

8 in.

„ 21 .

•082

206

« 22 .

•020

186

.. 28 .

•025

166

•\

.. 24 .

•022

150

Sent to Colooies.

„ 26 .

•020

112

Fig. U4.

"The flates or corrogations are made of varioiM
widths, those most usual in England being 8, 4, and
5 inch. Sheets with 5 inch flutes are commonly pre-
ferred by engineers. The depth D is generally | of
the width A, and the proportions can only be modi-
fied in the manufacture by making special new dies.
Sheets with flutes wider than 6 inch are occasionally
used when great strength is required, but in such cases
the thinner gauges of iron should not be employed." ^

The ordinary form of corrugation is shown in Fig. 144, the sheets, when

y^---^ ^wed for roof-covering, being laid with the comi-

y/ ,^r"^ gations parallel to the slope, A special form, shown

^"^'"•m^r ^^*""^ in Fig. 145, is sometimes made for sheets intended

^"""^"'W ^\ ^ ^® ^*^^ ^*^^ '^® corrugations parallel to the

^-^/ ridge.

^"^ Corrugated iron is generally galvanised (see next

Pig. 145. paragraph). ^

^ Matheson's Works in Iron*

VALUE OF WROUGHT IRON, 289

Galvanised Iron is iron covered with a coating of zinc by the procesB
described at p. 335.

The quality of galvanised sheets depends upon the kind and thickness of
the Iron, the purity of the zinc, and the care with which the process has
been conducted

Continuous Galtxinised Iron Boofing Sheets are made in lengths of 100 and
200 feet, and of the undermentioned widths, gauges, and weights. They
are very suitable for light roo& and save much expense and trouble as there
are so few joints required.

31 gauge 24 inches wide, weighs 8 ounces per square foot.

28 „ 24, or 30 „ „ ,,11 „ „ „ „

26 „ 24, 30 or 36 „ „ „ 13 „ „ „ „

24 „ 24, 30 or 36 „ „ „ 18 „ „ „ „

Hoop Iron is made of the widths and gauges specified in the list of extras,
p. 292.

It is not much use in building, except as an additional bond in brickwork,
for which purpose it is generally about 1^ inch wide and of No. 16 BWQ,
tarred and sanded, and laid as described in Part II. p. 228.

Mitis Wroaght Iron Castings are produced by Mr. Nordenfeldt's patent process.
They are made from scrap irofl containing a very small quantity of carbon. This is
melted in crucibles, and has to be raised to a very great heat produced by the use of
naphtha as ftieL The molten metal is poured into the moulds from ladles in which the
contents are kept hot by means of a surface blast. The best castings are made from the
highest class of irons, such as Swedish or Best Yorkshire. Raw material containing as
much as } per cent of phosphorus makes the castings too brittle. These castings may be
readily run into any form required, and the inventor claims for them that their strength
is 20 per cent greater than that of the best forgings.

A specimen mentioned by Mr. Warren ^ in his paper on cast steel gave the following
results:

Tensile test, 28 tons per square inch.
Elongation in 2 inches, 12'8 per cent

RELATIVE VALUE OF DIFFEEENT DESCRIPTIONS
AND FORMS OF WROUGHT IRON.

The price of iron of all kinds fluctuates continually according
to the state of the market. These Notes do not profess to deal
with the cost of materials; and the following lists are given
merely to show the relative value of iron from the districts
named, and the difference in cost of the various forms and
qualities.

The Table of Prices on page 291, and the list of extras charged
on British iron from Staffordshire, the North of England, Wales,

' In paper read before the Institute of Naral Architects, 21st May 1886.
B. C. — m U

290

NOTES ON BUILDING CONSTRUCTION

and Scotland, are taken from the current price-list for July 1885,
issued by Messrs. Boiling and Lowe, of 2 Laurence Pountney
Hill, London, E.C. The prices and extras for Lowmoor iron are
from the list of Mr. Berkeley Paget, of 2 Laurence Pountney Hill,
for September 1884.

The details which follow with regard to extras, brands, etc,
may appear to be superfluous, or at any rate too voluminous.

They serve, however, to impress upon the student that there is
a great variety as to these particulars in different districts ; and it
is hoped that they may be of value to those engaged in practice,
to whom a few condensed paragraphs on the subject would be
disappointing and almost useless.

Price Current, July 1885. — Merchant Iron.

Staffordshire aivd Midland.

North of Bwo-

LAND.

Wales.

SCOTLAKD.

TOEK

saiRL.

Com-
mon.

Good

marked

iron.

List
Brands.

"Bird"
Admir-
alty Test
Iron.

Quality.

Ordi-
nary.

L*>»
Superior itr-f.
Quality. Bowlitj:

Per Ton.

PerTon. PerTor

£ ». d.

£ s. d.

£ $. d.

£ ». d.

£ t. d.

£ 8. d.

£ s. ±

£ 8. d.

£ e. d, £ $.±

Bar Iron , . .
(Ordinary Siaas.)
Platbb, Ship .

e 7 «
8 7 6

7 0 0

8 10 0

8 2 6

5 10 0

6 10 0

6 0 0

7 0 0

5 5 0

6 5 0
6 15 0

6 10 0 19 0 0

7 10 0

Do. Boiler .

8 15 0

9 12 6

7 10 0

••

7 0 0

7 10 0 2S 0 0

Shebtb, singles .

8 7 6

8 16 0

9 12 6 1 » 12 6

7 5 0

8 0 0

7 10 0

8 10 0 26 0 C

Hoops (Ordinary

Gauges)
Akolb Iron . .
(To 8 united in.)
Te£ lR02f (ditto)

6 17 6

7 10 0

8 12 6

••

7 0 0

7 10 0

8 0 0

7 2 6
7 12 6

7 10 0

8 0 0

8 17 6

9 2 6

8 12 6

9 2 6

5 10 0

6 10 0

6 0 0

7 0 0

7 0 0
7 10 0

7 10 0

8 0 0

33 10 0

Extra for Best

Iron
Extra for Best

Best
Extra for Treble

Best

10..
808.
60s.

208.
40b.
60s.

20s.
408.
60s.

808.

10s.
SOS.
508.

lOs.

lOs. ' ..

80s.

508.

Jklivt

ry in LivtrpooL

Delivery in Tyw
or Tees.

Delivery
in New-
port or
Cardiff.

Delivery in Claa- Drftrrrj
gou> or Leith. cf

London
Hull .

1 6s. to 78. 6d. per
r ton extra.

London, 10s.
Liverpool, 12s. 6d.
Hull. 38.
per ton extra.

5 ,

11 &

London, 8s. 6d.

Liverpool, lSs.6d.

pertonextnk

EXTRAS ON WROUGHT IRON.

291

Juiflt Iron, Girder Iron, and Channel Iron are not included in the above list, but their
prices as given in Messrs. fiird*s other lists may be summarised as follows : —

BIZE8 IN INCHB&

Price m Ton.

FROM

Depth.

Width.

Thickness.

Depth.

Width.

Thickness.

Joist Iron, Eng-
lish

£8:5s.to£8:15s.

Girder Iron

£9 to £11

Channel Iron

8»

£7 to £11

Lengths up to 80 feet without extra. Sawing hot to lengths included. Dead lengths
cut cold, 7s. 6d. per ton extra.

The higher prices are for those sections with wider flanges and peculiar shapes.
Foreign joist iron may be obtained at about £2 a ton less than English joist iron.

lost of Extras on British Iron.
StaffbrdBhire.

BOUND AND SQUABB.

Ordinary dimensions are from ^ to 8 inches,
i A A H i W A H 8ito3J 8ito4 41to4i 4Sto6in.

40s. 508. per ton.

A A

70s. 60s. 40s. 858. 80s. 25s. 208. 15b. lOs. 58. lOs. 20s.

BOUND ONLY.

5f to 6 6| to 6i 6f to 7 inches.
90s. 110s. 180s. per ton.

FLAT IBON.

Ordinary dimensions are from 1 to 6 inches wide by ^ to 1 inch thick.

1 inch wide

i M .

I » .

4 ,. .

6 to 7,
20s.

208.
308.
808.
408.
408.

IDs.
lOs.
208.
808.
80s.

8 to 11 inches wide.
80s. per ton.

lOs.
lOs.
208.
20s.

10s.
10s.
208.
20s.

I inch thick. ^

... per ton.

lOs. • „
lOs. „
20s. „
208. „

3-aj

- si

HALF BOUND, OVALS, ETC.

„ ^ in thickness less than i inch .

•

xvs. per buu.
. 58. „

ANQLB AND T IBON.

i inch thick.

2i to 1 inch wide .... 208.
1 „ .... 80s.
J „ .... 408.

lOs.
208.
808.

... per ton.
lOs. „
208. „

For eyery inch or part of an inch exceeding 8 united inches, lOs. per ton.

292 NOTES ON BUILDING CONSTRUCTION.

HOOP IROH.

Ordinary widths and gauges are as followB : —

Inebet.

Inches.

81 to 6,

not thinner than No. 14 WG.

1| to 1 , not thinner than No. 18 WG.

2ito8i

ft »» ft 15 If

1 tol .. „ „ 19 „
ito 1 „ „ f. 20 „

l|to2

If II tf 1/ It

Should the above widths be required in thinner gauges than specified, lOs. per too
extra will be charged for each number of the Wire Gauge up to No. 20, and 20b. per ton
exceeding that No.

1 11 ^ ii>ch.

Extra for width . . 208. 408. SOs. 1208. per ton.

jles to No. 20 WG — . Doubles 21 to 24 WG, 80s. per ton ; and Latten 25 to 27
WG| OOs. per ton aboye the price of Singles.

For each No. thinner than 27 WG, and for sheets 8 inches wide and under, firam 14
to 27 WG, as per agreement

PLATB.

Up to 4 cwt per plate, not exceeding 80 feet super and not above 15 feet long or

4 feet wide, or narrower than 1 foot : —

From 4to5 5to6 dto7 7to8 8to9 cwt per plate.

lOs. 25s. 508. 75s. 1108.perton.

Welsh.

Ordinary dimensions are from | to 8 inches round and square, and Flats 1 inch wide
by i, and IJ by J inch to 6 by I inch.

SMALL FLATS.

I^ to 4 in. wide by -^iu. 4| by 6 in. wide by ^ in.

lOs. 208.

Isndliby^ IbyA 1 to If by | | by | A 1

lOs. 20s. . 808. lOs. lOs. 10s. SOs. 80b. per ton.

*^* * 1 * 1 *^' * 1 * 1 *^^* * 1 ^ 1

10s. 208. 20b. 80s. 408. 20s. 808. 80b. 40b. SOs. 80a. 408. 408. 508. 608. per ton.

LABGK FLATS.

7i to 8in.byfVto Ain. . SOs-pertoo.

7i f, 8 „ I „ 1 „ . 208. „

7i „ 8 „ iX „ 2 „ . 808.

9 „ 10 „ I „ 2 „ . 508.
ff I II 2 „

S^to 4in.by2ito8 in.

4^ ft 5 „ 2 „ 8 „

H If 6 „ u » n *f

5i „ 6 H 1} 11 2 „

^i II 7 „ A If A ft

108.perton.
208. „
108. „
208. „
808. „

12 „ 20 „ 1 ,1 2 „ . 60a. „

SMALL ROUND, SQUABB, AND OOTAQOV IBOV.
* 1 * 1 * 1 *

lOs. lOs. ' 20b. 808. 408. 508. 1008.perton.

LAROB SOUIfD AVB SQUABB IBOK.

Not over 6 cwt. per bar.

81to8i 8ito4 4ito4i 4Sto5 5ito5i 5ito6

lOs. 208. 808. ; Toundii only 508. 608. SOs. per ton.

Bundling sizes above A ^<^^ round* and squares, and 1| by } inch flats, 2s. 6d. per tou.

EXTRAS ON WROUGHT IRON. 293

SOOtolL

Qrdiiuury dimenrions are from ) to 8 inches ronnd and sqnaxe, and Flats IJ to 6
inches wide by J to 1 inch thick.

FLAT, HALF-ROUin), 0YAI» AJXD HALF-OVAL.

L iL !l tL L L

} inch wide ... lOOs. SOs. COs. ... ... per ton.

iV f> ••• ••• <(08. 608. 508. 208. „

\ „ ... 608. fiOs. 508. 408. ... ,,

I „ ... 508. 408. 408. SOs. 308. „

f „ 608. 408. 808. 808. 208. lOs. „

I „ 408. 808. 208. 208. 108. lOs. ,,

land It „ 808. 208. lOs. lOs.

lito6 „ ' ... 108. „

6|to7 „ ... 208. 10s. 108. lOs. lOs. ,,

7i 8 8i 9 10 11 12 inch.

208. 808. 408. 508. 508. 608. 608. per ton.

ROUim, BQUABB, AND OCTAGON.

81to8| 4 4i 4i 4| 5 5i 5i 5} 6 V^ i A i ui^-

10s. 208. 808. 40s. 50s. 608. 708. 808. 908. lOOs. lOs. 208. 808. 40s.
No. 4WG. No. 5WG. A and No. 6. No. 7 WG. No. 8 WG.

508. 608. 808. lOOs. 1208.

FLATS, BOUNDS, AND SQUABBS, WHBBB NOT BZTBA FOB SIZE.

For every half-cwt over 5 cwt, lOs. per ton.

Common quality of Rounds, Machine-straightened, lOs. per ton.

For Ovals, twice the extra, and for Half-ovals, three times the extra on above

sizes of Flats. Convex 1| inch broad and under, 20s. per ton.

Half-circles, 1^ inch broad and under, 20s. per ton in addition to above extras for

Half-ovids.

ANGLE AND T IBON.

i by I inch wide } by { inch wide A inch thick ( inch thick

20s. 80s. lOs. 208. per ton.

For every half-inch exceeding 8 united inches, lOs. per ton.

HOOP IRON.

6i inches to 2} inches wide, if thinner than 15 WG ^

2 „ „ 1} „ „ 17 „ 1 108. per ton for each

li „ „ 1| „ „ 18 „ jnumber of the WG.

I4 t» w 1 >» »» 19 „

} I i i inch wide

208. 408. 808. 1208. per ton. If thinner than 20 WG, 20s. per ton for each
number of WG.

SHEET IRON.

Doubles, No. 21 to 24 WG SOs. per ton.

Latten, „ 25 to 27 » 608. „

For each gauge thinner 208. „

If under 12 inches wide lOs. „

„ 24 „ long lOs. „

PLATES.

For each cwt above 6 cwt, per plate .... 10s. per ton.

„ foot „ 15 ft. long „ .... lOs. „

If under 12 inches wide „ .... lOs. „

„ 24 „ long „ . . . . lOs. „

294

NOTES ON BUILDING CONSTRUCTION

If above 51 to 54 inches wide, per plate .

lOs. per tan-

, 54 to 57 „ „ . , .

20s. „

, 57 to 60 „ „ . . .

80s. ..

From No. 7 WG to 1 inch bare thick, per pUte

lOs. „

North of England.

BOUND AND SQUABS.

FLAT IBON.

Per ton extra.

Ain.

. 108.

4ito4iin. . . 80s.

in. wide

30s.

f» .

. 208.

4i „ 5 „ finds, only 40s.

M »f ■ •

20s.

A,.

. 808.

5| „ 5J „ „ „ 60s.
5i „ 6 „ „ „ 708.

»» »» • •

lOs.

:: » •

.408.

>» »♦

10s.

8| to 3i in

. 108.

6J „ 6i „ „ „ 80s,

n n

15s.

3f ., 4 „

. 208.

•» »t • •

20a.

jV and under \ inch thick, 10s. per ton extra.

No oomn

ion Iron made above 6 inches wide, or 8 inches round or square, or below \

inch round

or square. 6 to 8 inch Flat is not rolled thinner than | inch.

ANGLE IBON.

lin

. by 1 in. \\ in. by IJ in.

IJ in. by li in.

20s. 108. lOs.

For every inch or part of an inch above 8 united inches, lOs. per ton.
A inch thick, 10s. per ton.
Up to 8 united inches, ordbiaiy length is 40 feet; above 8 and not exceeding 10
united inches, ordinary length is 85 feet

For every foot or part of a foot above ordinary lengths, 28. 6d. per ton.

FLATBB.

Ordinary sizes up to 15 by 4 feet, or 8 cwt per plate.
Best and Best Best above 6 cwt., Best, Best, Best f|^ above ) ^

4 cwt i

A and under | inch thick 10s. „

■ tf n » ......... 20s. „

Tot every 6 inches or part of 6 inches, exceeding 4 feet wide, 208. per ton.

„ „ „ under 1 foot „ 208. „

Above 15 feet and not exceeding 18 feet long .... 20s. per ton.

„ 18 „ „ 25 „ . . . . 40s. „

„ 25 „ „ 80 „ . . . . 60s. „

Torkshire.

The loUowing prices and extras chaiged upon Lowmoor Iron may be taken as a sample
of those for other Best Yorkshire Iron.

Babs— i^To^ Bound, and Square. Bona— Flat and Round.

Weight, cwts.. To 8^, 3} to 5, 5 and upwards.! Size...li x t" Under | to J* Under i to i" I'
Price per cwt. ..18s. 19s. 20s. | Price, cwt ISs. 198. 208. 28a.

For each i" less than l^" lOs. extra per ton.

BoDB^Square. Bods— Round.

Size i" and upwards. A" T and A' J" I Size, f upws. A' &»<! i" A' and |" tV* i"

Price per cwt 18s. 20s. 22s. 24s. | Price, cwt. 18s. 20s. 22s. 24s. 26^

Rivet Ibon — Same as above. Chatn Ibon — Stamped Lowmoor Chain, Is. per cwt extra.

LMB. — Best bars snd rods, 3s. per cwt extra,
Boilbb Platb— Weight in cwts. To88to8i8ito44to55to77tol0 above 10.
Price per cwt... .21s. 23s. 268. 27s. 80s. 338. 368.
All plates exceeding 6 feet wide, 2s. per cwt extra. All plates cut to a curve of 6
inches rise and upwards, or whose waste in shearing from a square form exceeds 20 per
cent, extra per cwt 25s. Thick-edged plates, 8s. per cwt extra.

L AND T IBON—Not exceediug 10 united inches, 20s. per cwt ; extra per additional
inch, 28. per cwt Shbbts, 11 to 17 WG, 238. per cwt

BRANDS ON IROS 295

LRANDS ON lEOX.

Pig-iron Brands.

The different pig-irons in the market are distinguished by brands, which
indicate the locality from which the iron was procured.

The brands, which are in raised letters on the pig, serve as a guide to the
quality and place of manufekcture. The brands are sometimes the initials of
the manufacturer, but more commonly refer to the place of production.
Thus the brands Blaenavon, Gartsherrie, Weaidale, indicate at once to the
initiated that the first is a Welsh, the second a Scotch, and the third a Kortb
of England pig'-iron.

G.M.B. are letters often quoted in price-lists, etc. ; they do not refer tu
any particular locality, but stand for '^ Good Marketable Brands."

As already stated, the engineer has but little personal concern with the
peculiarities and shades of difference between the brands of the same or differ-
ent districts. It is sufficient for him to specify that the finished iron he
requires must stand certain tests, and the selection of ores, pig-iron, and other
raw material, required to effect this is better left to the manufacturers.

It may be useful, however, to mention a very few of the principal brands
in each district, with their characteristice. The classification of pigs by
numbers has been described at p. 263.

Yorkshire Brands. — ^There are several ordinary descriptions. The best
works, such as Lowmoofy Bowling, FamUy, etc., use the local ores mixed
with other kinds.

Scotch Brands, such as Colder^ Clyde, Govan, Cambroe, Carron, Oart$-
kerrU, Langloan, CoUness. This pig-iron, chiefly from clay ironstone, and used
largely for foundry purposes ; sometimes mixed with N. England pig-iron to
improve its strength.

North of England Brands, such as Aetlam, RtdsdaU, Southbani,
WeardaU, etc, are chiefly from ores of the Carboniferous system, tougher and
stronger than Scotch, and used chiefly for foige purposes. Cleveland Iron is
from ore of the Lias formation.

Weubh Brands, such as Blaenavcn^ Gadlye, Fstah/fera, Pentyrch, are from
good but lean ores, generally mixed with Spanish, Cumberland, or other
haematite ores, and used in the district for rails.

Blaenavon is a cold-blast pig used for engine cylinders and other special
purposes.

UjUfATiTE ?ig-Iron — Askam, Barrow, Workingtcn, Cleator, Camforth,
Hamngton — ^is made from the rich ores of Cumberland. Is used largely by
steel, tin-plate, and sheet-iron manufacturers. A special quality — ** Bessemer
Pig " (see p. 263) — ^is made for the Bessemer steel workers.

Northamptonshire Pio-Iron is made from poor ore, but useful to mix
with other&

Shropshire Brands are LUleshaU, Madeley Wood, Old Park, eta

Staffordshire Pig-Iron differs very much in quality, and is mostly used
in the district Much of the Staffordshire iron is made from ores from other
counties.

296 . NOTES ON BUILDING CONSTRUCTION

Wrought Iron Brands.

In order to understand the different qualitieB of British wrought iron' in
the market, the relative cost of the different forms, and to form some idea of
the brands by which they are distinguished^ it will be well to examine the
current Price list given at page 276.

It will be seen from that list that the prices of iron vary according to
the shapes in which it is manufactured, according to the locality it comes
from, and also with its quality, i,e. best, best best, or treble best

Before proceeding further it should be mentioned that all good iron has
some sort of mark upon it to indicate where it came from, although it does
not follow that all marked iron is good ; an unmarked iron may be suspected
to be bad ; the maker is probably ashamed of it.

In most cases the only sure way of ascertaining the quality of a piece of
iron is to test it as described at p. 262 ; but as some engineers still specify
certain brands in order to secure a good quality of iron^ it will be as well to
know what some of those brands mean.

It may be stated with regard to brands generally, that, though they
differ in detail, they firequently consist of the maker's initials, name, or device
stamped upon the bar or plate near its end, immediately after which is stamped
either hest^ hat best, or best best besty to indicate the quality ; the letters B,
BB, or BBB are often used instead of the words. The crown which is intro-
duced in many brands has no special signification -, indeed, several crowns
have been known on very bad iron.

Some large exporters use their own marks for particular markets. Thus
Messrs. Boiling and Lowe sell certain irons branded Bird with a horseshoe,
crown, or similar device, or with stars so placed that they can always trace
the works whence the iron came.

Staffordshire Brands. — It will be seen that these irons are divided into
three classes, which are (putting them in order of price) lid brandy ^ood
marked iron, and cornmon iron^

List Brands are those used by some of the oldest established manufac-
turers, known as the lUt makers, who having years ago obtained a good char-
acter for their iron, and thereby secured a connection for their productions,
are able, as a rule, to dispose of it and to fix their own pricesw Of
late years many of the old Staffordshire firms have died out, and other
districts are coming to the front as making special classes of iron suitable for
special purposes. Many engineers however, who have heard of the good qualities
of the iron in former days, or are unwilling to take the responsibility of a
change, still specify the brands to which they have been accustomed, though
they pay a higher price for doing so.

As specimens of list brandsy the following are given : — ^

The iron from the Earl of Dudley's Round Oak Work« i ^ ^^S| ^
marked «»

and also best, double best, treble best, according to quality.

^ It will be understood that a few of the brands of each sort are given as speci*
inens ; it is not intended to assert that they are the best in the market.

BRANDS ON IRON. 297

H^ is the brand lued by Meflsn. Bradley of Stourbridge^ known by engi-
S Q neerg as " SC Crown Iron."

BBH is the mark used by Messrs. W. Barrow and Sons, of South Staf-
fordshire.

I B stands for John Bagnall and Sons (Limited), Staffordshire.

jf^l^ is the brand of the New British Iron Company.

the brand of various makers and firms with or without their initials.

is the brand of Messsrs. Philip Williams and Sons, Wednesbury
Oak Works, known as ** Mitre Iron."

are brands used by Messrs. Brown and Freer
_^ (late Hunt and Brown), Leys Ironworks near

BesTTl B Stourbridge.

J^ is the brand on galvanised iron of Messra William Lee and
0- M/ 0 Company, Gospel Oak Works.

Good Marked Iron is that produced by many manufacturers of repute,
who do not belong to the Ztst makers; their brands are well known, but not
so long established. Their iron can be purchased at 5& to 158. a ton cheaper
than the list brands^ though it may be of exactly the same quality when
gauged by the result of tests. They frequently brand iron with their names,
initials, or devices, and with the usual additions to denote quality — such as
best, best best, beet bed best, A good deal of this iron is made in North
Staffordshire.

Uses. — Of the qualities of iron above mentioned, BBB is used for rivets and
chaina BB iron is used for swing bridges and similar important structures.

B iron, or iron of equal quality, is generally specified for bridges, roofs, and
other ordinary structures in iron.

298 NOTES ON BUILDING CONSTRUCTION.

Under this head the following branda are given as specunens :

SHCLTON llf ^^^^^ ^7 ^® Shelton Bar Iron Company, Stoke.

6MHVILLE H^ do. do.

S& H ^B^ Silverdale (Stanier and Company).

Kinneraley and Company, Clongh Hall Iron Woiks, Kids-
grove.

by the BirchiUs Hall Iron Company, WaLsalL

B.I.C.

8WA^

SPC

BILSTON

8WAN
SPC ^'^ Other brands used by the same Company.

4i y<if\ *"* brands of the Darlaston Steel

«|A ^ ^^^^ \vy *^^ ^" Company, near Wed-

Qw2J T (H>*. DC« m ^^ nesbury, Staffordshire.

MflP Samuel Qroucutt and Sons, Bilstoa

SPARROW XXX. ^' ^^ ^' ^ Sparrow and Sons, Bilston.

OoMMON Iron is made by manufacturers who, being slovenly and careleas
in manufacture, or having but a small range of sizes, or being known to buy
common pig-iron and raw material, or having been found unreliable or want-
ing in uniformity of quality, etc., have to submit to lower rates. Common
iron is, or should be, used only for unimportant work which requires but
little heating or forging to bring it into the shape required.

mdland and other Districts. — The remarks upon the iron manufactured
by the less known makers in Staffordshire apply also to the qualities of iron
priced in this column of the Table, page 290.

gff is the brand used by the Midland Iron Company (Limited), Rotherham.

BRANDS ON IRON 299

PARKQATE ^fff ^tf ^ "^ ^7 ^® Parkgate Iron Company, llotherham.
^ ia the brand of the Pearson and Knowles Coal and Iron Company
B F (Limited), Warrington, for bars and plates.

V IB the brand of the same company for sheets and hoops.
WIW ^

ITorth of England. — The principal make in this locality is in rails, ship
plates, angles, and T irons for shipbuilding, also common boiler plates. The
better varieties of this iron are marked widi a crown.

Well-known brands i

used by Bolckow, Vanghan, and Company (limited), Middles-
boiongh, Cleveland, and Wilton Park Works.

,^_ -^' Jno. Abbot and Company (Limited), Qateshead-on-Tyne.

PALMERS, ^mp Palmer's Shipbuilding and Iron Company (Limited),
Jarrow.

RIDSDALE. Hawkes. Crawshay, and Company, Gateshead.

" CONSETT," by the Consett Iron Company, Newcastle-on-Tyne.

Torkahlre. — ^The term ** best Yorkshire qualities " is generally understood
to refer to iron made by the following works or manufiEicturers : — Lowmoor
Works and Bowling Works, near Bradford, Famley Works, Taylor Brothers,
S. C. Cooper's and Monkbridge Works — the last four in or near Leeds. These
makers owe their reputation to the good ore and coal used by them, and,
above all, to the great care with which their iron is made.

Every process is carefully watched. The different qualities and textures
of iron produced at the various stages of manufiEtcture are carefully selected,
sorted, and blended together, so that the resulting iron as turned out is
thoroughly homogeneous and uniform in quality, and may be relied upon as
equally good throughout

Iron of this class is generally branded with the name of the place where
it is produced in fuU : thus — ^LOWMOOR ; but it has no marks relating to
quality, because it is all of the very best description.

The above-mentioned works make a good deal of bar iron, but their chief
manufacture is in plates for boilers, and railway carriage and waggon tyres,
locomotive axles, armour bolts, eta

Their iron costs about double the price of ordinary brands, principally be-
cause it bears such a high character that it \b genersdly specified for parts of
structures which have to be subjected to great heat, changes of temperature,
or sudden shocks, combined with great tensile strains.

Wales. — The manufacture of bar iron and plates in this locality has of late
years nearly ceased, the chief business carried on being in making raila The
best known brands are WC (Crawshays), GL (Dowlais Company), JBS and
Lie (Llynvi Iron Company, Limited), TW and Company, BJ and Company,
blydach.

300

NOTES ON BUILDING CONSTRUCTION.

SootlancL — ^MannfactnTed iron brands of ordinary quality are ^CoatB"
(short for '' Coatbridge.") Somewhat better brands are Glasgow and Monk-
land.

Swedish Iron is marked, and the brands are noted and classified in an
official book. Examples of them will be seen in Percy's Metattwr^.

STEEL

Steel has been defined by Dr. Percy as ''iron containing a
small percentage of carbon, the alloy having the property of taking
a temper ; and this definition is substantially equivalent to those
found in the works of Karsten, Wedding, Griiner, and Tunner." *

On this point, however, there are many opinions, some of which
will presently be briefly referred to.

The amount of carbon in steel, as used in engineering, varies
from about '12 for very soft to 1*5 per cent for very hard steels.

It contains, therefore, less carbon than cast iron, but more than
wrought iron.

Practically, steel often contains other substances besides iron and carbon.

These substances are generally got rid o^ as far as possible, in the process
of manufacture. When, however, they remain in the steel, they influence its
characteristics in the manner described at p. 262.

In consequence of the practical existence of these impurities, and for other
reasons, it is difficult to give an exact definition of steel.

Several definitions have been proposed, some depending upon the chemical
composition, and some upon the physical characteristics of the material. None,
however, has at present been universally accepted.^

M. Adolphe Orenier, of Seraiog, has classified the irons and steels, aoooidiiig to the
proportion of carbon they contain, in the following manner : — *

Percentage of
carbon.

0 to 0-15.

0-15 to 0-45.

0-45 to 0-55.

0-55 to 1-50,
or more.

Series of the
irons.

Ordinary irons.

Qrannlar irons.

Steely irons or
puddled steels.

Cemented steels.
Styrian SteeL

Series of the
steels.

Extra soft steeL

Soft steel.

Half soft steels.

Haid steels.

Sir Joseph Whitworth has pointed ont that a definition based upon chemical com-
position is unsatisfactory. He proposes to do away with all distinetiTe names such as

^ Dr. Siemens' Address, Iron and Steel Institute, 1877.
* JvuTMl Iron and SUd ImiUule, 1873.

CHARACTERISTICS OF STEEI.. 301

blister stoel, tliear steel, cast steel, etc., end "to express what is wanted to be kiiowD
t>y two numbers which should represent tensile strength and ductility. ... Be
would suggest that the limit of tensile strength be taken at about 18 tons per square
inch, so that the metal exceeding this strength should be cnlled 'steel,* while any descrip-
tion of iron falling below this limit of tensile strsngth should be known as ' wrought
iron.' " 1

An International Committee sitting at Philadelphia in 1876 recommended a some-
what elaborate nomenclature for different descriptions of iron and steeL Dr. Siemens,
alluding to this, says —

" Difficulties . . . have hitherto prevented the adoption of any of the proposed
nomenclatures, and have decided engineers and manufacturers in the meantime to include
under the general denomination of cast steel aU compounds connUing ehi^y of iron
wkieh have been produced through /usion and are moileabU, Such a general definition
does not exclude from the denomination of steel materials that may not have been pro-
duced by fuion, and which may be ca{)able of tempering, such as shear steel, blister steel,
and puddled steel ; nor does it interfere with distinctions between cast steels pmduoed by
different methods, such ss pot steel, Bensemer steel, or steel by fusion on the open hearth. " *

In a paper on " Steel for Structures " Mr. Matheson said, " Steel for the purposes of the
present paper is any variety of iron or alloy of iron which is cast while in the liquid state
into a malleable ingot, and to go fturther, which will when rolled in a plate or bu-, endure
from 26 to 40 tons before fracture." '

To the engineer some practical definition which would enable him to know exactly
what material he would receive under a certain specification would be of great value.

In whatever way steel may be defined, it is of the utmost importance that the character-
istic differences between it and iron, both cast and wrought, should be clearly understood.

Some of these will now be pointed out.

OharaoteriBtios of SteeL — Habdening. — The characteristic
difference between steel and pure wrought iron is as follows : —

When steel is raised to a red heat and then suddenly cooled,
it becomes hard and brittle. This process, which is known as
hardening, has no effect upon pure wrought iron.

Tempering is a characteristic of steel which distinguishes it
from cast iron. If steel has been hardened by being heated and
suddenly cooled, as above described, it may be softened again by
applying a lower degree of heat and again cooling. This is known
as temperinff.

Cast iron, on the contrary, though it is hardened by the first
process, cannot be softened by the second.

When a bar of steel is struck it gives out a sharp meiaUic ring,
quite different from the sound produced by striking wrought iron.

Other characteristics of steel are its great datticUy and its reten*
turn of magnetism.

Amount of Carbon in Sled, — It has already been stated that the peculiarities of cast
iron, wrought iron, and steel are caused by the difference in the amounts of carbon
which they respectively contain.

Pure wrought iron contains no carbon. The wrought iron of commerce contains a
minute quantity, steel contains more, while the largest percentage is found in the softer
kinds of grey cast iron.

1 Prooeedinge Mechanical Engineers^ 1875.

' Dr. Siemens' Address, Iron and Steel Institute, 1S77.

» If.LC.E., vol. Ixix. p. 1.

3oa NOTES ON BUILDING CONSTRUCTION.

The tranaition from one dan to the other is so gradnal and inseuidble that
it is difficult to say where one ends and the other begins, but the following
remarks bear with them the high authority of Dr. Percy.

^ When the carbon reaches '5 per cent and other foreign mattets are present
in small quantity, iron is capable of being hardened sufficiently to give sparks
with flint, and may then be regarded as steeL But in the case of iron per-
fectly free from foreign matters, not less than *65 of carbon is required to
induce this property.

'^ Iron containing from 1*0 to 1 *5 per cent is steel, which, after hardening,
acquires the maximum hardness combined with the maximum tenacity.

** When the carbon exceeds the highest of these limits still greater hardness
may be obtained, but only at the expense of tenacity and weldability.

^ When the carbon rises to 1 '9 per cent or more, the metal ceases to be
malleable while hot ; and 2 per cent of carbon appears to be the limit be-
tween steel and cast iron, when the metal in the softened state can no longer
be drawn out without cracking and breaking to pieces under the hammer." ^

As a general rule it may be said that the varieties of steel containing the
larger proportions of carbon are harder, stronger, more brittle, and more easily
melted. Those containing less carbon are tougher, more easily welded and
forged, but are weaker as regards tenacity.'

VAEIETIES OF STEEL

Methods of Making SteeL — Steel may be produced either by
adding carbon to wrought iron, or by partially refining pig-iron,
thus removing a portion of its carbon until the proper amount
only remains.

There are several ways in which these processes may be carried
out, the result being that there are several descriptions of steel
in the market Of these, however, only a few of the most import-
ant can here be described.

Blister Steel is produced by placing bars of the purest wrought iron in a
furnace between layers of charcoal powder, and subjecting them to a high
temperature for a period varying from five to fourteen days, according to the
quality of steel required.

This process is called cementation. ^^

Swedish iron is generally used for the purpose, that marked Q^ , from the
Daimemora mines, being the best

The steel differs greatly from the bar iron from which it was produced

Its distinctive name is derived from the appearance of its surface, which is
covered with blisters due to the evolution of carbonic oxide.

The bars are now brittle, the fracture is of a reddish or yellowish tinge, with
but little lustre.

The structure is no longer fibrous but crystalline ; " the finer the grain and

' Percy's Metallurgy, * Rankine.

VARIETIES OF STEEI^ y>3

the darker the colour, the more highly carbonised, or harder, will be the steel
produced."

'* When the blisters are small and tolerably r^^larly distributed the steel
is of good quality ; but when large, and only occurring along particular lines,
they may be considered as indicative of defective composition, or want of
homogeneity in the iron employed.'* ^

£^«es.-^Bli8ter steel is full of fissures and cavities, which render it unfit for
forging except for a few rough purposes. It is used for welding to iron for
certain parts of machines, for facing hammers and steeling masons' points,
etc., but not for edge tools. Most of the blister steel made is used for con-
version into other descriptions of steel.

Spring Steel is blister steel heated to an orange red colour, and rolled or
hammered.

Shear Steel, sometimes called TUted steeL — ^By the process of cementation
just described, the exterior only of the bars is carbonised. To produce steel of
uniform quality throughout its mass, bars of blister steel are cut into short
lengths ; these are piled into bundles or faggots, sprinkled with sand and boi-ax,
placed at a welding heat under a tilt hammer, which by rapid blows removes
the blisters, closes the seams, beats and amalgamates the faggots into a bar of
Mingle ehear tied.

In order still further to improve the quality of the metal, this bar is
doubled or faggoted, and again subjected to the processes of hammering and
rolling, the result being a bar of double shear steel.

The oftener the processes of faggoting and hammering are repeated, the
more uniform is the resulting steel, but at the same time it loses carbon during
these operations, and therefore becomes softer.

Characteristics. — The processes to which the steel has been subjected restore
its fibrous character. It is still weldable, is more malleable, and tougher,
is close grained, and capable of receiving a finer edge and higher polish than
blister steeL

Uses. — Shear steel can be forged into such tools as are required to be tough
without extreme hardness, such as large knives, scythes, plane irons, shears,
etc., and it is useful for such instruments as are composed of iron and steeL

Cast Steel. — There are several ways of producing cast steel, some of which
will now be mentioned.

The ingots produced by any of these processes generally contain cavities. In
order to get rid of these, they are reheated at a low temperature and hammered
into bars, being increased in length and reduced in section, by which they
are made compact, solid, and homogeneous.

*' The appearance of the fractured surface of ingots of cast steel varies with their hard-
ness or relative proportion of carbon. The softer kinds are bright and finely granular.
The harder qualities often show crystalline plates of a certain size, arranged in parallel
stripes or columns at right angles to the suiface of the mould, so that in a square ingot
the columns intersect, forming a cross.** *

Crucible Cabt Stebl may be made by melting fragments of blister steel in
covered fireclay crucibles, and running the metal into iron moulds. This pro-
cess was originally introduced by Huntsman of Sheffield.

Most crucible steel, however, is now made direct from bars of the best wrought
iron (often Swedish iron produced from pure magnetic ores). The bars are broken

^ Bauennann's Metallurgy, ' Banermann.

304 .VOTES ON BUILDING CONSTRUCTION

into lengths and placed in the crucibles together with a smaU quantity of cW-
coal, the amount varying according to the temper of the steel to be produced.
Spi^eleisen (see below), or oxide of manganese, is subsequently added.

CharactentUes. — Oast steel is the strongest and most uniform steel tiiat is
made. It is much denser and harder than shear steel, but requires more skill
in forging.

Oast steel made in this way should never be raised beyond a red heat, or it
will become brittle, so that it cannot easily be foiged. It is unweldable, for
it will fly to pieces when struck by the hammer.

In making tools, after forging, the cutting edge should be weU hammered
down, so as to dose the pores or grain of the metal

The fracture of cast steel should have a slaty-grey tint almost without lustre,
the crystals being so fine that they are hardly distinguishable.

Utes, — It is used for the finest cutlery, for cutting tools composed of steel
only, especially those in which great hardness is required.

HecUh*8 Froeeu is an improvement on the method jost deierihed, and consists in add-
ing to the molten metal a small quantity of carburet of manganese.

" After this addition the cast steel possesses much more tenacity at a high temperature
and can be welded either to itself or to wrought iron, so that it may 1m employed far
the fabrication of many implements which were formerly obliged to he made of nheii
steel. Thus the blades of tahle knives can be made of cast steel, welded on to an iroa
(anfff as that part of the knife is called which is fixed into the handle.** *

Hmion*9 Process consists in adding nitrate of soda to molten pig-iron, thus rsmoTin;
most of the carbon and silicon.

MuskeCs Process. — In this malleable iron is melted In emdhies with oxide of manga-
nese and charcoal.

BE88BMSR Procers. — ^6y this process steel is made from pig-iron. The
whole of the carbon is first removed so as to leave pure wrought iron, and lo
this is added the precise quantity of carbon required for the steeL

The pig-iron used should be dark grey, containing a large proportioii of
free carbon, and a small percentage of silicon and manganese. It should be
almost free from sulphur and phosphorus.

The pigs are melted in a cupola,* and run into a converter^ which is a lai)^
pear-shaped iron vessel hung on hollow trunnions^ and lined with firebrick,
fireclay, or ^'^anister"*

A blast of air is then blown through the metal in the converter for about
twenty minutea

This removes all the carbon, after which from 5 to 10 per cent of spiegel-
eisen * (a variety of cast iron rich in carbon and manganese) is added.

The blowing may then be resumed for a short time, in order to thoroughir
incorporate the two metals, the steel is run off into a ladle, and thenoe into
moulds.

The colour of the flame issuing from the mouth of the converter indicates
the moment at which all the carbon has been removed, or this may be accu
rately ascertained by examining the flame with a spectroscope.

' Rloxaui's HfeiaU.

' In some works the melted metal is carried direct from the blast furnace to the
convertiT.

' A sandstone fh)m the coal measures much used in a powdered state for tliu mi
similar purposes.

* Mirror-iron ; so called from its shining appearance.

VARIETIES OF STEEL. y>S

The ingots produced contain aiivholee, and are not sufficiently dense. They
are therefore kept hot and rendered compact by the blows of a steam hammer,
after which they may be rolled or worked as required for the purpose for
which they are intended.

Uaet, — Bessemer steel is used chiefly for rails and tyres for the wheels of
railway carriages, also for common cutlery and tools, such as hatchets, ham-
mers, etc

It is sometimes used for the members of roofs and trussed bridges, also for
the expansion rollers of such structures, and for boiler plates.

The Basic Process, by Messrs. Thomas and Qilchrist, resembles the Besse-
mer process, but that the converters into which the fluid pig-iron is run are
lined with basic material, generally mafspiesian limestone or some refractory
substance as free as possible from silica. By this process the less pure ores of
the Cleveland district, containing a large proportion of phosphorous, can be
converted into steel. Lime having been added, the blowing in the converter
commences, the silicon passes off firsts then the carbon, and then the
phosphorus. When the operation is nearly completed, a small sample ingot
is cast, cooled, and broken, and by the fracture the amount of phosphorous
still remaining is estimated.

Siemens' Prock8& — In this process pig-iron and ore are the ingredients
employed to produce steel by fusion upon the open hearth of a regenerative
gas fmrnace. The pig metal is first melted upon the hearth of the furnace,
and after having been raised to a steel-melting temperature, rich and pure ore
(such as Mokta ore ^) and limestone are added gradually, whereby a reaction is
established between the oxygen of the ferrous oxide and the carbon and
silicon contained in the metal. The silicon is thus converted into silicic acid,
which with the lime forms a fusible slag, whereas the carbon in combining
with oxygen escapes as carbonic acid, causing a powerful ebullition in the
bath.

Modification of SUmen£ Ptoeess, — According to another modification of the
process, the iron ore is treated in a separate rotatory furnace with carbon-
aceous material, and converted into balls of malleable iron, which are trans-
ferred in the heated condition from the rotatory to the bath of the steel-melt-
ing furnace. This latter process is suitable for the production of steel of very
high quality, because the impurities, such as sulphur and phosphoruSi in the
ore are separated from the metal in the rotatory furnace.^

Siemens-Martin Process. — In another important modification of the
same process, which is known generally as the Siemeru-Martin Process, a bath
of highly-heated pig metal is prepared in the furnace, and three or four times
its weight of scrap-iron or steel is gradually added (preferably in a highly-
heated condition) and dissolved in the fluid bath.

^ Prom Algeria.

' See paper by Dr. C. William Siemens, ** Some farther Remarks regarding Pro-
duction of Iron and Steel by direct process," read at Newcastle meeting of Iron and
Steel Institute, September 1877.

B. a — m X

306 NOTES ON BUILDING CONSTRUCTION.

Towards the end of ihese varioiis operations samples are taken from the
bath in order to ascertain the percentage of carbon still remaining in the
metal, and ore is added in small quantities to reduce the carboD to about
•^th per cent At this stage of the process the furnace contains from 6 to 12
tons of fluid malleable iron, to which siliceous iron, spiegeleisen, or ferro-
manganese is added in such proportions as to produce steel of the required
degree of hardness. The metal is thereupon discharged, either by tapping
into a ladle, or more generally directly into ingot moulds by the aacenaioiyJ
process.

Uses, — This material has come rapidly into use for shipbuilding, and
modifications of the same have been extensiyely used for rails, tyres, boileis,
forgings for engines, wire rods, etc

It IB also suitable for bridges, roofe, and engineering work generally.

Whitworth'b Compressed Steel. — It has already been stated that ordi-
nary steel, as first cast, is porous, full of small cavities, which have to be
removed by hammering before a sound metal is produced.

In order to remedy this evil. Sir Joseph Whitworth subjects the molten
steel to a pressure of some six tons per square inch, by which all cavities are
closed up, the gases contained in them driven out, the metal is compressed to
about ^ of its bulk, its density and strength being greatly increased.

Sir J. Whitworth gives the steel a maximum ductility of about 30 per cent
He considers that more is unnecessary, ^ for cylinders of such metal do not
fly into pieces when hurt, but simply open out or tear like paper, and a metal
of greater ductility could not be required for structural purposesi"^ The
strength and ductility of the different varieties is given at p. 309.

Puddled Bteel is produced by stopping the puddling process used in the
manufacture of wrought iron before all the carbon has been removed.

The small amount of carbon that is left, «.& from '3 to 1*0 per cent^ is suf-
ficient to form an inferior steel.

It is used chiefly for making inferior boiler plates and plates for ship-
building.

A similar product resulting from imperfect refining is known as Naiwnl
Steel or German Steel

Mild Bteel contains from '2 to *6 per cent of carbon. When more carbon
is present it becomes Hard Steel

Mild steel is stronger and more uniform in texture than hard wrought iron,
and superior to it in nearly every way.

It is used for welding, also for steel rails, spades, and hammers.

Mild steel made by the Bessemer and Siemens-Martin process is now coming
greatly into use for boiler plates, shipbuilding, etc.

Tunffsten, Manganese, and Ohromium (or Chrome) Steels are made bj

adding a small percentage of the metals named to crucible steel ; the result in each ciso
being a steel of great hardness and tenacity, suitable for drills and other special tool&'

^ Proceedings InsL Meeh. Engineers^ 1875.

' Steel has latelv been made containing 13.75 per cent of Manganese, and haTing
a tensile strength of 60 tons per square inch, combined with 50 per cent elongation.
It bids fair to become an important material

HARDENING AND TEMPERING OF STEEL, 307

Homogeneous Metal is a name that was formerly given to a variety of
c&st steel containing about *25 per oent of carbon.

This material '^ welds with feusility, and, with proper precautions, may be
joined to iron or steel at a very high welding heat" ^

It is used for rifleproof shutters, guns, etc.

Hardening Steel. — It has already been mentioned that steel plunged
into cold water when it is itself at a red heat becomes excessively hard.
The more suddenly the heat is extracted the harder it will be.

This process of hardening^ however, makes the steel very brittle, and in
order to make it tough enough for most purposes it has to be tempered.

Tempering. — ^The process of tempering depends upon another characteristic
of steel, which is that if (after hardening) the steel be reheated, as the heat
increases, the hardness diminishes.

In order then to produce steel of a certain degree of toughness (without the
extreme hardness which causes brittleness), it is gradually reheated, and then
cooled when it arrives at that temperature which experience has shown will
produce the limited degree of hardness required.

Heated steel becomes covered with a thin film of oxidation, which becomes
thicker and changes in colour as the temperature rises. The colour of this
film is therefore an indication of the temperature of the steel upon which it
appears.

Advantage is taken of this change of colour in the process of tempering,
which for oidinaiy masons' tools is conducted as follows : —

Tempering MoMwf Tools, — ^The workman places the point or cutting-end of
the tool in the fire till it is of a bright red heat, then hardens it by dipping
the end of the tool suddenly into cold water. He then immediately withdraws
the tool and cleans off the scale from the point by rubbing it on the stone
hearth. He watches it while the heat in the body of the tool returns, by
conduction, to the point The point thus becomes gradually reheated, and
at last he sees that colour appear which he knows by experience to be an
indication that the steel has arrived at the temperature at which it should
again be dipped. He then plunges the tool suddenly and entirely into cold
water, and moves it about till the heat has all been extracted by the water.

It is important that considerable motion should be given to the surface of
the water while the tool is plunged in, after tempering, otherwise there will
be a sharp straight line of demarcation between the hardened part and the
remainder of the tool, and the metal will be liable to snap at this point

Tem^pering very emaU Tools, — In very small tools there is not sufGicient bulk
to retain the heat necessary for conduction to the point after it has been dipped.
Such tools, therefore, are heated, quenched, rubbed bright, and laid upon a
hot plate to bring them to the required temperature and colour before being
finally quenched.

In some cases the articles so heated are allowed to cool slowly in the air,
or still more gradually in sand, ashes, or powdered charcoal The effect of
cooling slowly is to produce a softer degree of temper.

Table of Temperatwres amd CoUnirs, — The following Table shows the tem-
perature at which the steel should be suddenly cooled in order to produce the
hardness required for different descriptions of tools. It also shows the colours
which indicate that the required temperature has been reached

* Muahet on Irm and SUsL

3o8 NOTES ON BUILDING CONSTRUCTION

Colour of Film. Di!%ir. ^**"* ®^ ^**^

Very pale straw yellow 480 Lancets and tools for metaL

A shade of darker yellow . 440 Razors and do.

Darker straw colour 470 Penknives.

Still darker straw yellow . 490 Cold chisels for cutting iron, tools for wood.

r Hatchets, plane irons, pocket knlTes, chipping

chisels, saws, etc
. Do. do. and tools for working granite.
Swords, watch springs, tools for catting sand-
stone.

Brownish yellow 600

Yellow tinged with purple 520

Light purple . . 580

Dark purple . 550

Dark blue ... 570 Small saws.

Pale blue 600 Large saws, pit and hand saws.

Paler blue with tinge of green 680 Too soft for steel instruments.

The tempering colour is sometimes allowed to remain, as in watch spiiugs,
but is generally removed by the subsequent processes of grinding and poliahing.

A blue colour is sometimes produced on the surface of steel articles by
exposing them to the air on hot sand. By this operation a thin film of oxide
of iron is formed over the surface, which gives the colour required.

Steel articles are often varnished in such a way as to give them an appear-
ance of having retained the tempering colours.

The exact tempering heat required to produce the same d^:ree of hardness
varies with different kinds of steel, and is arrived at by experience. It would
be impossible to go very fully into the subject in these Notes. The above
remarks will give some idea of the process, and the effects produced upon the
strength and ductility of steel by tempering in different ways is shown in the
Table, page 311.

Different Methods of Heating, — Tbere are several ways of heating steel
articles both for hardening and tempering.

They may be heated in a hollow or in an open fire, exposed upon a hot
plate, or in a dish with charcoal in an oven, or upon a gas stove.

Small aiticles may be heated by being placed within a nick in a red-hot bar.

If there is a large number of articles, and a uniform heat of high degree is
required, they may be plunged into molten metal alloys, or oil raised to the
temperature required.

Degree of Heat for Hardening, — In hardening steel care must be taken not
to overheat the metal before dipping. In case of doubt it is better to heat
it at too low than too high a temperature.

^ The best kinds require only a low red heat. If cast steel be overheated
it becomes brittle, and can never be restored to its original quality.** ^

If, however, the steel has not been thoroughly hardened it cannot be tem-
pered. The hardness of the steel can be tested with a file.

The process of hardening often causes the steel to crack. The expansion
of the inner particles caused by the heat w suddenly arrested by the crust
formed in consequence of the cooling of the outer particles, and there is a
tendency to burst the outer skin thus fonned.

Cooling, — When the whole bulk of any article has to be tempered, it may
either be dipped or allowed to cool in the air. '' It matters not which way
they become cold, providing the heat has not been too suddenly applied, for
when the articles are removed from the heat they cannot become more heated,
consequently the temper cannot become more reduced." But those tools in
which a portion only is tempered, and in which the heat for tempering is sup-

^ Kdes, 80.

CASE-HARDENING STEEL. 309

plied by condactdon from other parts of the tool (as described at p. 293^
'* must be cooled in the water directly the cutting part attains the desired
colour, otherwise the body of the tool will continue to supply heat and thei
cutting part will become too soft" ^

Habdbniko Ain> TBifPianio iv Oil. — ^When toughness and elasticity are required
rather than extreme hardness, oil is used instead of water both for hardening and tem-
pering, and the latter process is sometimes called toughening.

The steel plunged into the oil does not cool nearly so rapidly as it would in water.
The oil takes up the heat less rapidly. The heated particles of oil cling more to the
steel, and there is not so much decrease of temperature caused by vaporisation as there
is in using water.

Sometimes the oil for tempering is raised to the heat suited to the degree of hardness
required.

When a large number of articles have to be raised to the same temperature they are
treated in this way.

Blazing, — Saws are hardened in oil, or in a mixture of oil with suet, wax, etc.

They are then heated over a fire till the grease inflames. This is called being hlazecL

After blazing the saw is flattened while warm, and then ground.

Springs are treated in somewhat the same manner, and small tools after being hardened
in water are coated with tallow, heated till the tallow begins to smoke, and then quenched
in cold tallow.'

Annealing or Softening Steel is effected by raising hardened steel to a red heat and
allowing it to cool gradually, the result of which is that it regains its original softness.

Case-Hardening is a process by which the surface of wrought iron is
turned into steel, so that a hard exterior, to resist wear, is combined with
the toughness of the iron in the exterior.

This is effected by placing the article to be case-hardened in an iron box
full of bone dust or some other animal matter, and subjecting it to a red
heat for a period varying from half an hour to eight hours, according to the
depth of steel required.

The iron at the surface combines with a proportion of carbon, and is
turned into steel to the depth of from ^ to f of an inch.

If the surface of the article is to be hardened all over, it is quenched in
cold water upon removal from the furnace. If parts are to remain malleable
it is aUowed to cool down, the steeled surface of those parts removed, and
the whole is then reheated and quenched, by which the portions on which
the steel remains are hardened.

Gun-locks, keys, and other articles which require a hard surface, combined
with toughness, are generally case-hardened.

A more rapid method of case-hardening is conducted as follows : — ^The article to be
case-hardened is iK>liBhed, raised to a red heat, sprinkled with finely powdered pmssiate
of potash. When this has become decomposed and disappeared, the metal is plunged
into cold water and quenched.

The case-hardening in this case may be made local by a partial application of the salt

Malleable castings (see p. 266) are sometimes case-hardened in order that they may
take a polish.

To DiSTorauiSH Steel moM Ibon. — Steel may be distinguished from wrought iron
by placing a drop of dilute nitric acid (about 1 acid to 4 water) upon the surface. If the
metal be steel a dark grey stain will be produced, owing to the separation of the carbon.'

Tests for SteeL — Steel to be used in important work should
be tested as to its strength, ductility, and other qualities. The

1 Edes, 86. ' Holtzapffell.

* Bloxam's Chemistry.

3IO NOTES ON BUILDING CONSTRUCTION.

methods of testing are similar to those adopted for wrought iron
and described at p. 276.

Fraotored Surfsod. — Many people think that they can judge of steel by the appear-
ance of the firacture.

Mr. Kirkaldy found that " the conclusions respecting wrought iron are equally appro-
priate to steel, viz.— Whenever rupture occurs dowly^ a silky fibrous, and* when suddaUy,
a granular appearance, is invariably the result, bol^ kinds varying in fineness aocording
to quality.

"The surface in the latter case is even, and always at right angles with the length;
in the former, angular and irregular in outUne.

''The colour is a light pearl gray, slightly varying in shade with the quality ; the
granular fractures are almost entirely fr^ee of lustre, and, consequently, totally unlike the
brilliant crystalline appearance of wrought iron.^

The appearance of the fracture is, however, at the best but a vague and nnoertain
guide, and, without great ezperienoe on the part of the observer, almost useless.

Trial. — A better test in the hands of a practical man is to heat the steel, and try it
with regard to its tenacity, welding powers, and resistance to crushing when struck with
a hammer upon a hard surface.

Tensile Teats. — The only certain test, however, for tensile strength and ductility is
by direct experiment.

The tensile strength of steel may be tested in the same way as that of wrought iron.

The varieties of steel are, however, even more numerous than those of wrought iron,
and their strength differs accordingly. Moreover, it ia greatly influenced by the treat-
ment to which the steel has been subjected.

Admiraltt Tsars for Stebl.— Plates for shipbuilding, bars, angles, angle-bulbs, tees,
tee-bulbs or tee-bars, made by Bessemer and Siemens-Martin process.

Tensile Test — Stripe cut lengthways (or for plates either lengthways or crossways, or
in round bars a piece ftt>m the bar), ^ to have an ultimate tensile strength of not Im
than 26, and not exceeding 30 tons per square inch of section, with an elongation of 20
per cent in a length of 8 inches."

Forge TesL — ** Such forge tests, both hot and cold, as may be suifident in the opinkm of
the receiving officer to prove soundness of material and fitness for the service.'*

Tempering Test, — Stripe cut lengthwise (or for plates either lengthwise or cross-
wise) ** 1^ inches wide, or in round bars a piece from the bar, heated uniformly to a low
cherry red and cooled in water of 82'' Fahr., must stand bending in a press to a curve of
which the inner radius is one and a half times the thickness of tibe steel tested.

" The strips are all to be cut in a planing machine, and to have the sharp edges taken oil

** The ductility of every bar is to be ascertained by the application of one or both of
these tests to the shearings, or by bending them cold by the hammer.

" The pieces cut for testing are to be of parallel width from end to end, or for at lesat
8 inches in length."

Percussive Test far Rtnind Ban, — A specimen bar of 2* diameter is taken, when
required by the overseer, from every charge, or from every 50 bars or portions of 50, sad
subjected to a percussive test. The test for a bar of 2" diameter should be the fsll of 15
cwt. through 80 feet, or 20 cwts. through 22^ feet, whichever may be meet convenient
Sample must stand at least one blow without i^ury, and the f<dlowing facts must be noted.

a. The number of blows to break the bar.

b. The character of the fracture.

c. The reduction in diameter after each blow.

d. The reduction in sectional area at point of fracture.

e. The elongation in 8 inches and in the inch containing the fracture.

Welding Tests f&r all £ar«.— Sample pieces will be taken for testing the welding
qualities of the steel, by welding two pieces together and bending it in the way of the
weld when cold.

^ Eirkaldy's Experiments on Wrotight Iron and Steel,

TESTS FOR STEEL. 311

Lloyd's Tbstb.— The steel plates lued in ships to be clsssed in the register of Lloyd's
Insurance Oorporatlon have to stand a tensile stress of 27 to 81 tons per square inch,
with 20 per cent elongation in 8 inches ; the angles and beams 27 to 88 tons, with 16
per cent elongation, and the same tempftring tests as reqoired by the Admiralty.

Test by Bepeated and Falling Itoade. — Steel rails are sometimes
tested bj repeated loads, and generally by a fiilling weight The following
extract is from a recent specification for a steel rail weighing 79 lbs. per yard,
requiring both tests : —

''A length of 6 feet will be eat off ftom each sample rail and tested ss follows —

"IjL a piece will be placed in the position it would assume for traiflc, on solid
supports 8' 8" apart in the clear, and equidistant from the ends, and a weight of one ton
will be allowed to fall fireely upon the centre of the rail from a height of 12 feet 6 inches.
The rail must bear two sudi blows without showing the least sign of fifaetuie, and the
permanent set caused by the first blow must not exceed 2 inches.

" 2<i A piece of rail is to be placed on supports as before, and a weight of 18 tons is
to be applied at the centre, when the deflection must not exceed ^ of an inch."

The Admiralty percussive test for bolts is given at p. 283.

Steel fbr Bridges and Boofb ^ should have a high elastic limit which will
enable it to endure a high working stress. Good steel for such purposes can
be obtained having an ultimate tensile strength of 35 tons per square inch,
a limit of elasticity of 20 tons, and with 20 per cent elongation on the best
specimen of 8 inches length. Such a steel would endure a working stress of
8 tons to the inch.'

Recent specifications from the India Office for large steel bridges contain the following
requirements : —

Steel Bars and Plates must weld perfectly, and not crack or crumble at all when
hammered at a welding heat The strips, 1 inch wide and 8 inches long, to have a
tensile strength not less than 28 tons or more than 81 tons per square inch, an elonga-
tion of not less than 20 per cent, and a limit of elasticity of 15 tons per square inch.
The same tempering tests as the Admiralty require, except that the radius of the curve
to which the steel is bent is three inches instead of 1^ inches.

Buckle Plates 0/ Boadway to besr a concentrated load of 12 tons at centre without
permanent set, and of 24 tons at centre without fracture.

Rivets. — Tensile strength 26 to 28 tons per square inch, in test pieces of 10
diameters, elongation not less than 25 per cent A piece of bar heated to cherry red,
quenched in water of 82" Fahr., to bear being doubled quite close without ii^ury. A
piece heated to full red or orange, dropped into a hole in a cast iron block, so that \\
to 2 diameterd project, to bear having the Mid hammered out to a thin edge all round
without showing signs of cracking.

MARKET FORMS, RELATIVE VALUE OP DIFFERENT
KINDS, AND BRANDS ON STEEL.

Markbt Formsl — Steel may be obtained in most of the forms adopted
for wrought iron, and described at page 284. Angle and T of all sizes up
to 4 inches x 4 inches aie easily obtained, but many sections in the market
beyond that size are made.

BdaiUos value of differeni kinds of A00K.— The following extract fitim one of Blessra.
Boiling and Lowe's price lists for July 1885 is given to show the prices of different de-
scriptions of steel as compared with those of iron (see p. 290) : —

^ Katheson, M.LC.E., vol. Ixix. p. 21.

' In this cotmtry Board of Trade roles restrict the working stress on stocl in
bridges to 6) tons per square inciL

312

NOTES ON BUILDING CONSTRUCTION.

Per ton.

Percwt.

Ban

£7 17

to £8 17 6

Double shear .

£2 5

0 to £8 6 0

Plates

8 5

,,960

Single „ .

1 14

0 ..

8 0 0

„ boUer

Borer steel

1 8

0 «

3 15 0

quality

9 5

„ 10 6 0

Cast steel for

Sheets

9 0

„ 10 10 0

1 18

0 „

3 5 0

Hoops ^ .

9 0

„ 10 0 0

Special die steel

4 0

0 „

5 12 0

Angles .

7 0

,,800

tool

Tees

8 10

„ 10 10 0

steel

5 12

Bulbs .

7 10

,,900

Cast steel pktes

Bulb tees

8 0

„ 10 0 0

and sheets .

1 0

0 .,

2 10 0

Iron hoops

1 in. by 18 WG. 1 J in. by 17

WG.

IJ in. by 16 WG.

Equal strength in

L steel

I „ 20 „

1 M 20

»f

U »

19 ..

Iron hoops . . . IJ in. by 15 WG. If in. by 14 WG.
Equal strength in steel . 1 J „ 18 „ 1| „ 17 „

Steel bars (Bessemer or Siemens-Martin process) can be made in the following sizes : —
Rounds, i in. to 3 in., advancing by ^ in. 3 in. to 4 in., advancing by 4 in. 4 in.

to 6 in., by { in.
Squares. ^ to 8| in., advancing by ^ in., and 3}, 3}, and 4 in.
Flat bars. 1 in. to 2 in., advancing by } in. Thickness, | in. to | in.
2i, 2g, 2^, 2i, 2|, 3, 3i, 3^, 8} in. Thickness, i\ to 1 in.
4 in., 4i in. Thickness, ^ to 1^ in.

5, 5^, 5i, 5f, 6, 6^, 6^, 7, 8, 9, 10 in. Thickness, } to 1} in.
Steel hoops. { in. to 8 in. wide, advancing by ^V ^^- Thickness, usual gauges.
Steelplates. ^V in*^^^^i^^'o^^28super. ft. Max.length, 14 ft Max. width, 4 ft.
A »» »» 31 „

\ » M 49

A » »» 50 „

A M II 66 „

♦ » M 72 „

TW n »» 76 „

i »» u 86 „

Tnr II II 9o „

a II II 1^6 M

% II If 116 „

S „ I, 126 „

J „ „ 126 „

1 II f» 125 „

IJ ., „ 110 „

U ,1 II 110 „

Other sizes can be made by special arrangement.

Extras on Sted Plates, — The following list gives the extras upon steel plates, but steel is
generally sold to specification, as so much depends upon i^iA proportion of different sixes : —

18 „

i»

4i..

22 „

6 „

25 „

61 „

30 „

33 „

l»

6 „

85 „

»l

6i„

38 „

6i«

40 „

7 „

40 „

7i«

40 „

8i.,

87 „

8f.

34 „

8|,.

31.,

8 „

28 „

»»

8f„

26 „

>»

8}„

Limit.
Weight, 18 cwts.
Length, 23 feet
Width, 6 feet
Area, 80 square feet.

„ 40 square feet per xV-
Thickness, J" to 1".
Sketch plates.

Rxtra^
lOs. per cwt or part.
5s. per foot or part.

10s. for every 3 inches or part under 12 inches.
Is. i)er foot or part

»i i»

Under ^^ and not thinner than yVi lOs. per ton.
10 per cent allowed. Above 10 per cent 20s. per too.
(9'' taper allowed before counting as sketch.)

Butt straps are included without extra charge. Plates not rectangular to be counted as
such for overweight and area. A maiigin of 6 per cent, i.e. 2^ per cent over or under
calculated weight, to be allowed for rolling.

Brands on Steel. — ^There are no lid hrainds for steel (see p. 2&6X E&di
maker has his own trade mark, generally the name of his firm, with or with-

^ Steel baling hoops show an advantage of 20 to 30 per cent over iron hoope, as,
although higher in price, much lighter gauges can be substituted.

BRANDS ON STEEL. 313

out name of bis work. Thus — (Atlas), Jno. Brown and Company, Limited ;
(Cyclops), Cammell and Company, Limited ; (Globe), Ibbotson and Company ;
(Norfolk), Messrs. Thomas Firth and Sons, Limited ; (Vickers), Messrs.
Yickers, Sons, and Company, Limited. There are no marks to indicate
quality, such as best best, etc. etc.

The following are some of the marks used : —
\^^=^ I f.^^^ I Thomas Jowitt's double shear steel for the trade generally.

" BRADES." William Hunt and Son's '* Brades Company."
Mushet's borer steel. Titanic.

Blister steel, known as Hoop L Swedish brand, that iron being used in
the manufacture. Used by many firms.

Turton and Sons.
Osbom.

The Sheffield merchant steels have usually a paper wrapping with the
maker's name and address in full.

Crucible Cast Steel. — The ingots have each a paper label attached, on
which is marked the purpose for which the steel is best adapted, as follows —
hcrer^ wetdi/ng, tool, rivet.

Shear and Double Shear steel bars are marked with the words shear
and double shear in indented letters on each bar.

Bessemer Steel has no marks. Rails of this material are generally
stamped with the maker's name, and the word steel

Lanoorb Steel — ^*-^^^^m is the trade mark of the Landore

^' Siemens - Steel Company, Limited.

The following brands' in addition
indicate different qnalities of steel : —

LANDORE ) Dead soft steel, having a tensile strength of from 23 to 26 tons per
D 8 i square inch. Of this quality are produced bars for manuflEtcturing into
tin plates for deep stamping. Soft wire rods, having great conductivity,
for telegraph purposes are also produced from this brand.

LANDORE \ Soft steel, having a tensile strength from 26 to 31 tons per square inch,

8 /as may be specified. Of this brand are produced ship, bridge, and boiler

plates, angles, tees, bars, rivet bars, etc., such as are supplied under

contract to the Admiralty, or guaranteed to conform to the requirements

of the Board of Trade and of Lloyd's Committee.

N.B.— Bridge plates are supplied of higher tensile strain than above,
as engineers may specify.

LANDORE \ Special soft steel, of the highest quality, with a maximum tensile strength
8 8 j of 28 tons per square inch, and a minimum elongation of 25 per
cent in 8 inches. It is prepared from the purest brands of iron, and
specially treated. Plates made of this quality are recommended particularly
for boiler furnaces, tube plates, galvanising baths, hollow stampings, etc.,
and generally in place of the best brands of Yorkshire iron usually employed
for such purposes.

' From the Company's Circular, January 1878.

314 NOTES ON BUILDING CONSTRUCTION

LANDORE \ Medium iUd, having a tensile strength of from 81 to 50 tons per square

M / inch, as may he specified. It is used in the manafactuie of ailes, geneial

forgings, castings, wire rods, etc, and is of a tongh and malleahle natore.

LANDORE I Special medium eteel, same tensile strength as Mt hat prepared from

8 M ) special materials, similar to S S* Suitable for the highest class of axles,

foigingB, shafting bars, engineering porposes generally, wire rods, etc

LANDOEE I Hard itedy with a tensile strength of over 50 tons per sqnare inch. Snit-

H t ^^^ ^^ springs, wire rods, and some descriptions of castings.

LANDOEE \ Special hard steel, same tensile strength as Hi hut made from special

S H / materials, similar to S S &nd 8 M« It is recommended for the highest

class of wire rods, boring tools, jumper steel, stamp heads, shoes, and

dies, and for mining purposes generally, in place of the best crucible steel

STRENGTH OF CAST IRON, WROUGHT IRON, AND STEEL

It is beyond the province of these Notes to enter upon the general subject
of the physical properties of materials. The meanings of a few of the t^ms
used in connection with those properties are given at pp. 467-470, and the
subject will be further entered upon in Part IV.

The value of iron and steel to the engineer is, however, so entirely depend-
ent upon their strength, ductility, etc, that a few observations on these points
will be necessary in order to dear the way for an intellig^t selection and
testing of these materiaLs.

In considering the strength of materials care must be taken to distinguish
between the ultimate strength — that is, the stress per square inch of section
which will cause rupture — and the toorhing strength^ or the stress per square
inch which the material can safely bear in practice.

In the following pages the ultimate strength, as found by experiment, will
first be given for various descriptions of iron and eteeL

The effect upon this strength, produced by various circumstances, will be
briefly mentioned.

The working streesee ihat may be permitted in practice will then be stated.

Finally, one or two points regarding the effect of vibration, cold, etc, will
be merely glanced at

ULTIMATE STRENGTH AND DUCTILITY.

The tests which are applied in practice to cast iron, wrought iron (of dif-
ferent classes), and steel, have been described in previous pagea

In order to apply these tests intelligently, it is necessary to know something
of the peculiarities of the different descriptions of iron ordinaril j met with,
to see what their actual ultimate strength or resistance to rupture has been
found to be by experiment, and to understand how that ultimate strength is
modified by slight differences in their composition, form, treatment in
working, and other surrounding circumstances.

The strength of iron and steel will be considered only with reference to
their resistance to tension, compression, shearing, bearing, and transverse stress.

Their resistance to torsion, though of importance in machines, does not come
into play in buildings of any kind, and will, therefore, not be considered.

The breaking stresses, found by experiment and given in the following
tables, were, in all cases, produced by a dead loady gradually applied. Very
mnch RTTinller live loads, ie, stresses suddenly applied, would cause rupture
(see p. 318>

STRENGTH OF IRON AND STEEL,

315

Strencpth of Cewt Iron.

The ayenige ultimate strength of the ordinary varieties of cast iron found

in the market may be taken as follows : —

Tons per Square Inch.

Tension . .6 a.

Compression . . . 38 8.

Transverse .... 13^ B.

Shearing . 8| s.^

The above figures are intended to give a low average.

The following extracts from the most important experiments on the strength of cost
iron show the wide differences that occur in different specimens.

The Table below is condensed from the records of Mr. Eaton Hodgkinson's experiments
made for the Commission on the use of iron in railway structures.'

The experiments were made by crushing cylinders } in. diameter, some } in. and some
1^ in. high. The figures given below show the resistance of the cylinders IJ inch high ;
the shorter cylinders offer«l a greater resistance.

Table giviko Crushing and Tensile Strength of Different
Descriptions of Cast Iron.

DE3CIUTTI0N or Iboh.

Crashing
Strength.

Tensile
Strength.

In tons per square
inch.

Lowmoor Iron, No. 1 .

25-2

6-7

N«. 2 .

41-2

6-9

Clyde, No. 1 .

89-6

No. 2 .

46-6

7-9

No. 8

46-8

6-6

Blenavon, No. 1 .

85-9

6-2

No. 2 .

80-6

6-3

Calder, No. 1 .

83-9

6-1

Coltness, No. 8 .

46-4

6-8

Brymbo, No. 1 .

88-8

6-4

No. 8 .

84-8

6-9

Bowling, No. 2 .

88-0

6-0

Ystalyfera No. 2 (Anthracite)

42-7

6-6

Ynis-cedwyn No. 1 do.

86-1

6-2

No. 2 do.

88-6

6-9

Mean of irons tested by Mr. Hodgkinson in bis experimental researches

49-5

7-88

Morris Stirling's iron tested by Mr. Hodgkinson^mean . . 55*6

11-0

^ A. Anderson, mean of 850 specimens. S. Stoney. B. Barlow.
2 Beport of Commissioners appointed to inquire into the appliooHon of Iron, to HaH-
way Structures, 1849.

3i6

NOTES ON BUILDING CONSTRUCTION.

The mean of cxpcrimento made by the Ordnance anthoritiea, as analysed by lYofeswr
Poln, give

\
Breaking weight in tons
per Bqnaie in<:h.

Uax.

Min,

Mean.

Tension

Compression

Transverse^

15-8

62-6
20-0

4-2

19-8

4-6

10-4
40-6
12-6

The spedinens tried were generally samples received from the makera, of the second or
third mdting. The iron subsequently supplied in larger quantities was often inferior in
strength to the samples.

Influenoe of various ciroumBtaaces upon the Strength of Cast Iron.—
Sixe of Section, — ^The iron close to the surface of a casting has been found to be harder
and stronger than that within. In a small bar the amount of this hard akin is
greater in proportion t6 the section than in large castings, and hence the average strength
is greater.

Again, the interior of large castings is more spongy and open than that of small castings.

Mr. Eaton Hodgkinson found the relative tensile strength — per square inch — of bars
1 in. 2 in. and 3 in. square to be 100, 80, 77.

Repeated RemelUngs. — Repeated remelting of cast iron increases its strength, probably
in consequence of the carbon being burnt out of it, thus tending to assimilate it in oonh
position to wrought iron. Sir William Fairbaim, experimenting upon Scotch iron,
obtained the following results : —

Its resistance to cross breaking increased up to the twelfth remelting, and then fell off;
at the twelfth remelting its strength was { of what it originally possessed. Its resistance
to crushing was a maximum at the fourteenth remelthig, i.e. nearly 2| times its original
strength. Its resistance then fell off, until at the eighteenth remelting it possessed only
twice its original strength.

In America the iron is kept in a state of fusion for two or three hours at each remelting.

Major Wade found the result to be as follows : —

Strength of pigs
First melting .
Fourth melting .

5 to 6| tons per square inch.
12-4

The effect of remelting varied considerably, being greatest in No. 1 soft grey pig>iron.

This question can rarely be of any great importance to the engineer, though it might
possibly have to be considered in using old iron.

Effect qf Temperature. — Sir William Fairbaim's experiments led him to the foUowisg
conclusion : — ''Cast iron of average quality loses strength when heated beyond a mean
temperature of 120^ and it becomes insecure at the freezing point, or under 82"* Fahren-
heit** «

At a red heat its original strength is diminished by (. A mass of cast iron raised to
a red heat will crumble to pieces when struck. This property may be taken advantage
of in breaking up large pieces of oid cast iron, such as guns.

^ This is the value of the co-efficient C in the formula, WsC^

WhereW= breaking weight in tons.
h =breadth ^

d = depth V of beam in inches.
I =span J
ITiis subject will be explained in Part IV.
• AppUeation of Iron to Building Parpoaes, by Sir William Fairbaim, p. 78.

STRENGTH OF IRON AND STEEL

317

An increase or decrease of temperatnre amoonting to 27"" Fahr. causes such expansion
or contraction that it wonld bring a stress of 1 ton per sqnare inch upon the metal, if it
was rigidly secured at the ends before the change of temperature took place.

The Effect of mixing Different Brands^ when judiciously done, is doubtless to incream
the strength of the iron beyond that of any single brand. The exact increase depends,
of course, upon the mixtures used. As before mentioned, this is a question better left
alone by the engineer.

Strenffth and Ductility of Wrought Iron.

The strength and ductility of wrought iron depend upon the quality of
the material and the care with which it is manufactured.

A very small proportion of carbon is practically always present ; if this is

increased, the strength of the iron is considerably augmented, and its power of

welding diminlBhed, — in fact it approximates more to steel in its characteristics.

The presence of other impurities occasions the defects mentioned at pp.

248, 249.

The strength of different descriptions differs so greatly that an average is
somewhat likely to be misleading in any particular case ; but the following
may be taken as a low average for the ultimate strength of wrought iron under
different stresses.

Tons per sq. inch.
. 16 to 20
20

Tension

TBars .
jputesjj

Compression
Shearing .

Tons per sq. Inch.
26
f lengthways 21
[ croBSways 20

Tensile Strength. — The following Table shows the tensile strength,
contraction of area and elongation after fracture, ascertained by experiments
upon some of the more important descriptions of iron found in the market

AvBRAGB Tensile Strength and Duotilitt of Iron Plates and
Bars made by several noted Manufacturers.^

Tensile strength

Con traction

Manutacturkrs akd Dksobiptiov op Irok.

per square inch

of original

section.

^^^14 vft tmm^ i»s%/aa

of area
fractured.

Ultimate
elongation.

Rovfnd Oak Iron Works (see p. 296)—

Tons.
S 24-94 to
1 26-67

Percent.
48-2 to

Per cent

in 10 inches.

28-8

L.W.R.O. bars

27-5

Best bars

24-67

45-3

26-4

Best best bars

28-86

45-2

29-7

Best best best bars ....

28-60

46-9

80-7

Best rivet iron bars ....

24-76

46-7

26-6

Best best best rivet iron bara

24-26

47-2

27-4

Sh^Uon Iron A SUd Co,, Sioke-on-TreiU—

in 12 inches.

Best boiler plates, J-in. thick, lengthways

22-3

10-8

7-8

„ „ „ crossways

18-7

4-6

4-2

Best best boUer plates, ^iu. thick,

„ • lengthways

28-6

16-2

8-8

„ „ „ crossways

20-6

10-4

6-2

Rivet iron

25-0

40-0

270

Angle iron

26-6

84-1

27-0

JV. Hingley and Swie, Dudley—
Netherton crown best bar iron

22-6 to
28-8

45-0 to
85-0

800
24-0

„ „ „ rivet iron

28-5

50-0

20-0

Extracted from Tables in Hutton's Ptactical Engineer's Eamdbook,

3i8

NOTES ON BUILDING CONSTRUCTION

Table giving the Tensile Stbbnoth and Ductility of various Descriptions
of Malleable Iron. From Mr. Kirkaldy's Experiments.*

S3
&3
ll

District

Nsmes of ICaken or Work
snd Brands.

* Description.

BoUed Bars.

Percent

Parcel.)

Yorkshire .

Lowmoor

. Rolled Bars, round,
1" diameter

27-69

58-1

26-5

Do. .

Bowling

Do.

27-86

45-3

24-4

Do. .

Famley

Do.

28-07

60-6

25-6

Staffordshire

J. Bradley & Co., Lcirc
(charcoal)

le Do.

25-54

60-9

80-2

Do.

Do. B.B. scrap

Do.

26-5

520

26-6

Do.

Do. S.C. fJlP
J. Bagnall, J.B. .

Do. I'dia.

27-78

36-2

22-2

Do.

Do. ir do.

24-55

27-0

17-3

Scotland .

Qovan, Ex. B. Best

Do. rdo.

26-89

40-0

22 8

Do. .

Do. B. Best

Do.

28-05

28-9

191

Do. .

Do. # .

Do.

26-63

25-1

16-4

Do. .

Glasgow, 6. Best .

Do.

26-29

39-6

28-2 i

Wales

Ystalyfera (paddled)

Flat strips.

17-20

2-4

Blvet Iron.

Dfauneter.

Yorkshire .

Lowmoor

Round. H"

26-82

62-2

20-6

Do. .

Bradley & Co., f|p S.C.

Do. f

26-32

49-5

22-5 !

r^ancashire

Ulverstone, Rivet Best

Do. f

24-00

48-6

21-6

Staffordshire

Thomeycroft k Co., TN

3 Do. W

26-46

40-4

22-4

Do.

Lord Ward, L fj? W.

Do. H'

26-69

37-6

18<

Scotland .

Glasgow, Best Rivet

Da r

25-49

40-7

23-7

Iron Plates.

Thickness.

Yorkshire .

Lowmoor

. L. A'

28-21

19-7

18-2 ,

c. A-

22-55

12 1

9-8 I

Do. .

Pamley

. L. fT

25-00

17-8

14-1

c. 1'

20-63

18-2

7-6

Do. .

Bowling .

. L. r

23-32

15-8

11-6

c. r

20-73

6-9

Staffordshire

Bradley & Co., fjjp S.C.

^- *:

24-92

17-2

12-5

c. V

22-62

6-5

Do.

Thomeycroft, Best Best

' L. H"

24-48

12-5

11-2

C. H"

20-36

4-6

Do.

Lloyds, Fo0ter,& Co., Bei

>t L. A'toA'

20-07

8-7

6-8

C. Do.

19-92

6-9

4-6

North of Enslsnd

Consett, Best Best

• ^ *:

22-88

13-1

8-9 1

C. i"

20-85

10-2

6-4

Scotland .

Glasgow, Best Best

L. rtoi"

28-84

10-6

9-0 :

C. Do.

18-65

8-7

2-6 1

Ansle Iron.

Yorkshire .

Famley^. .

Thickness A'

27-34

41-4

20-9

Staffordshire

Albion V Best

Do. i"

25-07

191

14-0

Do.

Do. Best

Do. i'

23-28

22-8

14-1

Do.

Eagle .

Da W

22-34

15-8

8-8

Do. Rett Beat

24*42

23-4

18-7

Durham .

Consett

Do. A"

22-68

11-7

5-8

Do. .

Do. Best Best

Da V

23-90

18-3

12-6

Scotland .

Glasgow, Best scrap

Do. ft-

25-04

20-1

16 0

Do. .

Do. Best Best

Da r

24-78

11-0

8-6

STRENGTH OF IRON AND STEEL.

319

From the results above recorded, it will be seen that the ayerage of ordinary
qualities of bar iron is nearly 20 per cent stronger than that of the same qualities of
plate iron, and its elongation under a given stress is 2^ times as great ; also that plate
iron has a greater strength in the direction of the fibre or grain than acioss the grain,
the difference being on the average about 10 per cent.

The Slaatio Iiimit of a few different classes of iron is shown in the following TaUe
(see also p. 381) :—

Dksciuftioh of Iboh.

Blastic limit in

tension, tons

per square inch.

Breaking ten-
Rile stress per
sqnare inch.

Elongation In

10 inches per

cent.

Bowling iron ^ with grain .
„ across grain .
Barrow B.B.H.^ ....
Cleveland' |-inch and ^-inch plates—

With grain ....

Across grain . . . ,

Belgian joists*

Wrought iron from crank shaft .

12-6
11-1
14-5

18-7.

16-9 to

16-4

13-8

20-9
18-4
26-4

(21-0

j 18-2
22-4 to
20-9
14-18

19-8

7-6

22-8

in 8 inches.

7-5

8-0

in 8 inches.
4-0

The Cmahing Strength of wrought iron varies in different specimens with the
hardness of the iron.

"Ordinary wrought iron is oompliDtely crushed, ije. bulged, with a pressure of from
16 to 20 tons per square inch." ^

The best soft wrought iron begins to bulge sensibly with about 12 tons per square inch.'

The Shearing Strength of wrought iron has been proved by experiment to be
equal to the tensile strength of the materiaL

Bifeot of different Proceasea and Cirouxnstanoea ux>on the Strength of
Wrought Iron. — It has already been stated that the strength and elasticity of wrought
iron depend not only upon its quality, but upon the treatment to which it has been
subjected in working, and upon other surrounding circumstances.

The following Table shows concisely the effect produced by different modes of working,
by changes of temperature, etc

The conclusions given are founded upon a large number of experiments by Mr.
Kirkaldy and others. Those by Mr. Kirkaldy are clearly classified in Mr. Kinnear
Clarke's RvUa and Tables for Mechanical Enffineers,

Tensile Strength.

Ductility.

Reducing diameter by rolling, forg-
ing, or hammering
Turning or removing skin
Annealing

Welding

Stress suddenly applied .

Hardening in water or oil
Cold ToUvag— plates
bars .
Oalvanising .
Effect of frost 28" F.

Effect of frost, stress suddenly applied

Increased .

No alteration

Reduced .
Reduced from between
4*1 and 48*8 per cent

Reduced 18*5 per cent

Increased .
Doubled .
Increased 50 per cent
No difference.
Reduced 2*3 per cent

Reduced 3*6 per cent

Reduced.
No alteration.
Increased.

[Reduced.

{Reduced in nearly all
cases.
Reduced.
Destroyed.
Reduced 60 per cent.

Reduced 8 per cent.
Reduced between 0
and 30 per cent.

Efect of Temperature, — Sir William Fairbaim found that the strength of wrought
iron was practically the same at all temperatures between 0* and 400"* Fabr.*'

1 Kennedy, Ir(m, 11th May 1888.
^ Institute Mechanical Engineers, 4th August 1886.
' ArchiUet, 18th February 1882. ^ Stoney. * Downing^

* Usrfui Information for Engineers^ Series ii.

320

NOTES ON BUILDING CONSTRUCTION,

Strength and Ductility of SteeL

The strength And ductility of steel varies greatly in different descriptions. It depends
not only upon the original composition of the metal, bat also npon the treatment to
which it has been subjecteil, especially the rate of cooling. The following Tables give
some idea of the variety to be met with in different specimens.

Average Strength. — ^The great differences in strength caused by varieties in the
amount of carbon and in temper make it useless to attempt to arrive at an avenge
strength for all steels.

The following may be taken as a low average for the ultimate strength of soft cast-
steel which has not been hardened : —

Tons per sqoare inch.
Tension ..... 32

Compression ..... 80

Shearing ..... 24

Mr. Matheson says — " A tensile «nd compressional strength equal to a breaking stnin
of 30 or 40 tons, with a limit of elasticity of 15 to 20 tons, may be stated as the qoedity
of the plates L and T sections which are now made for constructional purposes." . . .
"Steel equal to a tensile strength of from 40 to 55 tons is made for special purposes,
such as chain-links for suspension bridges." . . . "With steel of this kind it is most
important to know the limit of elasticity." ^

The following Tables, selected from different records of experiments, show the great
variation that there is in the strength and ductility of different descriptions of steel :—

TsNSiLE Stbenoth, Elabtic Limit, and Ductility of Cast-Stkel.

Ultimate or

breaking tensile

stress per sq.

inch.

Elasticlimitin
tension.

Contraction of
area per cent

1
EloDgatioD
percent

C. Bessemer steel (average
of different qualities for
tyres, axles, and rails)

Tons.

83-9

22-2

46-9

12-0

C. Rolled .

820

19-0

861

18-0

C. Crucible steel (average
of different qualities for
tyres, axles, and rails)

C. Hammered

88-2

21-9

22-8

7-0

Rolled (for axles) .

80-6

18-7

10-1

10-6

C. Bessemer steel, tyres and
axles

887

C. Crucible cast-steel from
Swedish bar-iron, chisel
temper

52-8

26-0

5-3

Ci Crucible cast-steel, rolled

84-48

20-6

...

2-0

Ci „ „ hammered

87 06

25 0

...

13-5

Ci Cast-steel, piston rods .

88-7

2675

o-»

C. ExperimerUa on Steel by a Committee of Civil EngxTuerSy 1868. The ban experi-
mented upon were turned down from 2-inch square bars to a diameter of 1*382 =U
square inch.

Ci Further experiments of the same Committee results, bound up with the report jnrt
quoted.

* Works in Iron,

STRENGTH OF IRON AND STEEL,

321

TsNBiLB Strength and Ductilitt of Stebl of different descriptions.
Selected from Sir W. Fairbairn's Experiments.^

BieskiBg tensile

stress per

square inch

of section.

Corresponding

ultimate

elongation.

Contraction or

set due to

compression

under 1007

tons per square

Messrs. J, Brovfn and Company,

Tons.

Fer cent.

Per cent

Best cast steel from Russian and Swed-
ish iron for turning tools

80-53

•56

25-8

Do. mUder

40-85

1-50

26-8

English tilted steel made from English
and foreign pigs ....

26-57

7-6

55-8

Messrs, C, Cammell and Company.

Specimen of cast steel, termed " Dia-
mond Steel " ....

49-18

1-77

28-8

Specimen of cast steel termed " Tool
Steel •»

48-69

2-06

26-8

Specimen of cast steel termed " Chisel
Steel"

68-75

2-81

81-8

Specimen of cast steel termed " Double
Shear Steel'* ....

4815

2-50

80-8

Messrs. Naylor and Viekers.

Cast steel called " Axle Steel " .

89-58

6-25

42-8

Do. do. "Tyre Steel".

40-85

4-75

88-8

Do. do. *< Vickera' Cast Steel,
special" .

69-87

100

15-8

Do. da "Naylor and Vickera'
Cast Steel "

62-70

2-87

18-8

Messrs. S. Osborne and Company.

Specimen of best tool cast steel

44-17

1-56

20-8

Specimen of best double shear steel .

89-25

2-48

82-8

Extra best tool cast steel .

88-26

0-87

19-8

Cast steel for boUer plates .

49-85

10-62

88-8

H. Bessemer and Company.

Specimen of hard Bessemer steel

46-02

1-87

22-8

Do. milder do.

89-86

10-98

44-8

Do. soft do.

85-09

9-81

47-8

Messrs. T. Turton and Sons.

Specimen of double shear steel .

82-70

0-87

29-8

1 Iron ManufaOure, 1869.

British Assoeii

ition Beport, 1

S67.

322

NOTES ON BUILDING CONSTRUCTION.

Tensile Strenoth and Ductilitt of Steel Plateb With and Against

the Grain. From Mr. Kirkaldy's £zperimentfl^^

L. signifies lengthways of the grain ; C. across the grain.

Names of M aken or Works.

Thickness.

Tearing

weight per

square inch

of original

area.

Ultimate
elongation
or tensile
set after
fracture.

Contrac-
taunof

area at 1
fraetart..

Turton and Sons, cast steel

Inch.

8 f^

Tons.
42-09
42-99

Per c«ut.
6-71
9-64

Per cent j

J -6

IS'4 i

Moss and Gambles, cast steel .

Ato A

1 ^

^ Ic

83-74
89-84

19-82
19-64

28-2
38-6 ,

Shortridge and Co., do.

42-98
43-37

8-61
8.93

15-6
14-8

Shortridge and Co., puddled
steel

L
C

82-82
32-84

6-93
8-21

11-5
6-7

Mersey Company, puddled steel
(ship plates).

AtoA

L
C

46-29
37-93

2-79
1-26

6-4

4-4

Mersey Company, paddled steel
"Hard" ....

L
C

46-80
88-11

4-86
3-30

4-6
4-7

Mersey Company, mild steel

L
C

34-39
30-22

6-16
6-72

12-5
8-5

Mersey Company, mild steel
(ship plates)

81-93

8-67

7-6,

Tensile Strength and Ductility of Steel BARa
Kirkaldy's Experiments.*

Selected from Mr.

Average

Names of Makers or Works.

Description.

breaking

weight per

square inch

of original

area.

Ultimate
elongation
or set aOer

firactnre.

Contnetion

of area
atftactoze

Tona

Per cent

Percent

Turton's cast steel for tools .

Forged

69-0

6-4

4-7

Jowitt*s double shear steel .

Do.

630

13-6

19-6

Bessemer's patent steel for tools

Do.

49-7 '

6-6

22-8

Naylors, Vickers, and CJo., cast steel

RoUed.

47-69

8-7

32*8

for rivets

Wilkinson's blister steel bars .

46-6

21-4

Jowitt's cast steel for taps .

Do.

46-1

10-8

28-8

Krnpp's cast steel for bolts .

Rolled .

41-8

15-3

34-0

Shortridge and Co.'s homogeneous
metal ....

Do.

40-5

137

36-6

Jowitt's spring steel

Forged

82-3

18-0

240

Mersey Co., puddled steel

Do.

31-91

19-1

35-3

Blochaim puddled steel

Rolled .

31-32

11-8

19-4

Do. do. . . .

Forged

2913

12-0

19-0

» Kirkaldy's RxptrifmnU on fTroughi Iron and SUel, Table H. » Ibid, Tahlt F.

STRENGTH OF IRON AND STEEL.

Z^3

AvERAOB Tbnbile Stbbnqth and Ductilitt of Steel Plates and Bars
made by some noted Manufacturer*. ^

Msnn&etnrers snd DescripUons of SteeL

Tensile strength

per sqoaro Inch

of original

section.

Contraction of
area fhu^ured.

Ultimate
elongation
percent.

W. Beardmore and Co., Parkluad

WorJcB, Glasgow— ■
Steel bridge plates ....
Steel angles and bars

Rivet steel

Bolton Iron and Steel Company
Steel bridge plates ....
Steel angles, tees, bulb, beams for

bridge and shipbuilding
Rivet steel .....

29
31
27i

29J

291
27

...

40
50

In S.inches.

20
80

LanDOBE Stkbl. — Tennle Strength and DuctiUty, — The mean breaking tensile
stress for 101 samples of plates and angle irons, as given by Mr. Kiley, was 28*16 tons
per square inch, and the elongation 24*25 per cent.

A series of tests by Mr. Kirkaldy' gave the following nsnlts :—

Gnin Lengthways.

Grain Crosiways.

Annealed.

Unannealed.

Ultimate tensile stress

Elastic limit

Ck>ntraction of area at fhtctiue, )
per oent \

Ultimate elongation, per «ent

Tons per sq.
inch.

28*8
12-8

48-2

24*6

Tons per sq.
inch.
81 1
14*5

41*1

28-4 *

Tons per sq.
inch.

28*8
12*8

44*9

28*6

Tons per sq.
inch.
81-2
14-4

40-5

28*5

These experiments show that the difference in the strength of the steel, when tested
lengthwise and crosswise of the grain is almost imperceptible.

Whitworth'b Compressed Steel.^

Purposes for which the Steel is available.

Ttonslle
Strengtii
in tons per
sq. inch.

Ductility or
percentage

of
Elongation.

Axles, boilers, connecting rods, rivets, railway tyres, gun
furniture and barrels, and gun carriages

Cylinder linings, parts of large machines, and hoops and
trunnions for ordinance

Large, planing and lathe tools, large shears, smiths' punches
and dies and sets, small swages, cold chisels, screw tools,
com mill rollers, armour-piercing shells

Boring tools, finishing tools for planing and turning .

Alloyed with tungsten for particular purposes

40
48
58

68
72

82
24
17

10
14

^ Extracted from Tables in Hutton's Practical Engineer's Handbook,

* Proceedings Institute of Naval Architects.

* Proceedings Institute of Mechanical Engineers.

324 NOTES ON BUILDING CONSTRUCTION.

The Mastio Iiimit of steel plates hayiDg s tensile strength of 27 'S tons per sqnsre
inch either way of the grain, may be taken at 16*6 tons.^ The elastic limit of other
forms of steel are given at pages 320, 331.

Steel Wire is sometimes made for special purposes, e,g, for pianos and for wire rope,
with a tensile strength of 120 or even as much as 150 tons per square inch, and with an
elongation of about 83 per cent*

The Oruahinff Strength of steel varies greatly, according to the quality of the
steel and the hardness to which it has been tempered.

Some cylinders of cast steel (of a height = 2^ diameters) cut tnm. the same bar' wen
crushed under the weights given below.

Crashing wdfl^t per
inch of section.
Not hardened ....... 89 tons.

Hardened — ^low temper^ suitable for chipping chisels . . 158 „

Hardened — ^high temper, suitable for tests for turning hard steel 166 „

In the experiments of the Committee of Civil Engineers (see p. 806), steel cylinders of
1 inch area and 1 diameter in height bulged but did not crack under 89 tons, sod
cylinders of the same area, but with height of 4 diameters, crushed with wd^ts
averaging 20 tons.

It must be remembered that the steel begins to fail when its elastic limit is passed.
This was found by Mr. Berkley to be about 17 tons for Bessemer steel. In the experi-
ments of the Committee of Civil Engineers it ranged iMtween 27 and 15 tons, the avcfsge
as deduced by Mr. Stoney being 21 tons^ (see also p. 807).

Shearing Strength of Steel. — Mr. Kirkaldy's experiments led him to the followiDg
conclusion : — " The shearing strain of steel rivets is found to be about a fourth less thin
the tensile strain."'

The steel he experimented upon broke under a tensile stress of 88^ tons per squsre
inch of area, and the mean strain required to shear the rivets was 28^ tons per squsR
inch.

"The tests on torsion and tranaverse strain, tension and compression, show that th«
relation! which inbsist between the resistances to these strains in steel correspond very
nearly with those found by previous experiments in wrought iron ; that is to say, a fatf
of steel which has 50 per cent more tensile strength than a similar bar of wrought iron
will also have approximately 50 per cent more strength in resisting compression, toisioo,
and transverse strain." '

Eflbot of different Frooesees and Olroumstanoes upon the Strength of Steal
^^ff^ei qf Tmnpming.^Aftttr a series of experiments Mr. Kirkaldy came to the foUov-
ing conclusions as to the influence upon steel caused by its treatment in different ways.

" 85th. Steel is reduced in strength by being hardened in water, while the strength ii
vastly increased by being hardened in oil.

** 86th. The higher steel is heated (without of course running the risk of being homed)
the greater is the increase of strength by being plunged into oil.

** 87th. In a highly converted or hard steel the increase in strength and in hardnesi ii
greater than in a less converted or soft steel.

** 88th. Heated steel, by being plunged into oil instead of water, is not only oonsidtt^
aUy hardenedf but Umghened by the treatment."

The following are extracts from the results of the experiments which led to these ooa-
dusions : —

^ Head, InatUuU Mechanieal Engiiuers, 4th August 1885.

* Peroy, Iron and SUel InatUuU, > By Migor Wade, U.S. Anny.

* Stoney On Strains. > Kirkaldy's BtptrimtnU in Iron and SUeL

* Bepori by Committee appointed by Board of Trade, etc. etc

J Jill J -J.J.-

STRENGTH OF IRON AND STEEL.

325

Cast Stbel for Chisels.

,, yellow temper
„ spring
,, blue
in ashes, slowly

Highly heated, and cooled in oil
Do. do. in water

Do. do.

Medinm beat, and cooled in oil .
Do. do. in tallow

Do. do. in coal tar .

Do. do. slowly

Low heat, and cooled in oil
Do. do. in tallow .

Do. do. in coal tar

Do. do. slowly

Breaking

weight per

aq. inch, in

tons.

96
40
45
47
50
54
82
79
75
53
78
64
63
56

Contraction

of area per

cent

Elongation
per cent.

3-5

3-3

0 0

0-7

0 0

0-7

12-9

7 0

3-5

2-7

8-4

6-4

6 0

9-4

7*7

6-8

6-6

7-0

131

8-7

16-5

10 0

Effect of Antutding Steel Plates. — Hard steel plates are greatly improved in ductility
by being annealed. With soft steel, however, the increase of ductility is not necessary,
and the tensile strength is lessened.

Influence of Carbon upon Strength of ^SSfe^Z.— The following Table ^ contains the rela-
tion between the specific gravity and tensile strength of Bessemer steel of various degrees
of carbonisation, made at Sandriken, in Sweden : —

Percentage of
Carbon.

Specific Gravity.

TensUe Strength.

Soft

Hardened.

Tons per sq. inch.

1-5

7-785

7-736

84-39

1-2

7-832

7-771

87-40

0-9

7-874

7-808

56-59

0-6

7-879

7-807

87-41

0-4

7-893

7-839

80-84

The absolute strength appears to be greatest when the steel contains from 1 to 1| per
cent of carbon.

^ From Batiennaiui's MettUlwrgif,

326

NOTES ON BUILDING CONSTRUCTION

SAFE OE WOEKING STEESSES FOE CAST lEON,
WEOUGHT lEON, AND STEEL.

The limiting or working stresses that can be safely applied in practice to
cast iron, wrought iron, and steel respectively, depend not only upon the
quality and characteristics of the material, but upon the nature of the load
which causes the stresses, and in many cases also upon the form of the member
or structure under stressi

These points, and many others which bear upon the question, cannot here
be entered upon without anticipating the information to be given in Part lY^
where the subject will be more fully discussed.

Factors of Safety. — It will be sufficient at present to call attention to
the following Table, which shows the '* factors of safety " ^ recommended bj
eminent engineers for application in various cases that arise in practice.

Aatho-
rlty.

Mature of Stractare.

Nature of
Load.

Factor of
Safety.

CaH Iron,

Girders ....

Dead,

8-6

Do.

PlllaPB

Do.

Water tanks ....

Do.

Crane posts or machinery

Live.

. 8

Pillars subject to vibration

Do.

Do. do. transverse shock
Wrought Iron.

Do.

8. R.

Girders ....

Dead.

Live.

• 6

Bridges ....

Mixed.

4
in tension.

Roofs

Do.

Compression ban subject to
shocks

Live.

Compression bars not subject
to shocks

stea.

Dead.

Bridges ....

Mixed.

B. Board of Trade.

U. Unwin.

8. Stoney.

C. Commissloneiab

See page 449.

WORKING STRESSES FOR IRON AND STEEL. 327

The working streaaei are obtained by dividing the known breaking strength of the par-
tknlar daas of material to be need, by the factor of safety applicable to the structure
and load for which it is to be used.

The breaking strength is found by experiment, or taken from tables giving the results
of experiments on iron or steel of a similar class (see pp. 814 to 825).

The factor of safety is varied according to judgment and experience, or, in the absence
of these, may be taken ixom the Table above.

It is necessary here to state that the working stress should in no case exceed the
elastic limit of the material. The reasons for this are given at p. 329.

It will be seen, however, that the elastic limit is generally about \ of the ultimate
strength, whereas the worlcing stress is seldom more than ^ of the same, so that if the
factors of safety are carefully applied there is no danger of passing the elastic limit of
any ordinary material

In the abeence of experimental knowledge with regard to the particular materia]
about to be used, the engineer takes care to calculate for a low working stress, so that he
may be sure not to overtax the strength of the material

Working Stresses. — The following working Btreeses may be used in
practice: —

Cast Iron. — For girders, etc., to carry a dead load —

Compression .8 tons per square inch.

Tension . . . . \\ „

Shearing .... 2 „

An allowance of 30 per cent should be made to cover defects, such as air-holes, etc, in
the castings.

Cast iron is not well adapted for structures intended to carry a live load, but if used
for such, the working stresses would be reduced in the proportion shown by the factors
of safety for the different cases given in the Table, p. 826L

Wrought Iron. — The working stresses practically applied to wrought iron
are as follows : —

Built-up Plate-Iron Otrders and nmUar structures —

^ Tension ... 5 tons per square inclL

1 Oompresftion ... 4 „

' Shearing 4 to 4^ „

Bearing ... 5 „

These working stresses are in practice applied to girders with dead loads, and also to
those carrying moderate live loads. This, of course, is not theoretically correct When
the load is all dead the working stresses may safely be higher— equal to \ the break-
ing stress of the material ; and when the live load becomes large in proportion to the
weight of the girder (not a common case in girders connected with buildings), the work-
ing stresses must be reduced by a method which will be explained in Part IV.

For roUed girden Uie stresses may be taken slightly higher, w& at about 6
tons in tension and 5 tons in compression or shearing.

Where part of the load is live it is converted into an equivalent amount
of dead load as described at page 468.

When bar iron is used, as in roofs and braced girders, the working stresses
in tension may be considerably higher, because bar iron is, as a rule, stronger
than plate iron (see p. 317).

^ In calculating the area of the sections to which these stresses are applied, the rivet
boles are deducted in the tension flange, but are not generally deducted in the compression
flange. Some engineers deduct them in both flanges.

' The shearing stress might be taken as high as the tensile stress, but that the former
generally acts upon a group of rivets, some of which often get a larger share of th«
strass than the others, so that a lower limit is taken in order to be on the safe side.

328 NOTES ON BUILDING CONSTRUCTION.

ThuB, with good bar iron (such as V> see Table, p. 304) a factor of safetj

o C S7*78

of 4 for a dead load would give a working stress of — j-, or nearly 7 ton
per square inch of section.

However, taking into consideration the sudden shocks caused by the wind,
a working stress of 6 tons is high enough ; and where the iron is of aa
unknown quality, it is better to allow only 5 tons per square inch.

Board of Trade RuIa. — Thoogh the constmction of bridges is a subject eDtirelj
beyond the limits of any part of these Notes, it may be as well to mention here the Board
of Trade rule aa to the working stress for bridges, because this rule has governed the prac-
tice with regard to bridges, and has to a great extent influenced it in otiier structures.

*' In a wrought-iron Ixidge the greatest load which can be brought upon it, added to
the weight of the auperstructure, should not produce a greater atrain on any pari of the
material than 5 tons per square inch."

Practically this rule is modified by taking the working stresses, aa given above^ all o(
them except the tensile stress being lower than the limits laid down by the rule.

Bearing Strength. — The resistance of wrought iron to indentation by bolts
or rivets varies, of course, according to the quality of the iron.

For most ordinary work the safe statical pressure per square inch of bea^
ing surface may be taken at 5 tons,^ but in chain-riveted joints it may be
taken at 7j tons.*

Mr. Stoney takes it at 1^ times the safe tensile stress, or 7^ tons for all
structures.

Stbbl. — ^The factor of safety applied to steel structures should depend
(eortoris paribus) on the nature of the steel and its temper.

Thus a veiy hard steel, with high tensile strength and slight duetilitj,
should be worked at a smaller proportion of its breaking stress than a mild
and soft steel

Working Tensile Stress, — ^Mr. Stoney recommends a working stress of 8 tons
per square inch for mild steel plates, being about ^ of their ultimate tensile
resistance (see Table IIL p. 322).

Opinion of CommiUes appointed by the Board of Trade,— The use of steel in railway
bridges and other structures is not at present provided for by the Board of TYade rsga-
Utions, snd hence the working stress per square inch to which it may be submitted is
not officially laid down.

This has prevented the extensive use of steel for other structures in this country, and
consequently no conclusions can be drawn from actual practice.

A committee have, however, recently reported to the Board of Trade on this subject

The composition' of this committee renders their opinion of the greatest vidue to
engineers generally.

They baM their recommendations on an analysis of the experiments on steel made by
a committee of civil engineers in 1868-70 (see p. 820).

The following extracta fh>m their report will give the conclusions at which they
arrive: —

" As regards the ordinary steel of commerce, there appears to be no difficulty in obtain-
ing the usual amount of tensile strength, varying from 29 to 85 tons per inch. A point
requiring equal attention is the toughneas or malleability." . . .

*< We assume that with steel, as with iron, the engineer will take cars that, as well as
the required atrength, he aecures a proper amount of ductility. . . .

*' The steel employed should be cast steel, or steel made by some process of fnsioBi,

^ Latham On Wrought Iron Bridges.
* Unwin*s Wrought Iron Bridges and Boofk.

> Sir John Hawkshaw, ex., F.it.& ; Colonel W. YoUand, R.X., f.ba ; W. H
Barlow, E«i., C.B., f.ils.

LIMIT OF ELASTICITY. 329

rabseqnently rolled or hammered, and that it should be of a quality posaeasing conaider'
able toughnesa and ductility." . . .

" The greatest load which can be brought upon the bridge or structure, added to the
weight of the superstructure, should not produce a greater atrain in any part than 6}
tons per square inch."

From other parts of their report it appears that they consider that the working stress
upon steel should bear the same proportion to its ultimate atrength that the working
stress upon iron does to its ultimate strength.

Thus, taking the ultimate strength of iron at 20 tons per inch, and the working stress
allowed by the Board of Trade for bridges at V = ^ ^^^ ^^^7 '^^^^ ^^^ ^® ultimate
Rtrength of steel may very safely be taken at 26 tons per inch, and the working stress
applied to it at Y = 6^ tons.

JVorki'ng Stress in (hmpressioTi. — With regard to the working stress in com-
pression Mr. Stoney says : —

"The crushing strength of steel is so high that 12 or even 15 tons per
square inch is perhaps a safe compressive strain. When the material is not
permitted to deflect, but when in the form of a solid pillar, the strength of
mild steel seems to be only 1} times that of wrought iron.

" Experiments are, however, still wanted to determine this, and until such
are made it will scarcely be safe to adopt for steel pillars a higher load than
50 per cent above that which a similar section of wrought iron would safely
carry." ^

Bearing and Shearing Stress. — In default of experiments, the working stress
for bearing and shearing may be taken at the same proportion with r^ard to
the ultimate stress as in the case of iron.

Ijixnit of Elastioity. — In investigating the properties of a specimen
of iron or steel a very important point to be ascertained is its limit of
elasticity.

The meaning of this term has been defined in several different ways.

Mr. Stone/s definition is the one perhaps best suited to the engineer. He
says — ** The limit of elasticity may be defined to be the greatest strain that
does not produce a permanent set"

A short explanation will perhaps make the meaning of the term more clear
than the definition alone would da

If a small weight be auapended from a bar so as to cause a tenaile stress in the dire^
tion of its length, the bar will at once begin to elongate.

It will stretch a certain proportion of its own length. This proportion will vary
according to the description and quality of the material, and to the amount of weight
applied.

If a weight of 1 ton be hung (h>m the end of a wrought iron bar of average quality,
having a sectional area of 1 square inch, the bar will atretch about Triirv ?^^ of its
original length.

If the wdght be removed, the bar will soon recover itself— that is, it will return to its
original length.* If measured by any ordinary means of measurement, it will be found
to be of the same length that it was before the weight was imposed upon it.

This recovery of the bar occurs, however, only up to a certain point If the load be
increased until it amounts to a considerable proportion of the breaking weight, the result
produced is very different

For example, if^ instead of 1 ton, a weight of 12 tons be applied to the bar just men-

^ Stoney On Strains. * See page 317.

330 NOTES ON BUILDING CONSTRUCTION

tioned, the iroo will etretch about ^it^ ot itt length. Upon removal of the weight bov-
ever, it will not entirely noover itself, but will b^ found, upon measurement, to be a little
louger than it originally was.

This slight increase upon the original length of the bar is called the permanent eeL
The greatest stress that can be applied to the bar without causing an appreciable per-
manent set is called the limU of elasticUy, or the elaetic limiL

It is evident then, that there is a very important line to be drawn. On one aide of it
are weights, the application of which will produce no appreciable permanent set ; on th«
other side are the weights which produce an appreciable permanent set.

This line of demarcation is called the LimU of Elasticity, or the Elastic LimiL
It is, as before said, a certain proportion of die breaking load for the material, and its
▼alue is generally stated in lbs. or tons per square inch.

The proportion which the limit of elasticity bears to the breaking load Taries veiy con-
siderably in cast iron, wfought iron, and steel, and even in different speeimens of the same
classes.

The above remarks have been made with regard to a tensile stress, but the same thing
occurs with a bar under compression. Weights placed upon the end of the bar produce
no permanent contraction or act up to a certain point Weights greater than this per-
manently shorten the bar. This point is called, as before, the elastic limit, or limit of
elasticity.

The exact point at which the permanent set commences varies according to the quality
and characteristics of the material. A hard brittle iron has a high limit of elasticity, it
wiU not stretch much before breaking ; on the other hand, a soft ductile iron soon takes
a slight permanent set, bat stretches considerably before breaking. Practically, for ordi-
nary good wrought iron, the limit of elasticity may generally be taken at about ^ the
breaking stress.

So long as ductility is not sacrificed it is important to have material with a high limit
of elasticity for nearly all structures, but especially for those which are subjected to losd^
constantly repeated, as in the case of railway bridges. The reasons for this are given
below.

Fatiffue of Iron. — Many careful experiments made by Sir W. Fa^'^baim and others
have lod to the conclusion that a load may be applied to a wrought iron bar, removed
and reimposed thousands of times without the slightest injury to the bar, so long as the
stress per square inch does not exceed the elastic limit of the material

Directly this limit is exceeded, the first application of the load produces a permanent
set ; each repeated application increases that set, until at last rupture takes place.

The failure of iron under repeated loads or blows of this kind is known as the fatigite
qfiron.

It will be useful to notice one or two other points connected with the elastie limit
In wrought iron, steel, and indeed in most other building materials, the temporary
elongations produced before the limit of elasticity is reached are proportional to the lootis
which produce those elongations.

Thus, in the bar above referred to, if a load of 1 ton produce an elongation of itKt
in the length, 2 tons will produce tt^ttv* ^ tons TrfoT* ^^^ "o on, until 12 tons pn>>
duce an elongation of t^h^^t^^ the length.

At this point, however, the permanent set occurs, and beyond it the elongations are
not in proportion to the load, but increase more rapidly than the loads increase. Tims
18 tons will produce more than T^^frv elongation, and so on.

In cast iron, however, the temporary elongations caused, even by small loads, are from
the first irregular, not in proportion to those loads, and an appreciable set is noticed at a
very early stage.

False PermancTU SeL — In some cases, after imposing upon a bar a load far within the
elastic limit, a permanent set seems at first to have been caused, but upon leaving the
bar unloaded for a short time this set disappears, and the bar slowly returns to iti
original length.

Set caused by Continued Load. — It has been found that a load within the elastic limit,
which will not cause a permanent set if imposed and quickly taken off, will nevertheleis
cause a set if it be allowed to remain for a considerable time.

To put it in another way, the elastic limit is lower for a continued stress than for a
temporary one.

Elastic Limit raised by different Processes, — It has been shown that the prooessei of
hammering, rolling, and drawing iron or steel, when cold, into bars or wire, increase thf
tenacity and the elasticity of the material

ELASTIC UMIT OF IRON AND STEEL.

331

Elastie LimU raited by ttnteking. — ^Again, it has been shown that when a bar of iron
Juts been subjected to a load less than the elastic limit, and continued for several honn*,
so that a permanent set ensues, the elastic limit of the bar thus altered is considerably
raised. For example, Ghmeral UchatiuB tested a bar of soft steel, and found the follow-
ing results : — *

Limiting StTess.
Tons per square Inch.

Ultimate
EIoDgation
percent

AlMohite.

ElasUc.

Bar of soft steel ...

Same loaded for 24 hours so as to dovgate S*3 per
cent

Same oil-hardened .....

24-38

24-38
48-18

18-81

ir-77

17-77

26-8

21-6
10-6

Other DfJinUions of the Limit of EUuticUy. — It should here be mentioned that Mr.
Eaton Hodgkinson's experiments led him to the conclusion that the very smallest load
produces a permanent set. His conclusions have been questioned by more recent inves-
tigators, but even supposing they are correct, they do not affect the engineer. The
permanent sets, if any, produced by loads less than the limit of elasticity are so small
that they cannot be measui^ by an ordinary instrument — in fact, they are inappreciable.

When such loads are constantly repeated, though they may produce an inappreciable
set as regards the original length of the bar, yet it is net an increasinff set, does not lead
to rupture, and may therefore practically be ignored.

When, however, the load is greater than the limit of elasticity, an inerecuing set takes
place upon each application, which eventually leads to rupture.

Elastic Limit of Cast Iron, Wrotight Iron, and BteeL — Cast Iron is
very imperfectly elastic, that Ib, even a very small load will produce in it an
appreciable permanent set. There is no clearly-defined elastic limit. The
permanent sets are, however, very small at first, and may be practically
ignored until the load applied is aboat ^ of that required to produce rupture.*
The sets then become partially appreciable.

Wrought Iron, — The elastic limits for different descriptions of wrought iron
vary according to the nature of the iron.

As an average, however, it may be said that the elastie limit, both in com-
pression and tension, is as follows : —

Bars '5 of ultimate strength.

Plates . . . '6 „ „

being about 13 tons per square inch for "Best Yorkshire** iron, and ahout
11^ tons for Staffordshire crown iron^ (see p. 319).

Steel. — The elastic limit of different kinds of steel yaries considerably,
according to the nature of the material and the degree of temper to which it
has been subjected.

It ranges from about 12| tons in annealed Landore mild steel plates (see
p. 323) to 26f tons in very hard cast steel (see p. 320), the proportion of
the elastic limit to the ultimate strength varying from '45 to '8.

Live and Moving Iioads. — To consider the effect of moving and live
loads upon the strength of iron and steel would open up an interesting
subject, which, however, is outside the scope of these Notes.

Pole.

Froeeedings Institute of Civil Engineers, vol. xliz.

' From Experiments of Committee of CivU Engineers,

332 NOTES ON BUILDING CONSTRUCTION.

Live Loads. — Such loads are seldom met with in buildings, except peihaps
in the effect of wind upon roofs ; but they are of frequent occurrence in n^-
waj bridges and other engineering structures.

With regard to the effect of live loads, it will be sufficient to say that spnch
loads have a greater effect than if they were gradually applied as dead loads.

In practice, the effect of a live load is generally taken as equal to twice
that of the same load considered as dead.

Lire and moving loads frequently produce stresses (upon any member of a stmctiire)
which vary considerably in intensity from time to time— e.^. a bar in a bridge may be
subject to a stress of 8 tons per inch of section when a light train is passing, and 5 tons
per inch when a heavy train is passing.

Again, moving loadA sometimes cause the stresses upon a particolar bar to differ in
kind. Thus, trains passing over a bridge may cause a bar to be in oompressioD and
tension alternately.

It has been shown by Wohler that in either case the intensity of stress that the bar
can bear is much lower than what it can hear when the stress is of the same kind (either
tension or compression) throughout, and also of the same intensity.

To put it in another way, the stresses produced are much more trying to the bar than
a stress which is unvarying in kind (being either compression constantly or tension oon-
stantly), and which is also unvarying in amount.

BepeaUd Loads, — It has already been pointed out that repeated loads do
not tend to cause rupture so long as they are kept below the limit of elasti-
city of the material

Vibration. — ^The effect of such loads, or of vibration, has been commonly
supposed to be dangerous, and eventually to cause fracture by changing the
internal structure of the iron from a fibrous to a crystalline structure. There
is still considerable difference of opinion on the subject

Dr. Percy, who has carefully considered the cases bearing upon this question, says : —

** The question will naturally suggest itself whether gentle vibration — the result of
very frequently repeated light blows, or of vibration without impact, caused by janiog
grinding action — as in an axle working in badly lubricated bearings, or of straining aod
torsion in shafts, etc., very much less intense than would be produced by heavy ham-
mering — ^wonld tend to incline permanent disaggregation of the crystals of iron, and con-
sequent tenderness. . . .

'' Opinions are divided upon it, and I am not acquainted with any precise ezperimeiital
data to justify any very positive conclusion on the subject . . .

" Another point remaina to be considered, namely, whether vibration, caused by impact
or otherwise, may induce a crystalline arrangement which did not previously exist, or
was only imperfectly developed. I have not met with any evidence to justify an answer
in the affirmative."^

Extreme CJold. — The effect of extreme cold upon the strength of iron and
steel Ib another open question.

It has already been pointed out (see p. 256) that in some castings, the
bulkier parts, being the last to cool, are left in a state of tension.

Now, if such castings are exposed to cold, the parts already in a state of
tension may endeavour to contract still farther, and rupture may ensue.

With r4;ard to the effect of cold upon wrought iron and steel many
experiments have been made, but they afford up to the present time very
conflicting data.

The discrepancies between the results obtained seem to have been caused in
some measure by differences in the composition of the materials experimented
upon, the presence of phosphorus especially having a marked influence.

^ Percy's Metallurgy,

FORGING AND WELDING.

333

Iron tyres, chairs, and other parts of a railway which are made of iron or
steel, break more frequently during frosty weather than at other times. This,
however, has been accounted for by pointing out that the hardness and rigidity
of the ground during such weather causes the shocks to have much greater
effect upon the permanent way.

As a rule practical men incline to the opinion that frost and extreme
cold have a weakening effect upon iron and steel, and render them specially
liable to be broken by a sudden shock or concussion.

Thus it is the custom to pass the chains used for lifting heavy weights
through the fire on frosty days ; and there is no doubt that while the question
is unsettled it \& safe to take some precaution of this kind.

Forging. — ^Forging metal consists in raising it to a high temperature
and hammering it into any form that may be required.

It is not proposed to describe the process, but merely to mention one or
two points, the neglect of which will seriously impair the strength of the
material

FoBGiNO Iron. — Good wrought iron may he seriously injured by want of care or skill
in foiging it to different shapes.

Repeated heating and reworking increases the strength of the iron up to a certain point ;
hut overheating may ruin it (see below) ; the iron should therefore be brought to the
required shape as quickly as possible.

The form given toforginga is also important ; there should be no sudden change in the
dimensions — angles should be avoided — the larger and thicker parts of a forging should
gradually meige by curves into the smaller parts. Experiments have shown that the
" continuity of the fibres near the surface should be as little interrupted as possible ; in
other words, that the fibres near the surface should lie in layers parallel to the surface.*' '

Overheating. — If wrought iron be "burnt," i.e. raised to too high a temperature, its
tensile strength and ductility are both seriously reduced. These qualities may, however,
be to a great extent restored by carefully reheating and rerolling the iron.

This is well illustrated by the experiments made upon a specimen of bolt iron now
before the writer— of which the results are shown below in a tabular form.

Teneile
strength per
square inch.

Elongation.

Remaiks.

Tons.

Percent

Original specimen as
tested, 1} inch diameter

26-5

68*0

Fine fibrous frac-

Overheated and fhtctured

ture.

by slow tension .

14-0

20*0

Burnt leaden-look-

Reheated, roUed down to
\ inch diameter, and

ing fracture.

fractured by slow ten-
sion ....

26-8

180

Fine grey fibre.

Forging Steel requires still more care in onler to avoid overheating.
Each variety of steel differs as to the heat to which it can safely be raised.
Shear SUel will stand a white heat
Blister Steel will stand a moderate heat
OBUi Steel will stand a bright red heat

Welding is the process by which two pieces of metal are joined together
with the aid of heat

^ Rankine, Oivil Engineering.

334 NOTES ON BUILDING CONSTRUCTrON>

There are several different fonns of wdd.

It is not proposed here to describe the shape of the joint, or the prooess bj
which it is made, bat merely to give an indication of the principles npon
which the welding of metals depends. These are laid down in Dr. VeKf%
valuable work on MetaUurgy^ from which the information here given is ex-
tracted.

It will be sufficient to say that in welding generally the sai&ces of the
pieces to be joined having been shaped as required for the particular form of
weld, are raised to a high temperature, and covered «dth a flux to prevent
oxidation. They are then brought into intimate contact and well hammered,
by which they are reduced to their original dimensions, the scale and floz
are driven out, and the strength of the iron improved.

Welding Wrought Iron. — ^The property of welding possessed by wrought iron is due
to its contioaing soft and more or less pasty through a considerable range of temperatare
below its melting point

When at a white heat it is so pasty that if two pieces at this temperatnre be finnlr
pressed together and freed f^m oxide or other impurity they unite intimately and firmlj.

The flux used to remove the oxide is generally sand, sometimes salt

Welding Steel.—" The facility with which steel may be welded to steel diminishes u
the metal approximates to cast iron with respect to the proportion of carbon ; or, what
amounts to the same thing, it increases as the metal approximates to wrought iron witb
respect to absence of carbon.

" Hence in welding together two pieces of steel — cceUria paribus — ^the more nesrij
their melting points coincide — and these are determined by the amount of carbon tbcy
contain — the less should be the difficulty."

Puddled steel welds very indifferently, and so does cast steel containing a large ptf-
oentage of carbon. The mild cast steels, also shear and blister steel, can be welded with

In forghig and welding and tempering steel tools, more than the requisite heat is
detrimental, as it opens the grain of the steel and makes it coane. The heat should be
applied regularly, irregular heat causes fracture and irregular grain.

Tn weldincr cast steel borax or sal-ammoniac, or mixtures of them, are used as fluxes.^

Welding Steel to Wrought Iron. — If the melting points of two metals "sensiUx
differ, then the welding point of the one may be near the melting point of the other, sad
the difference in the degree of plasticity, so to speak, between the two pieces may be so
considerable that when they are brought under the hammer at the welding point of the
least fusible, the blow will produce a greater effect upon the latter, and produce sa
inequality of fibre."

" This constitutes the difficulty in welding steel to wrought iron.

" A difference in the rate of expansion of the two pieces to be welded produces unequsl
contraction, which is a manifest disadvantage. " '

Hard cast steel and wrought iron differ so much in their melting points that they
can hardly be welded together.

Blister and shear steel, or any of the milder steels, can, however, be welded to wroogbt
iron with ease, care being taken to raise the iron to a higher temperature than the steel,
as the welding point of the latter is lower in consequence of its greater fusibUity.

WisLDiNG OTHER Metals. — It is uot Certain that other metals do not become pastj
before fusion, but the range of temperature through which it occurs is so small that ii
would be scarcely possible to hit upon it with any certainty in practice.

^16 parts borax, 1 part sal-ammoniac, boiled over a slow fire, and when cold
ground to powder, may be used.
« Percy's MeUUlwrgy,

CORROSION S- PRESERVATION OF IRON &* STEEL. 335

COEEOSION AND PRESERVATION OF CAST IRON

WROUGHT IRON, AND STEEL.

Corrosion. — The different varieties of iron and ateel ¥rill not oxidise in dry
air, or when wholly immersed in fresh water free from air, but they all rust
when exposed to the action of water or moisture and air alternately.

" Very thin iron oxidises more rapidly than thick iron, owing to the scales
of nist on the former being thrown off as soon as formed in consequence of
the expansion and contraction from alterations of temperature.

" Iron plates are more durable when united in masses than when isolated.
The oxidation of iron is to a great extent arrested by vibration.^

** The comparative liability to oxidation of iron and steel in moist air,
according to Mr. Mallet, is — ^

Cast iron ..... 100

Wrought iron . 1 29

Steel . . . . laa."

Cast Iran does not root rapidly in air. When immersed in salt water, however, it
is gradoally softened, made porous, and conFerted into a sort of plumbago *

Mr. Mallet found that the rate of corrosion decreased with the thicknees of the casting,
being from iV ^ -x^r ^<^h daring a century in depth for castings 1 inch thick. Mr. D.
Stevenson found the decay to be more rapid than this.

Wrought Iron oxidises in moist air more rapidly than cast iron.

The evidence as to its rate of corrosion in salt water is rather contradictory.

Mr. Bennie found that it corroded less quickly than cast iron, but Mr. Mallet's experi-
ments showed that it corroded more quickly.

Steel rusts very rapidly in moist air, more quickly but more uniformly than wrought
iron, and far more quickly than cast iron. Low shear steel coirodes more quickly than
hard cast steeL*

Recent experiments show that steel immersed in salt water is at first corroded more
quickly than wrought iron, but that its subsequent corrosion is slower, and the total
corrosion after a long period of immersion is less than that of wrought iron.

Preservation. — OalvanUing consists in covering the iron with a thin coat-
ing of zinc

The iron is cleaned by being steeped for some eight hours in water con-
taining about 1 per cent of sulphuric acid, then scoured with sand, washed,
and placed in dean water.

After this the iron is heated, immersed in chloride of zinc to act as a
flux, and then plunged into molten zinc, the surface of which is protected
by a layer of sal ammoniac.

The process differs slightly according to the size and shape of the article.
It is a simple one, and may be applied to small articles in any workshop.

Mr. Kirkaldy found that galvanising does not injure iron in any way.

The zinc protects the iron from oxidation so long as the coating is entire ;
but if the sheet iron be bad, or cracked, or if the zinc coating be so damaged
that the iron is exposed, a certain action is set up in moist air which ends
in the destruction of the sheet

''The sheets are generally galvanised before they are corrugated ; but as in process of
corrugation the sheets, especially the thicker ones, sometimes crack slightly on the surface
(unless the iron is of tiie very highest quality), it is an advantage with all sheets thicker

* Proceedings Inst, Civ, Eng. vol. xxviL " Hurst.

' A form of carbon known as graphite or hlaMead,
* Mr. Mallet in Proceedings Ind, Civ. Eng. vol. ii.

336 NOTES ON BUILDING CONSTRUCTION

than 20 gauge (see p. 355) to galvanise after corrugation, so as to fill up with liiie any
cracks that may have occurred. As, moreoTer, a larger quantity of dnc adheree to the
corrugated than to the flat sheets, they hare, when so coated, a distinctly higher ▼alne." '

Paintinq is an effectaal method of preserving iron from oxidation, if the paint
is good and properly applied, and the iron in a proper condition to leceiTe iL

In order that the protection by painting may continue, the Bnr£ace should
be carefully examined from time to time, so that all rust may be removed.
The paint may be renewed directly it is necessary (see Part IL, pi 284).

The following hints on the subject are condensed chiefly from Uie emi-
nently practical book entitled Works in Iron, by Mr. Maiheson.

Coat Iron should he painted soon after it leaves the mould, before it has time to nsL
The object of this is to preserve intact the hard skin which is formed upon the suifaee of
the metal by the fusing of the sand in which it is cast

After this a second coat should be applied, and this should be renewed fh>m time to
time as required.

In any case, all rust upon the surface of castings should be carefully removed before
the paint is applied.

Small castings are often Japanned (see p. 435).

Wrought Iron. — Before painting wrought iron care must be taken to remove the hard
skin of oxide formed upon the surface of the iron during the process of rolling; and
which, by the formation of an almost imperceptible rust, becomes partly looee and
detached fh>m the iron itself.

An attempt to prevent this rusting is sometimes made by dipping the iron, while still
hot, in oil. This plan, however, is expensive, and not very suooeseful.

The scale is sometimes got rid of by ** pickling," the iron being first dipped in dilute
iron to remove the scale, and then washed in pure water.

" If the trouble and expense were not a bar to its general adoption, this is the proper
process for preparing wrought iron for paint, and it is exacted occasionally in very strict
specifications."

*' But somewhat the same result may be obtained by allowing the iron work to mst,
and then scraping off the scale preparatory to painting. If some rust remains upon the
iron the paint should not be applied lightly to it, but by means of a hard brash shoold
be mixed with the rust."

Ordinary lead paints, especially red lead, are often used for protecting iron work, bat they
are objected to on the ground that galvanic action is set up between tiie lead and the iroD.

Mr. Matheson recommends oxide of iron paints for iron work generally, and bitumi-
nous paints for the inside of pipes or for ironwork fixed under water.

The precautions to be taken in using these paints, and the objections to ardinary lead
paints, are given in chapter VI.

The ironwork for roofs, bridges, and similar structures, generally receives one cost of
paint before it leaves the shops, and two or three more after it is fixed.

Dr. Angus SmUtCs process is an admirable means for preventing corrosion in east^
iron pipes.

The pipes having been thoroughly cleaned fh>m mould, sand, and mst, are heated to
about 700"* Fahr. They are then dippMi vertically into a mixture consisting of ooal-tar, pitch,
about 5 or 6 per cent of linseed oil, and sometimes a little resin, heated to about 300* Fahr.

After remaining in the mixture several minutes, long enough to acquire the tempera-
ture of 800", the pipes are gradually withdrawn and allowed to cool in a vertical position.

Perfect cohesion should teke place between the coating and the pipe, and the farmer
should be free from blisters of any kind.

In practice the heating of the pipes before immersion is found to be very expensive, saA
is fluently omitted. However, many engineers consider it essential for really good work.

The Bower- BarJ" processes ' protect the surfaces of iron and steel by covering them with
a coating of black magnetic oxide.

In the original process, invented by Professor Barfff this was effected by subjecting
the articles to be coated in a heated mufl9e to the action of superheated steam. The
heated metel decomposes the steam and combines with some of ite oxygen to form the
coating of magnetic oxide.

A similar effect is produced by Mr. Bower's patent, under which the gas firxne a

' Matheson. * Proceedings Soe. Engineers, 1884, p. 59, Mr. Bower's paper.

CHARACTERISTICS AND USES OF IRON AND STEEL. 337

prodacer ii burnt with a slight excess of air, and taken into a brick chamber, in which
the articles to be coated are placed, a red coating of sesqoioxide is produced soon after the
articles are red, but after about 40 minutes the air is shut off, and the producer gases
only admitted, when, in 20 minutes more, the sesquiozide is converted into magnetic oxide.

" This alternate treatment goes on for different periods, depending upon the nature of
the articles and the purpose for which they are required.

" For indoor work 4 hours are sufficient, but the time varies from 4 to 8 hours, or
about half that necessary for coating by the aid of steam.*' ^

Both processes are now worked by Mr. Bower, Pro! Barff*8 process being better for
wrought iron, and that of Mr. Bower, which is much cheaper, for cast iron.

These processes are said not to impair the strength or other qualities of the iron, and
to protect it thoroughly against oxidation or corrosion from damp earth, salt-water, or
other causes.

Brioht Ibonwork. — The portions of ironwork that have been turned, or
fitted, and all tooled surfaces, should be protected by a coating of tallow, mixed
with white lead to prevent it from easily melting and running off the metal.

'^Dr. Percy recommends for the same purpose common rosin melted with a little
Gallipoli oil and spirits of tuipentine. The proportions, which may easily be found by
trial, should be such as will make it adhere firmly and not chip off, and yet admit of
being easily detached by cautious scraping."'

Bronzing is done with bronze powder, paint, or varnish, but does not
stand the weather welL

Gilding has to be done with special care, or the gold will be destroyed by
rust The surface of the iron, having been very carefully cleaned, is painted
with two coats of iron oxide paint, then with two coats of lead paint of light
colour as a basis for the '^ oil gold size '' upon which the gold leaf is placed.
When properly done the gilding will last fifteen or twenty years. ^

CHARACTERISTICS AND USES OF IRON AND STEEL.

The student will have perceived that the products of the iron manufac-
turer may be divided into three classes — cast iron, wrought iron, and steel,
the differences in which are caused partly by the amount of carbon they
respectively contain, and also by the processes they have undergone.

The following Table, from Bauermann's Metallurgy, gives the proportion
of carbon in different varieties of iron and steel according to Karsten : —

Namic

or Carbon.

Fbopibties.

1. Malleable iron . . .

0-25

Is not sensibly hardened by
sudden cooling.

2. Steely iron

0-86

Can be slightly hardened by
quenching.

8. Steel

0-50

Gives sparks with a flint when
hardened.

4. Do

1-00 to 1-50

Limits for steel of maximum
hardness and tenacity.

5. Do

1-76

Superior limit of welding steel.

8. Do

1-80

Very hard cast steel, forging
with great difficulty.

7. Do

1-90

Not malleable hot.

8. Cast iron ....

2-00

Lower limits of cast-iron can-
not be hammered.

9. Do. ... .

6-00

Highest carburetted compound
obtainable.

» RLCE. 1884, p. 59 (Bower).
B. 0. III

« Pole.

* Matheson.
Z

338 NOTES ON BUILDING CONSTRUCTION.

The great differences in the characteristics of cast iron, and wrought iroc
and steel, are briefly recapitulated below, and these determine the uaes to
which they are respectively applied.

Cast Iron has little tensile strength, but affords great resistance to com-
pression.

It is hard, brittle, wanting in toughness and elasticity, and gives way with-
out warning, especially under sudden shocks or changes of temperature. It
is easily melted and run into various shapes.

The castings thus produced are liable to air-holes and other flaws, which
reduce their strengtL Small castings are stronger in proportion to their size
than large ones.

Cast iron can be cut or turned with edge tools, but is not malleable either
when cold or hot, nor is it weldable.

It is not so easily oxidised in moist air as wrought iron. In salt water,
however, it is gradually softened and converted into plumbago.

Cast iron is peculiarly adapted for columns, bedding plates, stmts, chairs,
shoes, heads, and all parts of a structure which have to bear none but steady
compressive strains ; also for gutters, water pipes, railings, grate fronta, and
ornamental work of nearly every description.

It has been much employed for girders, but is an untrustworthy material
for those of large size, or in important positions. It is liable to crack and
give way without warning under sudden shocks, and also under extreme
changes of temperature, such as occur in the case of buildings on Are, where
the girders may become highly heated, and then suddenly cooled by water
being poured on them.

Malleable Cast Iron possesses originally the fusibility of cast iron, and
eventually acquires some of the strength and toughness of wrought iron.
It may be used for heads, shoes, and other joints in roofs, and for all articles
in which intricacy of fonn has to be combined with a certain amount of
toughness.

Wrought Iron has many most valuable qualities, though these differ con-
siderably as to degree in different varieties of the material.

Its tensile strength is three or four times as great as that of cast iron, but
it offers not half the resistance to compression.

It is, however, very tough and ductile, and therefore gives way gradually
instead of suddenly snapping.

Its elastic limit is equal to about half its ultimate strength, and it will
bear repeated loads below that limit without injury.

Wrought iron is practically infusible, is malleable hot and cold, is weldable
at high temperatures, and can be forged into various shapes.

It Ib subject to '' hot and cold shortness " produced by impurities, and to
other defects. Large sections are more likely to contain flaws than small
ones. Bars are, as a rule, stronger than plates, and plates are stronger with
the grain than across it.

Malleable iron rusts quickly in moist air, but stands salt water better than
cast iron.

The great tensile strength of wrought iron leads to its employment for tie-
rods, bolts, straps, and all members of any structure which are exposed to tensile
stress ; it Ib also much used for members which undei^ compression. It
should be employed for all important iron beams and girders, especially
those exposed to sudden shocks. In its various forms it cumes into play in a

COPPER. 339

variety of ways in roofs, braced girders, and iron structures of all kinds.
Corrugated sheets are much used for roof coverings.

Steel differs even more than wrought iron in the characteristics of its
several varieties.

It has a high tensile strength, much greater than that of wrought iron.
Its resistance to compression is also much greater. Moreover, it has a harder
surface, and is better able to resLst wear and tear.

Hard steels, containing a large proportion of carbon, are fusible, easily
tempered, have a high tenacity and elastic limit Their resistance to compres-
sion is enormous, especially when they are tempered, but they cannot be
easily welded or forged, are brittle, and very uncertain in quality.

Soft mild steels have a tenacity and resistance to compression, and an
elastic limit somewhat higher than wrought iron. They can be hardened and
tempered, but not easily. They are weldable and easily forged, and afford a
very reliable and ductile material adapted for structures subject to sudden
shocks.

Steel is more easily oxidised than wrought iron, and far more easily than
cast iron.

Steel is at present hardly used at all by the builder. Sometimes bolts and
cotters are made of steel for large roofis.

It is not adopted for engineering structures to anything like the fullest
extent of which it is capable, but is required by the engineer for tools, rails,
boilers, machinery, wheels, etc. etc., and is coming into use for some of the
larger roofs and bridges.

COPPER

Uses. — Copper is used by the builder chiefly for slate nails and
bell wires, sometimes for rain-water pipes and gutters, for covering
roofs, for lightning-conductors, and for dowels ; also for bolts and
fastemngs in positions where iron would be corroded or oxidised.
Moreover, it forms most useful alloys with other metals.

Copper wire cord is sometimes used for sash lines, and also for
lightning-conductors.

Ores. — It is frequently found in the metallic slate, and is also obtained
from copper pyrites, grey and red copper ores, from copper glance, and other
ores, by roasting^ calcining, refining, and melting them with certain fluxes
and oxidising agents.

The presence of sulphur and antimony decreases the malleability and ductility of copper.
Small quantities of arsenic and phosphorus increase its toughness, but large quantities
ligure it.

Properties. — The red colour of copper is familiar to all The
metal is peculiarly malleable, and can be hammered or rolled into
very thin sheets.

In tenacity it is inferior to wrought iron, but is superior to all
other metals. The tensile strength of copper wire is about 16

340

NOTES ON BUILDING CONSTRUCTION.

tons per square inch, that of cast copper being 8^ ton& It
is not so ductile as wrought iron, and cannot therefore be diawo
into such fine wires.

It can be worked either cold or hot — ^in the latter case it is
easily oxidised — but it cannot be welded.

Oxidation and Oobbobion. — Copper oxidises very slowly in sir, bdsg
covered with a fihn of carbonate, commonly called verdigru,^ The appear-
ance of this film is well known to all ; it forms a protective coating which
preserves the sniface of the copper from farther oxidation.

Copper is corroded by salt water if at the same time air has access to it ;
the presence of a small proportion of phosphorus is said to retaid the oor-
rosioiL

Market Forms. — Sheii Copper. — The most nsefal form for the hnilder
in which copper is sold, is in sheets measuring about 4 feet by 2 feet (in Scot-
land 4 feet by 3 feet 6 inches), and described according to their thicknen (b]F
the Birmingham Wire Qauge), and their weight per foot superficial, or their
weight per sheet

"Die gauges of the sheets vary from Na 1 to 30 W.Q. The weights of i
few of the most useful thicknesses are given in the Table below : —

Tablb of Wbioht of Shebt Copper.

Bfnnlngluun
WinGirage.

Weight Bar foot
onncM.

^\^

W^''

Bbmingbam
Wire Gauge.

Weight per foot

•aperflcial In

ounces.

Weifl^tpcr

Bheeiifeet

brjfcet.

fnlfae.

20
22
24

26
20
16

26
28
80

12
8
6

6
4

Sheet copper, weighing from 12 to 20 oz. per square foot, is used for too&,
flats, and gutters. Copper wire from 17 to 19 B.W. gauge for bell-hanging

When used for roofing, copper is laid in a way somewhat similar to zinc
(see p. 269, Part XL)

Copper Wirt Cord. — The following are the working loads * for the different
siies: —

Oixcamference in inches
Working load in lbs.

n. li 1. *. !> f I. I
448, 886, 224, 168, 112, 75, 50, 84.

Copper Wire-covered Steel Ribbon Sash Line is also made under Hookliani'f
patent in three sizes, having a breaking strain in cwt. as follows : —

No. 1 2 8

8 cwt 4^ cwL 7 cwt

r«rt{<j^m, properly so called, is a basic acetate of copper.
* Sfaeffifild Standard Lint

LEAD,

341

LEAD.

Uses. — Lead is much used by the builder for cisterns, pipes,
fiat rooft, etc., and from it is prepared white lead, the basis of most
ordinary paint The engineer requires it as a bedding for the
ends of girders, and for other minor purposes.

Ores. — Lead is not found in the metallic state, but is reduced chiefly from
the ore called galena (the sulphide) by roasting or smelting in a reverberatory
furnace, furnished with long flues to catch the particles of lead, which would
otherwise be carried away in the smoke.

Pboperties. — Lead is extremely soft and plastic, very malle-
able, fusible, heavy, and very wanting in tenacity and elasticity.

Market Forms. — Lead may be purchased in cast pigs, sheets, or pipes.

Sheets are either " cast," or ^ milled," and are described according to their
weight per foot superficial.

Cast lead is made in fiheets from 16 to 18 feet long, and 6 feet wide ; it is
thicker and heavier than milled lead, and has a harder surfiace.

It is, however, liable to flaws and sand holes, and is irregular in thickness,
on account of which it should not be used of a lighter substance than 6 lbs.
per square foot

Cast lead is often made by the plumber himself out* of the old lead waste
pieces and clippings that accumulate in the course of his work.

MiUed lead is rolled out thinner than the other, is more uniform in thick-
ness, bends easily, and makes neater work, but cracks if much exposed to the
sun. The sheets are from 25 to 35 feet long, and from 6 feet to 7^ wide,
Sheet lead is always described according to its weight in lbs. per foot
superficial

The following Table shows the thickness of sheet lead for different
weights per square foot.

Table giving Weight and Thickness of Sheet Lead.

Weight In Ita.

per superficial

foot

Weight In lbs.

per saperfldal

foot

Thickness
in inches.

Nearest
simple
Auction.

1
2
3
4
5
6

0017
0084
0-051
0-068
0-085
0-101

7
8
9
10
11
12
15

0-118
0-136
0-152
0-169
0 186
0-203
0-255

H
A
1

The weights of sheet lead generally used are as follows (see p. 150, Part I.) :
— For aprons, 5 lb. lead ; for roofs, flats, and gutters, 7 or 8 lbs. ; for hips
and ridges, 6 or 7 lbs. ; thicker if much exposed.

342 NOTES ON BUILDING CONSTRUCTION,

LokViiniiiedL Ltad is a very thin description of sheet used, made for oovenn*;
damp walls.

Action of Water upon Lead. — Soft water, especially when full of air,
or when containing organic matter,' acts upon lead in such a way that sume
of it is taken up in solution, and the water is poisoned.

This makes lead a dangerous material to use in many cases fur dsten>»
and pipes connected with the supply of water for drinking purposes, or for
roofs and flats whence that supply may be drawn.

Vitiated or impure air acts upon lead in a somewhat similar manner.

There has been a good deal of discussion with regard to the action of different kinds
of water upon lead, as the subject is an important one, the following remarks are inserted.
They are chiefly founded upon the valuable standard work on hygiene by the late Pro-
fessor Parkes.

Pure water, not containing air, does not act upon pure lead.

When the water contains much oxygen, the lead is oxidised ; and oxide of lead, a
highly poisonous substance, is to some extent soluble in water.

If there is much carbonic acid present it converts some of the oxide into carbonate A
lead, which is almost insoluble and therefore comparatively harmless.

ThA wcUen v/hieh act most upon lead are tlM purest and most highly oxygenated,
also those containing organic matter — nitrites, nitrates, and chlorides.

The vxUers which act least upon lead are those containing carbonate of lime sDii
phosphate of lime, in a less degree sulphate of lime. Some of these form a coating on
the inside of the pipe which protects it from further action.

Some vegetable substances contained in water, peaty matter for example, also protect
the pipe by forming an internal coating upon it.

It appears therefore that hard waters, containing (as they generally do) carbonate of
lime, do not readily affect lead.

Soft waters, such as rain water, and water obtained by distillation — ^water pollateii
with sewage— water in tanks having a muddy deposit — ^may all become poisoned whco is
contact with lead.

" The mud of several rivers, even the Thames, will corrode lead, probably from the
organic matter it contains, but it does not necessarily follow that any lead has been
dissolved in the water. Bits of mortar will also corrode lead." ^

Vegetables and fatty adds arising fh>m fruit and vegetables, cider, sour milk, etc,
also act upon lead.

rhe poisonous effects of lead show themselves in other materials connected with
building.

For example, white lead, the basis of most paints, is a highly poisonous substance, and
leads to serious diseases among the workmen who manudTacture the white lead, and
among the painters who use it (see p. 406).

Iiead Pipes are much used in connection with water supply, etc

Pipes of large diameter are generally made by the plumber out of sheet
lead.

Smaller pipes used to be cast in short lengths of considerable thickness, and
then drawn out to the proper dimensions.

Now, however, they are generally formed by forcing the molten metal, l^y
hydraulic pressure, through a die of the section required.

Soil pipet should always be " drawn," and are thus made of from 3| to *">
inches diameter, and of thicknesses equal to those, of sheet lead yarying in
weight from 6 to 10 lbs. per square foot.

Water pipes. — The thickness and consequently the weight of lead pipes
used for water supply should be regulated by the pressure of water they are
intended to bear.

^ Parkes' Ifygietu,

LEAD.

343

The following Table shows the sizes and weigjits per yard run of pipes
usually made and the heads of water to which they can be safely subjected
in practice ; —

Lenstha in
which loada

Intenuil
diameter of

Overflows.

Heads about
60 feet

Heads about
800 feet

Heads about
600 feet

Feet

Weight in lbs. per yard run.

15'

...

•«•

3-9

...

3-9

4-8

„

3-6

8-9

4-5

4-8

5-7

6-0

...

3-6

4.5

6-0

4-5

4-8

6-1

6-7

6-3

7-2

8-4

9-0

»» -

...

7-2

6-1

9-6

11-1

12-0

12-9

12^

10-5

12-0

12-9

150

»t

.11

120

14-1

18-0

21-0

240

J 5

...

•••.

18-0

21-0

24-0

»• .

-1

14-1

18-0

21-0

24-0

27-9

30-0

10-8

21-0

25-2

28-8

38-6

36-0

12-6

18-0

24-0

30-0

33-6

860

39-0

42-0

16-8

27-0

83-6

360

39-0

46-0

480

64-0

„

16-8

210

240

33-6

42-0

48-0

61-0

60-0

»»

4.1

19-8

25-2

33-6

42-0

51-0

60-0

660

51-0

600

70-2

76-2

84-0

Number of Column

The above are reduced from the price list of Messrs. John Holding and Sons, manu-
facturers.

Ck)ATiNa Lead Pipes to prevent Poisoiiino. — Several methods have been
proposed for coating and lining the insides of lead pipes to prevent the water
conveyed by them from being poisoned.

All of thefje are condemned by Professor Parkcs as being objectionable,
except the following : —

M^DougdCs PaUnt consists in applying an internal bituminous coating, which is said
to have been successful.

Schwartz's PcUent.^The pipe is boiled in sulphide of soda for fifteen minutes, by
which the interior is coated with sulphide of lead (a substance insoluble in water).

Lead ESnoased Pipes. — ^Tin pipes, and copper pipes, lined with tin, have been pro-
po.4ed as substitutes for lead pipes, but they are too expensive.

The lead encased pipe, made under Hainai'a paUfU, has, however, been found to be
perfectly successfuL

This consists of an inner pipe of block tin, encased in a lead pipe
as shown in section. Fig. 146. The two metals are so united that no
joint between them is perceivable, and they cannot be separated by
any amount of bending or twisting.

In consequence of the tin melting at a lower temperature than
the lead it is somewhat difficult to make a soldered joint in these
pipes. However, it may be done with care, or ffeap*8 mechanical
joints may be used, in which the union is effected by means of v. ynt

screwed couplings. Fig. 14«,

344

NOTES ON BUILDING CONSTRUCTION.

Weight €f iMuL-encaaed Pipe^—Aa the lead-encased pipe is stronger than ofdisiiy
iead pipe, it may be of Icj^s weight per yard for water supply under any giren pres-
sure. To meet the case iu which water companies require pipes to be of a certain
regulated weight according to the head, a special lead-encased pipe is made with a
smaller proportion of tin. The weights of pipes of this class are shown in cols. 9, 10,
11 of the Table below. They are heavier and cheaper than the pipes with full propor-
tion of tin, whose weights are given in cols. 6, 7, 8.

Table of Weights of Lead-Encabed Pipi£S in lbs. per Yard Rdx.»

c £ .5

I
i

i
I

11
1^
2

No. of
column

.Extra light Weights.

'ol

Weights suitable for sup
ply of water under
the heads stateil.

50 feet
heail
and
under.

Mto

250 feet

head.

124

ISi

251 to
500 feet
head.

9
12
14
21

Extra heavy wrigktK

with less tin for siiyply

of water under hvstlft

50 feet
head
and

under.

10
121
16
28

51 to I 251 to

250 feel 500 fw:

head, hmi

4i
6
8
9
11

5
7
9

10
12

14 I 16

18
26

21
30

Stre^igth of Lead Pipes and Lead^Encased Pipes, — Mr. Kirkaldy f«iuud tlu-
strength of lead pipes and of lead-encase<l pipes to be respectively as follows :— '

Lead Pipe. Lead-encased

Pi[«.

Bursting pn^-

sure i>er so. iu.

iulbs.

Internal
Diamr.

Thickness.

Weight per
foot.

Bursting pres-
sure per sq. in. Thickness.

in lbs.

Weight per
foot

• -2
•2
•22
•2
•21
•24
•21

2-3
2-6
3-8
41
5-3
71
9-2

U79
1349
1191
911
683
734
498

•14
•13
•15
•14
•13
•15
•17

1-3
1-4
19
2-4
27
8-8
6-4

1859
1454
1416
1265

885

849 ,

642

The tearing strength of lead pipe was 2159 lbs. per square inch, of lead-encased pipe
3759 lbs. per square inch.

Glass lined pipes may be mentioned here, though they are Iron pipes lined vith gUf^
tubes. They are stated to he safe against lead poisoning, to require no soldering, to l«
rat proof, to have but little internal friction, and to be not liable to choke from corrosiott
like iron pi))es. They ere made from ^ to 2^ inches in diameter, in various lengths vp
to 6 feet, with ends screwed into sockets, and with asbestos washers,

Prst Lead, for glazing, is made (as described at p. 421, Part II.) in anws,
x.e. long strips, of H section, the width of the groove (i.e. the lenj,'th of the
cross bar of the H) ; the width of the face (i.e. the aide of the H), and the

Lead Poisonbifj of Water and its Prevention^ by A. M 'Galium Gordon.

ZINC.

345
There are three

fihttpe of the face differ, the latter is made flat or round,
classes of fret lead, known as ordinary, narrow, and broad.

The following Table, from Seddon's Builder's Work, gives a general idea
of the sizes as obtained in the market : —

Width of
Grooves
in inches.

Shape of
Fftce.

Width of Fm6
In inches.

Bemarks.

Ordinary .

Narrow
Narrow
Broad
Broad

k
A

Flat

Flat
Bound.

Flat
Bonnd.

Swidthsftom^ toi
2 .. Atoi
5 „ AtoJ
2 „ Atoj

(Used for ordinary
< lead lights up to
I 21 oz. sheet glass.

Used for cathedral
and thick antique
glass, according
to its thickness.

ZINC.

Uses. — Zinc is much used for roofs, for light gutters and pipes,
for cisterns, chimney pots, ornaments, ventilators, etc. ; for slating
nails, for tubing, and for covering iron to protect it from oxida-
tion. It also forms a component part of several useful alloys,
and the oxide of the metal is used as a basis for zinc paint.

Ores. — ^The metal is produced from the ores known as " calamine " (the
carbonate), '* blende " or " blackjack" (the sulphide), and red zinc ore (the oxide).

The Ore is roasted, mixed with charcoal, and heated in peculiar retorts.
The zinc is converted into vapour, condensed, and then fused. Most of the
zinc used in this country comes from Belgium.

Properties. — Zinc is easily fusible. Cast zinc is brittle when
cold. If pure it becomes malleable at about 220° F., and can be
rolled into sheets, which retain their maUeabUity. At very high
temperatures, such as 400** F., it becomes very brittle again.

The presence of lead makes zinc too brittle to roll at any temperature.
Zinc should be cast at a low temperature, or the metal will become very
hard, and some of it will pass off in vapour.

Zinc is easily acted upon by moist air ; a film of oxide is soon
formed, which, however, protects the metal from further action.

If, however, the air contains acid, as it does near the sea and

in large towns, the zinc is destroyed.

Soot is very destructive to zinc, forming with it a galvanic couple, which
is brought into action by the moisture and acid in the air.^

Good sheet zinc is of an uniform colour, tough, and easily bent
backwards and forwards without cracking.

Inferior zinc is of a darker colour than the pure metal, and of a blotchy

* Proceedings Inst. Civ. Eng. vol. xxvii.

346

NOTES ON BUILDING CONSTRUCTION

appearance, cau&ed by the presence of other metals, which set up a galvanic
action and soon destroy the zinc.

There is no practical engineer's test for the quality of zina Good zinc
should, however, be as free from iron as possible. The following is an
analysis of Vielle Montague zinc, which shows that it is practically pure : —

Zinc . . 0*995
Iron . 0'004

Lead, etc. . 0*001

1-000

Zinc containing more than about 1 per cent of lead should be rejectetl.

Market Forms.^ — Zinc is sold in sheets 7 feet by 2 feet 8 inches, 7 feet
by 3 feet, or 8 feet by 3 feet, described by their thickness and weight in
ounces per foot superficial (according to a special gauge which varies with
different manufacturers).

ZiNO Gauge. — ^The follovring Table shows the weight of zinc per square foot for the
various numbers of the Zinc Gauge, properly so called. This gauge originated in Bel-
gium, and is sometimes called the Belgian Zinc Gauge, but it is Imown in the trade as
the Zinc Gauge, and is used by Messrs. F. Braby and Company, the Englisb agents of the
Vieille Montague Zinc Company, whose zinc, obtained from mines in Belgium, Sweden,
and Spain, is of excellent quality and extensively used in this country.

The thickness of the sheets is also given in the Table ; those from Nos. 10 to 21
(except 18) have been accurately measured and kindly furnished by Messrs. Braby ; the
others are calculated.

Qauge.

Approximate Weight
per square foot.

Approximate
Thickness.

Gauge.

Approximate Weight
per square foot

Lbs.

Oz.

Dr.

Lbs.

Oa.

Dr.

Inch. '
•0018

Inch
•0326

•0036

-0364

•0056

•O4O0

•0078

•0437

•0091

■0478

•0110

•0509

•0128

■0581

•0146

■0728

•0165

•0764

•0180

•0800

■0217

■0896

•0254

•0992

•0290 i

•1088

Of the above sheets, Nos. 1 to 6 are rolled only to order and of special dimensions.
The remaining gauges are made in sheets of all the three sizes mentioned above.

There are several other zinc gauges given in various Price Books, etc, but they are
generally based upon the above, the range of numbers being smaller and the weight not
so accurately given.

* The commercial name for zinc before it is converted into sheet and other useful
forms is Speller.

TIN, 347

The thicknesses of zinc recommended for roofing purposes are given at p.
273, Part IL

Tlie expansion and contraction of this metal with changes of temperatnre
are greater than of any other, and should be carefully guarded against by
laying sheets on roofs without rigid fastenings as described in Part IL

Zinc should not be allowed to be in contact with iron, copper, or lead. In
either case voltaic action is set up, which destroys the zinc This occurs
especially, and more rapidly, when moisture is present

Zinc should also be kept clear of lime or calcareous water, and of any wood,
such as oak, which contains acid.

Zinc laid on flats or roofs where cats can gain access is also soon corroded.

An objection to zinc for roofs is that it catches fire at a red heat and blazes
farioualy.*

TIN.

Uses. — Tin is used in building for lining lead pipes, occasion-
ally as a protective covering for iron plates, and for small gas
tubing.

Oasa — The metal is obtained from an ore called ^ tin-stone " — the bin-
ozide, and also from tin pyrites. The ore is stamped ; roasted to expel
sulphur and arsenic ; wash^, mixed with flux, and smelted in a reverberatory
furnace, whence the liquid metal is run into a basin, and thence into moulds.
The ingots thus produced are refined and boiled.

Properties. — Tin is very soft, more easily fused than any other
metal, very malleable, and very slowly oxidised, but its tensile
strength and ductility are very low.

Tin may be distinguished from other metals by its crackling when bent.
Its purity is tested by its extreme brittleness at high temperatures.

Tin Tubing is made of diameters varying from ^ to 1 inch, and of light
section, for the conveyance of gas, but is now not much used, having been
superseded by the composition tubing described below. The cost of the metal
makes it too expensive^ if made strong enough, for water supply.

Comf(i9iiion Tubing is made from a miztnre of tin, lead, and antimony. It is exten-
sively need for the smaller branches of gas supply, being much less expensive than tin
tubing^ is easily bent to suit any position, and can be attached to connections by soldering.

' Bloxam.

348 NOTES ON BUILDING CONSTRUCTION.

Weight in Oances per Yard Bun of Tin and of CoMPoemoN Tubiko.

Internal
Diametor.

Weight per Yard
in ounoes.

Internal
Diameter.

Weight per Yard
mooncea.

Tin.

Composi-
tion.

Tin.

Compoai-
tion.

i
A

7to8
9to9J

8
11 to 18
14 to 16
18 to 21
28 to 26

i
A

8
J
1
1

80
88

47 to 48

29 to 84
86

44 to 52
62 to 68
64 to 76
80 to 88

Tin Plate is iron plate covered with a coating of tin hj a process simiJAr
to that of galvanising, described at page 321, molten tin being used instead
of zinc.

Such plates are durable until once a hole is made in the covering, after
which galvanic action sets up between the tin and iron, and the former is
rapidly eaten away.

There are two kinds of tin plate, charcoal plate and coke plate, so called from
the plate iron being made with charcoal and coke respectively.

Teme Plate is described at page 273.

Block Tin or Doubles consists of tin plate with a mnch thicker coating of tin upon it
It is used for the best tin ware.

Orystallised Tin Plate is made by heating the surface of ordinaiy tin plate with hydro-
chloric and nitric acids, which gives it a variegated appearance. This is sometimes known
as Moir6 metallique.

Tinned Copper is often used for kitchen utensils. The surface of the copper is cleaned
before tinning with sal-ammoniac.

ALLOYS.

Allays are mixtures formed by melting two or more metals
together.

They are not, however, mere mechanical mixtures, for they often
exhibit properties different from those possessed by the metals in
the mixture.

For example, copper and tin are both very malleable metal&

Two parts of copper with one of tin form a white alloy {speculum metal) so
hard that it cannot be cut with steel tools, and as brittle as glass.

The tensile strength of this alloy is only i that of tin and -^ that of copper.

Nine parts of copper to one of tin make a tough, rigid gun metal^ harder
and more fusible than copper, but which cannot be rolled or drawn.

By adding tin (a softer metal than copper) to gun metal its hardness is
increased !

In preparing alloys the most infusible metal should be melted first, and the otheis
subsequently added.

If the metals are of different specific gravities they must be continuaUy stirred while
fluid, or the heavier will sink to the bottom and the alloy will not be homogeneous.

ALLOYS.

349

The specific gravity of an alloy is seldom eqaal to the mean of the specific gravities ot
the metals in the mixture. It is sometimes more and sometimes less dense.

The tensile strength of an alloy is generally much greater than that of the metals
soxnposingit

Brass is an aUoy compoeed of copper and zinc, the proportions of which
vary according to the purpose for which the metal is required.

The zinc is melted first, and the copper added in small quantities. A little
old brass in the crucible will facilitate the union of the metals. The crucible
must be covered with charcoal powder and a close lid, or the zinc will pass
away in vapour.

CoUmr, — The colour depends upon the proportions.

Common yellow brass contains 2 parts of copper to 1 of tin. If the copper
be in greater proportion than 4 to 1, the alloy is reddish ; if less than 3 to
1 , it becomes of somewhat the colour of zinc.

Properties. — Brass is tough, as a rule, but is rendered brittle by continued
vibration. The presence of iron injures its tensile strength and malleability.

It is more malleable than copper when cold, but cannot be forged at a red
heat, because the zinc melts at a low temperature.

The fusibility of brass increases in proportion to the quantity of zinc it con-
tains. The addition of a little phosphorus makes it very liquid and easily run
into fine castings.

The proportions of the constituents for the different kinds of brass, and the
uses to which these are applied, are shown in the Table on p. 350.

The name Brass is frequently given to all alloys of copper. Those a)n-
taining tin should properly be called Broms,

MwnJtz mekU or sheathing is cheaper than common brass and more easily rolled. It is
much used for sheathing ships, as it keeps cleaner than copper, and is sometimes
employed as a covering for small roofs.

Muntz metal made, as it usually is, of 60 parts copper and 40 zinc, has been found to be
attacked by salt water and to lose its zinc An alloy is therefore used instead of 68 parta
copper and 82 zinc.

Delta Metal, sometimes called Dick's metal, is an improved brass, which can be
made tough and hard ; it can be foiged or rolled hot, or worked and drawn into wire when
cold. It makes sound fine castings, is of the colour of gold alloyed with sQver, and when
exposed to the atmosphere tarnishes less than brass.

ElBKALDl

'8 TE8T8.1

Stress per square inch
in tons.

Contraction

of area

at fracture

per cent.

Ehctenslon

in 10 inches

per cent.

Ultimate.

Elastic
limit.

Bar 1 as drawn
„ 2 annealed
Cast in sand

83-6
27-2
21-6

22-1
8-8

15-0
19-9

8-8
17-6

Bronae is a mixture of copper and tin, the proportions being varied for
different purposes, as shown in the Table below.

The different specific gravities of the metals make it difficult to melt
them together. The tin is first melted into twice its weight of copper to

' From Patentee's Circular.

350

N07ES ON BUILDING CONSTRUCTION

make hard metal, which is then added to the proper proportion of copper
Beparately melted.

Large castings in bronze are often not homogeneous throughout their maa^.
in consequence of the difference in fusibility of the copper and tin.

QuN Metal also differs in the proportions of its constituents according tu
the purpose for which it is intended.

At one time it was much employed for casting ordnance, from which it
derives its name.

It is harder, more fusible, and stronger than copper, and is used for pump
valves and parts of machines.

Bell Metal consists of copper and tin, in the proportion of from 3 to 1
to 5 to 1. Small house bells contain 5 copper to 1 tin. Large bells 4
copper to 1 tin. Large church bells 3^ copper to 1 tin. The metal, after
being cast, is heated to redness and quenched, then again heated and allowed
to cool slowly.

Aluuinidm Bbonzb contains fh>m 90 to 95 per cent copper and 10 to 5 per cent
aluminium.

It may be cast or turned in a lathe, also forged cold or hot, but it cannot be welded.

Table giving the Composition of various

Allots.

Alloys.

Parts by Weight.

Iron.

Brass, ordinary .

„ forlocksanddoorhandles

„ „ turning and fitting .

„ „ engraving

A little

„ „ bushes and sockets .

...

„ to bear soldermg well .

„ pot metal ^ .

Bronze, hard, for bearings for

machinery

„ for stop cocks and valves

„ „ wheel metal for small

...

toothed wheels

1 ;

„ „ bearings for very

Man-

gaxieae.

heavy weights

Manganese bronze

...

Gun metal for ordnance

90i

...

„ of maximum hard-

...

ness for turning

„ soft . . .

...

Bell metal .

LMitiMa

Muntz metal *

„ nails for

Gedge's metal

38-2

...

1-8

Sterro- metal

55to60

34 to 44

lto2

2 to 4

Babbit's metal .

White brass

Bis.

i»

...

muth. t

Metal to expand in cooling . 1

...

<■ The lead prevents the liliugR from sticking to the tool, but renders the brass nnfit
for hammering.

* An inferior alloy, used for very common taps, etc, and called also cock mdai,
« Composition varies betveen 50 copper and 50 zinc, and 63 copper and 37 zinc

SOLDERS, 351

It Ib light, very malleable, dactile, and not easily taniished, bat its expense prevents it
from being used for anything but instruments.

Phosphor Bronze is any bronze or brass alloy, together with a small proportion of phos-
phorus. Its qualities may be made to vary by altering the proportions of its constituents.

It wears longer than gun metal in bearings, is very tough, and is useful in positions
where it is subject to shocks.

The phosphorus preserves the metal from the effects of the atmosphere.

Manqanbsb Bronzb is an alloy (usually white) of pure copper with fh)m 2 to 80 per
cent of manganese. It is made in different qualities for casting and for rolling. The latter
has a tensile strength of some 80 tons per square inch, with an elongation of from 25 to
45 per cent ; it combines the strength and toughness of steel with redstance to oxidation.

Stbrro-mbtal varies in composition as shown in the Table p. 850.

This alloy has great tensile strength, and may be used instead of wrought iron.

Babbit's Metal is used for bearings of machinery. It is very soft, wears smooth,
and reduces friction. If the journal becomes heated, the alloy melts.

Whiis Brass is a name given to various alloys used for bearings, and intended to
work smooth. These are made of various composition besides those given in the Table.

Pewter should consist of 4 or 5 parts of tin and one of lead.

It is used for drinking cups and other purposes, also sometimes for covering counters
where liquor is sold.

It should be remembered, however, that cheap pewter generally contains an excess of
lead, and in that case is apt to poison any liquid in contact with it

Pewter consisting of 4 tin and 1 lead *' has the specific gravity 7*8, so that spedmena
having a higher specific gravity than this will be known to contain more lead." ^

Solder is the name given to several different alloys used for
the purposes of making joints between pieces of metal.

The effect is not merely mechanical, for the solder itself com-
bines with the metal to be united, and forms a fresh alloy.

The composition of the solder used in connection with the different
metals varies immensely, and the proportions in which each different
kind of solder is mixed also varies according to circumstances.

Every solder must be more fusible than the metals it is
intended to unite.

Ha/rd Solders are those which fuse only at a red heat, and which can be
therefore used only to metals which will endure that temperature.

Soft Solders melt at very low degrees of heat, and may be used for nearly
all the metals.

The more nearly the solder agrees with the metal in hardness and malle-
ability, the stronger will be the joint.

Thus brass or copper united with soft solder could not be hammered with-
out breaking the joint, whereas a joint in lead or tin, made with soft solder,
can be safely hammered.

Soldering. — ^It is not proposed* here to describe the operations connected with solder-
ing of dilferent kinds, but one or two points may be noticed with advantage.'

The surfaces to be united must be perfectly dean, and (reed from oxide, which would
prevent adhesion and the formation of an alloy between the solder and the metal.

As the surfaces when heated are very easily oxidised they must be protected at the time —
this is done by means of d^fiux which covers the surface and protects them from the air.

The materials used for fluxes are mentioned at p. 853.

^ Bloxam's MetaU,

' Every particular connected with soldering of aU kinds is fully described in
Holtzapffel's Methanieal ManiptUaUon, whence much of the information here given
has been taken.

352 NOTES ON BUILDING CONSTRUCTION

Hard Soldbbs — Of theee there are two kinds in common use.

Spelter Solder made of copper and zinc in proportions which differ accord-
ing to circumstances (see Table, below).

It is generally granulated by pouring it when melted through a bundle of
twigs into water.

This solder is used for making joints in iron, copper, brass, and gun-metal .
the process is known as hraaing.

Silver Solder is a mixture of silver with copper, or brass in varying pro-
portions (see Table).

It is used for making fine and neat joints in iron, steel, brass, and gim
metal— to prepare the surface of metals for welding, also for joints in silver
and other light-coloured metals.

Brazing. — ^The proccass of braang is conducted as follows : —

Granulated spelter and borax, ground together in water, are spread over the caiefnllT
cleaned surfaces of the joint, and exposed gradually to the heat of a clean open fire ; tite
borax fuses first, and then the solder.

With silver solder the joint is covered with borax and water, or dry powdered lioiM,
and the solder, cut into little square plates, is laid along the joint.

Soft Soldbrs are mixtures of tin and lead. The proportions varr as
shown in the table.

Tin makes the Bolder fusible, but as it ic more expensive than lead, only
80 much tin should be included in a solder as will make it fit for the
purpose for which it is intended.

The addition of a little bismuth makes the solder still more fusible.

The more fusible solders are known in the trade as fine, and those containing
less tin as coarse eoldert,

'* Any zinc getting into plumber's solder will ruin it, by making it too brittle to woik.

" Solder may be purified of any foreign matter, such as zinc, if only present in smiU
quantity, by burning it out on the fire, letting the pot get red hot tiU It goes off is
vapour and scum, which can be skimmed off the top.*'^

*' In making solder the proportions of the metals can be judged of from the appear-
ance of the alloy. When it contains a little more than one-third of its weight of tin, its
surface on cooling exhibits circular spots due to a partial separation of the metals ; hot
these disappear when the alloy contahis two-thirds its weight of tin." *

** It is never advisable to buy ready-made solder, as you cannot depend upon the alloy:
too much lead and too little tin, which is the dearer of the two, is almost sure to be pot
into plumber's solder ; besides which there is always plenty of scrap lead about, which
can be used for the purpose.

'* When a good deal of soldering is to be done, the plumber will often start with a
little excess of tin in his solder, as by degrees it will pick up lead from the lead work on
which it is used, which will decrease its fusibility." ^

Soft Soldbriito. — Soft solder is applied in several different ways.

For joints in lead the surfaces to be soldered are carefiiHy cleaned and covered with
tallow — the space around is smeared with a mixture of size and lampblack, called md,
to prevent the solder from adhering — melted solder is then poured on and the excess
wiped off with a cloth or in other ways.

In joining thin sheets of tinned iron, zinc, copper, and other metals, the edges are
cleaned and sprinkled with powdered rosin ; a tinned copper bolt or soldering iron is made
hot and applied so as to heat the edges of the plates ; the stick of solder is at the same
time forced against the bolt, and the solder as it melts is dropped into the joint.

The copper bolt is also used to supply the heat in soldering light work in lead, such as
lattices. The soldering iron cannot be used for thick pieces of metal, as it will not im-
part sufficient heat to their edges.

When joints are to be made between thicker pieces, the latter must have their suxfues
first tinned separately and then the solder run in between them.

A blowpipe flame is sometimes used as the source of heat in soldering the roetalSL

> Seddon. > Bloxam.

FLUXES.

353

Solder for use wltb the copper bolt is cast in strips called ^^strap-solder" or in thin
cakes for gasfitter's work.^

Tablb showing the Pboportions of iNOBEDisiirrs of different Solders —
Melting Points — Purposes for which iwed.

Deieription of
solder.

Constituents and their melting points.

Melting

point or

solder,

Fahr.

Uses.

Tin.
440'

6ir

Zinc.
773*

Copper.
SOOO*

1
607'

1873-

If
use

Hard Soldbbs.
Brazing —

Very fine .

Fine . . .
Spelter— soft .

Do. hard .

Stiver solders^

Haixlest. .

Hard* . .
Soft . . .

Soft Soldbrs.
Plumber's—
Fine . . .

Coarse solder
Tinman*s —
Ordinary sol-
der
Very fusible do.
Peioterer^s—
Fine . . .

1
1

1
2

'4*

3to6

1«

8
2

885
441"

482*'

340'
820"

2or

For ordinary brass

work.
For copper, iron, and

steel
For silver, copper,

and brass.

For lead work, cis-
terns, jointing pipes.

Used with copper
soldering bolt.

Used by pewterers.

« The brass is put into the melted silver, or the zinc would evaporate. One brass
wire instead of one copper with 2 silver is used for soldering silver.

* Also called " pot metal ; '* is assayed by the Plumbers' Company, stamped as
genuine, and sold in ingots, hence called " Plumber's sealed solder."

Fluxes. — ^The fluxes used are as follows : —
For hard soldering — Borax.

For soft soldering — (with solders of about 2 tin, 1 lead) — the flux is varied
according to the metals to be united, as shown below : — ^

Metals.
Cast-iron, malleable iron, steel

Copper, brass, gun-metal

Tinned iron .
Zinc

Pewter .

Lead with coarse solder
„ fine solder

Soldering fluid is a concentrated solution of chloride of zinc.

Fluxes,
Borax or Sal ammoniaa^
Sal ammoniac, chloride of

zinc, or rosin.
Chloride of zinc or rosin.
Chloride of zinc
Gallipoli oil.
Tallow.
Rosin.

1 Se<Mon.
B. C-

-III

' Ammonium chloride,
2 A

354

MOTES ON BUILDING CONSTRUCTION

TABLES.

Tablea Bhowing the properties of metala, and giving the weights of pktes,
wires, tubes, angles, tees, and sections of various kinds, are to be found in
Molesworth's, Hurst's, and other engineering pocket-books, and would be too
voluminous for these Notes.

Only one or two tables are therefore inserted, giving the most necesBanr
information in its simplest form : —

Properties of Metals. — ^Table showing some of the Properties of
useful Mbtals.

Mrai.

Resistance in
tons per sq. inch.

cei

BellmeUl .

8-0

502

1-04

1-4

lbs. per
sq.inch.

Bismuth

9-8

614

1-28

1-45

...

507*

■0014

Brass, ordin-

ary—2 cop-
per, 1 zinc

8-3

519

1-08

13-0

9,170,000

1840*

•O019

Copper, cast .

8-6

637

1-12

100

„ sheet

8-8

660

114

13-0

...

•0017

„ wrought

8-9

556

1-16

150

...

15,000,000

1990*

•00179

Gun-metal, 9
copper to 1
tin .

8-5

628

14-0

9,900,000

1900*

•00181

Wrought iron
Bar
Plate .

77
7-8

480
487

1-00
1-01

25
20

i,.i

29,000,000
24,000,000

1 8280*

•0012

Cast

7-2

450

•94

17,000,000

2700**

•0011

Lead, Cast .

11-35

709

1-47

...

•0028

Sheet.

11-4

718

1-48

1-5

720,000

612*

•0028

Phosphor
hronze

14,000,000

Platinum

21-5

1344

2-8

...

8280'

•0008

Steel, cast, soft

7-8

488

1-01

30,000,000

8300'

•0012

Tin, cast

7-3

466

•95

2-0

442'

•0023

Zinc, cast

6-9

428

•89

...

770*

■0029

Muntz metal

8-2

611

106

The above Table is compiled from the works of Rankine, Pole, Anderson, Unwin, Moles-
worth, and others, who have extended the results of tiie bc»t experiments up to the present
time. The figures given are merely approximate averages— liable to be materiallj altered
by slight alteration in the composition of the metal and other circumstances.

It will be understood that there is great variation in the strength of different descrip*
tions of the same metal. Particulars regarding these are given for the more important
metals, such as iron and steel, in the Tables, pp. 319-326.

CONTRACTION AND MELTING POINT OF METALS. 355

Contraction of Metals in Cooling.—
Table showing the Contraction of
different Metau in Casting.

Melting Points of Alloys of
Lead and Tin.i

Degrees Fahr.

HSTAI.

CONTRACTIOK.

In fraetioiis of

linear dimen*

■ions.

In parts of an

anit per inch of

linear dimen-

•ions.

Cast iron
Copper
Zinc .
Gun metal .
Yellow brass
liead .

A
^
^

Temp.

Lead.

Tin.

Temp.

Lead.
14

Tin.

400

490

410

500

420

610

430

620

440

690

460

640

460

660

470

668

480

630

Oauges. — Imperial Standard Wire Gauge. — The following Table gives
the thicknesses of the Standard Wire and Shut Metal Oauges — sometimes
described as the SWG — approved by Her Mi^est/s order in Council 1st
March 1883 to be Board of Trade standards from 1st March 1884 : —

New Imperial Standard Wire Gauge. — Denominations of Standards.

Descrip.

tive
Number.

Eqnlyalenta
in partaof
an inch.

Deseilp.

tive
Nnmber.

Eqniyalents
in parts of
an inch.

Descrip.

tive
Number.

Equivalents
in parts of
an inch.

Descrip-
tive
Nomber.

Equivalents
in parts of
an inch.

0-500

0-144

0022

0*0052

6/0

464

128

6/0

482

116

. 18

4/0

400

104

00164

8/0

872

0-092

148

2/0

848

186

824

124

800

116

276

108

252

100

232

0-0092

212

00010

192

176

160

The Birmingham Wire Gauge, known also as the Bimmgham Iron Wire
Gaugey the Sheet Iron Gauge^ and the Wire Gauge^ was at one time used for
sheet iron, steel, hoop iron, tubes, and wire, but is now reserved for the three
latter, and is generally expressed by the initials BWG or WQ. The following
Table gives the thicknesses as carefully measured by Mr. Holtzapffel, and
given in his Medumical Manipulation, The mark 00000 is not shown in
his list, but is frequently added : —

^ Extracted from Box On EeaL

356

NOTES ON BUILDING CONSTRUCTION.

Mark or No
of Guage.

Thickness in
inches.

Mark or No.
of Gauge.

Thickness in
inches.

Mark or No.
of Gauge.

Thickness in
inches.

MaikcrNalrhiekBMm
cfOMgeL incte.

00000

0-600

0-180

0-049

0^13

0000

0-454

0-166

0-042

0-012

000

0-426

0-148

0*036

0^10 1

0-880

0-184

0-082

0009

0-840

0-120

0-028

0-008

0-800

0-109

0-026

oiwr

0-284

0-096

0-022

0-005

0-269

0-088

0 020

0-004

0-288

0 072

0-018

0-220

0-066

0-016

0-208

0-068

0 014

*< Although this gage seems only to possess 40 termS| in reality not leas Uian
60 sizes of wire are made, as intermediate sizes are in many cases added,
and occasionally, though the sizes are retained, their numbers are Taiiouslj
altered.'**

Whitworth's Standard Wire Gauge is given below. It will be seeo
that the number or mark of the gauge is the number of thousandths of an inch
in the thickness : —

No. or
Mark.

Thick-
ness.
Inch.

No. or
Mark.

Thick-
ness.
Inch.

No. or
Mark.

Thick-
ness.
Inch.

No. or
Mark.

Thick-
ness.
Inch.

No. or
Mark.

Thick-
ne» 1
Inch.

•001

-014

•084

•090

280

-280

•002

-016

•086

•096

3(N>

•800

-003

-016

•038

100

•100

325

•826

•004

-017

•040

110

-uo

350

•850

-006

•018

-046

120

■120

376

•876

-006

■019

•060

135

•186

400

•400

•007

•020

•066

150

-160

425

•425

-008

■022

•060

165

-166

460

•460

•009

•024

•066

180

•180

476

-475

-010

•026

•070

2(X)

•200

500

•600

-Oil

-028

•076

220

■220

-012

•030

•080

240

-240

•013

-082

•085

260

•260

The Birmingham Metal Gauge, also called the Metal Gauge or the Wf
Gauge^ is intended for sheet metals — except sheet iron and steel — sueh as
copper, brass, gold, silver, etc.

Copper is, however, frequently sold by the Birmingham Wire Gauge giTcn
above, and by the special gauges of manufacturers.

* Holtzapffel.

GAUGES AND WEIGHT OF METALS.

357

BlRMINQHAM PlaTE QaUGE.

Mark
or No.

Thick-
nessin
inches.

Mark
or No.

Thick-
ness in
inches.

Hark
or No.

Thick-
ness in
inches.

Mark

or No.

Thick-
ness in
inches.

•004

•024

•064

•120

•005

•029

•067

•124

•008

•034

•072

•126

•010

•036

•074

•133

•012

•041

•077

•143

•013

•047

•082

•145

•015

•061

•095

•148

•016

•057

•103

•168

•019

•061

•113

•167

The Shtit and Hoop Iron Oaiiget B6, was issued by the South Staffordshire Iron
Masters' Association for the nse of sheet and hoop iron makers, 1st March 1884, and is
adopted by the trade. It is important that in all transactions in sheet and hoop irod
the initial letters BG should appear, to distinguish the Sheet and Hoop Iron Gauge from
the Imperial Standard Wire Gauge. ^

Number

Thick-

Number

Thick-

Number

Thick-

nesB.

ness.

Gauge.

Inch.

Gauge.

Inch.

Gauge.

Inch.

7/0

•6666

3/0

•6000

•3147

6/0

•6250

2/0

•4452

•2804

5/0

•6883

1/0

•3964

•2-226

4/0

•5416

•3532

The more useful part of the Table is given above. The numbers continue to gauge No.
50, which has a thickness of '0010 inch.

Weight of Metals. — Weight in lbs. of a Square Foot of Different
Metals, in Thicknesses varying by -^^^tli of an Inch.

2-3

2 3

2 5

2^9

2-7

Z'7

6-0

6 1

6-8

4^7

6 3

5-5

4^8

7-4

7-5

7 0

7-6

8-7

7-0

8-2

7-2

11^2

10-0

9 4

10^2

11^6

9*4

11-0

10^9

9*6

14^9

12-5

11^7

12^8

14 5

11-7

13-7

13^7

12 0

18-6

150

14 1

15-3

17^2

14^0

16^4

14^4

22^3

17-6

16^4

17^9

20^0

16-4

19^2

19-1

16-8

26^0

20 0

18^7

20^4

22^9

18-7

21^9

19 3

29 7

22 6

21 •I

26 0

26-7

21 •!

24 6

24-6

217

38 4

25-0

23-5

25-5

28-6

23^4

27-4

27-3

24 1

371

27-5

25 •S

28-1

81 ^4

26 7

30^1

30*0

26 •e

40^9

}

30^0

28-1

30^6

34-3

28^1

82 9

32-8

28-9

44-6

325

30^5

83-2

372

80^4

85 •e

35^0

81-8

48^8

35 •©

32-8

36-7

400

82 •&

38 ^3

88-2

33 7

52^0

37 '6

35-2

38 •S

42^9

86 •I

41-2

41*0

361

65^7

40 0

37-5

40-8

45^8

37 •&

43^9

43-7

385

59^4

The weight per square foot to any gauge can easily be obtained from the above Table
by multiplying the weight of a square foot of the metal 1 inch thick by the thickness of
the gauge in inches or parts of an inch.

* Button's Works Manager's Handbook, where very useful Tables of the weight of
iron according to this and the Imperial Standard Gauge are given.

Chapter V.

TIMBER.

A THOROUGH knowledge of the nature and properties of
different kinds of timber is very important to the engineer
or architect.

Before entering upon a description of the different varieties of
timber under the forms in which they generally come into the
market, it will be advisable to make a few remarks on the growth
of trees. A very slight knowledge of this branch of the subject is
necessary in order that other points more intimately connected
with the practical use of timber may be clearly understood.

Growth of Trees. — ^The timber used in baildmg and engineering work ia
obtained from trees of the class known by botanists as ^ Exogens,"* or ontward
growers.

In trees of this class the stem grows by the deposit of successive layers of
wood on the outside under the bark, while at the same time the bark becomes
thicker by the deposit of layers on its under side.

Upon examining the cross section of such trees (see Fig. 147) we find
that the wood is made up of several concentric layers or rings, each ring con-
nisting in general of two parts — the outer part being generally darker in
colour, denser, and more solid than the inner part, the difference between
the parts varying in different kinds of trees.

These layers are called '* annual rings** because one of them is, as a rule,
deposited every year, in a manner which will be presently explained.

In the centre of the wood is a column of pith, p, from which planes, seen
in section as thin lines, m m (in many woods
not discernible), radiate toward the bark, and
in some cases similar lines, m m, converge from
the bark toward the centre, but do not reach
the pith.

These radiating lines are known as ^ medul-
lary rays " or " transverse septal* When they
are of large size and strongly marked, as in
some kinds of oak, they present, if cut obliquely,
a beautiful figured appearance, called ^silver
grain** or "feltr

The wood is composed of bundles of cellular
^*K- ^*^- tubes, which serve to convey the required

nourishment from the earth to the leaves.

TIMBER. 359

The proeefle of growth in a temperate climate is as follows : —

in the spring the root absorbs jnicrs from the soil, which are converted
into sap, and ascend through the cellular tubes to form the leaves.

At the upper surface of the leaves the sap gives off moisture, absorbs carbon
from the air, and becomes denser ; after the leaves are full grown, vegetation is
suspended until the autumn, when the sap in its altered state descends by
the under side of the leaves, chiefly between the wood and the bark, where
it deposits a layer of new wood (the annual ring for that year), a portion at
the same time being absorbed by the bark. During this time the leaves
drop off, the flow of sap then almost stops, and vegetation is at a standstill
for the winter.

With the next spring the operation recommences, so that year after year
a distinct layer of wood is added to the tree.

The above description refers to temperate climates, in which the circula-
tion of sap stops during winter ; in tropical climates it stops during the dr}'
season.

Thus, as a rule, the age of the tree can be ascertained from the number
of annual rings, but this is not always the case. Sometimes a recurrence
of exceptionally warm or moist weather will produce a second ring in the
same year.

As the tree increases ixl age, the inner layers are filled up and hardened,
becoming what is called '' duravunj* or '' heartwoodT ^ The remainder is called
^ ajthurnum^ or " sapwood^* The sapwood is softer and lighter in colour than
the heartwood, and can generally be easily distinguished from it.

In addition to the strengthening of the wood caused by the drying up of
the sap, and consequent hardening of the rings, there is another means by
which it is strengthened — that is, by the compressive action of the bark.
Each layer, as it solidifies, expands, exerting a force upon the bark, which
eventually yields, but in the meantime offers a slight resistance, compress-
ing the tree throughout its bulk.^

The sapwood is generally distinctly bounded by one of the annual rings,
and can thus be sometimes distinguished from stains of a similar colour
which are caused by dirty water soaking into the timber while it is lying
in the ponds (see p. 390). These stains do not generally stop abruptly
upon a ring, but penetrate to different depths, colouring portions of the
various rings.

The heartwood is stronger and more lasting than the sapwood, and should
alone be used in good work.

The annual rings are generally thicker on the side of the tree that has
had most sun and air, and the heart is therefore seldom in the centre.

Felling, — While the tree is growing the heartwood is the strongest, but
after the growth has stopped the heart is the first part to decay. It is
important, therefore, that the tree should be felled at the right age.

The proper age varies with different trees, and even in the same tree
under different drctunstances. The induration of the sapwood should have
reached its extreme limits before the tree is felled^ but the period required
for this varies with the soil and climate.

Trees cut too soon are full of sapwood, and the heartwood is not fully
hardened.

I Sometimss called the '•Spim.*' * Laslett

36o NOTES ON BUILDING CONSTRUCTION

The ages at which the under-mentioned trees should be felled aie stated
bj Tredgold to be as follows : —

Oak 60 to 200 yean ; 100 years the besk

Ash . . )

Larch > From 60 to 100 years.

Elm . . j

&Fir . JFromTOtolOOyear.

Oak bark, which is very valoable, is sometimes stripped in the spring, wbes
it is loosened by the rising sapi The tree is felled in the winter, at which
time the sapwood is found to be hardened like the heart. This practice is
said by Tredgold to improve the timber.

Mr. Laalett says that ** to select a healthy tree for felling we must seek fin
one with an abundance of young shoots, and the topmost branches of which
look strong, pointed, and vigorous, this being the most certain evidenee
that it has not yet passed maturity."

The best season for felling timber is at midsummer or midwinter in tem-
perate, or during the dry season in tropical climates, when the sap is at rest

Squaring. — Directly the tree is felled it should be squared, or cut into
scantling, in order that the air may have free access to the interior.

CharaoteriBtioB of Good Timber. — The quality of timbei
depends greatly upon the treatment the tree has received, the time
of felling, and, above all, on the nature of the soil in which it has
grown. •

These branches of the subject do not fall within the province
of the engineer or builder, and will not here be entered upon ; it
will be sufficient to point out some of the characteristics by which
good timber may be known.

Good timber should be from the heart of a sound tree — ^the sap
being entirely removed, the wood uniform in substance, straight in
fibre, free from large or dead knots, flaws, shakes, or blemishes of
any kind.

If freshly cut it should smell sweet ; " the surface should not be
woolly, or clog the teeth of the saw," but should be firm and bright,
with a silky lustre when planed ; a disagreeable smell betokens
decay, and " a dull chalky appearance is a sign of bad timber."

The annual rings should be regular in form ; sudden swells are
caused by rind-gaUs ; closeness and narrowness of the layers indi-
cate slowness of growth, and are generally signs of strength.
When the rings are porous and open, the wood is weak, and often
decayed.

The colomr of good timber should be uniform throughout ; when
it is blotchy, or varies much in colour from the heart outwards

DEFECTS IN TIMBER. 361

or becomes pale suddenly towards the limit of the sapwood, it is
probably diseased.

Among coloured timbers darkness of colpur is said by Bankine
to be in general a sign of strength and durability.

Good timber is sonorous when struck. A dull heavy sound
betokens decay within (see p. 393). Among specimens of the
same timber, the heavier are generally the stronger.

Timber intended for use in important work should of course be
free from the defects mentioned in page 388. The knots should
not be large or numerous, and on no account should they be loose.

The worst position for large knots is when they are near the
centre of the balk required, and more especially when they are so
situated as to form a ring roimd the balk at one or more
points.

The sap should be entirely removed. According to Mr. Laslett,
however, the heart of trees having the most sapwood is generally
stronger and better in quality than the heart of trees of the same
species that have but little sapwood.

The strongest part of the tree is generally that which contains
the last-formed rings of heartwood, so that the strongest scantlings
are obtained by remo\'ing no more rings than those containing the
sap.

Timber that is thoroughly dry weighs less than when it was
green (see p. 388) ; it is also harder, and consequently more diffi-
cult to work.

Defects in Timber. — ^There are several defects in timber caused by the
nature of the soil upon which the tree was grown^ and by the vicissitudes to
which it has been subjected while growing.

Hearlshakes are splits or clefts occurring in the centre of the tree. They
are common in nearly every kind of timber. The splits are in some cases
hardly \'isible ; in others they extend almost across
the tree, dividing it iuto segments.

When there is one cleft right across the tree it does
not occasion much waste, as it divides the squared
trunk into two substantial balks. Two clefts cross-
ing one another at right angles, as in Fig. 148, make
it impossible to obtain scantlings larger than one-
fourth the area of the tree.

The worst form of heartshake, however, is one in
which the splits twist in the length of the tree, thus ^^' ^^®'

making it impossible to convert the tree into small scantlings or planks.

Starthahes are those in which several splits radiate from the centre of the
timber, as in Fig. 149.

Cupshakes are curved splits separating the whole or part of one annual

362

NOTES ON BUILDING CONSTRUCTION.

Fig. 149. Fig. 150.

ring from another (see Fig. 150). When they occupy only a small portion of
a ring they do no great harm.

Rind-Cfalh are peculiar curved swellings, caused generally by the growth of
layers over the wound remaining after a branch has been imperfecdj
lopped off.

Upsets are portions of the timber in which the fibres have been injured bj
crushing.

Foxiruss is a yellow or red tinge caused by incipient decay.

Doatinesa is a speckled stain found in beech, American oak, and other
timbers.

Twisted Fibres are caused by the action of a prevalent wind, taming the
tree constantly in one direction. Timber thus injured is not fit for squaring,
as so many of the fibres would be cut through.

CLASSIFICATION OF TIMBER

The following classification of timber is a modification by
Professor Rankine and Mr. Hurst of that originally proposed by
Tredgold : —

Class I. — Pdtb Wood (natural order Coniferut),
Characteristics. Examples.

Annual rings very distinct ; pores
filled with resinous matter ; one
part of each ring hard and dark,
the other soft and light coloured.

Pine, Fir, Larch, Cowrie, Cedar,
Cypress, Yew, and Juniper. Of
these the first six only are in ordi-
nary use, and will be described.

DiT. I,

Class II. — Hard Wood or Lkaf Wood (non-resinous and non-coniferous).

Characteristics. Example*.

' Svhdiv. I. Annual rings distinct ; one^

side porous, the other V Oak.

compact. j

With distinct

large medulkry

rays.

f No distinct
Div. IL < large medullary
I rays.

, Subdiv, II. Annual rings not distinct ; ) Beech, Alder,
texture nearly uniform. { Plane, Sycamore.

' Suhdiv. L Ann\ial rings distinct; one ^ Chestnut Ash.

side porous, the other [■ "ElvL

compact. j

C Mahogany,

j Subdiv. II, Annual rings not distinct ; f Walnut, PopUr,

I texture nearly uniform. 1 Teak, Green-

L I heart.

CLASSIFICATION OF TIMBER. 363

With regard to the above Table Professor Banldne remarks : —

'' The chief practical bearings of this classification are as follows.

'' Fir wood, or coniferous timber, in most cases contains tur-
pentine. It is distinguished by straightness in the fibre and regu-
larity in the figure of the trees ; qualities favourable to its use in
carpentry, especially where long pieces are required to bear either
a direct pull or a transverse load, or for purposes of planking.
At the same time the lateral adhesion of the fibres is small, so
that it is much more easily shorn and split along the grain than
hardwood, and is therefore less fitted to resist thrust or shearing
stress, or any kind of stress that does not act along the fibres.
Even the toughest kinds of firwood are easily wrought

"In hard wood, or non-coniferous timber, there is no
turpentine. The degree of distinctness with which the struc-
ture is seen, whether as regards medullary rays or annual rings,
depends upon the degree of difference of texture of different
parts of the wood. Such difference tends to produce unequal
shrinking in drying, and consequently those kinds of timber in
which the medullary rays and the annual rings are distinctly
marked are more liable to warp than those in which the texture
is more uniform. At the same time, the former kinds of timber
are, on the whole, the more flexible, and in many cases are very
tough and strong, which qualities make them suitable for struc-
tures that have to bear shocks.'' ^

The classification shown above is that made by botanists and
given by most writers on timber.

For many practical purposes, however, the timber used upon
engineering and building works may be divided into two classes : —

Soft Wood, including firs, pines, spruce, larch, and all cone-
bearing trees.

Habd Wood, including oak, beech, ash, elm, mahogany, etc.

OlMsiiioatioii of Fir Timber.— Tbt different trees included imder the general head
of *' Fir Timber " are dirided by botanists into the pines and firs, which produce timber
of very different quality, and are distinguished in the growing tree by the leaves, the
shape of the cones, and by other peculiarities.

ThA PiiM (Finua) has slender green needle-shaped leaves, growing in clusters ol
from two to six (according to the species) from the same stalk. It has one straight tap
root, the trunk does not taper much, the wood is dose grained, fibrous, very durable,
fall of resinous matter, and of a high bright colour. The cones have thick woody scales
that do not fall away from the axis.

7%i Fir or Spruce (Abies) has straight short leaves, which come off singly from the
stalks. The roots are ramified, the trunk tapers more than that of the pine, the shape of
the tree is more pyramidal, the wood is of a much lighter colour, and not nearly so dur-

^ Rankine, (XvU Engineering, pi 440.

364 NOTES ON BUILDING CONSTRUCTION.

able. Tht cones an long and pendulous, with thin woody scales that do not fkll tvij
from the axis.

No attention ia, however, paid to these botanical distinctions in the daso-
fication adopted on building or engineering works.

The carpenter generally gives the name ^r to all red and yellow timber
from the Baltic, somewhat similar timber from America he calls pine^ wheresi
aU white wood from either place is known as tpruce.

Market Forms of Timber. — Before proceeding further, it wili
be well to describe the difiTerent forms to which timber is con-
verted for the market

A Log is a trunk of a tree with the branches lopped ofL

A Balk is obtained by roughly squaring the log.

Fib timber is imported in the forms and under the designations mentioned
below.

Hand Masts are the longest, soundest, and straightest trees after being
topped and barked.

The term is technically applied to those of a circumference between 24 and
72 inches. ** They are measured by the hand of 4 inches, there being also a
fixed proportion between the number of hands in the length of the mast and
those contained in the circumference taken at ^ the length from the butt end.' ^

Spars or Poles have a circumference of less than 24 inches at the base.

Incfi Masts are those having a circumference of more than 72 inches, and
are generally dressed to a square or octagonal form.

Balk Timber consists of the trunk, hewn square, generally with the axe,
(sometimes with the saw), and is also known as square Hmher,

Planks are parallel-sided pieces from 2 inches to 6 inches thick, 1 1 inchtf
broad, and from 8 to 2 1 feet long.

Deals are similar pieces 9 in. broad and not exceeding 4 in. in thicknesi

Whole Deals is the name sometimes given to deals 2 in. or more in thickness

Cut Deals are less than 2 in. thick.

Battens are similar to deals, but only 7 in. broad.

Ends are pieces of plank, deal, or batten less than 8 feet long.

Scaffold and Ladder Poles are from young trees of larch or spraosL TImt
average about 33 feet in length, and are classed according to the diameter of
their butts.

Bickers are about 22 feet long, and under 2^ in. diameter at the top end.
The smaller sizes are called Spars,*

Oak is supplied as follows in her Majesty's dockyards.'

Rouffh Timber, consisting of the trunk and main branches roughly hewn to
an octagonal section.

Sided Timber, being the trunk split down and roughly formed to a poly-
gonal section.

Thick Stt^, — Not less than 24 feet long, and of an ayerage length of tt
least 28 feet, from 11 to 18 inches wide between the sap in the middled
its length, and from 4^ inches to 8^ inches thick.

Planks. — Not less than 20 feet long, and of an average length of at lesst
28 feet, the thickness from 2 to 4 inches, and the width (clear of aap) reqnutd

1 Lulett. * Seddon's KoUs, > Laslett

DIFFERENT KINDS OF TIMBER. 365

at the middle of the length varjing aocoiding to the thickness, t.«. between
9 and 15 inches for 3, 3}, and 4 inch planks, between 8 and 15 inches for 2
And 2^ inch planks.

Wanbt Tdiber is a term used for logs which are not perfectly square. The
balk cut being too large for the size of the tree, the square comers of the
balk are wanting, and their place is taken by flattened or ronnded angles, often
showing the bark, and called imina.

OoMPASS Timber consists of bent pieces, the height of the bend from a
straight line joining the two ends being at least 5 inches in a length of
12 feet

DESCRIPTIONS OF DIFFERENT KINDS OF TIMBER*

PINE WOOD OR SOFT WOOD.

Northern Pine (Pinus sylvestris). — This timber, frequently
known as " red or yellow fir," is from the " Scotch fir " tree.

The tenn Northern Pine has been introduced by Mr. Hnrst for the reasons
given in the following remarks, extracted from his Handbook : —

" Much confusion has arisen among architects and builders owing to the
absurd practice of naming this timber after the ports of shipment, and also
from confounding the pines (Pinus) with the firs (Abies)^ although they belong
to distinct genera. . . . The P. aylvestrU is essentially a wood of north-
em climates, and will thrive at greater elevations and in higher latitudes
than even the fir ; hence the term ' northern pine ' given to it by the author
in his edition of l^dgold's carpentry, and also adopted throughout this work.**

This tree grows in Scotland, and also in the Baltic and Russia,
whence most of the timber used in this country is imported, both
in balks, and also in planks, deals, and battens.

Tredgold gives the following description of the appearance of
this timber : —

« The colour of the wood of different varieties of Scotch fir differs consider-
ably. It is generally of a reddish yellow, or a honey yellow of various
degrees of brightness.

'* It consists in the section of alternate hard and soft circles ; the one part
of each annual ring being soft and light coloured, the other harder and dark
coloured. It has no larger transverse septa, and has a strong resinous odour
and taste; It works easily when it does not abound in resin ; and the foreign
wood shrinks about i^th part of its width in seasoning from the log.

" In the best timber the annual rings are thin, not exceeding t4 inch in
thickncsaL The dark parts of the rings are of a bright and reddish colour,

' Taken chiefly from the works of Tredgold, Hnrst, Newland, Laslett, and Rankine.
These works contain a great deal 01 information regarding various foreign timbers
not used in this country, and also as to the less common Tuieties of home growth,
which it is unnecessary here to enter npon.

366 NOTES ON BUILDING CONSTRUCTION

the wood haid and dry to the feel, neither leaving a woolly sorfiEuse after Oie
saw nor filling its teeUi with resin. * * «

^ The inferior kinds have thick annual rings — in some the dark parU ol
the rings are of a honey yellow, the wood heavy, and filled with soft xesiBOTii
matter, feels clammy, and chokes the saw.

''Timber of this kind is not durable nor fit fur bearing strains. Hat
Forest timber is often of this kind. In other inferior kinds the wood is
spongy, contains less resinous matter^ and presents a woolly surfaoe after the
saw,

" Swedish timber is often of this kind, and is then inferior in strength and
stiffness."

Mr. Fincham, quoted by Mr. Hurst, says further —

'' If the timber is good, its parts, on being separated, appear stringy snd
oppose a strong adhesion, and the shavings from the plane will bear to be
twisted two or three times round the fingers ; whereas if the stick is of bed
quality, or in a state of decay and has lost its resinous substanceSy the chipi
and shavings come off short and brittle, and with much greater <

VARIETIES IN GENERAL USE.

Balk Timber. — The best balks of northern pine are imported
from Dantzic, Memel, Riga.

Dantzio Timber is grown chiefly in Prussia, and takes its name from the
port where it is shipped.

Appearance, — Its general appearance answers to the description given above,
though in colour it is rather whiter than other varieties^

Qiaracteristies, — ^This timber is strong, tough, elastic, easily worked, and
durable if well seasoned*

It contains, especially in small trees, a large proportion of sapwood, which
in fresh timber can hardly be distinguished from the heartwood, and it fire-
quently contains large and dead knotSL The heart is often loose and " cuppy*

Market forme. — Dantadc balks are from 18 to 45 feet long, and genenlly
14 to 16 inches square.

The deals vary from 2 to 5 inches in thickness, and in length from 18 to
50 feet

The classification of this timber, and of that from Memel, as to qualitieB,
etc., is given at pp. 384, 385.

Mbmel Timber is very similar to that from Dantzic, but is considered
hardly so strong. The scantlings of the balks are rather smaller, being from
13 to 14 inches square.

RiOA Timber is like the other varieties just described, but the annofll
rings are closer.

It is slightly inferior to Dantzic in strength, is remarkable for its straight
growth, for the small proportion of sap it contains, and for its freedom from
knots. It is, however, frequently a little shaky at the centre, and is therefore
not so fit for conversion into deals as other varieties.

This timber is only once sorted for masts before it is exported, and ij
placed in the market without the brands described on pi 384.

VARIETIES OF TIMBER. 367

Norway Timber is of small size, tougb, and durable, but it generally con-
tains a good deal of sapwood.

The^ balks are only about 8 or 9 incbes square.

Swedish Timber somewhat resembles that from the Prussian ports, but
the balks are generaUy tapering in form, of small size, and not of good
quality.

Appearance. — The wood is of a yellowish-white colour, soft, clean, and
straight in grain, with small knots and very little sap, but the balks are
generally shaky at the heart, and therefore unfit for conversion into deaK

Mr. Laslett says — ^* There is little to recommend the Swedish fir to favour-
able notice beyond the fact of its being cheap and suitable for the coarser
purposes in carpentry."

It is used chiefly for scaffolding.

Market forms. — The balks are generally from 20 to 35 feet long, and from
10 to 12 inches square.

The classification of Baltic timber is given at pp. 384, 38<5, in connection
with the description of the marks upon it.

Planks, Deals, and Battens. — Planks, deals, and battens from
the Baltic, when cut from the northern pine {Pmus sylvestris)
are known as yellow deal or red deal. When cut from the
spruce {AUes) (see pp. 363 and 371), they are called white deals.

It would be very difficult to give a list of all the different varieties of
planks, deals, and battens of northern pine to be found in the market, with a
detailed description of each.

The minute distinctions which exist in appearance and quality could
not be described on paper, and any attempt to point out these differences
would not be of any practical value.

Mr. Laslett says that taking deals, battens, etc., 'Mn a general way, the
order of quality would stand first or best with Prussia ; then with Russia,
Sweden, and Finland ; and lastly with Norway."

Tellow Deals. — The following list mentions only a few of the principal
ports from which manufactured timber is imported, and the salient or most
marked characteristic, if any, which is peculiar to each kind : —

Pbubsian. — Memel, BantziCy and, Suitin. — The deals imported are very
durable and adapted for external work, but they are chiefly used for ship-
building.

The export of deal flrom the Pnusian ports of Dantzic, Heme], Stettin, etc., is almost
entirely confined to yellow planks and deck deals, called also red deals, 2 to 4 inches
thick, need for shipbnilding."

** The reason for this is that the timber Arom the sonthern ports being coarse and wide
in the grain, could not compete in the converted form, as deals, etc, with the closer-
grained and cleaner exports from the more northern ports." '

Russian. — PeUrehurg^ Onega^ Archangel, Narva. — These are the best deals
imported for building purposes. They are very free from sap, knots, shakes,
or other imperfections ; of a dean grain, and hard well-wearing surface, whicli
makes them well adapted for flooring, joinery, etc

The lower qualities are, however, of course subject to defects.

^ Seddon.

368 NOTES ON BUILDING CONSTRUCTION.

Petersburg deals are apt to be shaky, haTing a great many oentret in the plsnki aad
deals, bat the best qaalities are very clean and free from knots.'* ^

These deals are rery subject to dry rot.

All the Russian deals are said ^ to be unfit for work exposed to damp. In titoie hm
Archangel and Onega " the knots are often surrounded by dead bark, and drop oit «ta
the timber is worked." '

Wyhorg deals are sometimes of rery good quality, but often Ml of sap.

Finland and Ntland are stated by Kewland to be 14 feet long, ray
durable, but fit only for the carpenter.

NoRWEOiAN. — GhrUtiawia^ Dram, — Yellow deals (as well as white, see ^
367) and battens are imported from Christiania, together with battens from
Dram. They used to bear a high character, being clean and carefully con-
verted, but are now very scarce.

A good deal of the Norw^an timber is imported in the shape of prepaied
flooring and matched boarding.

Dram battens are often found to be suffering from dry rot, especially vhea
they are badly stacked.

Swedish. — Gefle^ Stockholm^ Holmmndy SoderKam^ OotienXnarg, Hernomi,
SundswaU. — ^* The greater portion of the Swedish timber is ooane and b»d,
but some of the very best Baltic deal, both yellow and white, comes &MD
Gefle and Soderham.*'

*' The best Swedish deals run more sound and even in quality than the Busbisb ship-
ments, from the different way in which the timber is conrerted.

'* A balk of Russian timber is all cut into deals of one quality, hence the numenv
hearts or centres seen amongst them, which are so liable to shake and split ; whenii is
Swedish timber the inner and the outer wood are converted into different qualitifli of
deals. Hence the value of first-class Swedish goods.

'' 4-inch deals should never be used for cutting into boards as they are cot from tbs
centres of the logs. 3-inch deals, the general thickness of Russian goods, are sbo op^
to the same objection. Swedish 2^ and 2-inch deals of good quality are to be {A-
ferred to 3-inch, since they are all cut from the sound outer wood ; although, lieiog >
novelty in the market, and their value not understood, they are cheaper." ^

It will be seen from the above quotation that the first qualities of Svedisb
deals have a high character for freedom from sap, etc. The lower qtialities
have the usual defects, being sappy, and containing lai^ coarse knot&

Mr. Newland considers Swedish deals fit for ordinary carcase work, ao^
Mr. Hurst says that from their liability to warp they cannot be depended
upon for joiners* work.

CTs^s.— -Swedish deals are commonly used for all purposes connected vith
building, especially for floors.

American Pine. — There are three or four descriptions of this
timber in the market, which will now be described.

As a rule American pine is in many respects inferior to that
from the Baltic. It is generally weaker, and comparatively
wanting in durability. On the other hand, it is clean, free from
defects, and easily worked.

American Bed Fine {Pinus rkibru^^ also Pinm resinota^ takes its Dsa^
from the red colour of its bark, and is known generally as Canada Red Pi**-

» Seddon. « Newland.

VARIETIES OF TIMBER. 369

THiere fwitkdH — Canada.

App^aroiMt. — Reddish white, clean fine grain. Very like Memel, but with
lai^er knots.

CharaeterUties. — Small timber, vety solid in centre, not much sap or pith,
tough, elastic, does not warp or split, moderately strong, few large knots,
very dnrable where well ventilated^ adheres well to glue, not much loss in
conversion.

Uses. — By cabinetmakers for veneering, sometimes for internal fittings of
houses.

Market farms. — ^Logs 16 to 50 feet long, 10 to 18 inches square, and
about 40 cubic feet in content ; classed as '' laige,"* ** mixed," and ** building *'
sizes.

Amerioan Tallow Pine {Pinus strobus) is produced from a straight and
lofty tree found in North America ; used to be sometimes known as *' Wey-
mouth Pine," because it was first introduced into this country by Lord Wey-
mouth. In America it is called vjhiUpine from the colour of its bark.

Its leaves grow in tufts of 6. The cones are very long, with loosely arranged
scales.

Appearanee. — The wood when freshly cut is of a white or pale straw colour,
but becomes of a brownish yellow when seasoned. The annual rings are not
very distinct, the grain is clean and straight ; the wood is very light and
sofl^ when planed has a silky surface, and is easily recognised by the short
detached dark thin streaks, like short hair lines, which always appears run-
ning in the direction of the grain.

Characteristics. — The timber is as a rule clean, free from knots, and easily
worked, though the top ends of logs are sometimes coarse and knotty ; it is
ulso subject to cup and heart shakes, and the older trees to sponginess in the
centre. It adheres to glue, but does not hold nails well. This timber often
arrives in this country in an incipent state of dry rot, and it is very subject
to that disease.

It lasts well in a dry climate, such as that of America, but is not durable
in England.

Uses. — Yellow pine is much used in America for carpenters' work of all
kinds ; it is also used for the same purpose in Scotland, and in some large
English towns, but in London and the neighbourhood it is considered inferior
in strength to Baltic timber.

The great length of the logs and their freedom from defects causes this
timber to be extensively used for masts and yards whose dimensions are so
great that they cannot be procured from Baltic timber.

For joinery this wood is invaluable, being wrought easily and smoothly
into mouldings and ornamental work of every description. It is parti-
cularly adapted for panels on account of the great width in which it may
be procured, and it is also extensively used for making patterns for castings.

Market forms. — The best is imported as inch masts roughly hewn to an
octagonal form.

Next come logs hewn square from 18 feet to 60 feet long, averaging
about 16 inches square, and containing about 65 cubic feet in each log. A
few pieces are only 14 inches square, and short logs may be had exceeding
even 26 inches square. Some is imported as " waney timber " (see p. 365).

A few 3-inch deals are imported, varying in width from 9 to S4 inchea. uul
even as wide as 32 inches.

B. C. — in 2 B

370 NOTES ON BUILDING CONSTRUCTION.

ClamfiocAion}- — ^American yellow deals are classed as follows : —

Brights . Ist, 2d, and 3d quality,

Dry floated . . „ „

Floated ... „ „

their order of merit being first quality brights, first quality dry floated, fiist
quality floated, then second quality brighta, and so on.

Brighis are sawn from picked logs and have not been discoloured bj
being floated down the rivers, and are therefore of a much cleaner and
brighter yellow.

Floated deals, etc, have been floated or rafted down the riveiB from the
felling grounds.

Dry floated implies that the deals, etc., have been stacked and dried b^ore
shipment.

First quality yellow deals of each kind should be clean, straight gruned,
and quite free from shakes and knots. Second quality are a little inferior
in these respects, and third quality are inferior again.

Floating the deals damages them considerably, besides discolouring them.
The soft and absorbent nature of the wood causes them to warp and shake
very much in drying, so that floated deals should never be used for fine work.

The best ports are Quebec for yellow deals, and St John for spruce desk
Goods from the more southern ports, such as Richibucto, Miramichi, Shedae,
etc., are of an inferior quality.

Rafted or floated deals are shipped from all the Canadian ports except
St John, hence the superiority of St John deals, which are always bright or
unwatered.

Quebec Yellow Fine (Pinus varidbilis) is imported chiefly from the
place after which it is named. It is used for masts and yards of Luge ships,
but not much for other purposes.

Pitch Pine (Pintcs rigida) has its leaves in threes, scales of
cones rigid, sharp edges, rough bark.

The best of this timber comes from the southern states of North
America, chiefly from the ports of Savannah, Darien, and Pensacol&

Appearance. — The wood has a reddish-white or brown colour;
the annual rings are wide, strongly marked, and form beautiful
figures when the wood is wrought and varnished.

Characteristics, — The timber is very full of resinous matter,
which makes it extremely durable, but sticky and difiBcult to
plane. It is hard, heavy, very strong, hard to work, free from
knots, but containing a large proportion of sapwood. It is subject
to heart and cup shake, and soon rots in a moist atmosphere.
The wood is brittle when dry, and its elasticity, strength, and
durability are often reduced by the practice of "bleeding" or
tapping the tree for the sake of the turpentine it contains. It is
too full of resin to take paint welL

Uses, — Pitch pine is used for the heaviest timber structures in
1 From Seddon's Builder's Work.

VARIETIES OF TIMBER. 371

engineering works, where great strength and lasting properties are
required; also by shipbuilders for deep planks; by builders for floors
(being very durable under wear), for window sills, and for orna-
mental joinery of all kinds. The heartwood is good for pumps.

Marleet forms, — Logs 11 to 18 inches square (averaging 16
inches square) and 20 to nearly 80 feet long ; planks 3 to 5 inches
thick, 10 to 15 inches wide, and 20 to 45 feet long. As it is
subject to heart-shakes and cup-shakes, it is more economical to
purchase it in the form of planks when it is required to be used
in that f orm.^

White Fir or Bpraoe {Abies exedsa). — ^This timber is from trees
found in Norway, in most of the mountainous parts in the
north of Europe, in North America, and also in this country.

The peculiarities of the tree, leaves, eta, are given at page 363.

The wood is generally known in this country as white deal.

Appearance. — The wood is of a yellowish-white, or sometimes
of a brownish-red colour, becoming of a bluish tint when exposed
to the weather. The annual rings are clearly defined^ the surface
has a silky lustre, and the timber contains a large number of
very hard glossy knots, by which it may be easily recognised.

The sapwood is not distinguishable from the heart

Characteristics. — ^This timber is tough, sometimes fine grained,
light, and elastic, difficult to work, especially where the knots
occur, shrinks but little, and takes a fine polish.

It, however, shrinks and twists, and warps very much, unless
restrained when seasoning, and is wanting in durability.

It IB moreover knotty; inferior in strength to the red and
yellow pine, not so easily worked, and is apt to snap under a
sudden shock.

Uses. — ^The deals are used for the coarser descriptions of
joinery, cheap flooring boards, etc, for panels, also for packing-
cases and other common work where cheapness is the first object

** White deal " is a nice wood for tops of dressers, shelves, and
common tables, but being liable to warp it should not be cut too
thin, not tmder an inch if possible. For sticking mouldings and
the finer kinds of joiners' work it is not fit, as the hard knots turn
the plane iron."^

The trees being generally straight, strong, and elastic, are used
for small spars for ships and boats, for ladders and scaSbld poles.

Baltio Spruce comes chiefly from Norway, aUo Sweden, RntfiA, andPruBsiA.

1 Seddon.

372 NOTES ON BUILDING CONSTRUCTION.

Whitb Dbal.— " Some of the best white deal oomes from Christiania: bat that from tk
other Norwegian ports is not to be relied upon, being apt to warp and split in drying."'

Both good and bad qualities are sent from Drwn, The deals from the ap]sa<i air
more ft«e ftt>m shakes than the other.

Spruce from FrtderUestadt contains loose black knots.

^^CMiUnJbwrg white deals are hsid and stringy/' only fit for paddng-cMM nd
temporary work. " The same remark applies in greater deg^ to those fi^m Henmnd

The best Russian white deal is shipped firom Onega, Very good deals come fin
Narva, FUaraburg ; white deals are ^e and dose in grain, but expand and co&tnd
vrith changes of weather.

£iga deals are coarser and more open-grained than the other Russian deacriptioni.

Amerioan Bpraoe. — There are at least four varieties of the tree from
which this timber is produced : — The white spruce (Ahta alba)y which
flourishes in the colder parts of North America ; the black spruce {Ahia
nigra), and the Wenlock spruce {Abies Canademis), found chiefly in Lower
Canada; and the red spruce {Abies rubra), imported from Nova Scotisi

The red spruce is sometimes known as ** Neufoundland red pinej*

Appsaranoe, — ^The timber greatly resembles the spruce from the Bsltk,
having the same characteristic glassy knots. The wood of the black and
white varieties is the same in appearance — the difference of colour being
only in the bark of the tree ; the black produces the hungest and best timber.

Characteristics. — ^American spruce is inferior to that from Norway— it is
not so resinous or so heavy — ^is tougher, warps and twists very much, snd
soon decays.

The Canadian spruce is better than that from New Brunswick.

Uses, — ^This timber is used for the same purposes as Baltic spruce.

The Iiarch {Larix Ewrofce^ is found in various parts of Europe ; tb»
finest varieties being in Russia.

Appearance. — ^The wood is honey yellow or brownish white in colour, the
hard part of each ring being of a redder tinge, silky lustre.

There aro two kinds in this country, one yellowish white, cross-gninei
and knotty ; the other (grown generally on a poor soil or in elevated positions,
reddish brown, harder, and of a stndghter grain.

Characteristics. — ** Decidedly the toughest and most lasting of all the ami-
ferous tribe," ' very strong and durable — shrinks very much — stnught sul
even in grain, and free from laige knots, very liable to warp, but stands well
if thoroughly dry — ^is harder to work than Baltic fir — ^but surface is smoother,
when worked. Bears nails driven into it better than any of the pines.

Uses, — Chiefly for frosts and palings exposed to weather, railway sleepers,
etc. ; also for flooring, stairs, and other positions where it will have to
withstand wear.

American Larches aro the black variety {Larix pendula) known as Bad-
mata^ik or as Tamarak; and also the red variety {Larix tnicrocarpa).

The timber from these trees resembles that from the European larch.

The Cedar {Cedrtts Libant) properly so called, oomes from Mount Lebanoo,
and Asia Minor, and is not much known in this country.

The wood generally known as cedar is from trees of the genus Junipenu.

These trees are found in Virginia, Bermuda, Florida, and also in India.
Australia, etc.

*' Scddon. * Newland. ' Brown's Forester, p. 27^

VARIETIES OF TIMBER. 373

AfptammM. — ^The heartwood is a leddish brown, sapwood white, straight-
grained, and porous.

(JhaT(ui»rMc». — Veij light and brittle, and wanting in strength ; Tredgold
sajB it is about | the strength of the best red pine ; is easilj worked ; does
not shrink much ; is veiy durable when well ventilated. Has a pungent odour
which often unfits it for internal joinerj, but protects it from being attacked
by insects. A resinous substance exudes from the timber when freshly cut,
and makes it difficult to work.

TJw^ — ^For pencils, furniture, toys, carvings ; and in Bermuda for ship and
boat building, for doors, window frames, sashes, and internal joinery. It is
the best kind of wood to veneer upon.

Mofrhit fonoB, — ^Imported in logs from 6 to 10 inches square.

The Cypress (0upreMi» sempervirms) famishes a timber sometimes known

It is found in Cyprus, Asia Minor, Persia, etc

The wood is strong, veiy durable, has a strong odour, resists worms
and insects, and is mudb used in Malta and Candia for building purpoeea

The Oregon Fine or DougUu Pirn (Abies Doufflam) is found in N.W.
America.

It resembles Canadian red pine in appearance, but is slightly harder.

A few spars and a little timber and plank are sent to this countiy, but
there is no regular trade.

The Kawrie, Cowrie, or Cowdie Pine {Dammara Atutralis) is found only in
New Zealand.

Appearance. — ^The heaitwood is yellowish white, fine and straight in grain,
with a silky lustre on surface.

Gharadmetics, — Generally very free from defects ; may be obtained pei^
fectly dean ; is very light, strong, and elastic ; has an agreeable odour when
worked ; is less liable to shrink than most firs and pines, except when cut into
narrow strips ; unites well with glue, and is veiy durable.

Uees. — Makes first-rate masts and spars ; is used for parts of military
bridges ; is good for joineiy.

HARD WOOD OR LEAF WOOD.

The varieties of timber of this class most in use for building
purposes are oak, beech, ash, elm, mahogany, teak. These, with
a few others, will now be described in more or less detail, ac-
cording to their importance.

Oak. — Of this timber there are several varieties found, both in
this country, and also in America, Holland, and the Baltic.

British Oak. — ^The principal British varieties are —

2%6 StaJk-fruited or Old English Oak (Querms robur or Qaercm
pedunculata), in which the acorns have long stalks, and the leaves
short stalks.

The Cluster-frmted or Bay Oak (Querma sessiliflora), of which
the acorns grow in dose clusters with very short stalks, and the
leaves have longer stalks, some nearly an inch long.

374 NOTES ON BUILDING CONSTRUCTION.

Durmast Ocuc {Qwercus jmbeseens) has short stalks for the aoona
and long stalks for the leaves, like the bay oak, but is distin-
guished by ** the under side of the leaves being somewhat downy." ^

Appearance. — Good oak is of a light brown or brownish-yellov
colour, with a hard, firm, and glossy surface. A reddish tinge and
dull surface are signs of decay. The annual rings are very Ila^
row and regular, each having a compact and a porous layer, the
pores in the latter being very smalL Wide rings and large poies
are signs of weakness. The medullary rays are hard and oompfi^;
where they are small and indistinct the wood is stronger.

When the timber is cut obliquely across, beautiful markings of
silver grain appear, being caused by the cropping out of the laige
medullary rays.

Characteristics, — Sound heart of oak is very durable in eaitb
or water. It has been known to last 1000 years when well ven-
tilated.

The timber is very strong, hard, and tough, warps in seasoning.
[t is very elastic, easily bent to curves when steamed or heatei
It is not easily splintered, but is rather liable to the attacb of
insects.

It contains gallic acid, which makes it more durable, but cor-
rodes iron fastenings.

Young oak is tougher, more cross-grained, and harder to woil
than old oak.

Uses, — Oak is used for all purposes where strength and dnia-
bility are required in engineering structures.

ThQ builder employs it for window and door sUls, treads of
steps, keys, wedges, trenails, etc., in common work, also for snpe-
rior joinery of aU kinds, for gateposts, etc.

CfomparUon of the Different Varieties, — It is generally considered tluit the
timber from the Btalk-fraited oak is superior to that from the Bay oak

The respective characteristiGS of the two varieties, as given by Ttedgoli
Rankine, and other observers, are as follows : —

The wood of the stalk-fruited oak is lighter in colour than the other. It
has a straight grain, is generally free from knots, has numerous and distmet
medullary rays, and good silver grain ; it is easier to work and less liable to
warp than the timber of the Bay oak, and is better suited for omamentil
work, for joists, raftere, and wherever sti&ess and accuracy of form tn
required ; it splits well and makes good laths.

The timber of the cluster-fruited oak is darker in colour, more flexitie,
tougher, heavier, and harder than that of the stalk-fruited oak ; it has but

> Laslett

VARIETIES OF TIMBER.

375

few large mednllaiy rays, so that in old bmldixigB it has been mistaken foi
chestnut ; it is liable to warp, and difficult to split ; it is not suited for laths
or ornamental purposes, but is better than the other where flexibQity or reaist-
anoe to shocks are required.

Mr. Britton says that dry rot was introduced into ships by using the Bay oak.

Mr. Laslett says that the timber of the BemUJUfra is a little less dense and
compact than that of the pedunculata, but they so much resemble each other,
that ** few surveyors are able to speak poeitivdy as to the identity of either.**

The Durmast oak is decidedly of inferior quality.

FMng. — Oak is sometimes felled in the spring for the sake of the bark
instead of being stripped in the spring and felled in the winter as described
at p. 360). Hie tree being then full of sap, the timber it yields is not of a
durable character.

American Oak. — ^Iliece are many varieties of this timber, but that chiefly
imported into this country is the WhiU Oak {Queretu alba), so called from
the white colour of its bark. It is this variety that is generally known in
this country as Ammean Oaky or Pastwre Oak It is found from Canada to
Carolina; the best comes from Maryland.

Appearance, — ^The wood has a pale reddish-brown colour, with a straighter
and coarser grain than English oak.

CharOieteristicB. — ^The timber is sound, hard, and tough, very elastic, shrinks
very slightly, and is capable of being bent to any form when steamed. It is
not so strong or durable as English oak^ but is superior to any other foreign
oak in those respects.

Uses, — This timber may be used for shipbuildings and for many parts of
buildings in which English oak is used.

Market forms. — It is imported in very large sided logs varying from 26 to
40 feet in length, and from 12 to 28 inches in thickness, also in 2 to 4 inch
planks, and in thick stuff of 4| to 10 inches.

Other varieties of American oak i

The Oanadian or Bed Oak {Quereus rubra) has wood of a brown colonr, light and
spongy in grain, moderately durable ; is used for furniture and cask staves, but is unfit
for work requiring strength and durability.

The Live Oak {Quereus virens), with wood of a dark brown or yellow colour, fine
grain, minute pores, distinct medullary rings, twisted grain. The logs are crooked, very
strong and durable, suitable for ships. This wood makes good mallets and cogs for
machineTy. It is difficult to obtain in this country.

The Iron Oak {Quereus obtusiloba) is of great strength and durability, but of small
size, and is chiefly used for posts and fencing.

The BaUimore Oak, with wood of a reddish-brown colour, is generally weak, and soon
decays.

There are several other varieties of American oak, generally inferior to the above men-
tioned, and seldom met with in this country.

DantBic Oak is grown chiefly in Poland, and shipped at the port after
which it is named, also at Memel and Stettin.

Appearance. — ^It is of a dark brown colour, with a close, straight, and com-
pact grain, bright medullary rays, free from knots, very elastic, easily bent
when steamed, moderately durabla

Uses. — It is used for planking, shipbuilding, etc.

Mtnrket forms, — ^The timber is carefully classified as erown and crown brack
qualities.

The planks are classed in the same way, the crown and crown brack marked
respectively W and WW.

376 NOTES ON BUILDING CONSTRUCTION.

It is imported in logs from 18 feet to 30 feet long, 10 to 16 inches aqosR,
and in planks averaging 32 feet long, 9 to 15 inches wide, and 2 to 8
inches thick. ^

French Oak is stated by Mr. Laslett to closely resemble British csk in
oolour, quality, texture, and general characteristics.

Biga Oak is grown in Russia, and is like that shipped from Dantzic, but
with more numerous and more distinct mediillaiy rays. It is valued for ita
silver grain, and is imported in logs of a nearly semicircular aectioiL

Italian Oak — Sardinian Oak, — ^This timber is formed from several TlIi^
ties of the oak tree. It is of a brown colour, hard, tough, strong, subject to
splits and shakes in seasoning, difficult to work, but free from defects. It is
extensively used for shipbuilding in her Majesty's dockyardsw^

Afirican Oak, known also as African Teak or Mahogany^ is brought from
Sierra Leone, and has many of the characteristics both of oak and teak

It is of a dark red colour, hard, close grained, difficult to work, free £riib
splits or defects.

It is much used for shipbuilding, but is too heavy for architectural purposes.

Wainsoot is a species of oak, soft and easily worked, not liable to warp or
split, and highly figured.

This last-mentioned characteristic is obtained by converting the timber »
as to show the silver grain (see p 358). It makes the wood very valuable
for veneers, and for other ornamental work.

Wainscot is imported chiefly from Holland and Biga, in semicircular logs.

Clap Boarding is a description of oak imported from Norway, inferior tc
wainscot, and distinguished from it by being full of white-coloured streak&

Beeoh {Fagus sylvatica) is known as black, brown, or white
beech, aU procured from the same species of tree, the differenoe in
the wood being caused by variety in soil and situation.

This tree is found throughout England and Scotland, in the
temperate parts of Europe, in America, and Australia.

Appearance, — Has remarkably distinct medullary rays; the
annual rings are visible ; each is a little darker on one side than
the other, and is fuU of very minute pores. The colour is a
whitish brown, darker or lighter according to the variety; the
wood has considerable beauty, especially when the silver grain is
exposed.

Characteristics, — The wood is of quick growth, light specific gra-
vity, dose texture; hard, compact, and smooth surface; is of fine grain,
may be cut into thin plates, cleaves easily, is not difficult to work.

It is durable if quite dry or wholly submerged in water, but if
subjected to alternate wet and dry becomes overspread with
yellowish spots and soon decays. It rots quickly in damp places.
It is very subject to the attacks of worms, and contains juices
which corrode metal fastenings.

^ Laslett.

VARIETIES OF TIMBER. yjj

The white Yoriety is the hardest^ but the Uack is tougher and
more durable.

Uses, — ^This timber is not much used by the engineer except
for piles under water, and wedges ; also for mallets, carpenters'
planes, and other tools, for cogs of machinery, cabinet work, and
chairs.

Alder (Alma gluiinasa) is from a tree found in both Europe and Asia,
geneiaUj near swamps or the low banks of rivers.

Appearance, — ^The wood is white when first cut, then becomes deep red on
the surface, and eventually fades to reddish yellow of different shades. The
roots and knots are beautifully veined.

CharacterUtics. — Very durable in water when wholly submerged, but when
used above ground must be kept perfectly dry. Is soft, light, uniform in tex-
ture, with a smooth fine grain, and very easily worked. It is wanting in ten-
acity, and shrinks considerably.

Uses, — ^The wood is useful for piles, pumps, patterns, sides of stone carts,
packing cases, etc. ; also used for wooden bowls, turnery, and furniture. The
roots and heart are used for cabinet work. The bark is valuable to tanners,
and charcoal from the wood is used for making gunpowder.

Sycamore (Acer pseudo-platanus) is from a tree ^'generally called the
plane (free in the north of England.** It is very common in Great Britain,
and is found in Germany.

Appearance, — The wood is white when young, but becomes yellow as the
tree grows older, and sometimes brown near the heart

The texture is uniform, and the annual rings not very distinct

There are no large meduUaiy rays, but the smaller rays are distinct.

Characteristice. — Compact, firm, not hard, durable when diy, does not warp,
liable to be attacked by worms. In large trees the wood is generally tainted
and brittle.

Uses, — ^For furniture, tumeiy, and wooden screws.

Chestnut {Gastanea vesca), — ^This tree flourishes in sandy soils, and is found
in most parts of England, in the south of Europe, in Africa, and North
America.

Appearance. — ^The wood resembles that of oak in appearance, but can be
distinguished from it, as chestnut has no distinct large medullary rays. The
annual rings are very distinct, and the wood of a dark brown colour. The
timber is of slow growth, and there is no sapwood.

Characteristics, — Is remarkably durable, easier to work than oak, does not
shrink or swell so much ; the young wood is hard and flexible, the old wood
brittle.

Uses, — ^Formerly much used for roofs and other carpenters' work, and still
valuable to coachmakers, wheelwrights, etc. ; also for posts, hoops, etc

Ash (Fraxinus excelsior). — This tree flourishes throughout Great
Britain, in Asia, and America.

Appearance, — ^The colour of the wood is brownish white, with
longitudinal yellow streaks ; each annual layer is separated from
the next by a ring fuU of pores.

378 NOTES ON BUILDING CONSTRUCTION

Characteristics. — ^The most strikmg characteristic possessed by
ash is that it has apparently no sapwood at all — ^that is to say, no
difference between the rings can be detected until the tree is very
old, when the heart becomes black.

The wood is remarkably tough, elastic, flexible, easily worked;
very durable if feUed in winter, well seasoned, and kept diy, bat
soon rots when exposed to alternate wet and dry. Is subject to
the attacks of worms.

The timber is economical to convert, in consequence of the
absence of sap. " Very great advantage will be found in redudsg
the ash logs soon after they are felled into plank or board for
seasoning, since, if left for only a short time in the round state,
deep shakes open from the surface, which involve a very heavy
loss when Drought on later for conversion." ^

Uses. — This wood is too flexible for most building purposes, but
is very useful for tool handles, shafts, felloea and spokes of wheels,
wooden springs, and wherever it has to sustain sudden shocks.

Canadian and Amrrigan Ash, of a reddish-white colour, is imported to
this country chiefly for making oars. These varieties have somewhat the
same characteristics as English ash. They are darker in coloni. Hu
Canadian variety is the better of the two.

Elm (Vlmus). — No less than five varieties of this tree are found
in Great Britain, besides which it flourishes in many parts of
Europe and in America.

The principal varieties of this timber are as follows : —

The Common English or Eough-leaved "Rt.u {Ulmus cam-
pestris), found in England, France, and Spain.

Appearance. — ^The colour of the heartwood is a reddish brown.
The sapwood is of a yellowish or brownish white, with pores
inclined to red. The medullary rays are not visibla The wood
is porous and very twisted in grain.

Characteristics. — ^The wood is very strong across the grain ; bean
driving nails very well ; is very fibrous, dense, and tough, and ofifen
a great resistance to crushing. It has a peculiar odour, and is
very durable if kept constantly underwater or constantly dry, but
will not bear alternations of wet and dry. Is subject to attacks of
worms. None but fresh-cut logs should be used, for after expo-
sure, they become covered with yellow doaty spots, and decay
will be found to have set in. The wood warps very much on
account of the irregularity of its fibre. For this reason it shoald

1 Ltslett

VARIETIES OF TIMBER. 379

be used in large scantUng, or smaller pieces should be cut just
before they are required ; and for the same reason it is difficult
to work. One peculiar characteristic of elm is that the sapwood
withstands decay as well as the heart

If elm timber is stored it should be kept under water to prevent
decay.

The timber is very free from shakes, but frequently contains
large hollow places caused by rough pruning and subsequent decay.

Utes. — Elm is used in many situations where it is subjected to
contiQual wet — namely, for piles, parts of pumps, pulley blocks,
keels and planks under water in ships, heavy naval gun carriages,
coffins, naves and felloes of wheels, eta ; also for various purposes
by carpenters, turners, and cabiaetmakers.

Thb Wygh Elm, of which there are two varieties, the 1iroa<&-Ieaved {JJUmu
montona), the smooth-Ieayed wych elm {JJlumfM gldbrc^^ ib found chiefly in
the north of England, Scotland, and Ireland.

The wood is of a somewhat lighter colour than the common elm. It is
clean and straight in grain, tough and flexible, and used for the naves of
wheels and for boatbuilding.

Thb Dutch Elm {Ulmus major) and the Ccrhbarked Elm (Ulmua suherota)
both famish inferior timber.

The Canada Bock Elm (UlmuB raeemosa) is grown in North America,
and imported chiefly from Canada.

The wood is of a whitish-brown colour, with very close annual rings. It
is very tough, flexible, free from knots and sap, with a fine smooth grain,
durable under water, but liable to shrink and warp unless kept immersed, and
to shakes if exposed to the sun and wind.

Uses, — Being flexible, it is used for boat building, also, on account of its
dean appearance, for ladder steps, gratings, etc., on board ship.^

The sap is not durable like that of common elm, but subject to decay.

In selecting this wood only those logs should be taken which have an
uniform whitish colour, any with dark annular layers full of moisture being
left for inferior purposes.^

Common Acacia (Robinia pseudo-aecicia) is found in America.

Appsarance, — The wood is of a greenish-yellow colour, with reddish-
brown veins. Its structure is alternately nearly compact and very porous,
which marks distinctly the annual rings. It has no laige medullary rays.

Characteristics, — ^It is very durable, heavy, hard, and tough, rivalling the
best oak in these respects. The timber is generally of small size.

Uses. — It makes first-rate trenails, and very excellent durable posts for
fencing, sills for doors, etc

Sabigu {Acacia formosa\ or the tTue acacia, is found in the West Indies
and Cuba.

Appearance. — It resembles mahogany, but is darker, and is generally well
figured.

A Laslett

3»o NOTES ON BUILDING CONSTRUCTION.

CharaeUriritcs, — ^The wood is very heavy, weaUien admiiably ; ii veit
free firom sap and shakes.

Mr. Laslett Says that the fibres are often broken during the early stages of
the tree's existence, and that the defect is not discovered until the timber is
converted, so that it is seldom used for weight-carrying beams.

This timber is much used in shipbuilding, and also by the cabinetnuikei,
but not in engineering works.

Poplar {Poptdtu). — Of this tree there are several species common, in Eng-
land. The black and the common white poplar are the most esteemed. The
Lombardy poplar is inferior.

Appearance. — The colour of the wood is a yellowish or brownish wliite.
The annual rings are a little darker on one side than the other, and therefore
distinct. They are of uniform tez^re, and without large medullary rays.

Characteristics, — ^The wood is light and soft, easily worked and carded,
only indented, not splintered, by a blow.

It should be well seasoned for two years before use. When kept dry it is
tolerably durable, and not liable to swell or shrink.

Uses, — The wood not being easily splintered is used for the sides of carts
and barrows, for large light bam doors, for packing-cases, floors, eta

Mahogany comes chiefly from Central America as " Honduras "
or "Bay" mahogany, or from the West Indies as "Spanish
mahogany."

The latter is the best for strength, hardness, and stifihess ; the
former is most valued for ornamental purposes, furniture, eta

Honduras Mahogany is found in the country round the Bay of Hondnns,
the trees being of considerable size.

Appearance. — ^The wood is of a golden or red-brown colour, of variow
shades and degrees of brightness ; often very much veined and mottled.
The grain is coarser than that of Spanish mahogany, and the inferior qualities
often contain a large number of grey specks.

Characteristics, — ^This timber is very durable when kept dry, but does not
stand the weather weU. It is seldom attacked by dry rot ; contains a resin-
ous oil which prevents the attacks of insects ; it is also untouched by wonna.
It is strong, tough, and flexible when fresh, but becomes brittle when dry. It
contains a very small proportion of sap, and is very free from shakes and
other defects. The wood requires great care in seasoning, does not shrink or
warp much, but if the seasoning process is carried on too rapidly it is liable to
split into deep shakes externally. It holds glue very well, has a soft silky
grain, contains no acids injurious to metal fastenings, and is less combustible
than most timbers.

It is generally of a plain straight grain and uniform colour, but is some-
times of wavy grain or figured.

Utee. — The builder uses this timber chiefly for handrails, to a small extent
for joinery, and for cabinet work. It has sometimes been used for window
sashes and sills, but is not fit for external work. ^ It has been largely used
in shipbuilding, for beams, planking, and in many other ways as a substitute
for oak, and found to answer exceedingly well." ^

^ Laslett.

VARIETIES OF TIMBER, 381

Markd forms, — ^Logs from 2 to 4 feet square, and 12 to 14 feet in length.
Sometimes planks have been obtained 6 or 7 feet wide.

''Mahogany is known in the market as 'plain,' 'veiny/ 'watered/
' mottled,' ' velvet-cowl,' ' bird's-eye,' and ' festoon^,' according to the appear-
ance of the vein-formations."^

Gabs or Spanish Mahogany, from the island of Caba, is distinguished from
Honduras mahogany by a white chalk-like substance which fills its pores. The wood is
very sound, free from shakes, with a beautiful wavy grain or figure, and capable of re-
cdving a high polish. It is used chieflv for furniture and ornamental purposes, handrails,
etc, and also for shipbuilding.

Mexican Mahogany shows the characteristics of Honduras mahogany. Some varie-
ties of it are figured. It may be obtained in very large sizes, but the wood is spongy in
the centre, coarse in quality, and very liable to starshakes.

It is imported in balks 15 to 36 inches square, and 18 to SO feet in length.

St. Pomingo and Nasaau Mahogamy are hard, heavy varieties, of a deep red colour,
generally well veined or figured, and used for cabinet works.

They are imported in very small logs from 8 to 10 feet long, and from 6 to 12 inches
square.'

Jarrah, or Awtralian Mahogany {EuctUypttu mcn-ffinata), comes from West
Australia.

Appearance. — The wood is of a red colour, and close, wavy grain, with
occasionally figure enough for ornamental purposes.

Characteristics, — ^Trees decay at centre ; wood is very brittle ; when sound
contains a pungent acid repellent to the teredo, which is said never to pene-
trate beyond the sap. The Dutch Commission referred to at page 381 made,
however, no exception in favour of this wood. It is also said to resist the
white ant It is full of defects like cupehakes, but filled with resin. The
wood is deficient in strength and tenacity, and very subject to shrink and
warp if exposed to the sun.

Uses, — It is admirably adapted for piers, jetties, dock gates, piles, and for
shipbuilding.

Market forms, — ^Very little is imported to this country. The sound
trees yield timber from 20 to 40 feet long and 11 to 24 inches square.*

Teak (Tectona grandis), sometimes called Indian Oak, is
found in Southern India, Pegu, Java, Siam, and Burmah.

The lightest, cleanest, and most flexible comes from Moulmein ;
the heaviest and strongest from Johore ; and the most handsomely
figured variety from the Vindhyan forests. The Malabar teak forests
are nearly exhausted. The timber from these forests is darker and
stronger than that from Moulmein, but very full of shakes.

Appearance. — ^The wood has a fine straight grain. It some-
what resembles English oak in appearance, but has no visible
medullary rays. The annual rings are very narrow and regular.

The colour varies from brownish yellow to dark brown. The
texture is very uniform, though porous.

Characteristics. — ^The timber is stronger and stiflfer than Eng-
lish oak, light, and easily worked, but splinters very readily, so

^ Hunt. * Laslett

383 NOTES ON BUILDING CONSTRUCTION:

that it must be worked with care. It contains a resinons aro-
matic oil^ which makes it very durable, and enables it to resist tLe
white ant and worms. It does not corrode, but rather preeerves
iron fastenings.

There are seldom shakes on the surface, but it is subject to
heartshake, and is often woim-eaten.

The resinous oil which exists in the pores often oozes into and
congeals in the shakes, and will then destroy the edge of any
tool used in working the timber.

This oil is a preservatiye against rust, and teak is therefore
used for backing armour plates and other iron structures.

The oil is sometimes extracted while the tree is growing by
" girdling ; " that is, cutting away a ring of bark and sapwood
This practice makes the timber brittle and inelastic, and reduces
its durability.^

Uses, — This timber is used extensively for shipbuilding, for
armour-plated forts, and would be fit for many purposes for
which oak is used in ordinary buildings, but that it is too expen-
siva

Market formi, — ^Teak is sorted in the markets according to size, not quality.
The logs are from 23 to 40 feet long, and their width on the laiger sided
varies according to the class, as follows : — *

Class A. 16 inches and upwards.

B. 12 and under 16 inches.

C. Under 12 inchesL

D. Are damaged logs.

Qreenheart (Nectandra rodicn) is found in British Guiana snd
in the N.K portion of South America.

Appearance. — ^The section of this timber has a peculiar appear-
ance, being of a fine grain, and very full of fine pores like the
section of a cana The annual rings are rarely distingmshabk
The heartwood is of a dark-green or chestnut colour ; the centre
portion a deep, brownish purple, often nearly black. The sap-
wood is dark green, and often not distinguishable from the heart

Characteristics. — Greenheart is the strongest timber in use.
Its resistance to crushing is enormous, but when it gives way it
does so suddenly. It is also apt to split and splinter, and there-
fore requires great care in working. The timber is clean and
straight in grain, very hard and heavy. It contains an easentiAl
oil, and many authorities state that on account of this it is

■ Laslett

MARKS AND BRANDS UPON TIMBER. 3S3

entirely free from the attacks of worms. The Dutch Commissioii
that experimented some years ago on this subject reported that
this is not the case»^ and Mr. Laslett considers it doubtful It
appears, however, that in any case worms will only penetrate the
sapwood The presence of the oil above mentioned causes the
wood to bum freely, so that it is known in Demerara as " torch-
wood."*

Uses, — Greenheart is much used for shipbuilding, also for piles,
jetties, piers, and other marine structures, and posts of dock gates.

MofrkdfofVM, — The timber cornea into the market roughly hewn, a great
deal of bark being left upon the angles, and the ends of the butts are not cut
off square The logs are from IS to 24 inches square, and up to 60 feet in
length.

Kora (Aforo ezceZsa). — ^This lamber comes from Guiana and Trinidad.

Afpeeuixnce, — The wood is of a chestnut-brown colour, sometimes beauti-
fully figured.

OWoeftfruticiL — The timber is very tough, hard, and heavy ; the gram is
close, generally straight, but sometimes twisted so that the wood is difficult to
split An oil in the pores makes the wood very durable^ It is free from
dry rot, but subject to starshake.

Z7feiL — It is admirably adapted for shipbuilding.

Market forms, — Logs 18 to 36 feet long, and 12 to 20 inches square.

Hornbeam (Carpinui hdula) is from a British tree.

Appearance, — ^The wood is white and dose. The medullary rays zre
plainly marked, and there is no sap.

CharaeterieUee, — ^Hie timber is hard, tough, and strong. When subjected
to Tertical pressure the fibres double up instead of snapping ; it stands ex
posure welL If cut from old or unseasoned trees the wood is worthless

Ueet. — This wood makes the best mallets. It is very good for turned
articles, agricultural implements, cogs for wheels, eta eta

MAEKS AND BRANDS UPON TIMBER.

There are several distmgaishing marks used \>j the shippers
and importers of timber. Some of them refer merely to the num-
ber of the balk and to its cubic content^ others refer to the
quality.

In general terms it may be said that Bussian balk timber is
marked with a scribe, ie. letters or marks are cut upon it in thin
scooped-out lines.

Russian deals are either unmarked or are stamped with small
indented letters on their ends.

« Dent * Hsfdetl.

384

NOTES ON BUILDING CONSTRUCTION

Swedish deals are marked with large red or black stencilled
letters on their ends.

Inferior qualities are frequently without marks at alL

American deals are not generally branded, but are sometimes
marked with one, two, or three red chalk marks, to indicate quality.

The letters used to indicate quality are liable to change year
by year. A list of the principal marks in use is published
annually in Laxton's Price Book, and other similar works.

Nearly all the information contained in the following remarks is taken
from Colonel Seddon's BuUdei^s Work.

'' Shippers' and Quality Marks. — ^The different qualities of Meznel and Daatzk
timber are known as crovm, first or best middling , second or good middling, third xx
common middling ; whilst inferior balks are classed as " short and irregular."

<* Memel balks of first, second, and third qualities are almost always scribe-marked at
one end of the balk ; but these marks must not be mixed up with the number of float cr
raft, which is also scribed at one end of each balk, and the distinguishing number of balk
in Uie float, which, with the cubic content, is scribed about the centre of every balk
floated in the docks, where timber of the same shipment and quality is roped together is
separate floats or rafts, and an accurate registry kept of the cubic content, and what be-
comes of each piece.

** The scribe marks on Baltic timbers are often very numerous and perplexing, moat of
them being private marks put on by those through whose hands the timber has passed
after being squared. On Dantzic they are much more numerous than on Memel or Riga
timber ; but with these marks of ownership we have nothing to do ; all we care about art
the bracker's or sorter's marks, distinguishing the different qualities from each other.

" The following are the recognised marks for the middling qualities. Very little crown
timber is imported, being rarely used by builders, except perhaps for special Oovemment
purposes. Memel crovm timber is marked as below, but with only a single stroke : —

Quality Marks on Baltic Timber.

Port op
Shipment.

Riga.

(Scribed at

centre.)

First or Best
Middling.

Second or Gtooo
MmDUNO.

Third or Oohhov

MlDDURO.

Memel.

(Scribed at

end.)

III

^=^

nil

Dantzic

(Scribed at

centre. )

"h:

)

Stettin.

(Scribed at

end.)

)

' Stettin timber is seldom marked unless to distinguish different qualities in the same caigo.

' Some Riga shippers always use the quality marks for best and good middlings and others
only when different qualities are shipped hi the same cargo. The common mM^^iii^
quality is rarely shipped from Riga.

MARKS AND BRANDS UPON TIMBER. 385

" There is no absolute uniformity about these quality marks, as all shippers from the
same port do not adopt them, many using private marks of their own, either alone or in
addition to the ordinary marks, the latter being seldom omitted on Memel or i)antzic balks.
The safest plan, in the case of large and important works, is to order the timber direct
from the broker, selecting it out of shipments from houses who have earned a reputation, '
from the care with which their timber is bracked or sorted ; for there is a great difference
in the same market quality of timber from different shippers ; one shipper's good middling
being often nearly equal to another's beti middUnff,

** If, amongst a lot of good middling logs, one or two marked as common middling or
best middling, as the case may be, are found, it does not always follow that any deception
has been practhed, since the timber may have changed hands ; a balk here and there may
have been considered by the last owner as too good for eomnumt or too bad for best middling,
and been shifted into a good middling float." '

The following private mariLS used by a well-known finn of shippers are
given as an example : —

Crown . . SK K SKK R

Best Middling . SK SK R

Good do. . SK I SK I R

Common do. . SK K SK ii R

As the letters are very roughly marked with the scribe, it will require some
practice to recognise the marks. . . .

The addition of R to the SK marks indicates Russian timber shipped by
the same firm (S. Koehne).^

" Baltic Flanks, Peals, and Battens are, speaking in general terms, classed in the
market as CVtnon, Croum Brack, First Quality, Second Quality, etc, down to even F\fth
Quality.

" Very few crown, or crown brack, goods come into market^ there being little or no
demand for them for building purposes. The different classes of deals, etc., will be found
to Yary very much in quality, one sh^;)per's second quality being often equal to another's
first quality. Hence some shippers have become well known for the greater care with
which their goods are bracked or sorted, and their names or trade marks may be safely
taken as a guarantee of a high standard in the different qualities into which they are
classed."

Among the marks for Dantzic crown deck deals are — CSC. EH. EB.EB.EB.

ME.MK.MK. HP. HP. HP. JV ,WL Some Dantidc erown brack deck deal marks
GCB FGF.

are— FGF. MK. ^ BJ.

''Bnssian and JPinland Deals, which are chiefly first and second quality, or accord-
ing to the shippers prima and seeunda, generally come unmarked into the market, or only
dry stamped or marked at their ends with the blow of a brandiug hammer, such mariu
being also termed hard brands. Some good shipments from Uleaborg (Finland) are dry
stamped U S for " mixed " (first and second quality unsorted) and U S in red paint for
third quality goods. Onega and Archangel deads are dry stamped thus with the shipper's
initials, or private mark, and often with a number in addition, which, however, does not
denote the quality, but merely the number of the yard in which they were stored before
shipping.

*' In some cases, when the goods are not branded, the second quality have a red mark
across the ends ; third being easily distinguished Irom first quality goods.

"The well-known Oromoff Petersburg deals are, however, marked with C. and Co., the
initials of the shippers, Clarke and Company. Another good Petersburg brand is P B
(Peter Behiiefi) for best, and P B 2 for second quality.

" Swedish Goods are never hammer-marked, but invariably branded with letters or
devices stencilled on the ends in red paint, which makes it difficult to judge of their
quality by inspection, as they are stacked in the timber yards with their ends only showing.
Some of the common fourth and fifth quality Swedish goods are left unmarked, but they
may generally be distinguished from Russian shipments by the bluer colour of the sapwood.

" In the English market the first and second qualities, in Swedish deals, are classed

1 Seddon.
B. C. — ni 2 0

386

NOTES ON BUILDING CONSTRUCTION.

»&i

»S

♦ B8

*
*

+ ^ oXb ft
M Pm ^-«5a ft

« fa _
#5ft 3
M ft

i o

WW ^ «

S+ +^ J+ +><ft ft

A ^ W p^ ^-< ft

ft h3 ;z«
ft ft W

S« SI

MARKS AND BRANDS UPON TIMBER. 387

together as 'mixed,' being scarcely ever sorted separately; after which we get third,
down to fifth quality goods.

*' The French class the mixed as first, and our third as second quality, and so on."

*' Except for temporary purposes, or for rough work such as slate boiiu^ing, no deals of
a lower quality than mixed Swedish, or, as the timber merchants and contractors would
call them, heat Swedish, should be used on Government works."

The few brands on p. 386 are taken from the Timber Trades Journal List,^ and given
merely as characteristic examples. As before mentioned, the marks are constantly
changing, and any information regarding them should be renewed from year to year. A
long list is published annually in Laxton's Price Book, and at intervals in the Timber
Trades Journal Lists.

"To give an idea of the value of the different qualities, the miaoed are worth from 15 to
20 per cent more than thurd, and third from 12 to 15 per cent more than fourth quality.

"It may be noticed in the above brands that three similar letters, when used, generally
denote the shipper's third quality ; but a merchant would call these second quality goods,,
for it must be clearly understood that the term ' mixed ' is confined to the shippers and
brokers. Timber merchants always call the mixed 'best,' and the third quality second
quality, and so on, or one class higher than that at which they were shipped.

" The Norwegian marks are very numerous, but, as the chief import is of cheap and
very inferior battens (mostly 2} x 6^), they are not worth enumerating.

" From Christiania, however, some of ^e very best white deals come, marked H M H
for first quality, and H M M for second quality.

"Battens firom Dram have several marks, among which are for 1st class HK JB, for
2d class HK and Co. I 00, for 8d class IW B, etc. etc

" Norway also exports large quantities of cheap boards for flooring and other purposes,
matck or grooved and tongued boarding, mouldings, doors, window sashes, etc., all ready
for fixing, which may often be used with advantage for inferior or temporary purposes.

" Amerioan Gtoods are not branded as a rule, though some houses use brands in
imitation of the Baltic marks already described, though without following any definite
rules. The qualities may, however, very often be known by red marks I II III upon the
sides or ends, but the qualities of American yellow deals are easily told by inspection, the
custom in the London Docks being to stack them on their sides, so as to expose their
faces to view, and allow of free ventilation."

The following are marks upon some Quebec deals : —

l8t. 2d. 8d.

Hamilton's bright dry floated deals Tl J Ml J Mllj In red on flat

Gilmour and Co., pine deals, etc. A B C do. and on end.

Mahogany, Oedar, and other imported woods, are also marked with letters, a long
list of which is given in Richardson's Timber Importer's Guide,

The following extract, firom a valuable article in the Building News, shows the im-
portance of the subject.

"From these remarks it will be seen that brands upon timber is a great and important
subject. It is one in the hands of a small community of our traders, and is, consequently,
a class of knowledge over which they are strict conservators. It is a subject new to
aathors, and that portion of our tradesmen whose office it is to buy and consume timber.
This is somewhat strange, as the meaning of brands is well known on other goods that
people engaged in trade are called u]x>n to purchase. With architects, clerks of works,
and builders generally, brands upon timbers are looked upon with perfect indifference.
The current remarks are, ' I can tell a bit of good wood when I see it,' etc., and, as
builders generally pursue the old-fashioned system of buying from inspection, the ques-
tion carries but little importance.

"Were brands upon timber better known, architects would get better work and
buUders would obtain greater credit. The cheap builder would find his place, and what
are termed ' old-fashioned builders ' would again occupy the position they so richly merit"

Value of Timber, Deals, eto., and Method of Measuring. — llie prices of dif-
ferent descriptions of timber, deals, etc, vary at the different ports. They are published
weekly in the engineering and building journals, and also annually in the builders' price-
books. The method in which timber is measured and the " standards " under which
deals are sold, are described in Seddon's Builder*s Work, Hurst's Pocket Book, and in
works devoted to the subject of measuring and estimating.

> Published by W. Rider and Son, London, E.C.

388 NOTES ON BUILDING CONSTRUCTION.

SELECTION OF TIMBER

Iq consequence of the great number of marks used in the timber tzade, the
difficulty of ascertaining what they mean, and the frequent changes that take
place in them, the practical engineer or builder, as a rule, judges of the qnalitj
of the timber more by its appearance than by the way in whieh it is marked.

The characteristics of good timber and the defects to be avoided are ginen
in general terms at p. 360> but a few remarks on selecting balks and desk
may be usefuL It should be remembered that most defects show better when
the timber is wet.

Balk timber is generally specified to be free from sap, shakes, lai^ or desJ
knots and other defects^ and to be die-square.

In the best American yellow pine and crown timber from the Baltic then;
should be no visible imperfections of any kind.

In the lower qualities there is either a considerable amount of sap, or the
knots are numerous, sometimes very large, or dead. The timber may also
be shaken at heart or upon the surface.

The wood may be waterlogged, softened, or discoloured by being floated.

Wanes also are likely to be found which spoil the sharp angles of the
timber, and reduce its value for many purposes.

The interior of the timber may be soft, spongy, or decayed, the surface
destroyed by worm holes, or bruised.

The heart may be wandering — that is, at one part on one side of the balk,
at -another part on the other side. This interrupts the continuity of the fibr?,
and detracts from the strength of the balk. If on the same side of a balk
sap is visible at one end and heart at the other, it shows that tlie heart is
wandering ; in good timber the ^ spine " or heartwood should be visible gq
all four sidea Again, the heart may be twisted throughout the length of the
tree. In this case the annual rings which run parallel to two sides of the
balk at one end run diagonally across the section at the other end. This
is a great defect, as the wood is nearly sure to twist in seasoning

Some of these defects appear to a certain degree in all except the very best
quality of timber. The more numerous or aggravated they are, the lower is
the quality of the timber.

Deals, planks, and battens should be carefully examined for freedom (more
or less according to their quality) from sap^ large or dead knots, and other de-
fects, also to see that they have been carefully converted, of proper and even
thickness, square at the angles, etc As a rule, well-converted deals are from
good timber, for it does not pay to put much labour upon inferior material

The method in which the deals have been cut should be noticed, those from
the centre of a log, containing the pith, should be avoided, as they are likely
to decay (see p. 400).

SEASONING TIMBER.

The object of seasoning timber is either to expel or to dry up the tap
remaining in it, which otherwise putrefies and causes decay.

One effect of seasoning is to reduce the weight of timber, and this reductiaD
of weight is, to some extent, an indication of the success of the process^

Tredgold caUs timber ma$oned when it has lost \ of its weighty and says

SEASONING TIMBER, 389

that it is then fit for caipenters' work and common purposes. He calls it
dry, fit for joiners' work and framing, when it has lost \ of its weight.

The exact loss of weight must depend, however, upon the nature of the
timber and its state before seasoning.

Timber should be well seasoned before being cut into scantlinga The
scantlings should then be further seasoned, and after conversion the wood
should be left as long as possible to complete the process of seasoning before
being painted or varnished.

Mr. Britton states that logs season better and more quickly if a hole is
bored through their centre. This also prevents splitting.

There are several different methods of seasoning timber, the principal of
which will now be briefly described.

Natural Seasoning is carried out by stacking the timber in such a way
ihat the air can circulate freely round each piece, at the same time protecting
it by a roof from the sun, rain, draughts, aud high winds, and keeping it
clear of the ground by bearers.

The great object is to ensure regular drying. Irregular drying causes the
timber to split.

Timber should be stacked in a yard, paved if possible, or covered with ashes, and free
from vegetation.

The bearers used should be damp-proof, and should keep the timber at least 12 inches
off the ground. They should be laid perfectly level and out of winding, otherwise the
timber will get a permanent twist.

If possible, the timber should be turned frequently so as to ensure equal drying all round
the balks.

When a permanent shed is not available, temporary roofs should be made over the
timber stacks.

Logs are stacked with the butts outwards, the inner ends being slightly raised so that
the logs may be easily got out. Packing pieces are inserted between the tiers of logs, so
that by removing them any particular log may be withdrawn.

Some authorities have stated that timber seasons better when stacked on end. This,
however, seems doubtful, and the plan is practically difficult to carry out.

Boards may be stacked in the same way, laid flat and separated from one another by
pieces of dry wood an inch or so in thickness and 3 or 4 inches wide. Any that are
inclined to warp should be weighted or fixed down to prevent them from twisting.

Boards are, however, frequently stacked vertically, or inclined at a high angle.

Mr. Laslett recommends that they should be seasoned in " a dry cool shed, fitted with
horizontal beams and vertical iron bars, to prevent the boards, which are placed on edge,
from tilting over. "

The time required for natural seasoning difl*er8 according to the size of the pieces, the
nature of the timber, and its condition before seasoning.

Tredgold gives some algebraic formula for calculation of the time required, and a table
deduced therefrom.

Mr. Laslett has, however, compiled a table from practical observation.

He says : *' My experience of the approximate time required for seamning timber under
cover and protected from wind and weather is as follows : —

Pieces 24 inches and upward square require about
„ Under 24 inches to 20 „

„ 20 „ 16
>} M 16 „ 12 „

»» » 12 „ 0 „

}l If " M 4 „

** Plftuks from i to | the above time according to the thickness.*'

Mr. Laslett further states that if the timber is kept longer than the periods above named,

Oak.

Fir.

Months.

390 NOTES ON BUILDING CONSTRUCTION.

the fine shakes which show upon the surface in seasoning " will open deeper and wider
until they possibly render the logs nnfit for oonveraion. "
Tredgold says that the time required under cover is only f of that required in the opea.

Water Seasoning consiflts in totally ImmerBing the timber, chaining it
down under water, as soon as it is cat, for about a fortnighty bj which a
great part of the sap is washed out It must then be carefulij dried, with
free access of air, and turned daily.

Timber thus seasoned is less liable to warp and crack, but is rendered
brittle and unfit for purposes where strength and elasticity are required.

Care must be taken that the timber is entirely submerged. FEOtial
immersion, such as is usual in timber ponds, injures the log along the water
line.

Timber that has beon saturated should be thoroughly dried before use '
when taken from a pond^ cut up and used wet, dry rot soon sets in.

Salt water makes the wood harder, heavier, and more durable, but ii
should not be applied to timber for use in ordinary buildings, because it giveE
the wood a permanent tendency to attract moisture.

Boiling and Steaming. — Boiling water quickens the operation of eeaeon-
ing, and causes the timber to shrink less,^ but it is expensive to uae, and
reduces the strength and elasticity of the timber.

The time required varies with the size and density of the timber, awl
according to circumstances ; one rule is to allow an hour for every inch is
thickness.

Steaming has very much the same effect upon timber as boiling, but the
timber is said to dry sooner after the former process,^ and it is by some ctm-
sidered that steaming prevents dry rot

Mr. Britton says, however, " no doubt boiling and steaming parti j remove
the ferment spores, but may not destroy the vitality of those remaining."

Hot-air Seasoning, or denccaticn^ is effected by exposing the timber in
an oven to a current of hot air, which dries up the sap.

This process takes only a few weeks, more or less, according to the size of
the timber.

When the wood is green the heat should be applied gradually.

Great care must be token to prevent the timber from splitting, the h&U
must not be too high, and the ends should be clamped.

Desiccation is useful only for small scantling ; the expense of applying it to
larger timber is veiy great ; morever, '' as wood is one of the worst conductors
of caloric, if this plan be applied to large logs the interior fibres still r^ain
their original bulk, while those near the surface have a tendency to shrink,
the consequence of which would be cracks and splits of more or less depth.* *

Desiccated wood should not be exposed to damp before use.

Mr. Laslett says that during this process ordinary woods lose their strength,
and coloured woods become pale and wanting in lustre.

M^eile'a Prooees is one that has been some few years in operation.

It consists in exposing the wood to a moderate heat in a moist atmosphere
charged with various gases produced by the combustion of fuel.

The wood is placed in a brick chamber, in which there is a large surface of
water to produce vapour.

The timber should be stacked in the usual way, with free air-space ronod

^ Tmigold. • Britton.

DECA V OF TIMBER. 391

eyeiy piece ; about \ of the whole content of the chamber ahonld bo ab-
space.

Under the chamber is a fireplace.

The fire having been lighted, the prodacts of combustion (among which i£
carbonic acid gas) circulate freely in a moist state around the pieces of timber
to be seasoned.

The time required vsries with the nature of the wood.

Oak, ash, mahogany, and other hard wood planks 8 inches thick, take about 8 weeka.

Oak wainscot planks 2 inches thick take ftom 5 to 6 weeks.

Deals 8 inches thick something less than a month.

Flooring boards and panelling ahont 10 days or a fortnight.

" The greener the wood when first pnt into the store the better. As a mle, if too great
heat be not applied, not a single piece of sound wood is ever splits or warped, or opened
in any way. The wood is rendered harder, denser, and tougher, and dry rot is entirely
prevented. The wood will not absorb by subsequent exposure to the atmosphere nearly
so much moisture as does wood dried by exposure in the ordinary way, henoe it is better
for all purposes than aiinlried wood." ^

The process seemed to have no injurious effects upon the appearance or
strength of the timber.

It has been adopted by some of the principal firms in London and else-
where.

Smoke-drying. — It is said that if timber be smoke-dried over a bonfire of
furze, straw, or shavings, it will be rendered harder, more durable, and proof
against the attacks of worms. In order to prevent the timber from splitting
and to ensure the moisture drying oat from the interior, the heat should be
applied gradually.

Seoond Seaaoning. — Many woods require a second seasoning after they
have been worked.

Floor boards should, if possible, be laid and merely tacked down for
several months before they are cramped up and regularly nailed.

Doors, sashes, and other articles of joinery should be left as long as
possible after being made, before they are wedged up and finished.

Very often a board that seems thoroughly seasoned will commence to warp
again if merely a shaving is planed off the surface.

DECAY OF TIMBER

To preserve timber from rot or decay it should be kept con-
stantly dry and well ventilated. It shoidd be clear of the influ-
ence of damp earth or damp walls, and free from contact with
mortar, which hastens decomposition.

Wood kept constantly submerged is often weakened and ren-
dered brittle, but some timbers are very durable in this state (see
elm, beech, acacia, etc.)

Timber that is constantly dry is very durable. However, it
also becomes brittle in time, though not for a great number of
years.

* Patentee's Circular.

392 NOTES ON BUILDING CONSTRUCTION,

" When timber ia exposed to alternate moisture and dryness it
soon decays." ^

The general causes of decay in timber are the presence of sap,
exposure to alternate wet and dryness, or to moisture accompani^
by heat and want of ventilation.

Bot in timber is decomposition or putrefaction, generally occa-
sioned by damp, and which proceeds by the emission of gases,
chiefly carbonic acid and hydrogen.

There are two kinds of rot generally known to practical men
— dry rot and wet rot

The chief difference between them seems to be that wet rd
occurs where the gases evolved can escape. By it the tissues of
the wood, especially the sappy portions, are decomposed. Diy
rot, on the contrary, occurs in confined places, where the gases
cannot get away, but enter into new combinations, forming fungi
which feed upon and destroy the timber.

Tredgold says that wet rot may take place while the tree is
standing, whereas dry rot takes place only when the wood is
dead.

Dry Bot is generally caused by want of veutiladou. Confined air, with-
out much moisture, encourages the growth of the fungus, which eats into the
timber, renders it brittle, and so reduces the cohesion of the fibres that thej
are reduced to powder. It generally commences in the sapwood.

An excess of moisture prevents the growth of the fungus, but moderate
warmth, combined with damp and want of air, accelerates it.

'^ In the first stage of rottenness the timber swells and changes colour, is
often covered with fungus or mouldiness, and emits a musty snielL"

" When the fungus first appears on the sides and ends of timbers it covers the svifafec
with a fine delicate vegetation called by shipwrights a mildew.

** These fine shoots afterwards collect together, and the appearance may then be com-
pared to hoar-frost, and increases rapidly, assuming gradually a more compact form, like
the external coat of a mushroom, but spreads alike over wood, brickwork, stone, aiul
plastering in the form of leaves, being larger or smaller, most probably, in proportion ta
the nutriment the wood affords. The colours of the fungus are various, sometimes white,
greyish white with violet, often yellowish brown, or a deep shade of fine rich brown." *

T}i€ positwM in which dry rot occurs are, as already mentioned, those where
the timber is exposed to warmth and damp stagnant air.

The principal parts of buildings in which it is found are —

In warm cellars, under unventilated wooden floors, or in basements, parti-
cularly in kitchens or rooms where there are constant fires. " All kinds of
stoves are sure to increase the disease if moisture be present"

The ends of timbers built into walls are nearly sure to be affected by dry
rot unless they are protected by iron shoes, lead, or zinc. The same resvlt is
produced by fixing joinery and other woodwork to walls before they are dnr.

» Tredgold. • Britton Chi Dry RU,

DECAY OF TIMBER. 393

•

Oilcloth, kamptulicoii,andotherimpervioa8 floorcloths, by preventing accen
of air and retaining dampness, cause decay in the boards they cover. Car2)ets
do the same to a certain extent.

Painting or tarring cut or unseasoned timber has the same effect

Sometimes the roots of large trees near a house penetrate below the floors
atid cause diy rot

It is said that if two different kinds of wood — as, for example, oak and fir
— are placed so as to touch end to end, the harder of the two will decay at
the point of junction.

" There is this particular danger about the dry rot — viz., that the germs of the fungi
producing it are carried easily, and in all directions, in a building where it once displays
itself, without necessity for actual contact between the affected. and the sound wood."

" Before dry rot has time to destroy the principal timbers in a building it penetrates
behind the skirtings, dadoes, and wainscotings, drawing in the edges of the boards and
splitting them both horizontally and vertically. When the fungus is taken off they
exhibit an appearance similar, both in back and front, to wood that has been charred ; a
slight pressure with the hand will break them asunder, even though affected with the rot
but a short time, and in taking down the wainscot the fibrous and thin-coated fungus
will generally be seen closely attached to the decayed wood. In timber of moderate
length the fungus becomes larger and more distinctive in consequence of the matter con-
genial to its growth affording a more plentiful supply." ^

Wet Bot occurs, as before mentioned, in the growing tree, and in other
positions where the timber may become saturated with rain.

If the wood can be thoroughly dried by seasoning, and the access of further
moisture can be prevented by painting or sheltering the timber, then wet
rot can be prevented.

''The communication of the disease resulting from the putrefactive fer-
mentation or the wet rot only takes place by actual contact," not by the dis-
uemination of the germs of fungi as with dry rot

Detection of Dry Bot. — In the absence of any outward fungus, or other
visible sign, the best way is to bore into the timber with a gimlet or
augur. A log apparently sound, as far as external appearances go, may be
full of dry rot inside, which can be detected by the appearance of the dust
extracted by the gimlet, or more especially by its smell.

If a piece of sound timber be lightly struck with a key or scratched at one
end, the sound can be distinctly heard by a person placing his ear against the
other end, even if the balk be 50 feet long ; but if the timber be decayed,
the sound will be very faint, or altogether prevented from passing along
the balk.

Imported timber, especially fir, is often found to be suffering from inci-
]nent dry rot upon arrival. This may have originated in the wood of the
ship itself, or from the timber having been improperly stacked, or shipped
in a wet state, or subjected to stagnant, moist, warm air during the voyage.

Sometimes the rot appears only in the form of reddish spots, which,
upon being scratched, show that the fibres have been reduced to powder.
After a long voyage, however, the timber will often be covered with white
tibres of fungus.

Canadian yellow pine is very often found in this state.

The best way of checking the evil is to sweep the fungus off the timber,
and restack it in such a way that the air can circulate freely round each
piecei^

^ Britten.

394 NOTES ON BUILDING CONSTRUCTION.

PRESERVATION OF TIMBER.

The best means for preserving timber from decay are to haye it
thoroughly seasoned and well ventilated.

Several processes have, however, been introduced at difierent
times with a view of preventing decay in timber by excluding
moisture, or by drjring up or expelling the sap within it.

A few of these processes will now be described.

Fainting preserves timber if the wood is thoroughly seasoned
before the paint is applied. Otherwise the filling up of the outa
pores only confines the moisture and causes rot The same may
be said with regard to Tarring.

Sometimes before the paint is dry it is sprinkled with sand,
which is said to make it more durable.

Tredgold says — "For timber that is not exposed to the weather, the
utility of paiut is somewhat doubtful . . . Wood used in outdoor
work should have those parte painted only where moisture is likely to find
a lodgment, and all shakes or cracks and jointe should be filled up with white
lead ground in oil, or oil putty, previous to being painted over."

Charring Timber. — ^The lower ends of posto put into the ground are gener-
ally charred with a view of preventing dry rot and the attacks of worms.

Care should be taken that the timber to which this process is applied ii
thoroughly seasoned, otherwise by confining the moisture it will indnce
decay and do more harm than good.

It may here be mentioned that posts should be put in npaide down, with regard to tht
position in which they originally grew. The sap valves open upwards from the root, and
when thus reversed they prevent the aeoent of moisture in the wood.

Mr. Britton recommends that the charring process should be applied to the
embedded portions of beams and joists, to joiste of stables, wash-houses, etc,
to wainscoting of ground-floors, to flooring beneath parquet work, to the jointi
of tongues and rebates, and to railway sleepers.

Mons. de Lapparent applied the method on a laige scale by the use of a gas
jet passed all over the surface of the timber, but Mr. Laslett, who experimented
on timbers thus treated, says —

'* I should not myself be inclined to uae it on timber for works of oos*
struction, except as a possible means of preventing the generation of moisture
or fungus where two unseasoned pieces of wood are placed in juxtapoeition.*

Greosoting, known also as Bethell's process, is effected by
extracting the moisture and air from the tubes of the timber, and
then forcing in kreasote (oil of tar), generally called creosaU, at a
high pressure.

The timber after being dried is placed in a closed wrought-iron cylinder.
The air is then extracted from the cylinder and pores of the wood by t
pump.

PRESERVATION OF TIMBER. 395

Creosote at a temperature of about 120* is then forced into the cylinder, and
penetrates the wood under a pressure of about 170 lbs. per square inch.

The creosote should be thick, rich in naphthaline, and free from ammonia.'

The amount of creosote pumped in depends upon the nature of the timber
and the purpose for which it is intended. The sapwood absorbs it more
readily than the heart

Fir timber or other soft wood will take from 10 to 12 lbs. per cubic foot

Mr. BetheU recommends 7 lbs. per cubic foot for railway works and 10
lbs. for marine works.

Somewhat larger quantities than these are now generally used.

Into oak and other hard woods it is difficult to force more than 2 or 3 lbs.
per cubic foot'

To soft woods an imperfect form of this proceas may be applied by dry-
ing the timber over fires, and placing it while warm in hot creosote.

Of all the preservative processes at present known, creosoting
seems to be the most successful ; it coagulates the albumen of the
wood, fills its pores with an oily liquid, destroys insects and
fungi, repels worms, excludes moisture, and prevents dry rot.

Experience seems to show that creosote will render timber proof
against sea worms, and even against the white ant.

About twelve years ago a Commission was appointed by the Dutch Gk)veni-
ment to report upon the best method of protecting timber from the attacks of
the sea- worm, known as the Uredo (see p. 401).

This Commission tried every preservative means then known, including,
among others— charring the surface, covering with paraffin, with sheet metals,
nails (see p. 402), impregnation with all sorts of chemittd substances, creo-
soting, and kyanising.

The conclusion they arrived at was that " the only process that could be
relied upon for protecting wood from the attacks of the teredo was that of
creosoting, and that this fails if not properly carried out.** '

Eyan's Frooess oonsista in injecting corroilTO sublimate (bichloride of mercury) in the
proportion of 1 pound of sublimate to 15 gallons of water.

The Dutch experiments showed that this process did to a certain extent, though not
altogether, repel the seapworm, and it is said that it has some effect in retarding dry rot
It is now, however, seldom if ever used.

Bonoherie*8 Prooess consists in impregnating the timber with sulphate of
copper by a very simple process.

A reservoir filled with the solution (about 1 lb. of sulphate copper to 12^
gallons of water) is placed at a height of from 20 to 30 feet above the
ground.

From this reservoir leads a pipe into a deep incision in the wood, so
arranged that the liquid may reach the centre of the log. Thence it forces its
way (under the pressure caused by the height of the tank) along the sap
tubes, forces the sap out, and takes its place.

To see if the solution has passed right through the timber the far end is
rubbed with prussiate of potash, which upon coming in contact with the
sulphate of copper makes a brown stain.

1 Britton. ' Dent

396 NOTES ON BUILDING CONSTRUCTION.

Gardner'a Prooess is one that has been lately introduced.

It is said ^ to season timber more rapidly than any other process, to pre-
serve it from decay and from the attacks of all kinds of worms and inseas
It is also found to strengthen the timber, and render it uninflammable, and
by it the timber may be permanently coloured to a variety of shades.

The process takes from 4 to 14 days according to the bulk and denutv of
the timber. It consists in dissolving the sap (by chemicals in open tanks),
driving oiit the remaining moisture, leaving the fibre only.

A further injection of chemical substances adds to the durability, or will
make the timber uninflammable.

The process has been satisfactorily tested in mine props, railway sleepers,
logs of mahogany for cabinet work, and in smaller scantlings of fir and pine:

The exi^eriments showed that the sap was removed, that the resistance
of the timber to crushing was augmented from 40 to 90 per cent, and its
density was considerably increased.

Marsary's Prooess was to soak the wood in acetate or sulphate of copper. It does
not seem to have been successful.

Sir 'William Burnet's System consists in steeping the timber in a solation com-
posed of 1 lb. of chloride of zinc to 4 gallons of ivater.

Payne's Prooess involved two injections into the pores of the timber, the first heiof
sulphate of iron, the other sulphate of zinc. It is said to make the timber incombostibk
but brittle.

Combined Prooess. — ^In cases where the complete preservation of the timber is <A
vital importance, and expense no object, Mr. Britton recommends that the timber should
first be iivjected with metallic salt (as in Burnett's system), dried, and then creosoted. Bj
this means the whole is preserved ; the salts protect the heart, and the creosote the sapvood.

Odk Casings may be preserved from injury done by weather by two coats of boiled
oil applied cold.

Preservation from Fire.— Several methods for preserving timber from fire have bees
proposed from time to time.

It is said that timber that has been thoroughly Bumetised will only beoome charnd
and not burnt by fire.

Some years ago the following means of protection was recommended by Sir F. Abel

The wood having a smooth and clean surface is first painted over with a dilute solatiac
of the silicate, then with slaked fat lime of the consistency of cream, then with a tiUfmga
solution of silicate.

CyaniU is a fireproof solution, probably containing a soluble silicate, which hs$
been frequently tried lately, and apparently with success. It is stated that it will com
twice as much as an equal quantity of priming.

Asbestos Paint (see p. 428) affords some slight protection against fire.

TungstaU of Soda imparts fireproof qualities to timber or fiibrics covered witii repeated
coats of the solution.

CONVEKSION OF TIMBER

In reducing timber from the log or baulk to scantlings, the
dimensions and form that the timber ought to possess when actually
in use should be borne in mind, in order that proper allowance
may be made for the alteration that wiU take place in conse-
quence of the action of the atmosphere, which has an influence
more or less even upon well-seasoned timber.

1 Psper read before the Philosophical Society of Glasgow, byJas. Deas, E8q.,M.1.CML

CONVERSION OF TIMBER, 397

Atmosplierio Influence. — In straight-grained woods the changes in length
caused bj the effects of the atmosphere are very slight ; but the variations in
width and depth are very great, especially in new timber.

Rondelet found that the usual changes of weather produced the following
expansion and contraction in wood of average dryness : —

In fir from »4^ to it of width ; mean rir.
In oak from lir to 1^ of width ; mean liv.

Mr. Hurst makes a practical allowance for shrinkage in 9-inch deals
amounting to i inch for "northern pine" deals, and ) for " white deals."

The first effect of atmospheric influence upon a log is that the external
portions which are exposed to the air shrink ; but the interior, which is pro-
tected from the air, remains at its original bulk. The consequence is that
the exterior splits, as shown in Fig. 156.

The following extract, taken by permission from Dr. Ander-
son's lecture on applied mechanics given before the Society of
Arts, explains very clearly the manner in which timber shrinks
when cut into scantling : —

** Notwithstanding the extent to which timber is used in the mechanical arts,
it is singular that the natural law by which the contraction or shrinking of
wood is governed is too much disregarded in practical operations. It is a
subject which seems to have been entirely neglected by writers on the
subject . . .

" Au examination of the end section of any exogenous tree, such as the beech
or oak, will show the general arrangement of its
structure. It consists of a mass of longitudinal
fibrous tubes arranged in irregular circles that are
bound together by means of radical strings or
shoots which have been variously named. They
are the "silver grains" of the carpenter, or the
^ medullary rays " of the botanist, and are in
reality the same as end wood, and have to be con-
sidered as such, just as much so as the longitudinal
woody fibre, in order to understand its action.
From this it will be seen that the lateral contrac- Fig. 156.

tion or collapsing of the longitudinal porous or

tubular part of the structure cannot take place without first crushing the
medullary rays ; hence the effect of the shrinking finds relief by splitting
in another direction, namely, in radial lines from the centre, parallel with
the medullary rays, thereby enabling the tree to maintain its full diameter,
as shown in Fig. 156.

" If the entire mass of the tubular fibre composing the tree were to contract
bodily, then the medullary rays would of necessity have to be crushed in
the radial direction, to enable it to take place, and the timber would thus be
as much injured in proportion as would be the case in crushing the wood in
the longitudinal direction. If such an oak or beech tree is cut into four
quarters by passing the saw twice through the centre at right angles, before
contracting and splitting has commenced, the lines ac and c& in Fig. 157
would be of the same length, and at right angles to each other, or in the
technical language of the workshop they would be square ; but after being

398

NOTES ON BUILDING CONSTRUCTION.

stored in a dry place, say for a year, it would then be seen that a great
change had taken place both in the fprm and in some of the dimensioiis ;

fig. 167.

Fig. 158.

the lines ca and ch would be the same length as before, but it would ha?e
contracted from a to & very considerably, and the two lines c a and c h would
not be at right angles to each other by the portion shown here in black
in Fig. 158. The medullary rays are thus brought closer by the col-
lapsing of the vertical figure.

" But, supposing that four parallel saw cuts are passed through the tree
80 as to form it into five planks, let us see what would be the behaviour of
the several planks. Take the centre plank first After due seasoning and
contracting it would then be found that the middle of the board would
still retain the original thickness from the resistance of the medullary rays,
while it would be gradually reduced in thickness towards the edges for want
of support, and the entire breadth of the plank would be the same as it was
at first, for the foregoing reasons, and as shown in Fig. 159. Then taking
the planks at each side of the centre, by the same
law their change and behaviour would be quite dif-
ferent They would still retain their original thick-
ness at the centre, but would be a little reduced on
each edge throughout, but the side next to the heart
of the tree would be pulled round, or partly cylin-
drical, while the outside would be the reverse, or
hollow, and the plank would be considerably na^
rower throughout its entire length, more especially
on the face of the hollow side, all due to the want
of support Selecting the next two planks, they would
be foimd to have lost none of their thickness at the
centre, and very little of their thickness at the edges, but very much of
their breadth as planks, and would be
curved round on the heart side, and
made hollow on the outside. Sup-
posing some of these planks to be cut
up into squares when in the green
state, the shape that these squares
would assume after a period of season-
ing would entirely depend on the part
of the tree to which they belonged ;
the greatest alteration would be parallel wiUi the medullary rays. Thua, if

Fig. 169.

CONVERSION OF TIMBER.

399

the square were near the outside, as in Fig. i6o, the effect would be that it
would contract in the direction from a to 6, and after a year or two it would
be as in Fig. i6i, the distance between c and a being nearly the
same as it was before, but the other two angles a and h brought by the
amount of their contraction closer together. By understanding this natural
law, it is comparatively easy to know the future behaviour of a wood or
plank by carefully examining the end wood in order to ascertain the part of
the log from which it has been cut, as the angle of the ring growths and
the medullary rays will show thus, as in Fig. 162. If a plank has this
appearance it will evidently show to have been cut from the outside, and
for many years it will gradually shrink all to the breadth, while the next
planky shown in Fig. 163, clearly points dose to the centre or heart of the

Fig. 162.

Fig. 163.

tree, where it will not shrink to the breadth, but to a varying thickness, with
the full dimensions in the middle, but tapering to the edges, and the planks
on the right and left will give a mean, but with the centre sides curved
round, and the outside still more hollow.

" The foregoing remarks apply more especially to the stronger exogenous
woods, such as beech, oak, and the stronger home firs. The softer woods,
such as yellow pine, are governed by the same law, but in virtue of their
softness another law comes into force, which to some degree affects their
behaviour, as the contracting power of the tubular wood has sufficient
strength to crush the softer medullary rays to some extent, and hence the
primary law is so far modified. But even with the softer woods, such as
are commonly used in the construction of houses, if the law is carefully
obeyed, the greater part of the shrinking, which we are all too familiar with,
would be obviated." ....

Experiments have shown that timber beams having the annual rings paraUel
to their depth are stronger than those which have
the rings parallel to their width. Thus, in the log
shown in Fig. 164 the piece cut from A will be
stronger than that cut from B.
Again,the purpose forwhich
the timber is intended should
be borne in mind. Thus, in
preparing floor boards, care
should be taken that the hearts
should not appear on the sur-
face of the finished board. If
they are allowed to do so, as in Fig. 165, the central portions will soon
become loose, will be kicked up, as shown in dotted lines, and will form a
rough and unpleasant floor.

When planks which have shrunk to a curved form have to be used to form
a flat board, they are sometimes sawn down the middle and glued together^

Fig. 164.

Fig. 166.

400

NOTES ON BUILDING CONSTRUCTION

the alternate pieces being reversed as in Fig. i66 ; thus the curvature in each

piece is so slight as to be almost inappredabk,
and the reversal of the alternate pieces eanea
each to be a check upon the shrinkage of its
^'«- ^^^- neighbours.

GonverBion of Oak. — There are several methods of converting oak de-
scribed in Gwilt's Encyclopaedia of Architecturey from which the following w
taken ; Fig. 167 being very slightly modified.
The log is first cut into four quarters.

Each quarter may then be converted in either of the following methods:—

The best method is shown at A in Fig. 1 67, ** in which there is no waste, as

the triangular portions form feather-edged laths for tiling and other purpoeea."

c^x^^^;

viV- -■',' ■■■':'

Y '■

^N>vW^Z?^

^..^-====Sk^

Jf ^^\

Ji ^' *. " ' ' ^V

J^ : -,■ ..-->■.-*. - ■ \

/ ■ ■ . .- .. " - \

jt ■ ' ' " . • \

/ ■ ' ■ ■ ■ ' \

L V . ~ ■. : ~

,. J ^

r ■'■■'" -^'r'

li , ■ ■ ^r^-.

\ ' '- ■■■' '■ ■ ■

Y . >. . ■■..■.^.- ■ /

\ ■ ■"-■ ■" /

Y- - . ' -^ - /

\_ : ■- — 7

X '

X /

^■^1- - j.>^

Fig. 167. Fig. 167a

This method also cuts very obliquely across the medullary rays, and thu?
exhibits well the «t/ver grain of the wood, which is so much admired for
cabinet work and other ornamental purposes.

The next best method is at B. The method shown at C is inferior to
the others ; that at D is the most economical where thick stuff is required.

A good practical method adopted for cutting oak logs so as to get wi<le
boards is to cut all the boards parallel to the same diameter, but leaving the
heart to be used for quartering. See Fig. 167a,

Conversion of Fir. — At the great saw-mills in Sweden and Norway
each log is carefully inspected before it is sawn, to find out how many of the

most mfvfkdahU sizes can be made
out of it Thus if 4-inch deals are
in demand, or battens, they will
arrange so as to cut more of these
sizes, and fewer of the regular 3-inch
deals, and met versd.

Two methods are shown in the

accompanying figures, taken frow

Mr. Britton's work upon Dry Rot

Fig. 1 68 shows an arrangement generally adopted at the present tima

The 9x3 inch deals go into the English market ; those 9x1^ inches into

the French market.

Fig. 169 shows the method that was adopted until the French market im-
proved. It will be observed that the centre deal would include the pith,
and it is in such a case subject to dry rot

h'iir. 108.

Fig. 169.

WORMS, ETC, WHICH ATTACK TIMBER. 401

DESTRUCTION OF TIMBER BY WORMS AND INSECTS.

Timber both in its growing and converted states is subject tc
the attacks of worms and insects ; when these exist in large num-
bers they remove so much of the wood as seriously to impair the
strength of any structure depending upon the timber, and in some
cases they destroy the balks altogether.

It will not be necessary to describe these worms and insects in
detail But a brief notice of a few of the most important, gleaned
chiefly from the works of Tredgold and Britton, may be useful.

Worms. — ^The Teredo navalis is the most common enemy to timber
used in snbmarine work.

It is found in warm and cold climates, and in nearly every English port
It avoids fresh water and prefers clear water to that which Ib mnddy.
This is one reason why wood placed at the month of a river, or in turbid
water, is not so liable to be attacked as when it is in clear salt water.

The Teredo is first deposited upon the timber in the shape of an egg, from
which in time emeiges a small worm ; this worm soon becomes larger, and
commences its depredations.

Furnished with a shelly substance in its head, shaped like an auger, it
1x)re8 into the wood, chiefly with the grain ; at the same time it lines the hole
it makes with a thin coating of carbonate of lime, and closes the opening with
two small lids.

As the work of the Teredo advances its size increases. Worms two feet
long and | inch in diameter have been found at Sheemess, and even lai^r
ones are stated to exist.

The Teredo penetrates nearly all kinds of timber, but is most successful in fir.

The general opinion seems to be that the boring is mechanical, but some author-
ities think that it is done or assisted chemically by the aid of an acid secretion.

The Xylophaga doraalis is of the same Ikmily as the Teredo, not so common, but more
destractive ; it lines in all directions, not only with the grain, and does not line its hole
with shell

The LncNOBiA tebebbans is a marine insect, resembling in appearance a
very small woodlouse.

It is very abundant in British (salt) waters, and makes up for its diminutive
size by the numbers in which it attacks timber : ^ as many as twenty thousand
will appear on the surface of a piece of pile only 12 inches square.'' ^

Mr. Stevenson found that Memel timber was destroyed by the Limnoria at the BeU
Bock at the rate of about 1 inch inwards per annum. At Lowestoft, piles were eaten at
the rate of 3 inbhes inwards per annum.

This insect prefers soft woods, avoids knots, but will attack all woods except teak and
greenheart

*' The LimnoTia almost always works just under neap tides. It cannot live in fresh
water (or under the sand), and whilst it is destroying the surface of a pile, the Teredo is
attacking the interior."

The Tanais viUatxu, a species of the same family as the Ltmnorui, in appearance like a
very small caterpillar with enormous foreclaws, was found by Mr. Hurst in beech piles.

The Chelura terebrans, or wood-boring shrimp, is also an inhabitant of
British seas. It tunnels close below the surface of timber, the waves wash

» Dent. « Britton.

B.c.--m 2d

402 NOTES ON BUILDING CONSTRUCTION,

Away the thin covering of the tunnel, and then the shrimp drires another
below, 80 that the timber is removed in successive flakes.

" The Jjimnoria will exist in comparatiyely fool water if salt, but the ChHwru nmrt bare
sea water comparatively pure, hence the former is meet frequently found in harbomsaod
the latter along the sea coast.

" The Limnoria and Chdura terebrans do not attack wood more than a few indkes abov«
high water or neap tides." ^

The Ltgorib fucata is the enemy of the Teredo,

A little worm with legs, something like a centipede, it lives in the mud,
crawls up the pile inhabited by the Teredo^ enters the tunnel in which it L&
ensconced, eats the Teredo^ enlarges the entrance to the tunnel, and then
lives in it.

Protection against Wornuau — ^A great many different plans have h«a
tried in order to protect timber in marine works from the ravages of worms.

Copper sheathing is not effectual The worm gets in between the copper
and the timber, and moreover the sheathing decays.

Broad-head scupper nails driven in close together rust into a mass, and
80 form a good protection, but the process is expensive.

Creosoting by Bethell's process when properly carried out is quite succeo-
ful (see p. 394) but no other chemical process answers

Ants. — Of the ants proper, or those belonging to the order Hymenofter^
there are three species in particular which attack timber, Viz, — ^

1. The Black Carpenter Aivt {Formica fuliginosa), which prefers haid and
tough wood, rather in standing trees than in seasoned timber. A tinge ti
black is seen round the holes it makes, caused by iron in its saliva acting
upon gallic acid in the wood

2. The Dvjky Ant {Formica fusca),

3. The Yellow Ant (Formica flava).

The two last-mentioned species prefer soft woods.

The White Ant (genus Termes) is a disagreeable-looking cream-eoloured in-
sect of fatty substance not quite a ^ inch long, with a black head and loh6te^
like claws. It grows wings at the last stage of its existence in tlie nest aii^i
flies away to die.

It is found sometimes in Europe, but chiefly in tropical climates, moit
especially in Africa, the East Indies, the Mauritius, and St. Helena, genendlr
in damp soils near the sea or rivers. Its nests are in the ground or in timber,
but always where there is no vibration to destroy the cells.

White ants will eat the whole timber work of a house without noiie.
They bore close to the surface of the wood, but without destroying it, w
that there is no visible indication of what they are doing.

They will even bore through the boards of a floor and up the 1^^ of »
table, leaving the latter a mere shell.

No timber has yet been found which is sure to resist them. Teak is
riddled by them. Jarrah and greenheart are said to be more suocessfid, but
this is doubtful. Cedar while new keeps them at bay by its smell, but when
this passes off they devour it eagerly. Oregon pine particularly attracts them.
The natives of the countries infected by them use common unsawn yellov
pine of long fibre with more success against them.

Protection against the white ant, — Creosoting with bone oil is the bestpR-
servative against white ants, but on account of its smell is only adapted fur

* Hurst's Tredgold.

STRENGTH OF TIMBER, 403

out -door work, and can hardly be applied to very dense tropical timbers.
Kerosene is effective while its smell remains. The use of arsenic to guard
against them has been abandoned as ineffectual.

Other Inseots besides those above mentioned attack wood, among which
may be mentioned the GarfenUr bee of South Africa and the East Indies,
and toood beetles in Ceylon.

There are also two or three kinds of small beetles in this country which
destroy furniture, carvings, etc, and burrow into books in libraries. The
best way of destroying them is by subjecting them to the vapour of chloro-
form or benzine.^

VARIETIES OF TIMBER USEFUL FOR DIFFERENT
PURPOSE&

The undermentioned are the best of the ordinary descriptions of timber
to use for the purposes named.

Piles, — Oak, beech, elm.

Posts. — Chestnut, acacia, larch.

Great Strength in CcmstrueUan. — Teak, oak, greenheart, Dantadc fir, pitch pine.

Durable in Wd Positions, — Oak, beech, elm, teak, alder, plane, acacia,
greenheart

Large Timbers vn Carpentry, — Memel, Dantadc, and Riga fir.

Oak, chestnut. Bay mahogany, pitch pine, or teak, may be used if easily
obtainable.

FUwrs, — Christiania, St Petersburg, On^a, Archangel, make the beet;
Oeile and spruce inferior kinds ; Dram battens wear weU ; pitch pine, oak, or
teak, where readily procurable, for floors to withstand great wear.

Panelling. — American yellow pine for the best ; Christiania white deals are
also used.

Interior Joinery. — American red and yellow pine ; oak, pitch pine, and
mahogany for superior or ornamental work.

IVindow SUls, SUepers. — Oak ; mahogany where cheaply procurable.

Treads of iStoire.— Oak, teak.

Handles. — ^Ash, beech.

Patterns, — American yeUow pine, alder, mahogany, Cowslie pine.

STRENGTH OF TIMBER

The following Table, showing the strength and weight of timber, is gleaned
from the records of many experiments, chiefly those given by Hodgkinson,
Tredgold, Barlow, Rankine, and Ladett Some of these, in their turn, have
embodied the results of experiments made by Buffon, Muschenhoek, Rondelet,
etc

It will be seen that the figures given vary throughout a very wide range.
This is quite in accordance with practice.

Experiments made upon selected pieces of good quality show results differ-
ing greatly from one another, the difference being caused by variety in the
age or state of dryness of the specimen, the size and form of the piece tested,
the method in which the test has been applied, and the ddll of the
experimenter. •

» Britten.

404 NOTES ON BUILDING CONSTRUCTION.

Table showing the Weight, Stbbngth, etc, of Various Woods.

Modulus

1^^

llli

CompsratiTe
StiffneM aiKi

Wood seasoned.

}|3

"3 !.•

StreDgth, acc-Tr:-

Rupture.

EksUcit7.

ing to TrMJK-(»}.l

Oak being Iv-x:

Lbs.

Tona.

From To

Lbs.

Tons per
sq. inch.

t 1

^^- ^^^

Acacia

6-0 8-1

...

1,1 52,000 to
1,687,500

5^ |&

Alder .

4-5 6-3

1,086,750

Ash, Euglish

43 to 53

1-8 7-6

12,000 to
14,000

1,625,500 to
2,290,000

3-8 4-2

119

„ Canadian

2-45

10,060

1,380,000

2-5

Beech .

43 to 53

21 6-6

9,000 to
12,000

1,360,000

3-4 4-2

103

Birch .

45 to 49

6-7

11,700

1,645,000

1-5 2-8

Cedar .

35 to 47

1-3 51

7,400 to
8,000

486,000

2-5 2-6

Chestnut

35 to 41

4-6 5-8

10,660

1,140,000

...

Elm, Engliah

34 to 87

2-4 6-3

6,000 to
9,700

700,000 to
1,840,000

2-6 4-6

„ Canadian

4-1

14,490

2,470,000

4-1

189

114

Fir, Spruce .

29 to 32

1-3. 4-6

9,900 to
12,300

1,400,000 to
1,800,000

2-9 8-0

„ Dantzic .

1-4 4-5

13,806

2,300.000

130

108

„ American I'ed

1-2 60

7,100 to

1,460,000 to

2-1

132

pine

10,290

2,350,000

„ American yel-

0-9

8,454

1,600,000 to

1-8

189

low pine

2,480,000

„ Memel . .

4*2 4-9

1,536,000 to
1,957,760

114

„ Kaurie .

2-0

11,334

2,880,000

2-6

162

„ Pitch pine .

41 to 58

21 4-4

14,088
6,600 to

1,252,000 to
3,000,000

.. Rig* . .

84 to 47

1-8 5-5

9,450

1,328,000 to
8,000,000

Oreenheart .

68 to 72

3-9 4-1

16,500 to
27,500

1,700,000

5-8 6-8

165

Jarrah .

1-3

10,800

1,187,000

8-2

Lareh .

82 to 88

1-9 5-3

5,000 to
10,000

1,860.000

2-6

103

Mahogany, Spanish

1-7 7-8

7,600

1,255,000 to
3,000,000

8-2

„ Honduras

1-8 8-4

11,500 to
12,600

1,596,000 to
1,970,000

2-7

Mora .

57 to 68

4-1

21,000 to
22,000

1,860,000

...

105

164

Oak, English

49 to 58

3-4 8-8

10,000 to
13,600

1,200,000 to
1,750,000

2-9 4-5

100

„ American

80 4-6

12,600

2,100,000

114

Plane .

5-4

•••

1,848,250

...

Poplar

23 to 26

2*68

...

763,000

1-4 2-3

Sycamore

36 to 43

4-8 5-8

9,600

1,040.000

111

Teak .

41 to 52

1-47 6-7

12,000 to
19,000

2,167,000 to
2,414,000

2-3 6-4

126

109

Willow

24 to 35

6-25

6,600

1-8 2-7

Hornbeam .

47-5

9-1

...

8-7

...

lOS

1 From Hodgkinnon's experiments on short plllara 1 inch diameter, S inches high, flat ends.
Laalett's on 2-inch cubes.

t This ratio is not always conAnned by the Talnea of the moduli of elasticity as fboad by i
recent experiments, and giyen in the fifth column of the above table.

STRENGTH OF TIMBER,

405

Practical experiment upon material similar to that about to be used in any
particular case is preferable to information extracted from tables ; but if it
is necessary to use the latter, the engineer should be inclined to credit his
material with the lowest of the figures recorded, and then to apply a good
factor of safety to cover defects in the pieces used, which defects may not
have existed in the specimens experimented upon.

Mr. Hodgkinson found that timber when wet had not half the strength of
''.he same timber when dry. This is an important point to consider in sub-
aqueous structurea

Rui^taiMt to GnuUUng across the Fibres, — ^When a vertical piece of timber
stands upon a horizontal piece, the latter is compressed at right angles to the
length of the fibres, and in this position it will not withstand so great a com-
pressive force per square inch as does the vertical piece, whose fibres are com-
pressed in the direction of their length.

Not many experiments have been made on this point.

Tredgold found that Memel fir was distinctly indented with a pressure of
1000 lbs. per square inch, and English oak with 1400 lbs. per square inch.

Mr. Hatfield's experiments chiefly on American woods, are quoted in Hurst's
Tredgoldy and form the basis of a table in Huisfs Pocket-Booh^ from which the
following are taken : —

ffoToe per sq. Ineh required to
enuh the flbrea tnuuveraely
^ Inch deep.
'22 tons.

Pir, aprnce . . . .

PiM, Northern Memel

. . ^ ,.

„ White (P. strofms) American

•27 „

Mahogany, Honduras

•68 „

M St. Domingo .

1-92 „

Oak, English

•»o „

„ American

•84 „

Ash, Aroericaa

1-08 „

Ohestnnt ' . . .

•42 „

RmtiwMe to Shearing. — On this point also but few experiments have been
made.

The resistance to shearing in direction of the fibres of the wood is of course
much less than that across the fibres.

Wood.

per aq. inch in Iba.

Along Fihres.

Aeroaa Fltarea.

Oak .

American oak
Ash and elm
Spmoe
Redpine .

556to6S4'

2300 »

780"

1400 •

600 «

500 to 800«

4000 •

1 Barlow On Strength of Materials, p. 28. * Rankine*8 OivU Engineering.
' Hatfield, quoted in Hurtf s Tredgold,

Chapter VL
PAINTS AND VARNISHES.

TJAINTS and Varnishes are used by the engineer and boilder for
-■- covering the surfaces of wood, iron, and other materials, in
order to protect them from the action of the atmosphere, or to
improve their appearance.

The preparation of surfaces and the difiTerent processes involved
in painting and varnishing materials of different kinds have already
been briefly described in Part II.

It will now be necessary only to give a few particulars regard-
ing the paints and varnishes in common use on engineering and
building works.

The paints used by the engineer and builder as a rule consist
of a hase^ (generally a metallic oxide) mixed with some liquid
substance known as the vehicle ; upon this, permanen<;y of the paint
depends.

In most cases a drier is added to cause the vehicle to dry more
quickly, and a solvent is sometimes required to make it work more
freely.

When the final colour required differs from that of the base
used, the desired tint is obtained by adding a stainer or colouring
pigment.

It wiU be an advantage to glance at the properties of the sub-
stances used to effect the various objects above mentioned before
describing the paints most commonly made from those substances.

The materials most commonly used for the purposes above
mentioned are as follows : —

Bases. — White lead, red lead, zinc white, oxide of iron.

Vehicles. — ^Water, oils, spirits of turpentine.

Solvents. — Spirits of turpentine.

^ Sometimes called a pigment^ bnt here called the hose in order to ayoid ooafuaUn
with the pigment added to give the colour ; see p. 418.

BASES FOR PAINTS. 407

Driers. — Litharge, acetate of lead, sulphate of zinc, and
binoxide of manganese, red lead, eta

Cohwring Pigments. — Ochres, lampblack, umber, sienna, and
many metallic salts, the principal of which are mentioned at
pages 413 to 417.

BASES.

White Iiead is a carbonate of the metaL The best is produced hj the
Dutch process, which consists in placing gratings of pure lead in tan, and
exposing them to the fumes of acetic acid ; by these they are corroded, and
covered with a crust of carbonate, which is removed and ground to a fine
powder.

There are other processes for manufacturing white lead, in which it is
precipitated by passing carbonic acid through solutions of diifereut salts of
lead.

Clichy WhUiB is produced in this way by the action of carbonic acid gas upon acetate
oflead.^

The white lead produced by precipitation is generally considered inferior
to that prepared by corrosion. It is wanting in density or body, and absorbs
more oil — ^it however does not require grinding.

Pure white lead is a heavy powder, white when first made ; if exposed to
the air it soon becomes grey by the action of sulphuretted hydrogen.

It is insoluble in water, effervesces with dilute hydrochloric acid, dissolving
when heated, and is easily soluble in dilute nitric acid.

When heated on a slip of glass it becomes yellow.

This substance may be used as the basis of paints of all coloura

AduUeratum. — White lead may be purchased either pure or mixed with
various substances — such as sulphate of baryta, sulphate of lead, sulphate of
lime,^ whiting (see p. 254), chsdk, zinc white, etc These substances do not
combine with oil so well as does white lead, nor do they so well protect any
surface to which they are applied.

Sulphate of baryta, the most common adulterant, is a dense, heavy, white
substance, very like white lead in appearance. It absorbs very little oil, and
may frequently be detected by the gritty feeling it produces when the paint
is rubbed between the finger and thumb.

Market Forms. — White lead is sold either dry in powder or lump, or else
ground in ot^ in a paste " containing from 7 to 9 per cent of linseed oil, and
more or less adulterated, unless specially marked genuine."

When sulphate of baryta has been added, its presence is in most cases
avowed ; the mixture is called by a particular name, which indicates to the
initiated the proportion of sulphate of baryta that it contains. Thus —
Genuine Dry White Lead^ Newcastle White, Nottingham White^ Roman White^
London White, are all names for pure white lead.

KremnitZj or Krems White, known also as Vienna White, imported from
Austria in small cubes ; French White, or Silver White, in drops, from Paris ;
and Flake White, made in England in small scales, should also all be pure
white lead, but they differ considerably in density.

^ Dent * Barium sulphate, lead sulphate, calcium sulphate.

4o8 NOTES ON BUILDING CONSTRUCTION.

Venice WliiU contains 1 part white lead to 1 part sulpliate of baiyta.
Hamburg JVhUe „ 1 „ „ 2 „ „

Dutch White, or ) ^

HoUamd WhiU I " ^ » » ^ »»

" When the sulphate of baryta is very white, like that of the Tjrol, these
mixtures are considered preferable for certain kinds of painting, as the barvtes
communicates opacity to the colour, and protects the 1^ from being speedily
darkened by sulphurous smoke or vapours." ^

Old White Lead, — ^White lead improves by keeping. It should not be
exposed to the air, or it will turn grey (see p. 407). Old white lead of good
quality goes further and lasts better than if it is used when fresh ; more-
over, the paint made with fresh lead has a tendency to become yellow.

Fresh white lead often has a yellowish tinge, caused by the presence of
iron.

UeeBy Advantageif aiid Dieadvantagee, — Of all the bases for paints white
lead is the most commonly used, and for surfaces of wood it affords in most
cases the best protection, being dense, of good body, and permanent It has
the disadvantage, however, of blackening when exposed to sulphur acids, and
of being injurious to those who handle it.

Ted for Stdphaie of Baryta, — **The testiDg of the quality of white lead ia a very
simple operation, as it is only necessary in the case of dry white lead to digest it with
nitric acid, in which it dissolves readily on boiling. When ground with oil, the ofl
should be burnt oflT, and the residue treated with nitric acid ; or

"The ground white lead with the oil may be boiled for some little time with atrang
nitric acid, which destroys the oil, and dissolves the lead on the addition of water.

^ The sulphate of baryta being insoluble in acid remains behind, and can be collected
on a filter, washed with hot distilled water, and weighed."

Bed Iiead is produced by raising maeneot (the commercial name for oxide
of lead) to a high temperature, short of fusion, during which it absorbs
oxygen from the air, and is converted into red lead or minium^ an oxide of
lead.

It is usually in the form of a bright red powder. Ground by itself in oil
or varnish, it is durable and unaffected by light when the red lead is pure
and used alone, but any preparation containing lead, or metallic salta mixed
with it) deprive it of colour, and impure air makes it black.

Uees, — Bed lead is used as a drier (see p. 412), also for painting iron (see
p. 336) ; and in the priming coat for painting wood (see pw 419).

Adtdteration and Teste. — Bed lead is sometimes adulterated with brick dust,
which may be detected by heating the red lead in a crucible, and treating it
with dilute nitric acid ; the lead will be dissolved, but the brick dust will

remam.

Bed lead may also be adulterated with eoleothar, a sesquioxide of iron.

Antimony Vermilion, Sulphide of Antimonyj produced from antimony
ore, has been proposed as a substitute for red lead.

It is sold in a very fine powder, without taste or smell, and which is
insoluble in water, alcohol, or essential oil&

It is but little acted upon by acids, and is stated to be unaffected by air or
light It is adapted for mixing wiUi white lead, and affords an intensely
bright colour when ground in oiL^

^ Ure. ' Davidson. * Proceedings Society of Engineer*, 187&

VEHICLES FOR PAINTS. 409

Oxide of Zino is the basiB of ordinary zinc paint (see p. 421).

It is prepared by distilling metallic zinc in retorts, under a current of air ;
the metal is voktilised, and white oxide is condensed. It is filled into can-
vas bags, and pressed to increase its density.

Zinc white is durable in water and oil ; it dissolves in hydrochloric acid ;
it does not blacken in the presence of sulphuretted hydrogen (the sulphide
of zinc being white) ; and it is not injurious to the men who make it, or to
the painters who use it

On the other hand, it does not combine so well with oil, and is wanting in
body and covering power, and is difficult to work (see p. 421).

'' The want of density is a great drawback to the use of zinc white, and
the purest zinc oxide is not always the best for paint on account of its low
specific gravity ; and in this respect the American zinc whites, which are
frequently very pure, do not generally compete with the zinc white supplied
by the Yieille Montague Company, as made in Belgium." ^

Uses, etc — Oxide of zinc is the basis of zinc paint. It has considerable
advantages in certain positions, as mentioned at p. 421.

Ozy-Sulphide of Zinc is used as the basis of Griffith's patent white paint.
It is stated by Dr. Phipson to be prepared by precipitating chloride or sul-
phide of zinc by means of a soluble sulphate — of sodium, barium, or calcium.
The precipitate is dried ; and levigated, while hot, in cold water.

The paint made with this substance for a base has several valuable charac-
teristics, which are described at p. 424.

Oxide of Iron is produced from a brown hoematite ore found at Torbay
in Devonshire, and at other places. It forms the basis of a large class of
paints of some importance (see p. 425).

The ore is roasted, separated from impurities, and then ground. Tints,
varying from yellowish brown to black, may be obtained by altering the
temperature and other conditions under which it is roasted

Oxide of iron is also produced as a bye product in the manufacture of
aniline dyes.^

VEHICLES.

Oils are divided into two classes — Fixed oils and volatile oils.

Fixed Oils are extracted by pressure from vegetable substances ; they are
of a fatty nature, do not evaporate on drying, and will bear a temperature
short of 600* Fahr. without decomposing. They are subdivided into

Drying Oils, which' become thick upon exposure to air. Of these, linseed
oil is most commonly used as an ingredient for paint ; nut oil and poppy oil
are also used (see p. 411).

Non-Drying OiUy which become rancid under similar atmospheric influ-
ences. These are not used in preparing paint

Volatile or Essential Oils are generally obtained by distillation, and
have an odour resembling that of the plant from which they are obtained.
They are, as a rule, colourless at first, but upon exposure to air and light
they become darker, thicker, and eventually are converted into a kind of
resin.

Oil of turpentine, commonly called spirits of turpentine, is the only variety
of this class that is much used for ordinary paint

» Dent.

4IO NOTES ON BUILDING CONSTRUCTION

Mineral Turpentine or Petroleum OUib often uaedas a cheap vehicle instead
of ordinary turpentine.

Coal Naphtha is one of the products of the distillation of coal tar. It is
puniied in a mill with sulphuric acid ; the sediment and water drawn off, the
pure washed spirit remains.

Petroleum, a mineral oH, comes from America in casks. It is then distilled,
and from it oils of various density are obtained, and used for burning in
lamps, etc

Benaoline is one of the products obtained from petroleum, and is mach
used as a solvent for bituminous paints. Paints mixed with benzoline or
the heavier oils from petroleum do not set nearly so well, nor do they dn*
with so much cohesion as those in which naphtha is the solvent, but benzoline
is much cheaper, and is therefore often sold as naphtha, and used instead of iL

Iiinseed Oil» produced by compressing flax seed, is the most commonly
used, and by far the best of the oils used as an ingredient of painty putty, and
other simflar substances.

It oxidises and becomes thick upon exposure to the air. This property i«
is very much increased by adding other substances to it and boiling iheni
together (see Boiled Oil).

It is superior in drying powers, tenacity, and body to the other fixed oils.

The best oil comes from the Black Sea and the Baltic ; that from East
Indian seed is inferior, as the seed is less carefully cleaned, and contains too
much stearine.

Usee. — Raw linseed oil is clear and light in colour, works smoothly, and
is used for internal work, for delicate tints, and for grinding up coloui£.
Boiled oil is much thicker, darker, and more apt to clog. It is used for
outside work, as its greater body and rapidity in drying make it a quicker
and more efficient protection.

Raw Linsebd Oil is obtained by allowing the oil, as first expressed from
the seed, to settle until it can be drawn off clear.

When of good quality it should be pale in colour, perfectly transpsrenl,
almost free from smell, and sweet in taste.

When it is to be used for delicate tints, it is sometimes clarified by adding
an acid (such as oil of vitriol), which is afterwards carefully washed out

This clarification is stated to be of no permanent advantage, for the oil in
drying recovers its original colour.

Darkness in colour and slowness in drying are defects in inferior linseed
oiL

These, however, are greatly diminished, and the substance of the oil i^
improved by keeping.

The oil should never be used within six months after being expressed from
the seed, and it is better if kept for several years.

Raw oil is more suited for delicate work than boiled oil, as it is thinner
and lighter in colour.

The drying of raw linseed oil " may be improved by adding about 1 lb. of
white lead to every gallon of oil and allowing it to settle for at least a week ;
this also improves the colour of the oil, whilst the lead can be used afterwards
for common work.** ^

Raw oil spread in a film upon glass, or other smooth non-abeorbent

A Seddon.

VEHICLES FOR PAINTS. 41 1

material, takes from two to three days to diy, according to the state of the
weather.^

Boiled Linbebd Oil, frequently called Drying Oil, is prepared by heating
raw oil with certain driers or by passing a current of air throi^h raw oil.

The drying qualities of the raw oil can be greatly improved by boiling it
alone, but other substances, such as those mentioned below, are generally
added to it, which make it dry still more quickly.

When boiled it becomes much thicker, and not so suitable for indoor or
delicate work, nor will it do for grinding colours, as it clogs and thickens too
rapidly.

Boiled oil of a pale colour is necessary for use with light tints, but for deep
colours a dark oil seems to be generally preferred, though apparently with-
out much reason.

Dark Drying OH may be made from the following ingredients : —
1 gallon linseed oiL
1 lb. red lead.
1 lb. umber.
1 lb. litharge.

The linseed oil is heated to about 200** Fahr. ; when it looks brown and
the scum is all burnt off the other substances are added ; the whole is then
raised to about 400° Fahr., and kept at that temperature for two or three
hours. The oil is then drawn off, the albuminous matter being allowed
to deposit, and is now clear and ready for use.

The umber is added simply to give the oil a dark colour.

Acetate of lead is sometimes used instead of the red lead and litharge, and
tends to make the oil lighter in tint^ A little resin is sometimes added.

Cheyrenil states that oil heated to 160° with ^ its weight of oxide of manganese has
powerful drying pToi>erties.'

Qood boiled oil spread in a film upon glass should be dry in from 12 to 24
hours,^ if raw it would take from 2 to 17 days, according to the atmosphere.^

Pale Drying OH may consist of 1 gallon of linseed oil mixed with about
7 lbs. litharge or acetate of lead, and raised to a moderate warmth.

Boiled Oil to be need with ssine paimt must be free from oxides of lead. About
5 per cent by weight of powdered peroxide of manganese is boiled in the oil
for five or six hours, llie mixture is then allowed to cool, and filtered.

Drying Oil for common work may be made by boiling 1^ lb. red lead in a
gallon of raw linseed oil, and allowing the mixture to settle.

Poppy Oil is extracted by pressure from the seeds of the common poppy. It shonld
be oolonrless, or of a very light yellow tinge, sweet, and free from smcdl. Being very
pale it is sometimes used for light tints, but though its colour stands longer than that of
linseed oil, it eventually becomes of a brownish hue, and in dryix^ and other qualities it
is far inferior to linseed oil.

Nut Oil is expressed from walnuts. It should be nearly colourless, and therefore
adapted for white and any light tints. It dries more rapidly than linseed oil, hut is not
durable, and is used only for common work, being cheap.

•* Oil of Turpentine,'' "j^ptrite of Turpentine, or Turps,** is an essential or
volatile oil, produced by distilling turpentine tapped from pines or larches.
The residuum left after distillation is common ronn,

1 Dent * Miller's Organie Chemistry,

' Proceedings Society qf Engineers, 1875. ^ Seddpn.

412 NOTES ON BUILDING CONSTRUCTION.

*' The best oil of turpentine comes from America."

'^ The gummy material known as Canada BaUam is produced by the Ptmti
CanadieiMU^ Venice Turpentine by the larch (Pintu lar%x\ and Frend^ Ticrpoi-
tine by the Pinvs maritima, which is extensively grown in the south of
France." i

Characteristics and Qualities, — Ordinary oil of turpentine has a specific
gravity of about '86 to -87, and boils at a temperature of 320" Fahr. If pure
it should completely distil over at this temperature.

'* On exposure to the air it oxidises, and is converted into a resinous sub-
stance."

'' When spread upon any surfiEuse in a thin layer, as is the case when used
for x)aint, it should dry in. 24 hours, leaving a hard dry varnish." ^

Qood spirits of turpentine is lighter in weight and more inflammable than
bad. It is colourless, and has a pleasant pungent smell, whereas the smell of
inferior qualities is disagreeable.

Qood spirits of turpentine should leave a very slight residue when era-
porated.

Spirits of turpentine is often adulterated with mineral oiL The purer
vegetable turpentine loses bulk by evaporation, and gains weight upon
exposure to the air ; the spirit from the mineral oil flies ofi*, leaving the oil
without any assistance in hardening.^

Turpentine sometimes contains pyroligneous acid, and is the better for
being kept and allowed to settle a long time before use.

Uses. — Spirits of turpentine is used as a solvent for resins and other sub-
stances in making varnishes ; also in paint to make it work more smoothly.
It is useful also in flatting coats (see Part II.}, but will not stand exposure to
the weather.

DRIEBa

Driers are substances added to paint in order to cause the oQ to thicken
and solidify more rapidly.

The action of these substances is not thoroughly understood. CheTreoil
has shown that the drying of linseed oil ib caused by the absorption of oxj-
gen, and there can be no doubt that for the most part driers act as cairien
of oxygen to the oil, a very small quantity producing considerable effects

The best driers are those whidi contain a large proportion of oxj^
such as litharge, acetate of lead, red lead, sulphate of zinc, verdigrifl^ etc.

They are sometimes used to improve the drying qualities of the oil vith
which the paint is mixed, as explained at page 410, or they may themselves
be ground up with a small quantity of oil and added to the paint just befon
it is used.

Iiitharge, or oxide of lead, is the drier most commonly used, and is pro-
duced in the oxidation of lead containing silver. It can be procured on a
small scale by scraping off the dross which forms on molten lead exposed to a
current of air. Massicot is a superior kind of litharge, being produced br
heating lead to an extent insufficient to fuse the oxide.

Sugar of Ijead {acetate of lead) ground in oil, and Copperas and White
vitriol (sulphate of zinc), are also used as driers, especially for light tints.

1 Dent ' Cresy's Encydopcddia,

COLOURING PIGMENTS FOR PAINTS, ETC. 413

Oxide of Manganese is quicker in its effects, but is of a veiy dark
colour, and seldom used except for deep tints.

Japannem' Gk>ld Size and Verdigris {acdaJte of copper) are also used for
dark colours. Care must be taken not to apply too much of the size, or it
will make the paint brittle.

Bed Ijead {oxide of lead) is often used as a drier when its colour will not
interfere with the tint required It ib not so rapid in its action as litharge or
massicot.

Sulphate of Manganese is the best drier for zinc white, about 6 or 8
ounces only being used for 1 cwt. of ground zinc paint. The manganese
should be mixed with a small quantity of the paint first, and then added to
the bulk. If great care be not taken in mixing the drier the work will be
spotted.^

Sulphate of Zino is also a good drier for zinc paint.

Patent Driers contain oxidising agents, such as litharge or acetate of lead,
ground and mixed in oil^ and therefore in a convenient form for immediate
use.

There is great danger, however, in using such driers, unless they are of the
best quality from a reliable maker. Some of the inferior descriptions depend
for their drying qualities upon lime.

Terebine oonsiBts of a powerftil drier dissolved in spirits of taipentine ; it la used as a
sabstitate for patent and other driers, and is used in the proportion of 1 oz. to 1 lb. of
paint. Alone it will dry in about half an hour.

Xerotine Bicoative is a species of terebine, bnt differs from it in that when mixed
with oil the mixture does not become cloudy. The siccative becomes dangerously ex-
plosive when stored.

Freoautions in using Driers. — "The following points should be ob-
served in using driers : —

" lit Not to use them unnecessarily with pigments which dry well in oil
colour."

" 2d Not to employ them in excess, which would only retard the drying"
and tend to destroy the paint

^ 3(2. Not to add them to the colour until about to be used."

" 4tt% Not to use more than one drier to the same colour." *

COLOURING PIQMENTa

It IB unnecessary to give anything like a complete list of the pigments
used to produce the colours and tints used by the house painter and deco-
rator. A few of the most useful may, however, be mentioned.

It is not proposed to give a detailed description of them, but merely suf-
ficient to distinguish those that are injurious from the others.

Many of these colouring pigments, such as the ochres, umbers, etc, are
from natural earths ; others are artificially made.

They may generally be purchased either in the form of dry powder or
ground in oiL

Blacks. — Lampblack is the soot produced by burning oil, rosin, small coal,
resinous woods, coal tar, or tallow.

It is in the state of very fine powder ; works smoothly ; is of a dense

1 Dent ' Seddon.

414 NOTES ON BUILDING CONSTRUCTION

black colonr when dry, and durable, but dries badly in oU. It givea a grey-
ish black colour to paint, as compared with the deep hue produced by Teget-
able black of good quality.

Vbobtablb Black is a better kind of lampblack made from o£L It is very light, free
from grit, and of a good colour. It shonld be used with boiled oil, drien, and a little
varnish. Linseed oil or tnrpe keeps it from drying.^

IvoBT Black is obtained by calcining waste ivory in dote veeaela, and then grinding.
It is intensely black when properly bnmt.

BoNB Black is inferior to ivory black, and prepared in a similar manner from 'bonesw

Blub Black and Frakkfort Black of the best quality are made from vine twigs ; in-
ferior qnalities from other woods charred and reduced to powder.

Grant's Blaok, or Bideford Black, is a minersl substance found near BidefonL It
contains a laiige proportion of siliceous matter. It is denser than lampblack, bat has not
so much staining power.'

Blues. — Pbubsiak Blub is made by mixing pmssiate of potasli {Ferr^
cyanide of poUueivm) with a salt of iron. The prussiate of potash is obtained
by calcining and digesting old leather, blood, hoo£s, or other animal matter
with carbonate of potash and iron filings.

This pigment is much used, especially for dark blues, making purples^ and
intensifying black. It dries well with oil.

Slight differences in the manufacture cause considerable variation in tint and colour,
which leads to the material being known by different names — such as Antwerp Blue,
Berlin Blue, Haerlem Blue, Chinese Blue, etc

Indiqo is produced by steeping certain plants, from Asia and America, in
water, and allowing them to ferment

It is a transparent colour ; works well in oil or water, but is not durable,
especially when mixed with white lead.

Ui/TRAJfARnnt was originally made by grinding the valuable mineral Lt^ois laadK
Genuine ultramarine so made is very expensive, but artificial French and Oermaen
UUra/inarinee are made of better colour, and cheaply, by fusing and washing, and reheat-
ing, a mixture of soda, silica, alum, and sulphur.

It is used chiefly for colouring wall papers.

Cobalt Blub is an oxide of cobalt made by roasting cobalt ore. It is a beantiAil
pigment, and works well in water.

Smalt, Saxon Blub, and Rotal Blttb are coloured by oxides of cobalt.

Cblestial Blub, or Brunenoick Blue, and Damp Blub are chemical oompovmdt
(containing alum and other substances), which need not be described in detail.

Brbmbn Blub, or Verditer, is a compound of copper and lime of a greenish tint,

Blxtb Oohrb is a natural coloured day.

Tellowa. — Chromb Yellows are chromates of lead, produced by mixing
dilute solutions of acetate or nitrate of lead and bichromate of potash.

This makes a medium tint known as Middle chrome. The addition of sol-
phate of lead makes this paler, when it is known as Lemon dirome, whereas
the addition of caustic lime makes it Orange chrome of a darker colour.

The chromes mix well with oil and with white lead either in oil or water.
They stand the sun well, but, like other lead salts, become dark in bad air.

Chrome yellow is frequently adulterated with terra alba {gypium\

Naplbs Ybllow is a salt of lead and antimony, supposed to have been originally made
firom a natural volcanic product at Naples. It is not so brilliant as chrome, but has the
same characteristics, and is very difficult to grind.

* Davidson. " Dent.

COLOURING PIGMENTS FOR PAINTS, ETC. 415

Kino's Ybllow is made from arsenic, and \m therefore a dangerous pigment to oae in
internal work. It is not durable, and injures several other colours when mixed with
them. Chinese YelloWf Arsenic Yellow, and Yellow Orpiment are other names for
king's yellow,^

Turners, Cossets, Verona, Montpdlier, and Patent Ydlow are all ozychlorides of lead ;
Cadmium Ydlow a sulphide of cadmium. ^

Yellow Ochre is a natural clay coloured by oxide of iron, and found
abundantly in many parts of England.

It is not very brilliant, but is well suited for distemper work, as it is not
affected by light or air. It does not lose its colour when mixed with lime
as some other pigments do.

Spruce Ochbb is a variety of the above of a brownish-yellow colour.

Oxford Ochrb is of a warm yellow colour and soft texture, absorbent of both oil and
water.^

Stone Oohrb is found in the form of balls imbedded in the stone of the Cotswold
hills. It varies in tint from yellow to brown.

Terra db Sienna, or Baw Sienna, is also a day, stained with oxides of
iron and manganese, and of a dull yellow colour. It is durable both in oil
and water, and is useful in all work, especially in graining.

Yellow Lake is a pigment made from turmeric, alum, etc It is not durable, and
does not mix well with oil or metallic colours.^

Browns generally owe their colour to oxide of iron.

Raw Umber is a clay coloured by oxide of iron. The best comes from
Turkey.

It is very durable both in water and in oil ; does not injure other pig-
ments when mixed with them.

Burnt Umber is the last-mentioned pigment burnt to give it a darker
colour. It IB useful as a drier, and in mixing with white lead to make stone
colour.

Vandyke Brown is an earthy mineral pigment of dark-brown colour. It
is durable both in oil and in water, and is useful for graining.

Purple Brown is of a reddish-brown colour. It should be used with boiled
oil ; and a little varnish and driers for outside work.

Burnt Sienna is produced by burning raw sienna (see above). It is
" the best colour for shading gold."^

Brown Ochre is another name for spruce ochre (see above).

Spanish Brown is also an ochre.

Brown Pink is a vegetable pigment often of a greenish hue. It works well in water
and oil, but dries badly, and will not keep its colour when mixed with white lead.

Bistre is from wood or peat soot Vandyke Brown, Cassd Earth, Egyptian Brown are
bituminous earths. Asphaltum is bitumen, and Sepia comes from the cuttle fish. Light
Cappagh Brown or Euchrome and Deep Cappagh Brown or Mineral Brown are from bog
earth and manganese.''

Reds. — Carmine, made from the cochineal insect, is the most brilliant red
pigment known. It is, however, too expensive for ordinary house painting,
and is not durable. It is sometimes used for internal decoration.

1 Davidson. ^ Seddon.

4i6 NOTES ON BUILDING CONSTRUCTION

Red Lead has already been described (see p. 408). Ground by itself in
oil or varnish it forms a durable pigment, or it may be mixed with ochrea
White lead and metallic salts generally destroy its colour.

Vermilion ib a sulphide of mercury found in a natural state as Oinnabar.
The best comes from China.

Artificial vermilion is also made both in China and on the Continent from
a mixture of sulphur and mercury.

Genuine vermilion is very durable, but this pigment is sometimes adul-
terated with red lead, etc, and then will not weather.

Tests, — ^Vermilion can be tested by heating it in a test tabe. If genuine it shoold
entirely volatilise.
Pure powdered vermilion crashed between sheets of paper should not change coloixr.
Antimony Vermilion (see p. 408).
Obbm AN Vbrxiijon Lb the tersnlphide of antimony and of an orange-red colour.

Indian Bed is a ground haematite ore brought from BengaL It is some-
times artificially made by calcining sulphate of iron. The tints vary, but a
rosy hue is considered the best

It may be used with turpentine and a little varnish to produce a dull sur-
face, drying rapidly, or with boiled oil and a little driers, in which case a
glossy surface will be produced, drying more slowly.

Chinbsb Red and Pbrsiak Red are chromates of lead, produced by boiling white
lead with a solution of bichromate of potash. The tint of Persian red is ohtained by the
employment of sulphuric acid. These paints are much used for painting pillar post
boxes. ^

Light Red ia a burnt ochre. It shares the characteristics of raw ochres described
at p. 415.

VBinrriAN Red is obtained by heating sulphate of iron produced as a waste product
at tin and copper works. It is often adulterated by mixing sulphate of lime with it
during the manufacture. When pure it is known as Bright Med.*

"Special tints of purple and brown are frequently required which greatly enhance the
yalue of the material. These tints should be obtained in the process of manufacture, and
not produced by mixing together a variety of diflferent shades of colour. When the tint
desired is attempted to be obtained by this latter course it is neyer so good, and the pig-
ments produced are known in the trade as ' faced colours,' and are of inferior value.'* ^

Rose Pink is a chalk or whiting stained with a tincture of Brazil wood. It fades
very quickly, but is used for paperhangings, common distemper, and for staining cheap
furniture.

Dutch Pink is a similar substance made from quercitron bark.'

Iiakes are made by precipitating coloured v^table tinctures by means of
alum and carbonate of potash. The alumina combines with the organic
colouring matter and separates it from the solution.^

The tincture used varies in the different descriptions of lake. The best,
made from cochineal or madder, is very expensive.

The colour is not a durable one, and dries slowly. It mixes well with
white lead, and is used for internal work.

Dbop Lake is made by dropping a mixture of Brazil wood through a funnel on to a
slab. The drops are dried and mixed into paste with gum water. It is sometimes
called BrazU Wood Lake.

Scarlet Lake is made from cochineal, and so are Florentine Lake, ffamburg Lake,
Chinese Lake, Roman Lake, Venetian Lake, and CarmintUed Lake,

» Dent • Seddon. » Ure.

COLOURING PIGMENTS FOR PAINTS, ETC, 417

Oranges — Chrome ORA^'QE is a chromate of lead, brighter than ver-
milion, but less durable.

Orakqb Ochrb is a bright yellow ochre burnt to give it warmth of tint. It dries
and works well in water and oil, and is very durable. ^ It is known also as SipanisK Ochre.

Mabb Orange is also an ochre.

Obanob Rbd is produced by a further oxidation than is required for red lead. It
is a brighter and better pigment^

Qreens may of course be made by mixing blue and yellow pigments, but
such mixtures are less durable than those produced direct from copper,
arsenic, etc. The latter are, however, very objectionable for use in distemper,
or on wall papers, etc, as they are injurious to health.

Brunswick Grbbn of the best kind is made by treating copper with sal-ammoniac.
Chalk, lead, and alum are sometimes added. It has rather a bluish tinge ; dries well
in oil, is durable, and not poisonous.

Ordinary Brunswick green is made by mixing chromate of lead and Prussian blue
with sulphate of baryta.

MiNBRAL Green is made from bi-basic carbonate of copper. It weathers well.

Verdigris is acetate of copper. It furnishes a bluish-green colour, durable in oil
or varnish, but not in water. It dries rapidly, but is not a safe pigment to use.^

Green Verditer is a carbonate of copper and lime.

Prussian Green is made by mixing different substances with Prussian blue.

There are several other greens made from copper, such as Brighton Green, MaUichite.
Mountain Oreen, Marine Oreen, Saxon, African, French Oreena, Patent Green, etc. etc.

Emerald Green is made of verdigiis mixed with a solution of arsenious acid. It
is of a very brilliant colour, but is very poisonous, is difficult to grind, and dries badly
in oil. It should be purchased ready ground in oil, in which case the poisonous par-
ticles do not fly about, and the difficulty of grinding is avoided.'

Scheele's or Mitis-Green and Vienna Green are also arsenites of copper, and highly
poisonous.

Chrome Green should be made from the oxide of chromium, and is very durable.

An inferior chrome green is made, however, by mixing chromate of lead and Prussian
blue as above mentioned, and is called Brunswick green.

The chrome should be free from acid, or the colour will fade. It may be tested by
placing it for several days in strong sunlight

Terrs Verte is a natural coloured clay.

RiNMAN*s Green is composed of cobalt and ferrous oxide of zina

Uses of Pigments. — The uses for which the pigments above mentioned
are suitable may be classified as follows — *

(o). More or less transparent, and fit for graining and finishing, — Blacks
(except mineral black and Indian ink), umbers, chrome greens, cadmium
yellow, raw and burnt sienna, ochre, French ultramarine, mars orange, bistre
and the bituminous browns, sepia.

(b). Little if at all affected by heat or fire. — Whites, ochres, or natural clays.

(c). Fit for fresco or distemper work. — ^Whites from sulphate of baryta or car-
bonate or sulphate of lime, all the ochres, the reds, bJues, browns, and blacks.
{d). Injured by damp and impure air, especially sulphuretted hydrogen, unfit
to use in distemper. — White lead, all the yellows except the ochres, red lead,
Chinese and Persian lead, Prussian and cobalt blues, orange salts of lead,
and all greens.

(«). Fade in strong ligJits. — All vegetable colours more or less — including
the yellows — Prussian blue, indigo, the peaty browns, and in less degrees the
madders.*

^ Davidson. * Dent.

• The Paperhanger's, Painter*8, and Deeoraior's Assistant.

* Modified from a table in Seddon's Builders Work, * Uro,

B. C. III. 2 E

4i8 NOTES ON BUILDING CONSTRUCTION

PROPORTIONS OF INGREDIENTS IN MIXED PAINTS.

The exact proportions of the ingredients to be naed in mixing points tstt
considerably according to circumstances.

The composition of paints should be governed bj the fMlyKre of ihe matmal
to he painted. Thus the paints respectively best adapted for protecting wocd
and iron differ considerably. The kind of ntrface to he covered^ i^ a porous
surface, requires more oil than one that is impervious. The nature and ap-
pearance of the tpork to he done. Delicate tints require colourless oil ; a flattal
surface must be painted without oil, which gives gloss to a shining sai&ee.
Again, paint used for surfaces to be varnished must contain a minimnm of
oil (see p. 433X The climaUy and the degree of escpomre to whicfi the vork wiU
be subjected; thus for outside work boiled oil is used, because it weathcR
better than raw oil Turps is avoided as much as possible, because it evapor-
ates and does not last ; if^ however, the work is to be exposed to the sim,
turps are necessary to prevent the paint from blistering. The ekiU of tkt
painter also affects the composition ; a good workman can lay on even costs
with a smaller quantity of oil and turps than a man who is unskilful ; extn
turps, especially, are often added to save labour. The quality of ihs materials
makes an important difference in the proportions used Thus more oil i&d
turps will combine with pure, than with impure white lead ; thick oil miist
be used in greater quantity than thin oil. When paint is purchased retdv
ground in oil, a soft paste will require less turps and oil for thinning than a
thick paste. Lastly, the different coats of paint vary in their composition :
the first coat laid on to new work requires a good deal of oil to soak into the
material; on old work the first coat requires turps to make it adhere; the
intermediate coats contain a proportion of turps to make them work smooth!?,
and to the final coats the colouring pigment is added, the remainder of the
ingredients being varied as already described, according as the surface is to
be glossy or flatted.

Lead Faint. — Ordinary white paint is generally composed of white lead,
linseed oil, driers, and spirits of turpentine.

A coloured lead paint is produced by adding a pigment to the above.

In the mixture each constituent plays a part.

The oil soaks into the pores of the material painted, and then dries into a
resinous compound, keeping out the air, and preventing decay.

The drier causes the oil to oxidise and solidify more quickly.

The white lead gives body and opacity to the mixture. It does not merely
mix with the oil, but combines with it to form a creamy compound wkicb
dries into a soapy substance.

The spirit of turpentine is merely a solvent added to make the paint work
more freely ; it eventually evaporates and plays no permanent part.

Proportions of Ingredients. — The exact proportion of the ingredients
best to be used in mixing paints varies according to their quality, the nature
of the work required, the climate, and other considerations.

The composition of the paint for the different coats also varies considerably.

The proportions givep below must therefore only be taken as an approii-
mate guide when the materials are of good quality : —

PROPORTIONS OF INGREDIENTS IN MIXED PAINTS. 419

Tablb showing the Composition of the different Coats of White Paint, and
the Quantities required to cover 100 Square Yards of New Wrought
Deal

1
1

Remarks.

iNsiDB Work.

i coats not flatted.

LiM.

Lbs.

Pints.

Pinta.

Pinto.

LDe.

Priming .

...

Sometimes more
red lead is used,
and less drier.

2d coat .

•

...

* Sometimes just
enough red lead
to give a flesh-
coloured tint

Sdooat .

4th coat .

...

Inside Wobk.

icoatsand

flatting.

Priming .

Some palnten
make these coats

2d coat .

...

of the same com-
position as those

Sdcoat .

...

for non- flatted
work*

4th coat .

...

putting .

...

Outside Wokk.

4 eoata not flatted.

Priming .

...

colour is not to

2d coat .

...

be pure white» it
is better to have

Sdcoat .

...

nearly aU the oil
boUed oU. AU

4th coat .

boiled oil does
not work well
For pure white a
larger proportion
of raw oil is ne-
cessary, because
boUed oil is too
dark.

For every 100 sqnare yards, besides the materials enumerated above, 2} Iha. white
lead and 5 lbs. patty will be required for stopping (see Part II. p. 418).

420 NOTES ON BUILDING CONSTRUCTION.

The area which a given quantity of paint will cover depends npon the natnie of tbf
surface to which it is applied, the proportion of the ingredients, and the state of the
weather.

When the work is required to dry quickly, more turpentine is added to all
the coats.

In repaintiiig old work, the surface (after the necessary preparation, see Fart
II.) is considered as if it were primed. Only two more coats are geneiallr
applied, of which the first is called the second colouring ; a fourth coat k
seldom required. The second and third coats contain equal parts of oil and
turps ; all the remaining ingredients are as shown in the Table above.

For outside toork exposed to the sun, the second and third coats each contain 1
pint turpentine and 4 pints of boiled oil, the remaining ingredients being as
stated in the Table. The extra turpentine is introduced to prevent blisterii^;.

In cold wecUher more tuips is used to make the paint work freely.

Whitb Lead Paint. — Good paint of this description should be
made of pure white lead. If it is to be untinted, care must be
taken to exclude any substance which will detract from the
brightness of the white, and it must be kept in closed vessels, or
the action of the air will give it a brown shade.

Uses, Advantages, and Disadvanta^ges. — White lead paint itself,
and also as a basis for coloured paints, is one of the commonest
and best protecting coverings that can be applied to surfaces of
wood. Where it is exposed, however, to the fumes of sulphur acids,
such as^ are evolved from decaying animal matter, in laboratories,
and in some manufacturing towns, it soon becomes darkened by
the /ormisition of black sulphide of lead. It has also the disad-
vantage of producing numbness and painters' colic in those who
use it

Coloured Lead Paints are made by adding to a basis of white
lead paint certain stainers or colouring pigments described ^
p. 413.

These pigments should be separately ground in oil, and small
portions carefully added to the last two coats that are applit<
until the required colour is obtained.

A list of some of the pigments used to produce different tin:^
ifi given at page 422.

It is better to ascertain the proportion required by experi-
menting at first upon a small sample.

Where the colour is very deep, the amount of pigment becomes yery ^
in proportion to the white lead ; and in some cases, as in very common blK^
paint, the white lead is omitted altogether, to the great detriment of the pro-
tecting qualitiea of the paint.

LEAD AND ZINC PAINTS. 421

Mixing Lead Paint. — Dry white lead is ground by macliinery
iu oil for general paints. But for hard colours and filling up
compositions it is ground in turps with a portion of Japan gold
size or varnish added to bind it.

The paste is softened and made smooth by adding a small
quantity of oil and turps, and working it well with a palette
knife.

The colouring pigments, if any, are then added, and the paint
is brought to the consistency of cream by adding more oil and
turps.

It is then cleared by passing it through a canvas or tin
strainer.

When about to be used, the paint is thinned to the consistency
necessary to enable it to work freely, by adding more oil and
turps, called thinnings, and the driers are also added.

If the paint is too thick, it will be difficult to work, and will
make an uneven surface. If too thin, it will not have body
enough, and more coats will be required.

As the paint becomes thicker during use, or when put upon
one side for a time, it will require further thinning, and perhaps
repeated straining to clear it from skin and dirt

To prevent mixed paints from " skinning over," or drying up,
they should be kept constantly covered with w^ater or with a thin
film of linseed oiL

Injurious Effect of Lead Paint. — Lead paint produces most
injurious effects upon those who use it.

Entering the pores of the skin, it is absorbed by the system,
and leads to numbness and a kind of paralysis. It also produces
a complaint known as " painters' colic."

Zino Paint, ordinarily so called, is made with oxide of zinc (see
p. 409), instead of white lead, as a basis.

Characteristics and Uses. — Zinc white does not combine with
oil so readily as white lead. Its covering properties are therefore
inferior, and it talces a long time to harden.

It is acted upon by the carbonic acid in rain water, which dis-
solves the oxide, and it therefor^ weathers badly.

The acids contained in unseasoned wood have a great effect

upon iL^

^ D«ut.

422 NOTES ON BUILDING CONSTRUCTION.

Zinc paint may be used without fear of painteis' paialyais, and
as it has uo smell, places in which it has been used may be occu-
pied directly it is dry.

" Zinc white paint when pure retains its colour well, and will
stand washing for several years without losing any of its fresh-
ness. When dry it becomes very hard, and will take a fine
polisL"*

This paint is suitable in large manufacturing towns where it is
subjected to vapouis containing sulphur, or in places where foul
air is emanated from decaying animal matter. The zinc is sot
(Hke white lead) blackened by exposure to sulphuretted hydrogen.

In such positions of course zinc paint should not be mixed
with * patent" or other driers which contain lead. The best
driers to be used with it are sulphate of manganese and sulphate
of zinc (see p. 398).

Zinc white is recommended as being preferable to white lead
for painting on a dark ground. The reason for this is that
the soap formed by the combination of the lead and oil in lead
paints is semi-transparent, and the dark ground shows through it
Another form of zinc paint is described at page 424.

Coloured Faints. — It has already been mentioned that culoured kid
paints are produced by adding a suitable pigment to a white lead pti&t
until the required tint is obtained.

It would of course be impossible to give instructions for the compositioii of
the great variety of colours and tints in which paint may be required.

A few, however, of the most common tints produced by mixing two or
more colours may be mentioned.

The colours used are generally divided into classes as follows : —

Cbmmofi Ooloun^ including greys, bufib, and stone colours.

Superior J or Fine Coloun, such as bright yellows, warm tints, cloud cobnis.
and common greens.

DelieaU tintty such as blue verditer, pea-greens, pinks, etc

The following list shows the pigments that may be added to white leaJ
paint * to produce a few of the most frequently used compound ooloura

The same pigments, except those containing lead, may be used with a zinc-
white basis for coloured zinc paints.

PlOMXMTB FOR Ck>LOURBD PAIVn.

Common Colours : — StoM Colour. — ^Bumt umber.

Raw umber.
Yellow ochre.
Drabs. — Burnt umber.

Burnt umber and yellow ochre for a warm tint

1 SeddoiL " Or to white distemper ; see p. 254.

SPECIAL PAINTS. 423

BvffK — Yellow ochre.

Yellow „ and Venetian red.
Oftfyg. — Lampblack.

Indian red — indigo — for a warm sbade.
Egyptian blue— or French ultramarine — and
vermilion — for a warm shade,
firoimt. — Burnt sienna, indigo.

LakeyPnissian blue (or indigo) and yellow ochre.
StPEKroR CoLOUBS .' — Tis/^oto^. ^Ohrome yellow.

Chnm. — Prussian blue, chrome yellow.

Indigo, burnt sienna (or raw umber).
Prussian blue, raw umber.
Avoid arsenical greens.
SaLvMm. — ^Venetian red.
Vermilion.
F(EUOM. — Stone ochre and vermilion.
Delicate Tints : — Bk^-hlut. — Prussian blue.

Pea-gretn, — Brunswick green.
French „

Prussian blue, chrome yjsUow.

SPECIAL PAINTS.

During the last few years a great many substances Lave been
proposed as bases for paint instead of white lead.

llie paints made with these substances are called by special
names, and often have peculiar qualities which adapt them for
use under particular circumstances.

It would be almost impossible to give a complete list of all
these special paints, but it will be useful to mention a few of the
most prominent with their characteristics.

InodorouB Faint ^ is mixed without any turpentine, the evaporation of
which in ordinary paints causes a strong unpleasant smell, which in some
people produces headache, and even more injurious effects.

In this paint the ordinary white lead, or zinc white ground in oil, " in-
stead of being thinned with oil and turpentine, is mixed with methylated
spirit in which shellac has been dissolved, together with a small quantity of
linseed and castor oil"

^ This methylated spirit evaporates very rapidly, leaving behind the shellac,
which acts the part of the film of varnish left by the oil and turpentine in
the ordinary method of painting, protecting the wood or stone, and at the
same time attaching the pigment to the painted surface.**

This paint dries very rapidly. The second coat can be applied an hour
after the first, and three-coat work can be finished in one day. The rapid

* Uent.

424 AOTES ON BUILDING CONSTRUCTION.

drying makes it difficult to paint a large, uninteirupted surfaee^ witboat
showing marks where one portion dried before the next was commenced.

For interior work in occupied buildings this paint has rery great advan-
tages ; also where rapidity in execution is required, but it is not bo durable
as paint mixed in oil and turps.

'^ In oak graining it is desirable, perhaps better, that the Tamishii^ coat
should be put on as usual ; but in this case the odour arising from two eoau
of paint work is at all events avoided, and the whole is finished in a day,
insteatl of lasting over two or three days." ^

Freeman's "H'on- poisonous" White Iiead '*is prepared by grinding
under considerable pressure a precipitated sulphate of lead with 25 per cent
of zinc oxide, whereby the density of the mixture is greatly increased. This
preparation possesses the advantage of a very simple and unobjectionab>
method of manufacture and of keeping its colour better than ordinary white
lead when employed in situations exposed to air containing sulphur
compounds, such as in railway tunnels. It is equal to the ordinary
white lead in point of colour, and is reported to be so as regards ^body*
and durability,' but this last point can only be decided after the lapse of
sufficient time." ^

Charlton White is a mixture of sulphate of zinc with sulphate of baryta
or strontia. It is more pulverulent than zinc white, and more opaque.
Requires more oil than white lead, less than zinc white. Tested for body by
saturation with blue, it shows itself to be 60 per cent stronger than xinc
oxide and 30 per cent stronger than genuine* white lead. It must be nseJ
with lead, less direct, and is not affected by sulphurous vapours. In ontdc-oT
work it must be ^^ bound " by varnish, and in all cases it is perfectly harmlest
to makers or users.

Charlton Enamels are preparations of Cliarlton white, and gums, which dry
with a smooth hard surface and do not crack or blister.

Duresco is a preparation of Charlton white worked up by a process whicL
is a secret It dries out perfectly " flatt," is quite solid, washable^ and non-
poisonous, is much less expensive than oil paints, and more easily applied ; all
this makes it peculiarly valuable to internal wall decoration.

A patent White Sulphide of Zinc Paint is manufactured at Liverpool by the
Sanitary Paint Co., which consists of a mixture of sulphate of zinc and
sulphate of baryta. . . . This paint when not properly manufactured has
sometimes been found to become discoloured under the influence of strong
sunlight, the dark tinge which it assumes passing off again after a fev
hours." 2

Griffith's Patent White Paint is a form of zinc paint which has
recently been introduced. Its basis, oxy-sulphide of zinc (see p. 409), is saiil
to be cheaper than white lead. It has 25 per cent more covering power for
the same weight, is not poisonous, is more stable, is of a brilliant white
colour, dense, and opaque ; does not blister of[ yield to heat or gas, is not
discoloured by sulphui'etted hydrogen, is neutral towards iron, and will mix
with colours which white lead destroys.

Alharine is a white enamel which is found to be very superior as regard*
hardness, enamel-like appearance, whiteness, and easy application ; one gallon
will cover on an average 60 yards.

^ Dent. ' Dent's Cojttor Ledurt^

SPECIAL PAINTS. 425

Oxide of Iron Paints. — In these oxide of iron (see p. 409) forms the
basia They are free from injurious ingredients such as those of lead paints.
For painting iron work they are said to be particularly suitable, on the
ground that they do not set up any galvanic action such as is supposed to
take place between lead paints and iron snrfaces. It is very doubtful,
however, whether any such galvanic action exists. When the surface of the
iron is rusty, the rust becomes incorporated with the paint.

The paint must, however, be made from the sesquioxide or red oxide of
iron. If made from the protoxide it is liable to rust in itself.^

The cost of good oxide of iron paints is about the same as that of lead
paints, but in application they are cheaper, as weight for weight they cover a
greater surface.

1 lb. oxide of iron paint mixed in the proportion of § oxide to \ linseed
oil should cover 2 1 square yards of sheet iron.^

To ensure this power of covering a large area with a small quantity of
paint, the ingredients should be reduced to an impalpable powder before they
are mixed with the oiL They are ground for seven or eight hours.

" When mixed with about one-third of wliite lead they form a very hard
mastic similar to that made from red lead/' ^

ToRBAY Paint is produced from a brown hcematite iron ore found in
Devonshire. It contains from 50 to 65 per cent oxide of iron, the remainder
being siliceous matter.

The colour of the oxide varies from yellowish brown to red and black.

Blue, green, and other tints are produced by adding pigments which are
not oxides of iron, and which therefore alter the composition of the paint.

This paint has been in use for many years, it is especially suitable for
painting iron work, and has borne a high character for durability under
exposure to weather and fumes of manufactories.

An official report, quoted in the Manufacturers' Circular, says that "62
lbs. of the Torbay iron paint effectually cover as much surface as 1 1 2 lbs. of
either white or red lead paint"

There are several inferior imitations of this paint. A great deal of the
so-called Torbay paint is, however, nothing more than sulphate of baryta
coloured with oxide of iron, whereas sulphate of baryta is never found in the
genuine paint in any appreciable quantity.

Black Oxide of Iron Paint is made from the oxide obtained as a bye
product in making dyes, ground in oil with about 15 per cent of terra
alba, Paris white, or sulphate of baryta. It is said that without the
addition of these substances the oxide of iron would set with the oil into a
solid mass.

This paint is used for painting shot and shell.

Pulford's Magnetic Paint is made from the magnetic or black oxide of
iron.

Purple Brown Oxide is a hydrated peroxide of iron used as a basis for
paint.

Silicate Oxide Paint is prepared from an iron ore in Devonshire by
the Silicate Oxide Paint Company in three colours only — yellow, red,
and black. It contains more oxide of iron and less siliceous matter than
the Torbay paint.

* Proc Society of Engineers, 1875. • Seddon.

426 NOTES ON BUILDING CONSTRUCTION.

Titanic Paint is made by powdering a black iron ore, which contains oxide
of iron and oxide of titanium in nearly equal proportions, mixed with other
ores. It is said to harden without the aid of a drier, and to be portieiilarlY
well adapted for withstanding heat.^

Anti-CorroBion Paint is a name given to different compositions, which
consist chiefly of oil, some strong driers, and a pigment mixed with very fine
sand.

They are sold dry, and require only to be mixed, not ground with oiL

They are used chiefly for external work, " lasting longer than white lead
and costing less."

^ The original makers of this paint are Messrs. Walter Carson and Sons,
and if genuine, as supplied by this firm, it should consist of ground glass and
white lead in about equal proportions.

*^ The rubbish which is frequently sold as anti-corrosion has greatly injured
the reputation which this paint at one time possessed. It can be obtained as
low as 6s. per cwt, whilst the price of the genuine is from 22b. to 24a. It
is not at all uncommon to find anti-corrosion containing from 35 to 45 per
cent of sulphate of baryta, a substance which I am assured is never employed
by the original makers." ^

'' An anti-corrosive paint is also made of equal proportions of whiting and
white lead, with half the quantity of sand, dust, and any required colonring
matter. Being mixed with water, it can be used as a water colour, bat is
generally applied as an oil paint, the best oil for the purpose being 1 boiled
to 12 of raw linseed and 3 of sulphate of lime, all by weight One gallon of
the oil will take 7 lbs. of the paint" *

Enamel Paint consists of a metallic oxide, such as oxide of zinc or oxide
of lead, ground with a small quantity of oil, and mixed with petroleum spirit
holding resinous matter in solution.^

This paint can be prepared to dry either with a firm glossy surfEioe, like
porcelain, or with the appearance of an ordinary flatted coat

It can be made in any colour or tint, however delicate ; requires no oil,
turpentine, driers, griuding, or mixing, as it is sent out ready for use.

It is about the same price as ordinary paint, but two coats of it are said
to be sufficient

This paint has been extensively employed in the metropolis, and is said
to be particularly suitable for surfaces required to be hard and wadiable ;
also for those exposed to the action of steam, acids, or alkalies, or to the
fumes of gas (see Silicate Enamel Paint, p. 427).

Indestructible Paint is similar to enamel paint in composition and
characteristics, except that it contains bitumen and is made in three colonic
only — viz. bronze-green, chocolate, and black.

Gay's Impenetrable Paint dries quickly with hard enamel face, is very
durable, smells less than ordinary paint, and is said to resist heat and damp
tetter. It is supplied ready for use, and is familiar to all as the covering
used for the post pillar boxes.

Silicate Paints, made by the Silicate Paint Company, have for their basis
a very pure silica obtained from a natural deposit in the west of England.
This is levigated, calcined, and mixed with resinous substances.^

Dent ' Seddou. * Phipson, Intcniational Congitssa.

SPECIAL PAINTS. 427

These paints are stated to have no chemical action on metals, to stand
200" heat without blistering, to set quickly and dry with a hard surface, to
be indestructible, and, weight for weight, to cover double the surface as com-
pared with lead paint

This paint is sold in the same form as lead paints, and must be used with
special "silicate driersL"

" The silicate paints supplied by the Silicate Paint Company are highly
recommended by the architect of the London School Board for all internal
work where health and cleanliness are aimed at" ^

Oriffitli*8 Silicate Enamel Paint is stated in the patentee's circulrj to
possess the following characteristics among others : —

It is supplied ready for use ; forms hard enamelled surfaces ; prevents the
corrosion or oxidation of metal ; is proof against the penetration of damp ;
dries rapidly ; is not injured by gases, fumes, hot or cold water, soap, or dilute
acid ; requires no varnish.

One coat is sufficient for waterproofing, but two or more are required to
produce a highly -glazed surface. The bulk is about three times that of
ordinary paint for the same weight. On metal one gallon will cover 500
square feet ; the quantity required to cover other substances depends upon
the porosity of the material to be covered.

Silicate Oxide Paint is prepared from an ore in Devonshire in three colours
only — yellow, red, and black. It contains more oxide of iron and less siliceous
matter than the Torbay paint

BilicaU Alumina Paint is of the same description.

Wood's Compo Faints ^ are coloured varnishes rather than paints, and
very good for outdoor work, containing neither oil, turps, nor driers, and
drying rapidly with a bright gloss. They neither crack nor blister in the
sun, and one coat on bare iron, stone, or wood is equal to two of ordinary
paints." 1

aaerelmey's Compositions are of three kinds : — 1. Stone composition
(see p. 79). 2. Iron paints. 3. Liquid enamels.

The Iron Paints of several colours are sold in paste, ground in oil, or
in liquid. They are tough and elastic, and prevent or stop rust and
corrosion.

They dry in from 24 to 48 hours.

One pound of the paste will cover 4 square yards, and one pint of the
liquid 10 to 12 square yards. Two coats are generaDy sufficient

This paint was used for the iron roofs of the Houses of Parliament, and is
applicable to dry surfaces of iron or wood.

Szebblmby's Liquid Enamels are sold in a liquid state, and are applied
with a brush.

They dry in from two to four hours. 1 lb. covers about 4 square yards. ,
One coat is sufficient for iron, two are required for wood.

They can be applied to dry surfEUses of wood, iron, tin, whitewash, or
plaster.

Oranitio Paint is said by the manufacturers to be proof against heat, wet,
or frost ; to be more durable and cheaper than lead paints ; and to be
specially adapted for painting or making joints in iron work.

One cwt of the light colour will cover from 600 to 650 yards, and one

1 Seddon.

428 NOTES ON BUILDING CONSTRUCTION

cwt of the dark colour will cover firom 1000 to 1200 yards — one cwt on
wood, on stone or iron much more.^

The paint is sold in powder or ground in oil ; the latter only should be
used for flatting.^

Bituminous Faints are made from vegetable bitumen, asphalte, and
mineral pitches dissolved in paraffin, petroleum or naphtha, various oils, and
other substances.

They are also " largely made from the products of coal and oiher mineral
oils.

" They have various degrees of fineness, the cheapest kinds having a great
resemblance to tar, and they are admirably suited for painting the inside of
pipes, or for iron work fixed under water, such as bridge cylinders and sorew
pilea

*' The fine sorts, while possessing the same properties, give a smoother
surface, and can be used in ordinary situations, especially where water or
foul vapours have to be resisted.

''The price varies from 18s. to SOs. per cwt, and the paint is mixed for
use with specially prepared mineral oil.

" A paint made from bitumen dissolved in paraffin and linseed oils while
in a state of great heat, is said to possess special qualities of durability, in
that it can resist the action of ordinary detergents, and of all alkalies and
acids.

" When mixed ready for use this paint costs from 40& to 60a. per cwt,
according to colour and fineness." ^

A paint of this kind is also made by dissolving equal parts of asphalte
and resin in common turpentine.*

Champion^s Black Paint is a compound of lampblack, mineral matter, and
oil.

Tar Faint. — The paint successfully used for the canvas roof over the
tubes of the Britannia Bridge was composed as follows : — Coal tar, 9 gallons ;
slaked lime, 13 Iba ; turpentine or naphtha, 2 or 3 quarts — the whole being
dredged over with sand. Tlie addition of the quicklime is indispensable to
neutralise the free acid that exists in the tar.

A tar paint recommended by Mr. Hurst as the best protection for iron con-
sists of 1 gallon coal tar distilled to expel the watery vapour and naphtha, ami
afterwards mixed with \ pint naphtha and \ pint boiled oil.

Ordinary Tarring. — Boil 6 gallons Coal Tar with 1 lb. resin, 1 lb. pitch,
and apply hot ; or use Stockholm Tar, with the same proportion of pitch onlj.
Yellow ochre may be added to give a brown tinge.

Silicate Zoppisa, sold by the Granitic Paint Company, is a washable dis-
temper made in all colours ; it is said to dry hard and flat, and to render the
surface to which it is applied damp-proof and durable.^

Asbestos Paints are much used for internal rough woodwork, which tbey
will protect against sparks or light flames, but they cannot stand the weather.
They are, as a rule, mixed with oil in two coats, and are thinned when
necessary with warm water.

One gallon will cover 150 feet two coats.

* Circular. • Seddon.

' Matheson. ' Davidson.

VARNISH, 429

Aiiiedo$ OH Paiwts are also made, and it is claimed that their covering
power is greater than that of ordinary lead or zinc paints.

One cwt in fact when thinned will cover 600 square yards. One cwt
sent out ready for use will cover 480 square yards.

Oreas^s AntiwaJUr Enamel Faint for iron is a sort of silico-calcic cement.
It adheres to iron fairly weU, especially when the iron is nearly always sub-
merged in water.

Crease's Anticorrosion is a black bitumen paint useful for coating submerged
iron surfacea

Granulated Cork Paint is applied over paint to protect and roughen
surfaces upon which the condensed moisture of the atmosphere is likely to
deposit, such, for example, as the asphalte floors of cellars, paved ceilings and
the girders supporting them.

Coating floors. — For asphalte floors the composition is made and applied as
follows : — 4 parts (by weight) of Venetian red and 1 part of red lead are
mixed into a stiff paste with Stockholm tar and well worked together. It is
then laid on the surface of the asphalte about ^ inch thick, and f of the
granulated cork is sprinkled over the paint and pressed in with a float In
about 48 hours the composition is hard, and the loose cork can be brushed
oK As the granulated surface will not withstand wear, it must be protected
by open boardings or by gratings.

For surfaces overhead, such as slabs or iron girders, ordinary red lead paint
13 used as a matrix for the granulated cork, which is forced into it and then
painted over.

Coating Iron, — (1.) The surface of the iron is prepared and coated with two
coats of i-ed lead or oxide of iron paint (2.) An adhesive composition com-
posed of the ingredients mentioned below is then applied rather more thickly
than ordinary paint, and well sprinkled with granulated cork. (3.) After 4
days a coat of white zinc paint much thinner than ordinary paint is applied,
then one coat of distemper.

Froportums of adhesive composition to make 112 lbs : —

White lead, 22 lbs. ; driers, 10^ lbs. ; boiled oil, 3| gallons ;
sperm yellow, 44 lbs. ; resin, 2^ lbs.
Liuninous Faint is a preparation of sulphide of calcium made up with
varnish. Oil destroys its properties, and care should be taken to apply it
only to perfectly clean surfaces free from lead paint or corrosion.

The characteristic of this paint in presenting a luminous surface for
many hours or even days after the source of light has been cut oft' is well
known, and it is ca])able of various obviously useful applications.

The action is supposed to be due to *' molecular vibration set up in the
body by waves of light rich in actinic rays, which vibration is maintained in
the dark, and is the cause of luminosity so long as the energy remains active
and not absorbed."

VAENISH.

Varnish is a solution of resin in either oil, turpentine, or
alcohol.

The oil dries and the other two solvents evaporate, in either

430 NOTES ON BUILDING CONSTRUCTION.

case leaving a solid transparent film of resin over the surface var-
nished.

In estimating the quality of a varnish the following points
must be considered: — 1. Quickness in drying; 2. Hardness of
film or coating ; 3. Toughness of film ; 4. Amount of gloss ; 3.
Permanence of gloss of film ; and 6. Durability on exposure to
weather.*

The quality of a varnish depends almost entirely upon that of
the ingredients it contains.

Much skill is, however, required in rniYing and boiling the
ingredients together.

Uses. — Varnish is used to give brilliancy to painted suifaoea
and to protect them from the action of the atmosphere, or from
slight friction.

Yamish is often applied to plain unpainted wood surfaces in
the roofs, joinery, and fittings of houses, and to intensify and
brighten the ornamental appearance of the grain. It is also
applied to painted and to papered walls.

In the former case it is sometimes flatted so as to give a dead
appearance, similar to that of a flatted coat of paint.

INGREDIENTS OF VABNISa

The Owm* aie exudations from trees. At first they are generally mixed
with some essential oil. They are then soft and viscous, and are known u
BdUams ; the oil evaporates and leaves the iZenn, which is solid and brittle.

Begins are often called ^ gufM " in practice, but a gum^ properly speaking, ib
soluble in water, and therefore unfit for varnishes, while resitu dissolve only
in spirits or oiL*

Oum BttvM are a natural mixture of gum with resin, and sometimes with
essential oil found in the milky juices of plants. When rubbed up with
water the gum is dissolved, and the oil and resin remain suspended.

Beslns. — ^The quality of the resin greatly influences that of the vaniisb.
The softer varieties dissolve more readily than the others, but are not so hud,
tough, or durable.

CoiocoN Rosin or Colophtmy is either brown or white. The brown vaiietf
is obtained by distilliDg the turpentine of spruce fir in water ; the white is
distilled from Bordeaux turpentine.

The principal resins used in good work are as follows : —

Amber, obtained chiefly from Prussia, is a light yellow transparent tsah-
stance found between beds of wood coal, or, after storms, on the coasts of the
Baltic It is the hardest and most durable of the gums, keeps its colour well
and is tough, but difScult to dissolve, costly, and slow in dr3ring.

> Dent ' Seddon.

INGREDIENTS OF VARNISH, 43'

Gum Anim^ is imported from the East Indies ; is Dearly as insoluble, hard,
and durable as amber, but not so tough^ It makes a varnish quick in drying,
but apt to crack, and the colour deepens by exposure.

Copal is imported from the East and West Indies and America, etc., in
three qualities, according to colour, the palest being kept for the highest class
of Tarnish. These become lighter by exposure.

Mastic is a resinous gum from the Mediterranean ; it is soft and works

QuM Dammar is extracted from the Kawrie pine of New Zealand, and also
from India. It makes a softer varnish than mastic, and the tint is nearly
colourless.

Gum Elbmi comes from the West Indies, and somewhat resembles copal.

Lac is a resinous substance which exudes from several trees found in the
East Indies. It is more soluble than the gums above mentioned.

Stick Lac consists of the twigs covered with the gum. Sui Lac is the
insoluble portion left after pounding and digesting stick lac. When seed lac
is melted, strainedy and compressed into sheets, it becomes SheU Lac. Of
these three varieties shell lac is the softest, palest, and purest, and it is there-
fore used for making lacquers.

Sandarach is a substance said to exude from the juniper tree. It resembles
lac, but is softer, less brilliant, and lighter in colour, and is used for pale
varnish.

Dragon's Blood is a resinous substance imported from various places in
dark brown-red lumps, in bright red powder, and in other forms. It is used
chiefly for colouring varnishes and lacqners.

Solvents. — These must be suited to the description of gum they are to
dissolve.

BoiLiHO LmrsEED Oil (and sometimes other oils, such as rosemary) is used
to dissolve amber, gum anim^, or copaL

TuRFSNTiNB for mastlc, dammar, and common resin.

MxTHYLATBD SPIRITS OF WiNB ^ for lac and sandarach.

Wood Naphtha is frequently used for cheap varnishes. '* It dissolves the
resins more readily than ordinary q>irits of mne, but the varnish is less bril-
liant, and the smell of the naphtha is very offensive. It is therefore never
employed for the best work.'

Driers are generally added to varnish in the form of LUhargty S%tgar of
Leadf or WkiU Oopperas,

The sugar of lead not only hardens but combines with the varnish.

A large proportion of driers injures the durability of the varnish, though it
causes it to dry more quickly.

DIFFERENT KINDS OF VARNISH.

Varnishes are classified as oil varnish, turpentine varnish, spirit varnish, or
water varnish, according to the solvent used. They are generally called by
the name of the gum dissolved in them.

Oil VamisheSy made from the hardest gums (amber, gam

* Spirits of wine to which a little wood naphtha has been added to make it undrink-
mble, and therefore not liable to duty. ' HoltxapffeL

432 NOTES ON BUILDING CONSTRUCTION

anim^, and copal) dissolved in oil, require some time to diy, but
are the hardest and most durable of all varnishes. They are
specially adapted for work exposed to the weather, and for such
as requires polishing or frequent cleaning. They are used for
coaches, japan work, for the best joinery and fittings of houses,
and for all outside work.

Turpentine Vamiahes are also ma^e from soft gums (mastic,
dammar, common resin) dissolved in the best turpentine. They
are cheaper, more flexible, dry more quickly, and are lighter in
colour than oil varnishes, but are not so tough or durabla

Spirit Varnishes or Laoquers are made with softer gums (lac
and sandarach) dissolved in spirits of wine or pyroligneous spirit
They dry more quickly, and become harder and more brilliant than
turpentine varnishes, but are apt to crack and scale off, and are
used for cabinet and other work not exposed to the weather.

Water Vamiahes consist of lac dissolved in hot water, mixed
with just so much ammonia, borax, potash, or soda» as will dissolve
the lac. The solution makes a varnish which will just bear wash-
ing. The alkalis darken the colour of the lac.

Mixing Varnishes requires great skill and care. Full details of the pro-
cess are given in Holtzapffers ManipiUation and other worksi

Space does not pennit here of more than the mention of one or two pointi
that may be useful in mixing vaniisbes on a small scale: As a rule, it u
better to buy varnish ready mixed when possible.

Mixing Oil Varmishbs. — The gum must first be melted alone till it i!
quite fluid, and then the clarified oil is poured in very slowly. The mixture
must be kept over a strong fire until a drop pinched between the finger wi
thumb will, on separating them, draw out into filamenta The pot is then
put upon a bed of hot ashes and left for 15 or 20 minutes, after which the
turpentine is poured in, being carefully stirred near the surface: The mixtnie
is finally strained into jars and left to settle.

Copal varnishes should be made at least three months before use ; the
longer they are kept the better they become. When it is necessary to use
the varnishes before they are of sufficient age, they should be left thicker
than usual. ^

The. more thoroughly the gum is fused, the stronger the varnish and tbe
greater the quantity.

The longer and more r^ular the boiling, the more fluid the varnish.

If brought to the stringy state too quickly more turpentine will be reqmRil,
which makes the varnish less durable.

Mixing Spirit and Turpentine Varnishes simply consists in stirring or
otherwise agitating the resins and solvent together. The agitation must be
continued till the resin is all dissolved, or it will agglutinate into lumps.
Heat is not necessary, but is sometimes used to hasten the solution of the
resin. The vanish is allowed to settle, and is then strained through muflliiL

> HoltzapfieL

RECIPES FOR VARNISHES. 433

Mixing Turpentine VoimUhee. — In many cases the resin, such as mastic,
dammar, or common resin, is simply mixed with turpentine alone, cold or
with slight heat. CSare must in such cases be taken to exclude all oiL

Application of Varnish — In using varnish great care should be taken to
have everything quite clean, the cans should be kept corked, the brushes free
from oil or dirt, and the work protected from dust or smoke.

Varnish should be uniformly applied, in very thin coats, sparingly at the
angles.

Gbod varnish should dry so quickly as to be free from stickiness in one or
two days. Its drying will be greatly facilitated by the influence of light ;
but all draughts of cold air and damp must be avoided.

No second or subsequent coat of varnish should be applied till the last is
permanently hard, otherwise the drying of the under coats will be stopped.

The time required for this depends not only upon the kind of varniish but
also upon the state of the atmosphere.

Under ordinary circumstances spirit varnishes require from two to three
hours between every coat ; turpentine varnishes require six or eight hours ;
and oil varnishes still longer, sometimes as much as twenty-four hours.

Oil varnishes are easier to apply than spirit varnishes, in consequence of
their not drying so quickly.

Porous surfaces should be sized before the varnish is applied, to prevent it
from being wasted by sinking into the pores of the material.

Varnish applied to painted work is likely to crack if the oil in the paint is
not good ; also, if there is much oil of any kind, the varnish hardens moi*e
quickly than the paint, and forms a rigid skin over it, which cracks when the
paint contracts.

The more oil a varnish contains the less likely it is to crack.

AU varnishes improve by being kept in a dry place.

One pint of varnish will cover about 16 square yards with a single coat.i

RECIPES FOR VARNISHES.

The following recipes give the proportions of ingredients for a few var-
nishes in connection with house-paiuting : —

Oil VamiBhas.— Copal YAnmBwa.—BeH Body Copal Vamuh.^—¥'aa% 8 Ibe. of
fine African gum copal, add 2 gallons clarified oil. BoU very slowly for four or five houn
till quite stringy, and mix with 8^ gallons turpentine.

This is used for the body part of coaches, and for other objects intended to be polished.

The above makes the palest and best copal varnish, possessing great fluidity and plia-
bility, but it vA very slow in drying, and, for months, is too soft to polish.

Driers are therefore added, but they are ii^urious (see p. 431).

To avoid the use of driers, gum anim^ is used instead of copal, but it is less durable and
becomes darker by age.

The copal and anim^ yamishes are sometimes mixed ; one pot of the latter to two of
the former for a moderately quick drying varnish of good quality, and two pots of the
animd to one of the copal for quicker drying varnish of common quality.

Be»l Pale Carriage Copal Varnish.* — Fuse 8 lbs. of second sorted African copal, add
24 gallons of clarified oiL Boil slowly together for 4 or 5 houni until quite stringy ; add
bi gallons of turpentine mixed with i lb. dried copperas, { lb. lithai^ ; strain, and
ponr off.

> Seddon. » Holtzapffd. » Ure, Si^on.

b. C. ill 2 F

454 NOTES ON BUILDING CONSTRUCTION

In order to hAsten diying^ mix with the above while hot 8 lbs. of second aovted pim
anim^ 2| gallons clarified oil, | lb. dried sugar lead, \ lb. Uthaigei 5^ gallana of tar
pentine.

This Tarnish will, if well boiled, dry hard in 4 honrs in sommer or 6 in winta-. Sobir
Gopal Tarnish takes, howoTer, 12 hours to dry.

This Tarnish is nsed for carriages, and also in home painting for the beat gnined woiIe,
as it dries well and has a good gloss.

A stronger Tarnish is made for carriages, known as Best Body Copal Vanush.

Second Carriage Famish, — 8 lbs. of second sorted gnm anim^ 2] gallons fine clari-
fled oil, 5^ gallons turpentine, i lb. litharge, ^ lb. dried sugar of lead, { lb. dried copperas,
boiled and mixed as before. Used for Tanushing black japan or dark house paintins-^

PcUe Amber Varnish, — Ponr 2 gallons of hot clarified oil on 6 lbs. of very pale trans-
parent amber. Boil till strongly stringy, and mix with 4 gallons tiiri>entine. This wil*
work Tery well, be Tery hard, and the most dnrable of all Tarnishes, and improves other
oopal varnishes when mixed with them ; but it dries Tery slowly, and is but little used
on account of its expense.'

White Coburg Varnish is of a Tery pale colour, dries in about 10 hours, and in a few
days is hard enough to polish.

WAiirscoT Varnish is made of 8 lbs. gum anim^ (second quality), 8 gallons clarified
oil, \ lb. lithai^, \ lb. sugar of lead, \ lb. copperas, boiled toother till stron^y stringy,
and then mixed with 5-^ gallons turpentine.

It may be darkened by adding a little gold size.

This Tarnish dries in two houi-s in summer, and is used chiefly for house pft^i«*3«g and
japanning.'

Spirit Varnishes. — Chxap Oak Vabkish.— I>iBsolTe 8^ lbs. of clear good resin is
1 gallon of oil of turpentine. Darken, if required, by adding well-ground umber or fine
lampblack.'

Oak Tarnish is used for common work. It dries generally in about 10 hours, though
some Sb made to dry in half the time, and known as Quick Oak VamiA ; another variety
is called Hard Oak Vamishf and is used for seats. ^

" OopaX Varnish (spirit). — By slow heat in an iron pot melt \ lb. of powdered copal
g^m, 2 oz. of balsam of copivi, previoufily heated and added. When melted, remove from
the fire and pour in 10 oz. of spirits of turpentine, also previously warmed. Oopal will
more easily melt by powdering the crude gum, and let it stand for a time covered
loosely. •»»

Whitb Hard Spirit Varnish may be made by dissolving 8^ lbs. gum sandarach in 1
. gallon spirits of wine ; when solution is complete adding 1 pint of pale turpentine and
shaking well together.

Brown Uard Spirit Varnish is made like the white, but shellac is substituted for
the sandarach. It will bear polishing.

French Polish. — The simplest and probably the best is made by disaolT-
ing 1^ lb. of shellac in 1 gallon spirito of wine without heat

Other gums are sometimes used, and the polish may be darkened by add-
ing benzine, or it may be coloured with dragon's blood.

It is used chiefly for mahogany work, in joinery, hand-rails, etc, and ie
applied by rubbing it well into the surface of tiie wood, which has been pre-
viously made smooth with sandpaper, etc.

Hardwood Lacquer is made by dissolving 2 lbs. shellac in 1 gallon spirite of i
It is generally used for turned articles, being applied to them with a rag while they are
on the lathe.

Lacquer foe Brass. — ^The simplest and best lacqner for work not requiring to be
coloured is made by dissolving with agitation \ lb. of the best pale shellac in 1 galloa
cold spirits of wine. The mixture is allowed to stand, filtered, and kept out of the influ-
ence of light, which would make it darker.

Turpentine Varnishes. — ^Turpentine Varnish consists of 4 lbs. of common (or
bleached) resin dissolved in 1 gallon of oil of turpentine, under slight warmth.

> Spon. ' HoltzapffeL ' PainJter^ Paperhanger, and Deooraior^s AssisUmi

* Mr. Manders' Circular.

RECIPES FOR VARNISHES. 435

It U wed for indoor painted ivoik, and also to add to other vamiahes to give them
greater body, haidneaa, brilliancy. >

Black Yarnish for Metal Work.— Fuse 8 Ibe. of Egyptian asphaltam ; when it is
liquid add \ lb. shellac and 1 gallon turpentine.^

Bruntwick Black.— BoVL 46 Ibe. asphaltum for 6 hours over a slow fire. During the
same time boil 6 gallons oil which has been previously boiled, introducing lithaiige
gradually untU stringy, then pour the oil into the boiling asphaltum. Boil the mixture
until it can be rolled into hard pills, let it cool, and then mix with 26 gallons turpentine,
or as much as will give it proper consistency.'

Varnish for Iron "Work. — ^The following is recommended by Mr. Matheson as very
effectiye : — 80 gallons of coal tar, fi-esh, with all its naphtha retained ; 6 lbs. tallow ;
\\ lb. resin ; 8 lbs. lampblack ; 80 lbs. ftesh slaked lime, finely sifted— ndxed inti-
mately and applied hot "When haxd, this ▼amish can be painted on by ordinary oil
paint if desired."

Crystal Varnish consists of melted Canada balsam thoroughly mixed with an equal
quantity of oil of turpentine. A coating of it will oonyert good thin paper into tracing
paper.

Water Varnish. — Lighi Coloured, — Mix 16 oz. ordinary water of ammonia with 7
pints water, 2 oz. pale (or white) shellac, and 4 oz. gum arable.

Ordinary, — Mix 6 oz. borax, 2 lb. shellac, and 4 oz. gum arable with 1 gallon water.

Vamiah for Paper consists of 4 lbs. of dammar dissolyed in 1 gallon of turpentine,
with moderate agitation or gentle heat. It is suitable for paperhangings ^and similar
purposes.^

Japanning consists in applying successive coats of japan, i.e.
ordinary lead paint, ground in oil and mixed with copal or anim^
varnish. Each coat is dried in turn at the highest temperature it
will bear without melting. The surface is then treated with from
two to six coats of the best copal or anim^ varnish without
driers.

Common so-called japanned work is not dried by heat, but
merely painted and varnished.

Proper japanning wiU stand a very high temperature, and may
therefore be used for baths and other metal work subject to con-
siderable heat

Stains are liquid preparations of different tints applied to the
carefully-prepared smooth unpainted surface of common light-
coloured wood, such as fir, in order to give it the appearance of
more rare and highly coloured woods, such as rosewood, maho-
gany, walnut, etc^

Liquid Stadn$ are prepared in all colours to imitate different woods, such
as rosewood, walnut, ebony, oak, maple, etc., and sold in powder, or in the
liquid state ready for immediate application.

The powder is dissolved in hot water before use.

The liquid stain or the solution from the powder is laid on plentifully with
a brush or sponge in one or two coats according to depth of tint required.

When the wood is thoroughly dry it must be twice sized with a very strong
solution of size, and then vamiBhed.

HoltzapifeL * Um.

436 NOTES ON BUILDING CONSTRUCTION.

When stains ready prepared are not procurable, they may be made without much
difficulty.

The following are a few receipts : —

Mahogany Stain,— K thin mixture of burnt sienna groond in rinegar may be ue^,
grained and shaded while wet with the same, thickened with more sienna.^

Black WaihwU, — Same as above, bat using burnt umber.'

Wainui Stain, — Boil together for ten minutes 1 quart water, I4 oz. washing soda.
2§ oz. Vandyke brown, ^ oz. bichromate potash.'

Oak Stain.— Diaaolye 2 oz. of American potash, 2 ox. peailaah, in about a qout ol
water ; keep corked, and dilute with water for lighter tints.

Black Siain.— Boil \ lb. logwood in 2 quarts water, add 1 oz. peariash, and tpplj
hot ; then boil \ lb. logwood in 2 quarts water, add | oz. verdigris and \ oz. copptfu ;
strain, put in \ lb. rusty filings ; with this apply a second coat

Bed Stain. — Use a solution of dragon's blood in spirits of wine.

Wash fbr Bemovlng Faint. — ^Dissolve 2 oz. soft soap, 4 oz. potash, is
boiling water, add ^ lb. quicklime. Apply hot, and leave for twelve to
twenty-four hours. This will enable the old paint to be washed off with hot
water.

This is a quicker and neater process than either burning or acrapiiig ofl
(see Part II., p. 416).

Cleaning Old Faint is effected by washing with a solution of pearlasli in
water. K the surface is greasy it should be treated with fresh quicklime
mixed in water, washed off, and reapplied repeatedly.

Sztract of liOthlritLm is a ready-made preparation which removes old
paint very quickly.

For this purpose the pure extract must be thinly brushed over the saibee
twice or thrice.

To remove a single coat of paint the extract is diluted with thirty tiroes ita
bulk of water

To clean painted surfaces it is diluted with 200 or 300 parts of water.

The extract must be carefully washed off with vinegar and water before
laying on another coat of paint.

Marvel Fluid is another patent preparation for washing off old paint

Mordant to make paint adhere to zinc surfaces is composed as follows :—
Soft water, 64 paite.

Chloride of copper, 1 part
Nitrate of „ 1 „
Sal-ammoniac, 1 „

Hydrochloric acid, 1 „

• The PaptrhangeTf Painter, Orainer, and Deeoralor^ Atsistant. ■ Spot

Chaptkb VII.

GLASS.

(General Bemarks. — Glass of the kind used in buildings is a
mixture of pure sand, soda, and chalk, with a proportion of broken
glass,^ etc. These are melted together at a very high temperature,
and brought by different processes into convenient forms for use.

It is not of importance to the engineer or builder to know the
exact nature or proportion of the constituents in different kinds of
glass, as he can never be called upon to make these for himself.
A knowledge of the processes involved is useful only so far as it
enables him to distiuguish one kind of glass from the other.

The different varieties of glass in ordinary use will now be men-
tioned in turn, with brief notes as to the qualities sold and the
purposes for which they are used.

Before considering the various descriptions of glass used by tho
builder, a few points may be noticed which are common to all
kinds of glass.

Large panes are more expensive than small ones, as it is more difficult to
preserve the entire sheet of glass in making, whereas the smaller panes can
be cut from what is technically called " breakage."

An extra price is charged for moderate curves in one direction, and furthei

> The following are the proportions (roughly) for a few different kinds of glass : —

Pbrcbntaob in

Cominon
Glass.

Crown
Glass.

Plate
Glass.

Fine white sand
Sulphate of Koda
Chalk .
Broken glass .
Manganese

60
20
20

88
19

5
88

40
Atrace'15

438 NOTES ON BUILDING CONSTRUCTION

extras on donble curves ; also for obacaring, poliahing, and grmding mdes a
edgea.

All glass diflfering from that in ordinary consumption, however tnfling tht
{ difference, is also charged extra. The extra labour and risk in carrying out

I exceptional work is charged for. Triangular and other irregular shapes are

charged as square — i^ the area measured is that of the drcumsciibed rect-
angle.

The various descriptions of sheet glass are identified by their weight per
foot superficial in ouncea

The different descriptions of rolled glass have their thickness stated in
fractions of an inch.

In bending roiled plate the smooth side is outside unless ordered to the
contrary.

In fixing gla&d those varieties, such as crown glass, that are slightly convex,
should have the convexity outwarda

In the case of glass having only one smooth side, it is generally recom-
mended that the smooth side should be placed outwarda It is better, how-
ever, to place the rough side outwards, for the rays of light are then retained
and the surface appears flat ; if the smooth side is outwards, the rays are
reflected, and the slightest imdulation in the glass is easily perceived.

Crown Glass is made as follows ; — A blowpipe is dipped into melted
glass, wnich is then blown into the form of a large globular bottle. A tyxI
tipped with a blob of hot glass is so placed that the blob or '^punty " sticks
to the centre of the bottom of the blown globe: The globe is then detached
from the blowpipe, heated, and rotated vigorously until it whirls out hy cen-
trifugal force into a flat disc or " tabU*^ having a blub or '' bullion ** of gUss
in the centre.

It will be seen that this process of manufacture tends to make the disc
gradually thicker from the circumference to centre. In cutting the disc into
panes the boss in the centre must be avoided, so that there is a good deal of
waste.

The area of panes that can be produced from a table varies according to
circumstaucea

Of course the centre bullion must be cut out in a small pane. This pane
varies in size from 5 to 10 inches square, and is often used for stables or venr
common cottagea Lately, however, such panes have been in demand for use
in better houses built in the Queen Anne style of architecture.

If the remainder of the table be cut into panes of the most advantageooe
size to produce a maximum quantity, it may yield about 13 feet superficial
But if the panes are cut as required, they wiU amount to only 10 or II
square feet The largest " squares ^ produced are about 33 x 25 inchea

The portion containing the bullion cannot be flattened ; the smaller halves of the
disc (which do not include the boss or " bullion ") may be flattened, if desired, at as
extra cost, so as to correct the slight convexity that exists in the tables.

Market Forms. — Crown glass is sold in crates of tables, i.e, half discs ; crates of slabs,
flattened or unflattened ; and in squares, t.s. rectangular pieces cut to varioua dinuB-
sions.

Thicknesses. — ^There are two thicknesses —

The usual, about Vfrth inch thick, and weighing some 10 oz. per square foot ; and tlM
extra^ about iV^h inch thick, and weighing some 16 oz. per square foot.

The QttanUUy in Orates varies according to the thickness and kind of ^aaa, and k
shown in the following Table :—

GLASS.

439

Usual Thtoknen.

BztiaThiekneu

Grmto of Tables
GrmtoofSUlM

18 Tables, averagiog 58 inches
diameter.

86 Slabs, ayeraging 24 inches,
ineztrame 22{ „
width ( 211 „

12 Tables, ayeraging 62 inches
diameter.

24 Slabs, avenging (24 inches,
in extreme • 22} „
width (214 „

The extreme widths of slabs given as 21 4» 22], 24, etc, refer to the distance bom the
line where the disc is cat in two to the farthest point of the circamference. Extra
siied slabs, flattened and miflattened, are made in 12 sixes, each increasing 4 inch in width
from 244 to 80 inches.

Sixes, — The maximum area of the squares kept in stock is 5 superficial feet

QuoZi^Mf. — ^There are four qualities classed as mentioned below, which may be used
where comparatiyely small panes or squares are required.

Picture Qualities. } ^ \ ^®"® ™*y ^ ''■•^^ ^^"^ lactures, or for the very best window

Glazing qualities. Best For the best class of dwelling-houses.
Seconds. „ second „ „

Thirds. „ third „ „

Fourths, or coarse, for agricultural cottages.

Cha/radmdicB. — Crown glass is said to be more free £rom colour thau
sheet glass, and it has a finer surface, as it does not come into contact with
any other substance during the process of manufeMiture ; but it is being rapidly
superseded by the latter, in consequence of the demand for lai^ sizes, and
some of the principal manufactories have ceased to make crown glass alto-
gether.

Unflattened glass, *' unless specially selected, is so much curved as to neces-
sitate cutting the sash bars, or using a laige amount of putjiy."

Sheet Glass is first blown in the form of a large hollow cylinder. The
ends of the cylinder are then cut off, and it is split down one side with a
diamond, after which it is placed in a flattening kiln, where, under the influ-
ence of heat, it opens out into a flat sheet, which is carefuUy annealed
and then cooled very gradually.

Qualities, — The qualities of sheet glass are as follows, and may be used for the pur-
poses mentioned : —

A. For pictures (the best).

B. Do. (ordinary).

Best For the best glazing in first-class dwelling-houses.

Seconds. Good glazing.

Thirds. Ordinary glazing.

Fourths. Coarse. Unfit for most purposes. The supply is limited.

The different classes may be used for the same purposes as the corresponding qualities
of crown glass, as given above, but are available for large panes.

ThichMSS and JV0ight.—The following are the weights of glass made, and the thick
oesses which correspond to the respective weighti : —

440

NOTES ON BUILDING CONSTRUCTION.

w«Wit.

ThlekiMMin
InchtM.

16 oimcs >
21 ..
26 „
82 „
86 „
42 „

A
i

i
i

Every ^ inch adds 13 oz. to the weight per foot saperflciaL

Sitits, — ^The largest sizea which, for all practical purposes, are made in th«
snbstances of sheet glass are as follows : —

Weight per foot

•npexilcial in

ounces.

Mazimum
length..
Inches.

width.
Inches.

area in feet
superfldaL

16
21
26
82
86
42

86
85
86
70
70

88
49
49
49
44
44

18
22
22
22
19
19

It will be understood that the size is governed by the maximum area. A sheet may
be of the maximum length or of the maximum breadth, but no combination of leqgth
and breadth must exceed the area given in the last oolunm.

The usual stock sizes of sheet glass are from 48 inches x 34 inches up to 50 indiM x
86 inches. Any size above these comes under a special tariff of prices.

The variation of price, according to weight per foot superficial and size, is given in the
ordinary builder's Price Books.

Marktt Fottm, — Sheet glass is generally sold in crates. The number of abeets in a
crate varies according to the thickness of the glass, and is as follows : —
16 oz. glass 40 sheets^

21 ,, . 84 „ }• of stock sizes.

26 28 , J

ChMnKUristicz, — Sheet glass has a somewhat duller surface than crown
glass, but can be made thicker and to yield larger panes.

Cylinder Glass, Gebmak Plate Glass^ and British Sheet Glass,
are various names given to sheet glaaa

Fluted Sheet Glass is of a wavy section, having flutes or corrogatioDs
on both sides.

The sizes kept in stock do not exceed 13 feet in area, or 55 inches in
length, or 38 inches in width. It is not advisable to make fluted sheets
larger than this, but, if ordered, they can be made of the same size as ordi-
nary sheetflL

> This glass, though sold as 16 oz., generally weighs 16 os. per foot superficial. an<l
\n ^ inch Id thickness.

GLASS.

441

This glass is used in sitnations where it is necessary to secnre priyaeji
without so much obstruction to light as is offered by obscured glassL

Patent Plate Glass, or EUnion PUUe, is made by polishing sheet glass on
both sides.

It must not be confounded with British plate glass, which is a better and
more expensive material

Patent plate may be distinguished from British plate by the bubbles in the
glassL In the former case these are elongated and irregular, in consequence
of the glass having been blown after the bubbles were formed. In British
plate the bubbles are circular. The surface of the patent plate is also more
wavy than that of British plate. ^

QtialUisa. — Patent plate Ib made in the three qnalitiee which are respectiyely uaed for
the purposes mentioned below.

Best. B| For engravinge or very good gladng.

Second. C, For good glazing.

Third. C C, For ordinary glazing.

Colour, — Messrs. Chance of Birmingham make each of the qualities above mentioned
in two colours— the UnuU (or Orystal)^ and the Extra vjhiie. The usual is the better
for glazing, as it is harder, more lustrous, and less liable to be scratched in cleaning.
The extra white is better for engrarings and water-colour drawings, etc

Thickneat and fVeighL — Each quality (with the exception stated in Table) is made in
the following gradations of thickness and weight, identified as Nos. 1 to 4 : —

ATenge
thickness.

Average weight

perfect

saperflciaL

Remszks.

No. 1
No. 2
No. 8
No. 4

A inch
A »

i to i in.

18 ounces
17 „
21 „
24 „

Extra white is made
in Nos. 1 and 2
thicknesses only.

jSUmt. — ^The squares kept in stock do not exceed 10 or 12 feet in area, the length
being not greater than 60 inches, or the width than 86 inches.

'' Flattened sheet glass and patent plate should be cut with the convex
side of the air bubbles downwards, or it will be liable to crack starwise, and
it should be glazed with the convex face outwards, or it will present the
appearance of being hammered on the face." ^

British Plate Glass, ordinarily known as PlaU OUuSj is made by pouring
white-hot glass on to an iron table, and rolling it out under a heavy metal
roller.

The surface is either left rough, or polished, or indented by a pattern cut
upon the surface of the table: The several varieties of plate glass differ
from one another according to the nature of the surface thus formed, and
are named Rough-^ast Plate, Rolled Plate, or Polished Plate, accordingly.

Advantages. — ^All plate glass has the advantage of being strong. If of
sufficient thickness it keeps out the cold, and, moreover, is a ^ preventive to
robbery, as it will not yield to the diamond and allow of being noiselessly

Seddon.

442 NOTES ON BUILDING CONSTRUCTION.

remored." Other advantages are poeiewcd by the diflferent deaaiptions
accoiding to the nature of their sorfaoeL

BonOH-OABT Platb, or Bou^h PlaU^ ia the glaaa east aa above described
and rolled upon a smooth iron table:

One side has a wavj bnt polished appearance ; the other side is also wary
but dull

QuaUtif. — This is the cheapest plate glass made, and there is only one
quality.

Siz$ and Thiehua, — ^Tlie plates kept in stock range as hi^ as those contaiimig 60
snperflcial feet
The thickneeses made are |, j, |, i, aod 1 inch.

Utet. — Rongh plate may be used in all situations where a certain amount
of light is required, combined with strength — such as lights in pavementSy in
risers to steps, in windows close to the ground, etc etc

RouoH Rolled Platb, or BoUed Plate, is made after the patent of
Messrs. Hartley and Ca, Sunderiand, and is often called HaHktft Rolled PlaU^
or HaHley'e Patent Rough Plate,

The melted glass is rolled as before, but upon a table having lines, or, in
some varieties, flutes, cut upon its surface.

Qlass of this description is wavy, but smooth on one side ; the other side
being marked with pandlel ridge lines, or with flutes.

Rough rolled plate is divided into

Plain, which has very narrow parallel ridge lines close together.

Fluted, — Small, with about 1 1 flutes to the inch.
Laige, with about 4 flutes to the inch.

Sizes, — Those kept in stock range as high as 80 feet in area, the length not exceeding
120 inches, or the width 86 inches.

Thickness, — Both plain and fluted (large and small) are made in the following thick-
nesses : — i, <A, I, j inch. The | thickness weighs about 2 lbs. per square foot, and the
other thicknesses in proportion.

Uses, — This glass is suitable to any position where coarse, strong, trans-
lucent material is required. The light is admitted without scorching or
glare.

It is used for skylights, conservatories, cupolas, roofs of all kinds (the large-
fluted form in espedally large roofs). It is also used for the windows of
railway stations, factories, etc

British Poushed Plate Glass Lb made from material of a superior
description, cast and rolled in the same way as rough plate, and then care-
fully ground down to a plane surface, and polished on both sides.

Quo/i^tM.— There are three qualities : —

Silvering quality for looking-glasses.

Thickness. — The usual thidmess of polished plate glass is about \ inch, but special
thicknesses are made as follows : — ^^ \t f , f , {, 1 inch.

iSize.— The plates kept in stock (| inch thick) range as high as 100 feet superficial ;
larger plates, or plates exceeding 160 inches long, or 96 inches wide, are charged an extra
price.

The limit of area for special thicknesses la as follows : —

Thickness (inches) i'« I I I 2 1

Maximum area in square feet . 26 60 50 40 20 20

GLASS. 443

Uses. — Polished plate is lued for large windows and glass doors in the
best houses. It has all the advantages of other thick plate glass, and in addi-.
tion is very clear and colourless, and transmits a large proportion of light.
When scratched on the face it can be repolished.

Patent Diamond Bough Platb Glabs has one side smooth but slightly
wavy ; the other side with a raised oblique loisenge-shape pattern filled in
with narrow lidge lines*

Patent Quarry Bough Plate Glabs is similar to the above, but the
pattern is larger to imitate the quarries or small panes used in leaded quarry
work.

There are two sizes, the meaBurement of the quarries, from point to point, both ways
being as follows : —

Laige size, 6 x 4} inches.
Small „ 8x2^ „

The large size is used for churches, chapels, etc. ; the other for schools, staircase
windows, waiting rooms, etc. etc

In glazing, the smooth side of the glass should be inside.

Perforated Glaas. — Patent rough plate ^ and ^ inch thick, and 26 oz.
sheet glass, are both made in panes containing up to 8 feet superficial The
perforations run across the width of the pane, and are useful for purposes of
ventilation.

'^ There are two kinds of perforated glass : one having the perforations
manufactured in the glass, the other having them afterwards cut. The latter
is the best, as the former break very readily.*' ^

Cathec^al Glass is generally rolled or sheet glass of a neutral tint
It is much used for ecclesiastical work*

Patent Boiled Caihedral is a species of thin rolled plate I inch thick, wavy
on both sides, and tinted ; and rolled white cathedral is of the same colour
as ordinary glass without the lines.

Sheet CatiUdral is also tinted and used for the same purposes. One variety
has sand thrown upon its surface when hot, so that it fuses in, giving an
appearance which is useful for artLstic purposes. This is known as Sanded
Sheet Cathedral,

Ghround Glass, or Obsoured Glass, has one side covered with an opaque
film, formed either by grinding the surface or by melting powdered glass
upon it.

The names for this glass seem to be used indiscriminately, without reference
to the process by which it is made. Such glass is useful wherever light is
required without transparency.

Enamelled Glass is obscured in parts to a design which is stencilled
upon it Powdered glass, or enamel, is placed so as to form the pattern, and
is then fluxed in by heat as before.

Stained Enamelled Glass is made as follows: — The whole is first
covered with enamel ; the parts to be coloured are rubbed off with the aid of
stencil plates, and then treated with chemical substances ; these, when sub-
jected to the heat of the kiln, produce the colour required.

Embossed Glass is also obscured in parts so as to form a pattern, as fol-
lows : — The design is drawn or stencilled on the glass to be enamelled,

' Seddon.

444 NOTES ON BUILDING CONSTRUCTION

and the remainder of the surface oovered with Brunswick black. The
whole is then covered with fluoric acid, which eats into the unprotected
portions, obscuring them in the form of the pattern drawn.

Coloured Olasa can be made in every variety of tint by adding metallic
oxides and other substances to the materials before fiisioa

Flashed Ooldubs are those in which plain sheet glass is covered on one
side only with a thin layer of coloured gkss.

Designs may be formed in this glass by eating off the coloured layer, where
it is not required, with fluoric acid.

Pot Mbtalb are those in which the glass is coloured throughout its thick-
ness.

Special hinda of Glam are made for painted windows and other work of an
artistic kind, but the description of such glass Calls outside the scope of these
Notes.

OlasB Tilea are made both in rough plate and sheet glass, either plain,
fluted, or to correspond with the various shapes of earthenware tiles, so aa to
be worked in with them in roofs, and admit light without the expense ol
skylights, etc.

Glass Slates are also made both in rough plate and in sheet glass : the
former in thicknesses from i to ^ inch ; the latter of glass varying from 16 to
32 oz. The areas of the glass slates correspond with those of ordinary build-
ing slates as given at p. 27.

Interoeption of Light by Glass. — The efiect of different descriptions of
glass on the diminution of light has been shown by experiment ^ to be as
follows : —

British polisbed plate \ inch thick intercepts 13 per cent of the light
Rough-cast plate „ „ 30 „

Do., rolled, four flutes to an inch „ 63 „

Sheet glass, 32 oi. . . n ^^ n

1 Galton.

Chapter VIII.

PAPERHANGING.

WALL papers may be divided into tliree classes : —
Common ob Pulp Papers, in which the ground is the natural colour
of the paper as first made^ the pattern being printed upon it

Satin Papers, of .which either the whole ground, or the pattern, or both,
are of a polished lustre, having somewhat the appearance of satin. They are
made by painting the paper over with the required colour, mixed with
Spanish white, etc., after which it is polished with a burnisher. Or the
colour is mixed with plaster of Paris, laid on, sprinkled with powdered French
chalk, and then rubbed over with a hard brush to give the appearance oi
satin.

Satin papers are very susceptible to damp, even from the paste used in
hanging them ; they require to be hung with care, on dry walls, and should be
protected by a lining paper. When once hung, if thoroughly dry, they can
be kept cleau for a long time, as the smooth surface of the paper prevents
dust and dirt from adhering to it

Flock Papers, the design on which is formed by the adhesion of flock
sheared off from the surface of woollen cloth. The pattern is first printed
on the paper in size, next in varnish, the flock is then thickly sprinkled on,
and adheres to the varnish, thus forming the pattern.

Printing. — The pattern on the best papers is printed from wood blocks.
The position of each block is guided by four pins in its comers, and a sepa-
rate block is required for each colour.

Wall papers are printed also in large quantities, and very cheaply, by
machinery, the patterns being engraved on metal rollers, one for each colour
required, and printed on continuous bands of paper several hundred yards
long.

Machine-printed papers are inferior to those printed by hand ; the colours
of the former often wear off from not being properly set

Some of the common grained, marbled, and granite papers are roughly
coloured by band, and elaborate papers of the highest class have to be painted
by artistsL

DlBtinction In Appearanoe between Different Classes of Paper. —
Pulp papers can easily be distinguished from others, as the back is of the
same colour as the ground of the front.

Hand-printed papers can be distinguished from those that are machine-
printed, as the former retain the marks of the pins used as guides for the
position of the wood blocks.

* Galtor-

446 NOTES ON BUILDING CONSTRUCTION.

Mcurket Fomifl* — ^Wall papen are sold by the ptactf, except in the ewe d
borders, which are sold by the yard, or dozen-yards run.

The price varies according to the description and quality of the paper, and
the nature of the pattern, an extra being chaiged for eyeiy additional oolov
included. The introduction of gold or silver in the pattern also enhances
the price considerably, in proportion to the amount used.

Down each side of the paper is a blank margin about ^ inch wide. In
hanging good papers both these margins are cut off, and the adjacent piece?
are placed edge to edge. In common papers, however, only one maigin is
cut off, and the cut edge of one piece of pai>er overlaps the mazgin of the
adjacent piece.

Enqlish Papers. — In these each piece la generally 12 yards long and 21 inches vid«.
It therefore contains 7 square yards.

After the margins are removed the paper is 20 inches wide.

Each yard in length of the paper then contains 86 x 20 inches = 5 feet aaperfidsl, acd
each piece 12 x 5 = 60 feet superficial

The number of pieces of paper required for a room is therefore equal to the number r'
superficial feet to be covered divided by 60.

An allowance of from ^ to ^ must, however, be made for waste. This allowuce '»
greater for good papers and large patterns than for common papers and small pattenu.

Some manufacturers make papers of special widths differing firom those mentioned sbovv.

French Papers are made in pieces containing 4^ square yards. The length aoi
breadth of a piece vary considerably, according to quality, but they often run about f
yards long and 18 inches wide.

Borders are sold in pieces containing 12 yards, technically known as doaeuM,

Lining Paper is common uncoloured paper placed under the better classes
of paper, in order to protect them against damp and stains from the wall
below, and to obtain a smoother surface to work upon.

ColoiirB. — The colouiing pigments used for wall papers are as a rule ham-
less, being pretty much the same as those given at page 422.

Some of the white grounds contain, however, a proportion of white lead,
and in some red papers arsenic is used to fix the dye.^ Papers containiD?
green are as a rule very objectionable, because they are often coloured witi
pigments containing arsenic, mercury, copper, arsenite of copper (Schede?
green), and other deleterious substances. These fly off in the form of dost,
and may poison the occupants of the room in which the paper is hung.

" Green is by no means the only dangerous colour, others are fully as harmful BhM.
mauve, red, and brown have been found to contain great quantities of arsenic. E^
the delicate French greys yield it very considerably." *

** Arsenic is often found to the extent of from 6 to 14 grains to the superficial foot ^
wall ; and Dr. A. S. Taylor has stated that he found some deep green papers wli^"^
contained from 20 to 70 grains per superficial foot."'

Teat for Arsenite of Copper. — " The presence of arsenite of copper in a sample of ta^
paper is readily proved by soaking it in a little ammonia, which will dissolve the axwciu
of copper to a blue liquid, the presence of arsenic in which may be shown by scidifyic^
it with a little pure hydrochloric acid and boiling with one or two strips of pure oop]«f<
which will become covered with a steel-grey coating of arsenite of copper.

" On washing the copper, drying it on filter paper, and heating it in a small tube, the
arsenic will be converted into arsenious acid, wUch will deposit in brilliant octahedrd
crystals on the cool part of the tube. It is obvious that, to avoid mistakes, the ammoou.
hydrochloric acid, and copper should be examined in precisely the same way, so u to
render it certain that the arsenic is not derived frt>m them." ^

1 Ure. ' Morris, Healthy Homes, ' Hurst. * Blozam.

PAPERHANGING. 447

liinonista Walton is a mixture of boiled linseed oil with diyers and fibre
rolled on to a textile material and subjected by machinery to pressure,
under which designs are formed upon it in relief.

It is made in lengths like wall paper, and in five colours — green, drab, red,
brown, and buff.

The surface is hard, and can be washed or scrubbed without injury. It is
a non-conductor of heat, and very durable.

It is fixed to walk by a thick mixture of \ glue to J paste. Where the
wall is very damp it should receive two coats of Uncrusta yamish before the
material is hung — and if the weather is cold the lincrusta should be put in a
warm place before it is used, as it will then hang better.^

Damp Walla should be covered with a thin sheet of some waterproof
material before the wall paper is hung.

Thin sheet lead, tinfoil, indiarubber, gutta percha, and thick brown paper
have all been used for this purpose, the metals being the best but most
expensive. The foil is made so thin that it may be fastened to the wall with
paste.

Varnishing and Fainting Wall Papers. — ^Wall papers (except the most
delicate) may be finished with good copal varnish over two coats of sixe, or
they may be bought ready varnished.

Flock papers may be painted (after well sizing) when they become shabby.
In some cases they have a roller covered with wet paint passed over them, so
that the raised pattern only receives the paint

Washable Faperhangings, made by Messrs. Wilkinson and Son, of
London, are said to become as hard as stone when hung, to withstand wash-
ing, and to be non-absorbent of the contagion of infectious disorders.

Such papers would of course be better than those of the ordinary descrip
tion for a sick room. The walls of hospital wards, however, are generally
rendered in cement, and brought to a highly polished non-absorbent surface,
thus avoiding the use of paper altogether.

Fai>erhanging. — ^The points to be attended to in hanging wall papers
have been mentioned in Put II.

Expensive papers require to be hung with the most skill and care. At the
same time, common papers are more difficult to hang well, as they are very
apt to tear with their own weight when saturated with paste.

In hanging flock or other thick papers, the paste should be applied some
time before they are hung, in order that it may soak well into them.

The ceilings should be finished before the paperhanging begins.

Uhs, — Wall papers are intended chiefly for ornament ; they relieve the
bareness of the walls, and give the room a bright cheerful appearance.

A plain white paper may sometimes be applied with advantage to ceilings,
especially where, from want of stiffness in the floor above, or from some
defect in the plastering, the ceiling is inclined to crack.

^ JowmaX of Decorative Art, March 1884.

Chapter IX.

MISCELLANEOUS.

THIS Chapter will include the description of a few materials
which could not be conveniently brought under any of the
heads comprised in the fonner chapters.

GLUE

Glue is prepared from waste pieces of skins, horns, hoofiB, and other amnul
ofifaL

These are steeped, washed, boiled, strained, melted, reboiled, and cast into
square cakes, which are then dried.

The strongest kind of glue is made from the hides of oxen ; that tram the
bones and sinews is weaker. The older the animal the stronger the glue:

Characteristics of Good Ghu, — Good glue should be hard in the cake, of a
strong dark colour, almost transparent, free from black or doudj spotB, and
with little or no smell.

The best sorts are transparent, and of a clear amber colour.

Inferior kinds are sometimes contaminated with the lime used for remoTing
the hair from the skins of which they are made.

The best glue swells considerably (the more the better) when immersed in
cold water, but does not dissolve, and returns to its former size when dry.

Inferior glue, made from bones, will, however, dissolve almost entirely in
cold water.

Preparaium of Olue. — To prepare glue for use it shotdd be broken up into
pieces, and soaked in as much cold water as will coyer it, for about twelve honn.

It should then be melted in a double glue pot, oovered, to keep the glue from dirt.
Care must be taken that the outer vessel is fuU of water, so that the glue shall not bom,
or be brought to a temperature higher than that of boiling water.

The glue is allowed to simmer for two or three hours, then gradually melted, so much
hot water being added as will make it liquid enough just to run off a brush, in a ooDtinii-
ous stream, without breaking into drops.

When the glue is done with, some boiling water should be added to make it very this
before it is put away.

Freshly made glue is stronger than that which has been repeatedly
remelted. Too large a quantity should not therefore be made at a time.

*' Olue may be f^:eed from the foreign animal matters generally in it by softening it ia
cold water, washing it with the same several times till it no longer gives out any ooloar,
then bruising it with the hand and suspending it in a linen bag beneath the surfaoo of a
large quantity of water at 60'' Fahr."

SIZE, 449

By doing this the pure glue u retained in the bag, and the soluble impuritiee pass
through. If the sofUmed ghie be heated to 122° without water, and filtered, some other
impurities wiil be retained by the filter, and a colourless solution of glue obtained.^

fZstf. — Glue is used chiefly by the joiner for joints, yeneering, etc
The precautions to be attended to in using glue have already been men-
tioned in Part U., p. 295.

A minimum amount of glue should be used in good work, and it should be
applied as hot as possible. The surfaces of wood to be united ^ould be
clean, dry, and true ; they should be brought together as tightly as possible,
so that the superfluous glue is squeezed out.

Strength of Glue, — " The cohesion of a piece of solid glue^ or the foree required to
sexMuate one square inch, Mr. Beyan found to be 4000 lbs.**

From other experiments Mr. Beran found that the adhesion of two pieces of ash glued
end to end amounted to at least 715 lbs. per square inch.

" The lateral adhesion of a piece of board cut out of Scotch fir, which had been quite
dry and seasoned, was 662 lbs. to the square inch. Therefore, if two pieces of this board
had been well glued together the wood would hare yielded in its substance before the
glue."

** The strength of common glue for coarse work is increased by the addition of a little
powdered chalk." •

Glues to Resist M(»sti7RB. — " A good glue for outside work is sometimes made by
grinding as much white lead with linseed oil as will just make the liquid of a whitish
colour and strong, but not too thick." '

" Mix a handM of quicklime in 4 oz. of linseed oil ; boil them to a good thickness, then
spread it on tin plates in the shade, and it will become very hard, but may be easily dis-
solyed over the fire as glue. " '

" Skimmed milk, in the proportion 1 lb. glue to 2 quarts of milk, is sometimes used to
dissolve glue, with the view of increasing its capability of resisting moisture."'

" Ordinary glue can be rendered insoluUe in water by adding to the water with which
it is mixed a small quantity of bichromate of potash ; the ezaet proportion must be ascer-
tained by experiment, but for most purposes ^th the amount of glue will be sufficient ** *

Marine Glue. — One part of indiarubber is dissolved under gentle heat in
12 parts of mineral naphtha or coal tar. When melted, 20 parts of powdered
shellac are added, and the mixture is poured out on metal plates to cooL It
Ib applied by a brush in a melted state, and is specially suitable for all work
exposed to wet or moisture.

SIZE.

Size is, or should be, made from the best glue. The glue is prepared by
boiling down the skin ard homy parts of animals, parchment clippings, etc

Inferior glue is said to remain damp and to become mildewed.

To make size, a piece of glue is placed in the pot and covered over with
water. When melted, it is thinned by adding more water.

A pound of glue makes about a gallon of size.

Very good size may easily be made by boiling parchment clippings for
seveml hours and straining them through a cloth.

Size is U8ed with earthy colouring matters to make them adhere to surEaces, j

also for clear cole, as described below. :

Double Sise is merely size of double the strength of ordinary size. I

Patent Size " is a gelatine, and can be used without any soaking as required for glue |

size." * I

Kilvin Dry Sise is said to be colourless and odourless. It is sold in powder, and

becomes gelatinous on cooling after a minute's boiling. It will keep several days in the

hottest weather, and will not affect the most delicate tints.^

* Uro. « Tredgold. » Spon. * Seddon.

B.C. — III 2 G

450 AVTES ON BUILDING CONSTRUCTIOiW.

Clear Cole is the name given to a coating of size which is often used to
fill up the pores of wood or plaster in order to prepare them to receive w
nish, colour, etc., without absorbing too much.

Parchment Sfse is used by gilders. It is made by dissolving shreds of fins psrdi-
meat ia warm water.

Hold Size, of different kinds, is applied to surfaces to be gilded, as a baab to receive
and secure the gold leat

Oil Gold Size is made by grinding ochre in boiled linseed oil. The mixtura is made
as stiff as possible, kept for several years, if possible, and thinned down with boiled liaaeed
and fat oil for use.

This is the best size to use for outside work, and for any work that is not bomished. It
is, however, rather slow setting, and must be applied some 12 to 18 hours before the leai
is laid on.

Burnish Gold Size is laid over a basis of size and whiting to secure gold leaf that is
to be rubbed bright with a burnisher.

It may be made with a mixture of " black lead, deer suet, and red chalk, 1 oz. each,
with 1 lb. of pipeclay, ground together to a stiff paste," but it is generally purchase
ready made.

jAPiiNNEBs' Gold Size is made by boiling gum anim^ in linseed oil with driers. The
process is an elaborate one, and is fully described in Spon's Workshop Rtceipis.

This size sets very quickly (in from 20 to 80 minutes when pure), and is used for
gilding when but short time is available, also for repairs.

It is not so durable, nor does it make such good work, as oil size.

In gilding or japan work it is used as a basis to seouro gold leaf or gold powder.

KNOTTING.

Knotting is the material used by painters to co^er over the surfaces of
knots in wood before painting.

The object is to prevent the exudation of turpentine, etc, from the knots,
or, on the other hand, to prevent the knots from absorbing the paint, and
thus leaving marks on the painted surface.

Ordinary Enottins is often applied in two coats.

First Size KnoUing is made by grinding red lead in water and mixing it with strong
glue size. It is used hot, dries in about ten minutes, and prevents exudation.

Second Knotting consists of red lead ground in oil, and thinned with boiled oil and
turpentine.

Patent Knotting is chiefly shellac dissolved in naphtha.

The follovring is a receipt for a similar knotting : —

" Add together ^ pint japanners' gold size, 1 teaspoonful red lead, 1 pint vegetable
naphtha, 7 oz. orange shellac. This mixture is to be kept in a warm place whilst the
shellac dissolves, and must be frequently shaken. " ^

Hot Lime is sometimes used for killing knots. It is left on them for about 24 houn,
then scraped off, and the surface coated with size knotting ; or if this does not kill the
knots, they are then painted with red and white lead ground in oil, and when dry rubbed
smooth with pumice stone.

Sometimes after application of the lime the knots are passed over with a hot iron, and
then rubbed smooth (see Part II.)

When the knots are very bad they may be cut out^ or covered with silver
leaf, as described in Part II.

* Davidson.

PASTE— GOLD-LEAF. 451

PASTE.

Paste Ib required by the paperhanger, in different degrees of Btrength,
according to the thiclmeaa and weight of the paper to be hnng with it.

Paste should be made with the best white wheat flour.

The following receipts ^ are for paste of different strengths, the strongest
being the last : —

No, 1. — ^Beat ap 4 lbs. of good white sifted wheat flour in cold water to fonn a itiff
batter, taking care to get rid of all lumps ; then add enough cold water to bring it to tbt
consistence of padding batter.

Pour boiling water over the batter, stirring rapidly. When the mizture swells and
loses the white colour of the flour it is ready.

This makes about } pailful of paste, enough for a day's work« It should be used cold,
and is adapted for ordinary work.

No, 2 is made in the same way as No. 1, except that just before the boiling water is
poured on 2 oz. of alum are mixed with the batter.

The alum imparts strength to the paste, but is said to make it more difficult to lay on.

This paste is used for hanging flock papers.

No, 8. — Make a batter as in No. 1, but of less consistency, and to 2 quarts of batter
add \ oz. of pounded rosin ; set the mixture oyer a moderate fire, stirring till it boils and
thickens, then allow it to cool, and thin with thin gum arabio water.

This paste is used only where strong adhesiveness is required, and is indispensable in
papering over varnished or i>ainted surfaces.

No. 4 is the same as No. 8, but without gam, and is osed for securing the edges of
flock papers.

GOLD LEAF.

Qold leaf is required for gilding, in order to ornament different parts of
buildings, more especially the internal fittings, such as the mouldings of the
joinery or the decorations of the ceilings or walls.

It is classed as nn^^, iofMeHy or trebles^ according to thickness, and sold in
books, each containing 25 pieces, whose dimensions are 3^ by 3^ incbesi
They are placed between the paper leaves of the book, which are rubbed with
red chalk to prevent the gold from adhering.

The book should be warmed before use, so as to make the leaves quite dry
and easy to detach from one another.

There are several different tints of gold leaf^ varying from deep orange red
down to a pale silveiy hue.

Foreign Gold Luif is thinner than that made in England, and the area of the leaves is
smaller.

PaU Leaf Oold is an alloy of silver and gold beaten into leaf.

Dutch Oold is copper leaf coloured yeUow by the fumes of molten zinc It is much
cheaper than genuine gold leaf, and useful for laige surfaces, where it can be protected by
varnish. Without such protection it becomes discoloured.

Besaevner's Oold Paint is in the form of powder. It is mixed with a little transparent
varnish, and laid on with a brush.

1 Slightly modified f^om those given in the P^perhanffer, PairUer, Omtner, and
Deeuralor's AasisUmL

4S3 AOTES ON BUILDING CONSTRUCTION.

PUTTY.

Painters' and aiasiers' Putty is made with whiting (see p. 254) and
oiL The whiting is reduced to veiy fine powder, carefullj dried, passed
through a fine sieve (about 45 meshes to the inch), mixed with raw linseed
oil into a stiff paste, well kneaded, left for 12 hours, and worked up in
small pieces till quite smooth.

For particular purposes, such as in femlights, where the lap or hold is very
naiTow, a little white lead may be added with advantage.^

Hard Putty may be made by sabstitating tnrpe for part of the oiL
Vert Hard Puttt, from oil, red lead, white lead, and sand.
SoFr Pttttt, horn 10 Ibe. whiting, 1 lb. white lead, mixed with \ gill beat salad ofl and
enough boiled linseed oil to bring it to the proper consistenoe.^
The harder kinds crack unless they are soon painted.

Plaaterera' Putty (see p. 246).

Thermo-Plastio Putty contains tallow, which keeps the putty pliable, eo
that it is not loosened by the expansion and contraction of large panes of glass
under changes of temperature.'

RUST CEMENT.

BMd Cement, known also as Cfast Iron Cement, and by other names, is used
for caulking the joints of cast iron tanks, pipes, eta

It is composed of cast iron turnings, pounded so that thej will pass through
a sieye of eight meshes to the inch ; to these are added powdered sal-ammoniac^
and sometimes flour of sulphur.

The ingredients having been mixed are damped, and soon begin to heat
They are then again well mixed and covered with water.

The exact proportions of the ingredients vaij. A simple form is 1 oi. of
sal-ammoniac to 1 cwt. iron turnings.

The following are recommended by Mr Molesworth : —
Qutck-eetting Cement — 1 sal-anunoniac by weight
2 flour of sulphur.
80 iron borings.
Slow-Getting Cement — 2 sal-ammoniac.

1 flour of sulphur.
200 iron borings.
The latter cement being the best if the joint is not required for immediate
use. In the absence of sal-anmioniac the urine of an axrimal may be substi-
tuted

The cement will keep for a long time under water. Its efficacy depends
upon the expansion of the iron in combining with the sal-ammoniaa

» Spon. • Seddon.

LATHS— VULCANISED INDIARUBBER, 453

LATH&

The laths principally required by the builder are of two kinda — those used
for plastering, and those used for iooDb to support the covering of slates or
tiles.

Flaaterers' Iisths are thin stripe of wood, about an inch wide generally, 3
or 4 feet long, and of a thickness varying according to the work for which they
are to be used (see Part XL)

They should be straight ; free from large dead knots, which fall out and
weaken them ; from splits ; and from sap, which leads to decay.

They are sometimes made by hand, sometimes by machinery. In either
case they should be split or rent from the log, so that each lath has its longi-
tudinal fibres intact In sawn laths the fibres are generally cut across in
places, which makes the laths weak and apt to break across.

Oak laths are sometimes used, but for ordinary work laths should be of the
best Baltic fir.

ThideMMi, — Plasterers' laths are made in three thicknesses classified as
follows : —

Single laths . i to A inch thick.

Lath and half laths ...
Double laths

They are made also in various lengths, varying from 2 to 5 feet, but the
lengths most commonly used are 3 feet and 4 feet

Market forms, — Laths are split in this country, and are also imported from
the Baltic and from America, and sold in bundles, round or half round, being
either the whole or half of a young tree split up.

The bundles generally contain 360 lineal feet, but sometimes as much as
600 feet run of laths.

Metal Latha are manufactured from 26 BWO iron in any lengths up to
36 inches. They are fixed in the same way as ordinary laths, and the key
for the plaster is afforded by the dovetail form into which the metal is bent
They are of common fireproof, and are very useful in special circumstances.^

Slate or Tiling Laths, or Battem as they are often called, are generally
sawn out of boards and sold in 10-feet lengths, the width and thickness vary-
ing from 1^ inch x | inch to 2 inches x 1 inch, or even 3 inches x 1 inch.

VULCANISED INDIARUBBER.

Vulcanised Indiartibber consists of indiarubber mixed with 44 per cent
oxide of zinc and 4 per cent of sulphur. An excess of sulphur injures the
material, causing it to become brittle with age.

This material is used chiefly for jointing pipes, for valves, etc.

A rough way of testing its quality is to throw a piece into water ; if it
sinks, it probably contains an injurious excess of sulphur.

A good sample should stand a dry heat of 270"* Fahr. for 1 hour and a
moist heat of 320** Fahr. for 3 houra

^ Patentees' Circular.

454 NOTES ON BUILDING CONSTRUCTION

TAR.

Ck>al Tar is produced by heating coal in close iron veasel^ and is a bje
product in the manufacture of gas. When itself distilled it produces, in
various stages — first, coal naphtha^ which is useful for dissolving indiarubber,
etc ; then dead oil or creosote^ used (see p. 394) for preserving timber ; and,
lastly, pitchy which ia used for asphalte work (see p. 253), also as an ingre-
dient of varnishes, etc.

Wood Tar is produced by the distillation of pine and other resinoos
trees. It has strong preservative qualities, owing to the creosote it contains.
It is imported in barrels containing about 30 gallons, from the north of
Europe as Stockholm and Archangel tar, and from the United States as
American tar. Of these varieties Stockholm is considered the best ; the
residue left after distillation is pitch (see p. 253).

Mineral Tar is a natural substance found in Burmah, and also obtained
by distilling bituminous shales, such as those found in Dorsetshire and eI9^
where. It contains less volatile matter than the other kinds of tar, but is
otherwise of similar composition.

CREOSOTE.

Creosote is a product obtained in distilling tar. It is an oily, dark
liquid, varying in composition according to the quality of the coal from which
it is obtained, and containing hydrocarbons of different degrees of volatility
and varying antiseptic qualities. Until lately the portions of low specific
gravity were considered the best, but experience shows that the lighter
portions are volatile and soluble in water, so that the valuable acids may be
washed out ; a heavy oil, well heated, and with high pressure, gives a better
result. The naphthaline is dissolved by the heat, and afterwards fills the
pores of the wood and then solidifies.^

"The minute glistening scales generally obeenrable on newly creosoted wood consist of
naphthaline, a sabstanoe that possesses considerable antLseptic properties ; when this
substance exists in the liquor in moderate quantities it thickens and confirms its cod-
sisteucy, but when there is a very large proportion ... it makes the liquor too soUd."*

Dr. Tidy's specification for creosote is here summarised.^

1. To be quite liquid at 100"* without deposit until the temperature &lls to 95*.

2. One-fourth not to distil over in a retort at less temperature than 600*, and this
fourth to be heavier than water.

3. To contain 8 per cent of tar acids by analjrsis with caustic soda and sulphuric scid.

4. No bone oil or shale oil or any oil not distilled from coal tar.

There are two classes of creosoting oils, known in the trade as London oils
and country oils.

'*The London oils, which consLst of those obtained firomthe gas tar derived from
Newcastle coal, contain a large proportion of naphthaline, and are heavier and thicker than
the country oils of the Midhmd districts, whidi yield a large proportion of tar acids, as
they are called."

Previous to 1863 but little of this thin country oil was used, but since that tbej
became more in demand, under the impression that the tar acids were the most valasble
part of the oil. Subsequent experiments have shown, however, that the "so called green
oils distilling over at a high temperature formed the best portion of the creosoting liquor,
and that the importance of the tar acids had been much overrated."

The specific gravity of creosote depends upon the locality in which it is
* Dent's Cantor Lectures. ' It.E, Journal,

FELT, 4S5

distilled. The material is aold in caska containing from 36 to 38 gallons
each.

Hygeian Bock Building Composition is a bituminous substance used
for keeping damp out of houses.

The walls are built in two thicknesses, with a space of about \ inch or
more between them, into which as the wall is carried up the composition is
run in a liquid state. Existing walls are made damp-proof by adding a
lining of tiles or bricks with the composition between. The material is said
not only to keep out damp and vermin, but to add to the strength of the
wall It is sold in bags of I cwt, which will cover about 2^ square yards
\ inch thick." ^

FELT.

Felt, generally saturated with bitumen and other substances, is sold in
various forms useful to the engineer and buUder. The following information
regarding the dififerent descriptions is from the circular of Messrs. Engert and
Rolfe:—

Asphalted Booflng Felt is nearly black in colour, haa a strong odour of
asphalte, and is about \ inch thick.

It is made 32 inches wide, and in any lengths up to 35 yards ; and is
used as a roof covering for temporary buildings, the lining under slates, etc.,
on roofs, etc.

A coat of lime whiting or whiting and size is recommended where the
smell of the asphalte would be objectionable.

Sarking Felt is like the above, but only about -^ inch thick. It is made
in rolls 32 inches wide and 30 yards long, and is used as a roof covering for
temporary sheds, and under slates.

Inodorous Bitumen Felt is of a brown colour, about ^ inch thick. It
is made 32 inches wide, and in lengths up to 36 yards. It is used for damp
walls, for lining iron houses, under slates or roofs, for laying under floors to
deaden sound ; for bedding girders, columns, and heavy iron work.

Fibrous Asphalte is a sort of felt well impregnated with asphalte mixed
with grit.

It is made in slabs 32 inches long, and either 4^, 9, 13^, 18, 23, 27, 30,
or 36 inches wide.

These slabs are very tough and waterproof They are used for damp-proof
courses (see Part II.), being bedded in cement or mortar ; the joints overlap
2 inches, and are kept clear of mortar.

Hair Felt, for preventing the escape of heat from boilers, pipes, etc, is
dry, and not impregnated with asphalte, etc.

It is made 3 feet wide, and in lengths up to 20 yards ; also in sheets 34
inches by 20 inches.

The felt is cla»ed by nnmbers, aoeording to weight per sheet, as follows : —
Nos. ... 0 1 2845

Weight of sheet Thin 16 24 82 40 48 ounces.

Thickness of sheet . ... i g i { } inch.

This felt is attached to the boUer by a cement composed as described
below, then covered with canvas and painted.

Cement for attaching Hair Felt to Boilers. — 1 lb. red lead, 8 lbs. white lead, and
8 Ibe. whiting, are thoroughly mixed with boiled linseed oil to the consistency of treacle,
and spread over the edges of the felt and on the side next to the boiler.

' Patentees' Circular.

456 NOTES ON BUILDING CONSTRUCTION.

Tarring FdU — Three parts coal tar are boiled with one part daked lime, poirdend
chalk, or whiting. The mixture is applied warm, and dusted with as much sand or giil
as it will absorb. Stockholm, Archangel, or thick purified coal tar may be nsed after
merely warming, not boiling.

Fainting Fdt for Exterior Work, >-First prepare with a coat of lime whiting, thes
paint with red lead, boiled oil, and driers (no turps), on which sprinkle fine white slTer
sand ; over this any paint may be used.

ASBESTOS.

Asbestos, the well-known fireproof and acidproof fibrous mineia], is the
basis of several substances useful to the builder.^

The raw material comes firom Italy, Canada, California, Australia, etc. The two first
are the best in the order given. ItaUan asbestos is grey or brown in cQlonr, Canadian
white, Asbe^oa Paints (see p. 428).

Asbeatat Concrete Coating is of a drab colow, and is used to cover beams to retard tk
action of fire ni)on them ; 100 lbs. will cover 200 square feet ^ inch thick.

Asbesioa Roofing is made from canvas cemented to a surface layer of felt and a Maailb
lining in compact flexible sheets resembling leather.

It is supplied in rolls about Z&\ inches wide, containing 200 square feet, and vdgb
about 85 lbs. per square.

Asbestos Sheathing is fireproof, and used for lining wooden partitions, ceilings, etc. It
is made in rolls of from 60 to 100 lbs. 42 inches wide, weighing about 6 Iba. per eqaaie ;
also ''double thick," weighing about 10 lbs. per square.

Asbestos Building Fdt is fireproof ; it is made in rolls of about 70 lbs. weight, 36 incks
wide, weighing about 60 lbs. per square ; also "extra heavy," weighii^ about 16 Ibs^ ^
square.

WILLESDEN FABRIC&

WiUesden Fahiies ^ are vegetable substances which have been treated with
certain compounds of copper and ammonia, the effect of which is to coat and
impregnate them with cupro-celluloae, a varnish-like substance which not onlj
protects the surfaces but adds strength to the fibres by cementing them together.

This enables the fibre to resist the weather, and renders it less liable to
catch fire. Ropes, cordage, and netting are treated in this way, but the iabiics
most useful to the builder are the WiUesden paper and canvas

'WiUesden Paper is of three classes.

Unwbldbd (marked WPG 1), or "one ply" paper, is made 54 inches wide, of indefioitie
length, and is chiefly used for packing.

Wbldbd, which consists of several '* plys" or thicknesses of paper formed (while thej
are still gelatinised by the action of the cupro-ammonia solution) into a compact ibect
or thickness.

The difierent classes of this paper are known as follows. They are aU made in brova
and neutral green colours.

Willesden 2 ply (WPG 2) is in contmuous lengths, 54 inches wide. It is vseAil for
underlining slates, tiles, internal decorations, floors, damp walls, leaky roofs, etc

Willesden 4 ply (WPG 4) is weatherproof and strong, a bad conductor of heat, fnc
from condensation, does not easily catch fire, does not require painting, and is said to be
proof against the white ant ; it is useful for roofing, sides of huts, etc

The relative covering povrers of this and good ^dvanised iron are stated by the msDO-
factiu^rs as follows : —

Wniesden paper. Oalvanised

WPG 4 iron.

Weight of one square in lbs. . . . . 15 to 18 103 to 2S0

Area covered by one ton in squares . . . 125 te 150 8 to 22

Willesden 8 ply may be used as panel board.

Willesden Canvas is prepared in a similar way to the paper, and can be used with ad-
vantage for most purposes to which canvas is applied, including making hose.

^ Patentees' Cii-culors.

NAILS, 457

WIRE WOVE ROOFING.

Wire Wove Booflng consiBts of a semi-transparent substance, apparently
some preparation of linseed bil upon a basis of very fine wire mesh. It is said to
be waterproof, tough, elastic, strong, and not affected by atmospheric changes,
and is made in sheets of 10 feet by 4 feet and of 10 feet by 2 feet

EMERY.

Emery Cloth,^ consisting of ground emery of different degrees of fineness
attached to calico by glue, is used for finishing and polishing metiQ surfacea

Emery Paper is not much used for builder's work.

GlsMB Cloth and Qlass Paper are made respectively from calico and paper
coated with ground glass, and are used for producing a smooth surface on
wood or for rubbing down painted surfaces.

SILICATE COTTON.

Silicate Cotton ^ or Slag Wood is a glasslike fibre blown from blast furnace
slag. It is incombustible, vermin-proof, and very light, one ton covering 1800
square feet 1 inch thick, and is therefore useful for making floors and ceilings
sound and fireproof.

NAILS.

There are some 300 varieties of nails, named chiefly from the shape of
their heads and points, or according to the particular use for which they are
intended.

No attempt will be made to describe them all, but it may be useful to the
student to know the names and characteristics of some of those in most com-
mon use for building and engineering work.

The thickness of different classes is expressed by the terms "fine^'*
'* baetard" ^strong ;^ and their weight is generally given in lbs. per 1000,
and their length in inchea

In former times nails were described according to their price per 100 —
thus, ''tenpenny nails" and ^'fourpenny nails" were those costing lOd.
and 4d. per 100 respectively. These terms are still sometimes used, but
their meaning is now indefinite. It varies in different localities, and no
longer refers to the price of the nails. The term " Tenpenny nails " now
generally means nails about 2f inches long, not nails at lOd. per 100. In
the same way ''Sixpenny naOs" are generally 1^ inches long, ''Eightpenny "
2 J inches, and " Twentypenny ** 3 J inches. Makers differ, however, as to
the lengths con-esponding to the different names.

Cast Kails, made by running molten iron into moulds, are brittle and
inferior in strength, but cheap. They are used for horticultural purposes,
for lathing, and for many other purposes in common work.

Malleable Nails are made in the same way as cast nails, but are after-
wards rendered malleable by the process described at page 266. They can
be made thinner than the common cast nails.

Hand- Wrought Nails are forged by manual labour. They are tougher
and stronger than other varieties, and will bear clenching, but are more
expensive. Their angles are sharp and clear, and the shanks are slightly
compressed just under the heads.

Cut Nails are of a cheaper description, cut by machinery out of sheets of iron.

^ Manufacturers' Circulars.

458 NOTES ON BUILDING CONSTRUCTION.

Patent Machine- Wrotight Nails are made out of wrought iron pressed

while red-hot into shape by grooved rollers, then cut up, and the head^
formed by a die. They have not such sharp clean angles as the hand-wrought
nails, and are not so strong or elastic. The shank under the head is rather
flattened out, and their grip is maintained by the shank being slightlv
thicker near the point than in the centre. They are slightly cheaper than
hand-wrought nails, and at present Rose and Clasp nails are the chief varie-
ties made.

Varieties of Nails in Common ITse. — ^The following descriptions are
of nails in common use : —

RosB NA.IL8 are either wrought, cut, or pressed. They take their distinv-
tive name from the shape of their headis, and are divided into clasaes acconl-
ing to the nature of their points.

Rose Sharp Points are used for ooopering, fencing, and for coarse pnipoMs with hard
woods. There are both wrought and stamped varieties. They are classed according U
stoutness, as " Fine '* (or " Canada*') and " Strong,**

Rose Flat Points (Fig. 170) have chisel points, and are used when the ordinary points
would act as wedges and split the wood. They are driven with the flat point along the
grain, so aa to prevent splitting and hold faster. These also are classed as " Fioe " or
"Strong."

Rose Clench, are sqaare ended, and easily punch through thin metal covnings vithoc:
first boring a hole. They are used by boat-builders» and also for packing casesL

Fig. 170. Fig. 171. F%. 172. Fig. 178.

Clasp Nails are much used by carpenters in soft woods, such as fir.
They have heads which project downwards and stick into the wood, holding
it together. They are also easily driven below the surface, so as to allow
the plane to pass over them.

Fig. 171 shows the shape of the wrought description. The cut clasp
have heads nearly flat on both sides, as in Fig. 172.

JVrotighl Clasp are divided into two classes — Fine and StroTig^ and are used for ledges
to doors and other work where the nail requires to be clenched.

To effect this a nail is selected of a length greater than the thickness of the wooii
through which it passes, and the projecting point is hammered, so as to be tamed back
into the wood.

Cut Clasp are used for fixing rafters, ceiling joists, also architraves, skirtings, linings,
and other joinery.

Brads (Fig. 173) are flat-sided nails, either wrought or cut, with heads
of the same thickness as the shank, of a shape known as JnUed, and being
driven with the flat sides parallel to the grain, are not liable to split the
wood.

NAILS.

459

176.

These

The larger sizes are nsed for flooring ; the smaller for light work, such eh
fixing small mouldings, beads, etc.

The ends of cut brads are not pointed as in wrought brads.

The lighter varieties are called Joiner^ Brad» and Cabinet Brads,

Glaziers* Brads or Sprigs, used for securing large panes of glass, are of
the shape shown in Fig. 1 74, and have no heads.

Clout Nails (Fig. 175) have flat, circular heads ;
shanks round under the head, and with points either
tapered or flat. The smaller sizes are mostly sharp, and
the larger have flat chisel points. They are used for
fastening sheet metal, felt, nailing hoop iron to wood,
etc, and are made in two varieties, ^ne and strong.

Countersunk Clouts (Fig. 176) have heads shaped so as ''igs-174. 176.
to fit a counter-sinking, and are generally made with flat points.

They are much used by wheelwrights and smiths, and for securing iron
plates, etc., to woodwork.

Wire Nailb, known also as French Nails (or Pdntes de Paris), are round
or square in section, very tough and strong. They are said not to split the
wood, and to require no hole bored for them. They are sold in lengths from
I to 4 inches, and of different thicknesses, varying from Nos. 5 to 18 B.W.6.,
and are nsed for packing-cases and other purposes.

Dog Nails are made with solid and slightly countersunk heads,
are sometimes hemispherical ('* die-heads '*) ; the shanks are
generally round, at least under the head, and their points flat.

They are nsed for nailing down heavy ironwork, and for
various other purposes when the heads are not required to
be flush with the surface of the work.

Spikes are very large wrought nails iwed for heavy work,
when great strength is required, as in wood bridges, scupper-
ing, etc. They range from 4 to 14 inches in length ; the
smallest sizes have rose heads, but the larger ones have square
heads with flat tops, as shown in the figure, which, it must
be observed, is on half the scale of the sketches of the smaller
nails.

Tacks are small, short, and light nails, and are divided into
three classes — ^Rose, Clout, and Flemish ; the two former are
named according to the shape of their heads. Clout tacks
resemble the nail shown in Fig. 175. Flemish are similar. Figs. 177. 178.
but that the shank tapers throughout the upper portion, and
is not finished in a cylindrical form as shown in Fig. 175. Tacks are used
for close nailing very light sheet metal, but chiefly for upholsterers' work.

Tacks are generally wrought, but some of the smaller kinds are cut.
They are either blacked, blued, or tinned.

Copper Nails are made of the same shapes as iron nails, and are nsed
in positions where the latter would be subject to corrosion.

CompoBition Kails are those made of different alloys to avoid corrosion,
or to prevent the galvanic action set up by iron when in contact with zinc
or other metals. They are varied in shape according to the purpose for
which they are to be used.

46o NOTES ON BUILDING CONSTRUCTION.

Slating Nails have circular flat heads and sharp-pointed fihanTra ; M)rj(
are slightly countersunk, as in Fig. 179.

They are made of various metals. For temporary work ca$t. nail-
may be used, for better work malleahU nails ; these, however, aoi
coiTode away unless galvanised or dipped hot in boiled oiL Zi>'
nails are cheap, and sometimes used, but are too soft Copper ntil'
are often used in superior work, but are also soft. Compogilion sab*
..^ are cast from an alloy (about 7 copper to 4 zinc) which is hard as^
does not corrode. When made of a really good strong alloy they a.t
the best for superior work.

Tile Pegs is the name given to short cast-iron nails too thick for slating
and used for securing tiles to roofs.

Steel Nails, made from molten metal pressed in moulds, have lately her~.
introduced, and used largely for the best class of work. They are finer aii
cleaner than ordinary nails, but much dearer.

Lath Nails may be obtained either wrought, cut, or cast The cast asc
the cut are the cheapest The cut nails are generally used.
Wrought nails should be used for oak laths.

The length of the nails varies acording to the thickness of the lath, being
} inch for single laths.
I „ lath and half laths.
1 „ double laths.

Misgellaneoub. — ^Besides the above-mentioned there is an innumeraUt
variety of patent nails of different descriptions and in different metals, al»j
brass-head&i and fancy-headed nails, and nails used for special pnrpciso,
unconnected with buildings. These need not be further referred to.

Weight of Nails. — The Table on the next page, which is taken chieflr
from Government schedules, shows the weight per 1000 of some of the mosi
useful sizes of different kinds of nails.

Spikes are generally sold by the cwt. Their weight may be taken as follows : —
Length ... 5 6 7 8 9 inchee.

Weight per 1000 . . 100 200 300 450 600 lbs.

Pound Nails are of a particularly heavy description, and are also sold by the cwt

I^AILS,

461

0 1

^s-i ss ^ : 1

0 -s: <nS ^: ^:

g g :§ •:;> : ;

: : : : co ^ co : :

«^

»« : : : : '0 : : :

«"

C4 0 GO : » : 00 :
eo <N ri : . w. .c^

: : :

: : : 0 : : : : :
: : . <N . ...

:: s i : : § S : i 2i"3s s |

l-t r-l rl rl r-t l-t "^ « W • r-l r-l iH r-t rl rl A •<•<

C<l r^

0 0 e4e -to

00 (NO :o : o^o r-4(NWr-iQ0 -♦* 'y*
r-tr-t :ri : cow : : ''-•'-•J. "^ ^

GO 06 rS iH

W r-t : r-t i-i rH I O rH i-i

»-t rH

l-t

::r^::t^i»oJSS*^S-^ oooooico J: JJJ

:gT : i'* icS'-*<»2^ • ' • ^r^*^^^ J J Jtf

f-H

-*♦
l-t

liliililiiilii - iiii: : =: 5i

,^7»^t • -net ' .... -t«:::::: :*t
rHrH»o:(N:coco:w.:::'>* eo<o::: . :. -g^^

i : i 1 i : : i„ 1 i I i i :;:::: :f;f : :

r-t

^$ : IS' i ioi i i i i i i ^ S* i i i i i ^« :^

Hod

-Hoo-^a : : : : : : •»• : : :

:::::::::::::« rn h- : : : : . , rn .

,^«*» ::::: rH :::::: p^ rH : : : : . . : . .

: : ; i i i i 1 ! ! ; i : I i 5:1 i : i : : : i i i i

: 1 i i : ; : : ! ! 1 ; : ; • T$ i = : : i ; i i ; ;

; : : : i i • : i i ; ; i ; ;±$ ! i : i : i i : : i 1

•^Ct

•?•*• i i : i 1 : i : i 1 ; \->"*<T-« = : = = = ■ :* \ \

■^

I i : ; : i 1 : 1 : : 1 : : ; ■ i< = • i : ; : 1 ; ; ; i

■m

•: 1 i ; ! : • : i i i : •: i •:^:^:-c: : ; : ; : : = =* i i

-S

:::::::::::::::::"♦♦ : : : i : : : i : : :

::::::::::::::: '♦•'^*HS : : : : : : : : hh : :

1.-

.2 =

':::::: I :':::::::: i'^* : : : : : : i : : : :

■h: :::::::

1 i

i!riiaiiii|ii|iiriliii«jrit:

.5 8 6 al ^1 6 1 ^ aia i si

'- 1

46«

NOTES ON BUILDING CONSTRUCTION

AdheslTe Force of Nails. — The following abstract of records of experi-
ments on the holding power of nails may be useful : —

Holding Powsr of WaouaHT Irok Tsnfennt Nails, 77 to the lb., abont 8 inebo
long, nailed through a 1-inch board into a block, from which it was dragged in a
direction perpendicular to length of nails. ^

N«. of
Nails in

Kind of
Plank.

Kind of
Block

Average
Break-
ing
Weight

NaU.

No. of
Nails in
Square
Foot

Kind of
Plank.

Kind Of
Block.

Average
Break-

We^t

lis.

lbs.

Pine

380

Oak

642-5

Oak

415

Pine

463-5

»»

Oak

465

Oak

»»

832-5

Pine

841

Oak

437-5

Oak

446

Pine

289

*»

Oak

661

Oak

420

Pine

612

Oak

433

Oak

556-6

The surfaces in contact were from 1 to 2 square feet The average strength decnned
generally with the increase of surface.

Adhesive Force of Nails forced into dry Christdinia Deal at right angiles
to grain of wood.*

Number

to the

lb.

Length

in
inches.

Length
forced
into the
Wood.

Force
in lbs.
required
to ex-
tract

Fine sprigs .

Threepenny brads .
Cast-iron nails
Wrought iron 6d. nails

99 » »>
99 9» 99

6d. „ .

4,560

8,200

618

380

189

0-44
0-68
1-25
1-00
2-50

2-00

0-40
0-44
0-50
0-50
1-00
1-50
2 00
1-60

187

827

580

320

The relative adhesion when driven transversely and longitndinally is in deal about 2 to

1, in elm about 4 to 8.
To extract a common sixpenny nail from a depth of 1 incti required —

lbs. lbs.

Beech, dry, across grain . .167 Elm, dry, across grain . . 827
Deal, Christiania, dry, do. . 187 Do. do., with grain . . 257

Do., do., with grain . 87 Oak, do., across grain . 507

Sycamore, green, do. . 818

From experiments by Lieutenant Fraser, RE., it appears that the holding power of

spike nails in fir is 460 to 780 lbs. per inch in length.

Haupt's MUUary Bridget,

* Tredgold, Bevan's Experiments.

SCREWS, 463

SCREWS.'

Wood-Borews (for flcrewing into wood) are made of metal, with sharp
or bevelled threads of dififerent forms. The most usual is shown by the
section Fig. 180.

The points are generally made sharp, so that they may penetrate the
wood ; the body of the screw is tapered, so that the deeper it is driven the
more tightly it will fill the hole ; the thread does not extend throughout the
length of the screw, but a considerable portion below the head is left smooth ;
the thread is formed to an acute angle, and there is a considerable pitch,
or distance between the threads.

Wood-screws are made in various sizes, and are divided as to strength into
three classes — Strong, Middling, and Fine.

Each length is made in from 15 to 30 different thicknesses, identified by
numbers.

The followiDg are the thicksesses or diameters corresponding to «ome of the nnmbers.
The thicknesses of the other numbers are interpolated between those given, varying in
succession abont -j^ inch : —

Number . . . 00 0 1 5 10 14 18 22 27 82 40

Thickness or diameter inji. iia 1 s 3 r 1 5

parts of an inch. .{VaifiiViTVtAliV* 8

The following Table shows the numbers or thicknesses in which iron wood-screws of
different lengths are made : —

Length from top «f head to point in parts of on inch.

i i J I f i 1 U iJ ij

Kumben made.
0tol6 ltol6 ltol6 ltol8 2to20 Sto24 4to26 5to28 6to30 7tod2

Length fh>m top of head to point in parts of an inch.
2 ai 2i 2} 8 3i 4 4i 5 6

Numbers made.
C||bo86 9to88 10to40 llto40 12to40 14to40 16to40 16to40 18to40 20to40

They are also classified according to the shape of their heads, as round-
headed, flat-headed (or countersunk), square-headed, cone-headed, ball-headed,
hexagon-headed, Gothic-headed, etc. etc.

Wood-screws are sold by the dozen or by the gross of 12 dozen. Those
varieties that are used for securing furniture to doors,
etc, should be, and by some houses are, supplied with the
furniture.

Flatheaded Screws (Fig. 180) are used in wood for fix-
ing all metal work or furniture whose thickness is sufficient
to admit of the head of the screw being countersunk into
them, so that the top of the head is flush with the face
of the metal to be screwed on.

Round-headed Screws (Fig. 181) are used where the
metal is too thin to be countersunk, as in some forms of ^ig^- ^80. 181.
locks, latches, etc.

* Sc. Screw-nails,

464

NOTES ON BUILDING CONSTRUCTION,

PatejU Pointed Screws are made with sharp points like that of a gimlet^ as shown ia
Fig. 1 8a They resemble the general description given above,

and are commonly used. ,

Fig. 182 shows an old-fashioned form of screw, with an
angular thread and blunt point, formerly known as NettUf old's
Patent Screw. The advantage claimed for it was that the top
side of the thread being horizontal or inclined upward, offers
great resistance to the screw being dragged forcibly out

Coach Screws are large heavy screws used where gr^at

strength is required in heavy woodwork, and for fixing iron

Fig. 182. work to timber. They have square heads, so that tbey can be

screwed home with a spanner or wrench, and a thread like that

shown in Fig. 183.

Handrail Screws are of a peculiar construction, and an intended
for joining together two lengths of a staircase handrail, as shown in
Figs. 184, 185.

.' fr— i

i ®.

Fig. 183.

Fig. 185.

Fig. 184.

Fig. 186.

The screws are from about 3 to 6 inches long, and are threaded at each end.

A square nut s is made for one end, and for the other end a circular nnt c, the latter
having at intervals deep nicks in its circumference to receive the end of a screwdriver.

The sketches at s and e show the form of these nuts. Deep slots are cut from the
under side to the centre of the handrail, through which they are dropped into the pofri-
tions 9 c in Fig. 184. A longitudinal hole, ab, is bored in the handrail, in which th«
screw is placed so as to pass through the nut at each end. The circular nut is tamed on
the screw by means of a screwdriver, so that the portion of the handrail in which it u
fixed is drawn toward the other until the joint between them is quite tight, dd are
dowels inserted to strengthen the joint

Fig. 186^ shows another form of handrail screw, known as a dowel-screw.

Brass Screws may be obtained in nearly every form, at about three times the cost of
iron screws. They are very useful for securing work which requires to be easily remoT-
able — such, for example, as the beads of sash frames (see Part I.)

Screws are made in several other forms besides those mentioned, for special purposes,
which need not be further referred to.

Screws for Metal are made in different forms from wood screws ; the
diameter of the screw is the same throughout ; the threads are close together.
V-shaped, but with the points of the Vs rounded off.

The great difference between screws for metal and those for wood is that
the latter, by the pressure of their threads against the fibres make a hole into
which they will fit exactly, whereas in metal such a hole has to be tapped of
the exact size to receive the screw.

Unless the internal thread of the nut, or of other metal into which the screw
is to be driven, exactly fits the thread of the screw, one or the other will
become distorted in screwing ; they will bear unequally upon one another,
and great loss of strength would ensue, together with difficulties in working.

^ Knight's Dictionary of MecJianies,

SCREWS.

465

Whitwortli's Standard Thread. — Screws for bolts and nuts, and for
metal work, are now generally made according to Sir J. Whit-
worth's standard, the same form of thread being used through-
out, and the same pitch and depth of thread being always used
for screws of the same diameter, so that both screws and nuts
are always interchangeable, which is an immense advantage in
case of loss or fracture.

WhitworiJCs Standard Screw Thread is shown in section in Pig. 187.
The sides of the thread are inclined at 65° to one another, and the sharp
angles at the top and bottom are rounded off, each to a depth of about ^
of the depth of the thread— thus the depth of the thread is only ) of
what it would be if the angles were left sharp.

The following Table shows the number of threads per inch for screws of different
diameters : —

Nnmber of
threads
per inch.

Diameter

of screw.

Dec. of inch.

Number of
threads
per inch.

Diameter

of screw.

Dec. of inch.

Number of
threads
per inch.

Diameter

of screw.

Dec. of Inch.

•100

•600

2-376

•125

•626

2-500

•160

•660

2-625

•175

'675

2-750

•200

•700

2-876

•226

•750

8-000

•260

•800

8-260

•275

•875

8-600

•300

•900

8-760

•825

l^OOO

4000

•850

1^126

.24

4-250

•375

1-260

4-500

•400

1-376

4-760

•425

1-600

5-000

•450

1-6-25

6-250

•475

1-760

6-500

•500

1-875

5-750

•625

2-000

6-000

•550

2-125

•675

2-260

WhitioorUCs Gas Threads. — For the screwed ends of wrought-iron gas-tubing and for
common metal work a shallower thread is used, as shown in the following Table : —

Diameter in inches . . i i I i i 1 lil li 1} 2

Number of threads per inch 28 19 19 14 14 11 11 11 11 11

Stove Screws are small screws of the form shown in Fig. 188, used for
uniting the different parts of stoves, grate fronts, etc. The heads are some-
times square, or cup-shaped, instead of being circular and flat as shown in
Fig. 188.

Adhesive Power of Screws. — Mr. Bevan experimented on iron wood-
screws 2 inches long, -^^ diameter at exterior of threads, threads yffir deep,
12 to the inch. These were driven into boards 4 inch thick. The force nHjuired Fig. 188.

B. C. — III 2 H

466 NOTES ON BUILDING CONSTRUCTION.

to «rtnct theiL wao — from hard woo«ls about 790 Iba., from aoft woodt aboot half that
tuDoimt.^

Making Screws is a subject which is beyond the scope of these Notes.

Wood screws ordinarily used by the carpenter and joiner are made by
machinery, the thread being turned in a sort of lathe. Very large aoews an
also turned in lathes in ordinary workshops.

Small metal screws are cut in ktwo plaiei^ larger ones with stocki and duf ;
and the threads to receive screws may be tapped by the aid of hard nuuia
taps, turned by means of a long double handle.

Bolts and Nuts are a good deal used by the carpenter for heavy work,
and are also required in connection with iron roofs, etc

They hardly come within the range of notes on mAt^rials, and ii ii
impossible, for want of space, to describe them at alL

1 Tredgold.

.APPENDIX.

SHORT NOTE ON THE

rnysicAL properties of materials, and on the loads

AND stresses TO WHICH THEY ARE SUBJECTED.

A DETAILED description of the physical properties of materiids, and of the loads and
stresses to which they are subjected, would be beyond the province of this Tolume,
espedaUy as the subject will be entered upon in Part IV. The following short expla-
nations of some of the terms employed in describing those properties and stresses may,
howcTer, be usefuL

Ix>ad. — ^The combination of external forces acting upon any structure is called the
load.

Dead load is that which is veiy gradually applied, and which remains steady.

Thus the weight of any structure is itself a dead load. Grain gradually poured on to
a floor, or water run slowly into a tank, would also be dead loads.

Live load is that which is applied suddenly, or is accompanied by shocks or vibration.

Thus a fast train coming on to a bridge, or a sudden gust of wind upon a wall or
roof, causes live loads.

Without going into the theory of the subject, it is sufficient to state that practically a
live load produces in most cases very nearly twice the stress and strain which a dead load
of the same weight would produce.

Therefore to find the dead load which would produce the same effect as a given live
load, the latter must be multiplied by 2.

This is called converting the live load into an equivalent dead load.

IUuttraiion,—A. bridge may weigh one ton per foot of area (t.e. dead load), and carry
a lire load of two tons per foot of area ; the equivalent dead load would be (1 + 2 x 2) »■
6 tons per foot of area.

Th€ hnaking load for any structure or piece of material is that dead load which will
just produce fracture in the structure or material.

The Factor of Safett is the ratio in which the breaking load exceeds the working
load (ie. the load which can be safely applied in practice). This ratio varies with the
nature of the load and the nature of the material, and is found by experience.

For the reasons steted above^ the factor of safety for a live load is generally taken at
double that for a dead load.

The factors of safety for several different kinds of iron structures are given at p. 326.
The following Table shows those reconunended by Professor Rankine ^ for general prac-
tice :—

Factors ow Sapirt.
Doad Load. Uve Load.

For perfect materials and workmanship ... 2 4

For good ordinary ma- f Metels 8 6

terials and work- < Timber . 4 to 5 8 to 10

manship iMasonry .... 4 8

When a load is mixed, is. partly live and partly dead, the live portion may be
converted into an equivalent amount of dead load, and the factors of safety for dead load
then applied to the whole ; or

A compound factor of safety may be deduced by applying the following rule : —

1 Ranklne'a U»^ RuU$ and Tabkt,

468 NOTES ON BUILDING CONSTRUCTION

Multiply the factor of safety for dead load by the fraction that the dead load is of the
whole load, and multiply the factor of safety for liye load by the ftaction that the lire
load is of the whole load. The sum of the results thus obtained will give the oompoiuid
factor of safety.

For example : — In a certain iron bridge the dead load is 5 tons per bay, the live loail
9 tons per bay ; the total load is therefore 14 tons per bay.

The dead load is ^ of the whole.

„ lire „ ^^ „

The factor of safety for dead load is 8, and for liTe load Ia 6.

The compound factor of safety will be equal to

lA X 8) + (A X 6) = tt = 41! = say 6.

Th€ vHJrking load is the greatest dead load the material can with safety bear in prac-
tice. It is found by dividing the breaking load by that factor of safety which ia fouDd |
to be suitable to the particular case. j

The proof load is the greatest load that can be applied to a piece of material to prove |

or test it by straining it to the utmost extent without producing permanent deformstioB I

or iivjury, ».e. not beyond the elastic limit (see p. 829).

The breaking load or working load may be either live or dead, or a combination of both,
but for coDvenience it is usual to reduce it all to an equivalent dead load, by doubling
the live load and adding it to the dead load.

StresBes. — Stbess and Strain are words often used indifferently, either to mean the
alterations of figure produced in a body by any forces, or to mean the forces prodndng
those alterations.

Of late years, however, the word strain has been taken to mean only the alteratkmt of
form caused by the forces, and stress to mean the forces producing these altemttona.

Materials are subject to the under-mentioned stresses, which produce strains, and (whec
carried far enough) fracture as stated.

Btresaes. Strain.

Tensile or ) \ Stretching

Pulling j * ' * } Elongation

Compressive or ) \ Shortening

Thrusting i * ' I Squeezing
Transverse or Bending . Bending .

Shearing .... Distortion

To™^"j . . . Twiating.

Mode Of
Fractore.

I Tearing.

I Crushing.

Breaking acroasL
Cutting asunder.

I Twisting or wrsnching
asunder.

LUensity of stress is the amount of stress on a given unit of surface, and ia expressed ia
Iba., or sometimes in tons, per square inch.

The ultimate stress, or breMng stress, on any piece of material ia the aUesa pro-
duced by the breaking load.

The proof stress is the stress produced by the proof load.

The working stress is that produced by the working load. It is always much smaller
than the proof stress, in order to leave a maigin of safety to cover defects in material, etc.

A bar of 1 square inch sectional area might have a breaking strength of twenty tons, but
the working stress to which it was subjected might be only five tons. The factor of
safety in that case would be four. Its proof strength might be ten tons, this being tht
weight the bar could bear without exceeding the elastic limit.

Strength. — Tenacity or tensile strength is the resistance offered by material to Usisioo,
that is to a stress tending to tear it asunder, as, for example, in the case of a vertical rod
having a weight suspended from it, or in the tie rod of a roof, or the tension flange of a
girder.

Strength to resist crushing Is the resistance offered by material to a compressive stress,
thrust, or pressure. Such a stress tends to make it shorten, and eventually to cniah it
Examples of this stress occur in the case of a short column supporting a weight, or in a
strut which keeps two tottering walls from falling toward each other, or in the compras-
sion flange of a girder.

It should be observed, however, that long columns and stmts tend to fail by bending
outwards in the centre and then breaking across. This form of failure is caUed buekHng,

Transverse strength is the resistance offered by a body to forces acting across it, tend-
ing to bend it, and eventually to make it break across. Thus a beam supported at both
ends and loaded over any part of its length, bends downward and tends to break i

APPENDIX. 46Q

When a body is subjected to transTene stress, some parts of it are in eompression,
some in tension, and others ate exposed to a shearing stress, therefore transverse stress is a
combination of these throe stresses. A beam secured at the ends, and subject to pressure
fipom below, bends upwards and also tends to break across.

Shearing strength is the resistance offered by a body to being shorn, that is, to being
distorted by one part of it sliding on another part Thus, if two lapped plates united by
a rivet be drawn longitudinally in opposite directions, the rivet would tend to shear by the
upper plate sliding upon the lower.

TorgioTuU Hrength is the resistance offered by a body to being broken by torsion, ie.
twisting. This stress finequently occurs in madunery, but not in structures connected
with buildings.

Strength to resist hearing is the resistance offered by a material to being indented, or
partially crushed by another body pressing upon it. Thus, the shank of a rivet may be
indented by the plate bearing upon it, or the edge of the hole in the plate may be in-
dented by the rivet ; again, a beam may be indented by the end of a post bearing upon
it Indentation by bearing is merely one form of crushing.

The ultimate strength of any material is the intensity of stress required to produce
fracture in any specified way.

The proqf strength is the intensity of stress required to produce the greatest strain of
a specific kind without injuring the strength of the material.

Pliability is the tendency of a body to change its form temporarily under diflCurant
stresses.

StifEheas or Bigidity is the reverse of pliability, and expresses the disinclination of
some bodies to change their form under stresses.

Thus stones and bricks are rigid up to a certain point

Slastioity ' is the property which all bodies have (in greater or less d^free of perfec-
tion) of returning to their original figure after being distorted (i,e. strained) by any
kind of stress.

When the original figure is completely and quickly recovered, the elasticity is said to
hepetfeet.*

When the original figure is not completely recovered, but remains permanently dis-
torted to a certain extent, the elasticity is said (o be imperfect^* and the distortion pro-
duced is called a permanent set, or set.

It has been found by experiment that the elasticity of most building materials is
practically perfect up to a certain point. When stresses below this point are applied and
removed, the strain, distortion, or change of figure is only temporary. There is no
appreciable set Stresses above this point, however, cause sets (see p. 330).

The Elastic limit of a material is the maximum bitensity of stress that can be applied
to it without causing an appreciable set

A ModvXus 0/ Elasticity is a number representing the ratio of the intensity of stress (of
any kind) to the intensity of strain (of any kind) produced by that stress, so long as the
elastic limit is not passed.

The modulus of tensile elasticity is found by dividing the tensile stress in lbs. per
square inch of sectional area by the elongation (produced by that stress) expressed as a
fraction of the length of the body.

Thus, if a weight of one ton hung from an iron bar produce an elongation of yr^ of
the length of the bar, the modulus of elasticity of that bar will be 2240 lbs. -r- ttWv ™
26,880,000 lbs. This is rather lower than the modulus of average wrought iron.

Similarly the modulus of compressive elasticity is found by dividing the compressive
stress in lbs. per square inch of section by the contraction (or rather shortening) produced
by that stress, expressed as a fraction of the length.

In most building materials the modulus of tensile and that of compressive elasticity
are practically equid to one another so long as the stresses do not exceed the elastic
limit

1 The elastidty here referred vo is aometlmea called elasticity of flgoie ; there is also an elasticity
of volume, which need not he considered in connection with bnilding materials.

t Hr. Eaton Hodgldnson's investigations seem to show that the elasticity of every solid is really
imperfect that the slightest strain prodaeea a set Up to a certain limit of stress, however, the aetM
produced are so small that they cannot be measnred with ordinary iustroments, and therefore
within that limit the elasticity may be said to be ttntibly perfect for all practical purposes (see
p. 817X

s Becaose the elongations and shortenings under equal stresses are pnustically equal up to tho
•bstte limit : beyond that they are iiresuUir.

470 NOTES ON BUILDING CONSTRUCTION.

The modulus is generally denoted by the letter E, and its value is given in the tables,
because it is useful in calculating the stiffness of beams and girders.

In advanced works on applied mechanics several other moduli are used, vbich,
however, are not required in ordinary calculations, and need not be referred to in these
Notes.

Deflection is the bending caused by a transverse stress. If the intensity of stres \»
below the elastic limit the deflection will disappear when the stress is removed, bot if tbe
intensity of stress be in excess of the elastic limit a permanent aei will remain.

Beailienoe is a term used to express the quantity of "work done" in deforming a
piece of material (up to the elastic limit) by the application of any kind of Btress. It is
equal to the product of the alteration of figure into the mean load which acts to prodoce
such alteration. Thus the resilience of a bar in tension is found by multiplying the
proof load by half the corresponding elongation.^

Besilience may be tensile, compressive, transverse, shearing, etc., according to tlic
nature of the stresses imposed.

Malleability is the property of being permanently extensible in all directiooslr
hammering or rolling.

Ductility is the property of being permanently elongated or drawn out under a ten-
sile stress higher than the elastic limit. The change of form remains after the force is
removed. It is therefore the converse of elasticity.

Brittleneas is the inclination to break suddenly under any stress.

Hardness is the property of resisting indentation, or wear by friction.

Softness is the converse of hardness.

Toughness is a term defined in several different ways.

Mr. Stoney defines it as the union of tenacity with ductility.

Ultimate toughness is defined by Professor Rankine as being the greatest strain which
a body will bear without fracture ; proof toughness the greatest strain it will bear with-
out injury. He points out that malleable and ductile solids have ultimate toogfanes"
greatly exceeding their proof toughness, but that brittle solids have their ultimate sod
proof toughness equal, or nearly equal.*

Fusibility is the property of becoming fluid when subject to heat. The temperatoie
at which this is effected differs in each metal, and is called its melting pcint,

Weldability is the power possessed by some metals of adhering firmly to portioai o(
the same — or to other metals — when the two pieces are raised to a high temperatore and
hammered together.

Hardening is the property of becoming very hard when heated and quenched.

Tempering is lowering the degree of hardness after the process just mentioned, \f3
reheating and cooling at different temperatures (see p. 307).

1 Rankine*8 Applied Mtchania. s Raukine's V^ful Rules and TabU$.

INDEX.

Abercarne sandstone quarries, 41.

Aberdeen granite, resistance to wear,
84; strength of, 81.

Aberdeenshire granite quarries, 16,
20, 21.
„ serpentine, 34.

Aberllgeney slate quarries, 31.

Aboyne marble quarries, 53.

Absorption of bricks, 110, 114 ; of
firebricks, 124 ; of granular and
shelly limestones, 67 ; of lime-
stones, 83 ; of sandstones, 36, 83 ;
of slates, 25; of stone, 11, 83.

Acacia, common, 379 ; appearance,
characteristics, and uses of, 379,
404 ; weight and strength of, 404.

Acetate of copper and lead as driers,
413.

Acid, ferro-fiilicic, as a preservative for
stone, 80.
„ test for stone, 11.

Adds, action of various, on stone, 3.

Ackworth sandstone quarries, 41.

Action of foreign constituents on limes
and cements, 230.
„ of water on lead, 342.

Adunantine clinkers, 109; size and
weight of, 112.

Adaie limestone quarries, 71.

Adhesive force of nails, 462.
„ power of screws, 465.

Adie's cement- testing machines, Ka 1,
182 ; No. 2, 184.

Admiralty tests for wrought iron,
280 ; for Landore steel, 310 ;
for steel plates, 310.

Adulteration in Portland cement^
187 ; of red lead, 408 ; of white
lead, 407.

African green, 417.

„ oak or teak, 376.
Agents whch destroy stone, 10.
Agglom^, Coignefs B4ton, 220.
Aggregate for concrete, 210 ; materials
used for, size and shape, 211;
packing, 212.
Agricultural drain pipes, 130.
Air-slaking of quicklime, 146.
Air bricks, perforated, 134.

„ flues, combined smoke and, 136.
Aish stone, position in quarry, 7, 61.
Aislaby sandstone quarries, 39.
Alburnum or sap wood, 359.
Alder, 377 ; appearance, characteris-
tics, and uses of, 377 ; strength,
weight, etc, of, 404.
Alkalies in clay for brickmaking, 87 ;
colouring action of, 89 ; hydraulic
properties of, 148.
Alkaline silicates as a preservative for
stone, 78.
„ „ for artificially pro-

ducing hydrauli-
city, 180.
Alloys, 348-351 ; Babbit's metal, 350 ;
bell metal, brass, bronze
(aluminium and phosphor),
gun metal, and Muntz metal,
350 ; sterro-metal and white
brass, 350 ; table of com-
position of various, 350.
„ of lead and tin, melting points
o^ 355.
Altmorer sandstone quarries, 47.
Alumina in clay for brickmaking, 86,
88; in fireclay, 122.
„ soluble oxalate of, action o^
on limestones, 80.
Aluminium bronze, 350.
Amber, 430 ; varnish pale, 434.

472

INDEX.

Ambleside slate qnarries, 31.
American ash, 378.

„ concrete-mixer, 229.

„ larches, 372.

„ oak, 375 ; weight, strength,

etc., of, 404, 405.
„ pine, 368 ; red, 368 ;
yellow, 369 ; weight,
strength, etc, of, 404.
„ spruce, 372.
„ tar, 454.

„ timber, marks and brands
on, 387.
Analyses of cUys for making fire-
bricks, 122.
„ of magnesian limestones, 5 8.
Analysis of brick earth or brick, 143;
of Chilmark stone, 64 ; of Has-
sock, 66 ; of Kentish Rag, 66 ; of
limes and cements, 239 ; of mag-
nesian limestones, 59 ; of Port-
land stone, 60 ; qnantitatiye, of
a brick earth or brick, 144.
Ancaster limestone, absorption o^ 83 ;
colour, weight, etc, of, 68 ; quar-
ries, 68 ; strength of, 81.
Ancient marbles, 51.

„ serpentine, 34.
Angle brick, hollow, 117.

„ iron, Admiralty tests for, 280 ;
forge tests for, 280 ; market
forms and sections of, 284,
285 ; prices current for,
291-293, 294 ; tensile
strength and ductility of,
318.
Anglesea granite quarries, 18.
„ limestone, strength of, 81
„ marble quarries, 53.
„ serpentines, 34.
Angliham limestone quarries, 71.

„ marble quarries, 54.
Angus Smith, Dr., on carbonic acid
in air, 3 ; process for preserving
cast-iron pipes, 336.
Anim^ gum for varnish, 431.
Annealing steel, 309 ; plates, effect

of, 325.
Annual rings or layers in trees, 358,
362.

Anston marble quarries, 69.
Anti-corroeion paint, 426.
Antimony, effect o^ on wioo^t iron,
263.
„ sulphide of, as a snbstitate
for red lead, 408.
Antique, Vert, serpentine, 34.
Ants which destroy timber, 402;
black carpenter, dusky, white, and
yellow, 402 ; protection against
white, 402.
Antwerp blue, 414.
Apoenite, 75 ; absorption of 83.
Application of varnish, 433.
Arbroath paving, tensile strength of,
82.
„ sandstone qoairies, 46.
Arch bricks, 116.
Archangel deals, 367.
Ardbraccan limestone quarries, 71.
Arden lime, 155 ; weight o^ 256.
Ards-Caledon limestone quarries, 71.
Ar^nes, 196.

Argyleshire granite, strength o( 81.
Armagh (Navan) limestone quarriesi

71.
Arran granite quarries, 20.
Arsenic, effect of, on iron, 263, 276,

„ yellow, 415.
Arsenite of copper, test for, 446.
Artificial cements, 156, 159 ; bow
manufactured, 1 59 ; Poit-
land, 1 60 ; selenitic, 1 79.
„ hydraulic lime, 155.
„ marbles, 76, 247-248 ; par-
ing, 76.
„ stone, 74-76 ; apoenite, 75 ;
Chance's, 76;Ransoine's»
74 ; Rusfs vitrified
marble, 76 ; silicated,
Sorel, and Victoria, 76.
„ pozzuolanas, 196.
Asbestos, 456 ; paints, 428;
concrete, roofing, sheathing, etc,
456.
Ash, 377 ; age at which it should be
felled, 360 ; appearance, 877;
Canadian and American, 378;
characteristics and uses, 378;
resistance o^ to crushing and

INDEX.

473

sheariDg, 406 ; weighty strength
eta, of, 404.

Ash, Scotgate, sandstone, 37.

Ashford marble quarries, 52.
„ slate quarries, 32.

Asphalte, 250-263, 466 ; advantages,
disadvantages, characteristics, and
uses of, 250 ; Bamett'sliqaid,253;
British patent, 253 ; Brunswick
lock, 253 ; Claridge's patent or
Seyssel, 251 ; fibrous, 455 ; in-
ferior, 253 ; laying, 250 ; Lim-
ner, 253 ; mastic and Montrotier,
253 ; pitch in, 263 ; Pyrimont
and Seyssel, 251 ; Seyssel, 251 ;
Trinidad, 263 ; Val de Travers,
252 ; varieties in the market,
251.

Asphalted roofing felt, 455.

Assynt marble quarries, 53.

AtemshiU slate quarries, 32.

Atkinson's cement, 169 ; strength o^
201.

Atmospheric influence on stone, 3 ;
on timber, 397.

Aubigny stone, 66.

Auchray sandstone quarries, 46.

Auston limestone, strength of, 81.

Australian mahogany, 381.

Aydiff limestone quarries, 70.

Babbit's metal, 360 ; composition of,
351.

Backs, 91.

Bacon tier, position of, in quarry, 7,
61.

Bagnalstown granite quarries, 21.

Baile/s and Reid's cement-tester, 187.

Bakewell marble quarries, 52.

Baldwin Latham's directions for form-
ing bends and junctions, 132.

Balk timber,. 364, 366.

Ballachulish marble quarries, 53 ;
slate quarries, 32.

Ballakiltry limestone quarries, 71.

Ballast used for concrete, 211.

Ballinafad limestone quarries, 71.

Ballinahinch serpentine quarries, 34.

Ballinasloe limestone quarries, 71.

Ballingdon bricks, 107.

Ballintemple limestone quarries, 71.

Ballisadare „ „ 71.

Ball's Green „ „ 68.

Bally Enocken and €k>lden Grove
granite, quarries, 21 ; strength
of, 81.

Bally connell limestone quarries, 71.

Ballyheigan sandstone quarries, 47

Ballykiloboy marble quarries, 54.

Ballymore „ „ 54.

Ballyshannon limestone quarries, 71

Balsam, Canada, 412.

Balsams, 430.

Baltic fir, 384.

„ planks, deals, and battens, marks

and brands on, 384, 385.
„ spruce, 371.

„ whinstone, resistance to wear,
84.

Baltimore oak, 375.

Banffshire serpentine, 34.

Bangor Royal Slate Co. quarries, 31.

Bannis Kirk sandstone quarries, 46.

Bar iron, best, best best, etc., 275 ;
different qualities of, 274 ; fiat,
284 ; market forms of, 284, 285 ;
merchant, 274 ; price of, 290 ;
puddled, 274 ; rail, market forms
of, 286 ; rolled, tensile strength
and ductility of, 318 ; scrap, 275 ;
Swedish, strength of, 279.

Bar steel, tensile strength and duc-
tility of, 323.

Barbadoes sandstone quarries, 46.

Bardiglia marble quarries, 55.

Bardon Hill stone, 23.

Barff*s process for preservation of iron,
336.

Bargate sandstone quarries, 39.

Barley Hill limestone quarries, 71.

Bamac Mill „ „ 68.

Bamack limestone, strength of, 81.

Barnard Castle sandstone quarries, 41.

Bamett's liquid asphalte, 253.

Barrow lias lime, strength of, 181.

Baryta, solution of^ as a preservative
for stone, 80.
„ sulphate of, test for, 408.

474

INDEX.

Basalt^ 23 ; bulkmen of, 84 ; dism-
tegrated. Band from, 196.

Baaaltfl^ strength of, 81.

Baaebed roach, 8, 62 ; position o^ in
quany, 7, 61.
„ stone, 8, 60, 63 ; position of,
in quarry, 7, 61.

Baaes for paints, 407-409.

Basic process, 305.

Bastard roach, 8, 60, 62.
„ stucco, 247.

Bath stone, 59 ; absorption of, 83 ;
colour, 59 ; geological position of,
59 ; quarries and quarrying, 59 ;
seasoning and weathering, 59 ;
size and uses of, 59 ; strength of,
81 ; varieties in common use, 59,
60.

Bats, brick, 106.

Battens, 364, 367 ; Baltic, marks and
brands on, 385.
„ for slates or tiles, 453.

Bay or cluster-fruited oak, 373.

Beading iron, 286.

Bearing and shearing stress of steel,
329.
„ strength of wroughtiron, 328.

Beart's patent bricks, 107.

Beaulieu bricks, 107.

Bed of limestone, natural, 57.

Beds of Kentish rag, 64-66.
y, of stone, natural, position in a
building, 9.

Bedston sandstone quarries, 40.

Beech, 376 ; appearance and charac-
teristics of, 376 ; uses, 377, 403 ;
weight, strength, etc, of, 404.

Beer sandstone quarries, 39.

Beeswax dissolved in naphtha as a
preservative for stone, 78.

Beetles, wood, protection against 403.

Belgian zinc gauge, 346.

Bell metal, 350 ; composition of, 350 ;
properties of, 354.

Belleek granite quarries, 21.

Belton sandstone quarries, 40.

Bends for pipes, 132.

Benduff slate quarries, 32.

Benledi „ „ 32.

Benmore sandstone quarries, 47.

Berlin blue, 414.

Beny Pomeroy marble quarries, 52.

Bessemer iron, 263 ; pig, 295 ; pro-
cess of making steel, 304 ; steel,
brands on, 313 ; steel, tensile
strength, elastic limit, and ducti-
lity of, 320-322 ; uses of steel,
305.

Beasemer's gold paint, 451 ; patent
steel for tools, strength and duc-
tility of; 322.

Bethell'a process for preserving timber,
394.

B^ton, 220; agglom^ Goignet's,
220.

Bideford bkck, 414.

Billing's chimney terminals, 136.

Binnie sandstone quarries, 41 ;
strength of; 81 ; tensile strength
of; 82.

Birch, weight, strength, etc., o^ 404.

Birmingham metal gauge, 356 ; wire
gauge, 355.

Bimam slate quarries, 32.

Birsmon granite, 20.

Bismuth, properties of, 354.

Bitumen of Judea, 253.

„ felt, inodorous, 455.

Bituminous paints, 428.

Black bricks, 108.
„ Brunswick, 435.
„ carpenter ant, destruction of

timber by, 402.
„ oxide of iron paint, 425.
„ stain, 436.

„ varnish for metal work, 435.
„ walnut stain, 436.

Blackband iron ore, 258.

Blackenston (Dartmoor) granite quar-
ries, 18.

Blackhill granite quarries, 20.

Blacks for colouring, 413 ; blue, bone,
Frankfort, Grant's or Bideford,
ivory, lamp, and vegetable, 413.

Blairgowrie marble quarries, 53.

Blazing saws, 309.

Blessington granite quarries, 21.

Blister steel, 302 ; forging of, 333 ;
uses o^ 303.

Block tin, 348.

INDEX.

475

Blocks, invert and junction, 136 ; of
terra cotta, 125 ; slate, 29 ;
sleeper, 135.
Blood, dragon's, for vamishes, 431.
Bloom, 273, 275.
Blown plate glass, 441.
Blue, Antwerp, 414.
„ black, 414.

„ bricks, Staffordshire and Tipton,
108.
Blue lias lime, strength of, 181 ;
weight of, 256.
„ Prussian, 414.
Blues for colouring, 414 ; Antwerp,
Berlin, Bremen or verditer, celes-
tial or Brunswick, Chinese, cobalt,
damp, Haerlem, indigo, 414 ;
Prussian, 414 ; Roman, Saxon,
and smalt, 414.
Board of Trade, opinion of committee
appointed by, as to
use of steel, 328.
„ „ rule for working

stresses on wrought
iron bridges, 328.
Boarding oak, clap, 376.
Bodham granite quarries, 20.
Bodmer's concrete bricks, 109.
Body copal varnish, best, 433.
Boiled linseed oil, 411.
„ oil to be used with zinc paint,
411.
Boiler plates, price of, 290; extras
charged for, 292, 294.
„ Beatings, 119.
Boilers, cement for attaching hair felt

to, 455.
Boiling and steaming timber, 390.

„ linseed oil as a solvent, 431.
Bolsover Moor limestone, quarries,

70 ; strength of, 81.
Bolton Wood sandstone quarries,

41.
Bolts and nuts, 466.
Bonding bricks, Jennings', 135.
Bone black, 414.
Borders for wall papers, 446.
Boscastle slate quarries, 31.
Boss granite „ 18.

Boston marble „ 54.

Bottom Quarry sandstone quarries, 40.
Boucherie's process for preservation of

timber, 395.
Bower's process for preservation of

iron, 336.
Box Ground Bath stone, 60 ; absorp-
tion of, 83 ; strength of, 81.
„ Hill limestone quarries, 68.
Brackenhill sandstone quarries, 41.
Brackemagh limestone „ 71.
Bradford sandstone „ 41.

Brads, 8, 458 ; cabinet^ glaziers', and

joiners', 459 ; size and weights of,

461.
Braichgoch slate quarries, 31.
Bramham Moor limestone, quarries,

70 ; strength of, 81.
Bramley Fall sandstone, 37 ; quarries,

41; strength of, 81, 82.
Brandon Hall sandstone quarried,

41.
Brands on iron, 295-300 ; common,
298; effect of mixing dif-
ferent, 317 ; good marked,

297 ; list, 296 ; Midland,

298 ; North of England,
295, 299 ; pig, 295 ; Scotch,
295, 300 ; Shropshire, 295 ;
Staffordshire, 296, 298 ;
Swedish, 300 ; Welsh, 295,

299 ; wrought, 296 ; York-
shire, 295, 299.

„ on steel, 312 ; Bessemer, cru-
cible cast, shear, double
shear, and Landore, 313.
„ on timber, 383-387 ; Ameri-
can, 387 ; Baltic iir, 384 ;
Baltic planks, deals, and
battens, 385 ; Norwegian,
387 ; remarks by Building
New on importance of a
knowledge of, 387 ; Rus-
sian and Finland deals,
385 ; Swedish, 385.
Brard's test for stone, 11, 36.
Brass, 349 ; colour and properties of,
354, 349 ; composition of, 349 ;
contraction of, in cooling, 355 ;
lacquer for, 434 ; screws, 464 ;
weight of, 357 ; white, 351.

476

INDEX.

Brazil wood lake, 416.

Brazing, 352, 353.

Breaking weights of briquettes of

selenitic cement mortar, 208.
Breeze from gasworks used for con-
crete, 211.
Bremen blue, 414.
Brick clays, analysis of, 88.
„ earths, 85-89 ; characteristics
of different kinds, 68 ; clas-
sification of, practical, 87 ;
constituents of, 85 ; good,
composition o^ 88 ; prepara-
tion of, 90.
Brickmaking, 89-120.
Bricks, 85-124; absorption of, 110,
114 ; arch, 116 ; Ballingdon,107;
bats, 106 ; bearing off, 92 ; Beart's
patent, 107; Beaulieu, 107; black,

108 ; blue Staffordshire and Tip-
ton, 108; Bodmer's concrete, 109;
boiler seatings, 119 ; bonding,
135 ; broken, used for concrete,
199; bull-nosed, 118; buU-
heads, 116 ; burning of, 94 ;
burning in Bull's patent semi-
continuous kiln, 103 ; burning in
clamps, 95; burning in Hoffmann's
kiln, 101 ; burning in kilns
and Scotch kiln, 98 ; channel,
119 ; characteristics of good,
110 ; classification of, 103 ; classi-
fication of clamp-burnt, 104
classification of kHn-bumt, 106
colour of, 89 ; colouring, 120
compass, 116 ; concrete, 109
coping, 119 ; cornice, full, hol-
low, and moulded, 118 ; cutters or
rubbers, 103, 104 ; different forms
of, 116-120; double cant, 118;
drab, 108 ; drain, 119 ; dressed,
94 ; drying in sheds, 92 ; drying
out of doors, 93 ; dust, 108 ;
Dutch clinkers, 109 ; enamelled,

109 ; Farehamred, 108 ; freedom
of, from flaws and lumps, 110;
frog in, 94 ; Qault, 107 ; grizzle
or place, 104 ; gutter, 119 ;
hacking, 93 ; hand moulding, 91 ;
Hoffmann's kiln for burning, 101 ;

hollow, 117 ; in a wall, strength
of mortar as compared with, 1 88 ;
kerb, 119; Lancashire red pressed
facing, 109 ; machine moulding,
93 ; malm for making, 91 ; malms,
price of, 105; manger, 120;
method of distinguishing clamp-
burnt, kiln-burnt, and machine-
made, 111 ; moulded, 109 ; names
of different varieties, 1 04 ; Not-
tingham patent, 108 ; ordinary
building, 103, 104, 116 ; pallette,
109; i>aying, 118; perforated,
117; perforated air, 134; Peth^s
ornamental, 109 ; plinth course,
118 ; polished, 94 ; pressed, 94 ;
price of, 105 ; purpose-made, 116;
quality of clamp-burnt^ 96 ; red,

108 ; round-ended, 118 ; ialted,

109 ; sand moulding, 92 ; ecint-
ling, 93 ; shape and surface, 1 10 ;
side wedge, 116 ; sill, 120 ; sink,
119; size of. 111, 112; slag,

110 ; slop moulding, 92 ; soaps,
117; sough, 119; splay, 118;
splits, 117 ; Staffordshire bine,
108 ; stock, force necessary to tear
apart, 171; strength of, 1 15, 116 ;
strength of, in a wall, compared
with mortar, 188 ; string coarse,
118 ; Suffolk white, 107 ; table
of absorption and weight of^ 114 ;
table of resistance of, to compres-
sion, 115 ; table of sizes and
weights of, 112 ; tensile strength
of, 116 ; tests for, 113 ; texture
of. 111 ; time of burning in
clamps and kilns, 96, 99 ; Tipton
blue, 108 ; transverse strength of^
116; tubular, 117; tunnel-head,
119; underbumt and mis-shapen,
103, 104 ; varieties of, in the
market, 106 ; washed, 91, 105 ;
weight of. Ill, 112, 114 ; white,
106 ; Wood's patent concrete, 110.

Brickwork, strength of columnso^ 116.
Bridge rail, 286.
Bridston marble quarries, 52.
Bright fronts, bricks, 105 ; price of,
105.

INDEX.

477

Bright ironwork, preservation of, 337.
„ pig-iron, 264.
„ red, 416.
Brighton green, 417.
Brights, American yellow pine, 370.
Brilley sandstone quarries, 46.
Briquette of Portland cement^ 172 ;
method of making, 172 ; shape
of, 173.
Briquettes of selenitic cement mortar,

breaking weights of, 208.
British asphalte, patent, 253.

„ iron, extras charged on, 291.
„ iron ores, 257.
„ oak, 373.

„ plate glass, 441 ; polished plate
glass, 442 ; sheet glass, 440.
Brittleness, definition of term, 470.
Brixham limestone quarries, 71.
Brocatella marble quarries, 55.
Brodsworth limestone, quarries, 70 ;

strength of, 81.
Broken brick and stone used for con-
crete, 211.
Broomjard sandstone quarries, 46.
Bronze, 349 ; aluminium and phos-
phor, 350 ; composition of, 351.
Bronzing bright ironwork, 337.
Broomhall Company's patent roofing

tiles, 140.
Brown and Company's steel, strength

of, 321.
Brown bed, Chilmark stone, 64.

„ haematite, 258.
Browns for colouring, 415 ; for com-
mon colours, 423 ; for hard spirit
varnish, 434 ; ochre, pink, purple,
Spanish, and Vandyke, 4 15 ; oxide
paint, purple, 425.
Brown's HiU limestone quarries,

71.
Brunswick black, 435 ; blue, 414 ;

green, 417 ; rock asphalte, 253.
Brunton sandstone quarries, 41.
Buckled plates. Mallet's, 287.
Building bricks, ordinary, 104.
„ clamps for burning bricks, 95.
„ position of a stone in a, 4.
„ stone, characteristics o^ 2.
9 terra cotta, 126.

Buildings in which Chilmark stone is
used, 64.
„ in which Portland stone is

used, 63.
Built-up plate-iron girders, working

stresses for, 327.
Bulb iron, 286 ; forge tests for hot

and cold, 282 ; price of, 312.
Bulk of concrete produced from given
quantity of materials, 218.
„ of mortar produced from given
quantity of materials, 205.
Bulkiness of different classes of stone,

84.
Bull-nosed bricks, 118.
Bull's patent semi-continuous kiln for

bumiug bricks, 103.
Burdiehouse limestone quarries, 71.
Burdon Hill granite, 18.
Burghead sandstone quarries, 46.
Burham bricks, size and weight of,
112.
„ lime, strength of, 181.

Burlington Slate Company's quarries,

31.
Burnet's, Sir "Wm., process for pre-
serving timber, 396.
Burning bricks, 94 ; comparative
advantages of kiln and
clamp, 99 ; in Bull's
semi - continuous kiln,
103 ; in clamps, 95 ;
in cupolas or ovens, 103 ;
in Hoffmann's kiln, 101 ;
in kilns, 98 ; in Scotch
kiln, 98 ; time of, 96, 99.
„ of fireclay ware, stoneware,

and terra cotta, 130.
„ of limes and cements, 188-

194 ; general remarks
on, 192.
Burnish gold size, 450.
Bumstall (Longford) slate quarries, 3 1 .
Burnt clay as a substitute for sand,
196 ; for concrete, 210.
„ sienna, 415 ; umber, 415.
Burr, soft, position in Portland quar-
ries, 7, 61.
Burrs, 96, 105.
Burtley granite quarries, 18.

478

INDEX,

Burton sandstone quarries, 41.
Bushel, striked and trade, used for
cements, 158.

Cabinet brads, 459.

Cadebj limestone, quarries, 70 ; re-
sistance of, to crushing, 81.

Caen stone, 66.

Caimgall granite quarries, 20.

Caithness paving, tensile strength of,
82.

Calcination, definition of term, 145 ;
effects caused by different degrees
of, on lime and cement stones,
234 ; of hydraulic limes and
cements, 232 ; of ores, 257 ; of
pure or fat lime, 230.

Calcareous clays, 87.

„ sandstones, 36.

Calcium hydrate, 145.

Calderwood cement, 159.

Calp lime.<itone, 155.

Calverley sandstone quarries, 39.

Calverly Wood „ „ 41.

Cambrian sandstone „ 47.
„ Slate Co.'s „ 31.
„ slates, 25, 30.

Camel slate quarries^ 31.

Cammell and Co.'s steel, ductility of,
321.

Canada balsam, 412.
„ rock elm, 379.

Canadian ash, 378 ; weight, strength,
etc., of, 404.
„ or red oak, 375.

Cann slate quarries, 31.

Cant bricks, double, 118.

Cap rising, position in quarry, 7, 61.

Capped pipes, 133.

Carbon, amount of, in cast iron, 261,
337 ; in pig iron, 261 ; in steel,
261, 301, 337 ; in wrought iron,
261, 337 ; effect of, on cast iron,
261 ; influence of, on strength of
steel, 325 r percentage of, in iron
and steel, 337.

Carbonaceous matter objectionable in
brick clays, 87.

Carbonate of Hme in brick clays, 88 ;
in limestones, 146.
^ of magnesia as a consti-

tuent of limes and ce-
ments, 148, 156, 237.
Carboniferous limestone, hydraulic
Hmes from, 155 ; quarries, 70,
71.
Carlin Enowse stone, 23.
Carlisle sandstone quarries, 40.
Carlow marble „ 64.

Carminated lake, 416.
Carmine as a colouring pigment^ 415.
Camsew granite, 18.
Camsore Point granite quarries, 21.
Carpenter ant, black, destruction of
timber by, 402.
^ bee, destruction of timber

by, 402.
Carpentry, large timbers in, timben

suitable for, 403.
Carrara marble quarries, 55.
Carriage varnish, best pale copal

433 ; second, 434.
Carrick sandstone quarries, 47.

„ Slaim limestone quarries, 71.
Carrickcocagh „ „ 71.

Carrickreagh sandstone „ 47.

Carrigacrump limestone „ 71.

Carton pierre, 249.
Case-hardening, 309.
Cashel limestone quarries, 71.
Cast iron, 264 ; amount of carbon in,
261, 337 ; cement, 452 ; char-
acteristics and ujses of, 338 ;
chilled, 266 ; corrosion of,
335 ; effect of repeated re-
meltings and temperature on
strength of, 316 ; effects of
arsenic upon, 263, of carbon,
261, of copper, 263, of
manganese, phosphorus, and
sulphur, 262, of titanium,
263 ; elastic limit of, 331 ;
factor of safety for, 326 ; grey,
265 ; how obtained, 265 ;
influence of various circum-
stances upon the strength o^
316; malleable, 266, 338;
Matheson's remarks on tests

INDEX.

479

for, 272 ; mottled, 265 ; pipes,
examinations of castings of,
271 ; preservation ofj by paint-
ing, 336, Dr Angus Smith's
process of preserving, r 336 ;
properties of, 354 ; strength
of, 315 ; tests for, 271 ; to
distinguish grey firom white,
265 ; toughened, 266 ; weight
of, 357 ; white, 265 ; working
stresses for, 327.
Oast lead, 341.
„ nails, 457.
„ rough, 247.

„ steel, 303 ; crucible, 303 ; brands
on crucible, 313 ; for chisels,
325 ; forging, 333 ; strength
of, 320.
Casterton limestone quarries, 68.
Casting, contraction of metals in,
355 ; in loam, 268 ; in sand,
* 267 ; pipes, 268.
Castings, 267-272; description of
pig iron for, 266 ; examination
of, 271 ; form of, 269 ; Mitis
wrought iron, 289.
Castlecary sandstone quarries, 41.
Castlehill „ „ 46.

Castle wellan granite „ 21.
Catcraig sandstone „ 41.

Cathedral glass, 443 ; patent rolled,
sanded sheet, and sheet,
443.
Catlow sandstone quarries, 41.
Caustic lime defined, 145.
Cedar, 372 ; appearance, characteris-
tics, market forms, and uses of,
373 ; brands on, 387 ; weight
and strength of, 404.
Cefn sandstone quarries, 40.
Celestial blue, 414.
Cement, Atkinson's, 159, 202 ; burn-
ing, 191 ; Calderwood, 159 ;
cast iron, 452 ; clinker, Portland,
193; East Kilbride, 159 ; effect
of fine grinding, 166 ; for
attaching hair felt to boilers, 455 ;
Harwich, 158 ; Heating's, 243 ;
Eeene's, 243 ; kilns, Portland,
191, Roman, 192; lias, 244;

Martin's, 243 ; means for testing
tensile strength of, 182 ; Medina,
158, 201 ; metallic, 244 ; mix-
ture of lime and, 198; mortar,
208 ; mortar made from given
quantities of cement and sand,

205 ; mould, split, 182 ; Mul-
grave's, 159 ; nodules, 157 ;
Parian or Heating's, 243 ; Par-
ker's, 157; Portland, 160-182,
203, 243 ; quantity required for
mortar, 205 ; quick and slow set-
ting rust, 452 ; Robinson's, 244 ;
Roman, 157, 452 ; rust or cast
iron, 243 ; Scott's, 179, 201 ;
selenitic, 179 ; selenitic for mortar,

206 ; Sheppy, 158 ; should be
used for important works, 198 ;
stones, composition of, before cal-
cination, 149 ; containing clay,
232 ; stones or nodules, 157 ;
storing Portland, 176 ; storing
Roman, 158 ; strength of Port-
land, 171,172, 177, 178; stucco,
Portland, 244 ; stucco, John's,
244 ; testing machines, 176,
182-187 ; tests for Portland, 162-
176 ; to be used in mortar, 197 ;
weight of, 256 ; Whitby, 159.

Cementation, 302.

Cementing material to be used for

concrete, 217.
Cements, 156-194 ; action of foreign

constituents in, 230 ; analysis of,

239, 241 ; artificial, 159, 241 ;

classification of limes and, 148 ;

dangerous, 1 94 ; effect of sand in

mortars made from various, 201 ;

hydraulic, containing clay, 232 ;

natural, 156 ; strength of, 159,

171, 172, 177, 178, 181 ; used

as plasters, 242 ; weight of, 256.
Cenfas sandstone quarries, 41.
Chain iron, 287 ; price of, and extras

charged for, 294.
Chairs for drain pipes, 132.
Chalk for concrete, 211 ; lime, grey,

155, white, strength of, 181 ;

lower, limestone quairies, 67 ;

strength of, 81 ; used in manu-

48o

INDEX,

tacture of Portland cement, 160 ;
weight of, 84.

Chance's artificial stone, 76.

Channel bricks, 119.

„ iron, 285; forge tests for, 282.

Charcoal plate, 287, 348.

Charlbury limestone quarries, 68.

Charlton white, 424.

Chamwood granite quarries, 18.

Charring timber, 394.

Cheesewring granite, colour, quarries,
weight of, and where used, 18.

Chelura terebrans, or wood- boring
shrimp, 401.

Chemical analysis of a brick or a
brick earth, 143 ; of
ChUmark stone, 64 ; of
limes and cements, 241.
„ composition of a building

stone, 2 ; of Mansfield
'stone, 66; of Portland
stone, 60.

Chemical test for limes and cements,
239.

Cherry and Wade's roofing tiles, 140.

Chestnut, 377 ; appearance, charac-
teristics, and uses of, 377 ; pur-
poses for which it is useful, 403 ;
resistance of, to crushing, 405 ;
weight and strength of, 404.

Chilled iron, 266.

Chilmark liinestone, 63 ; absorption
of, 83 ; buildings in which used,
64 ; chemical analysis of, 64 ;
colour of, 67 ; general bed, 64 ;
quarries, 64, 67 ; resistance of, to
crushing, 81 ; tensile strength of,
82 ; Scott or Brown bed, 64 ;
strength of, 64, 81, 82; trough
or hard bed, 64 ; weight of, 67 ;
working of, 64.

Chimney flue pipes, 136.
„ pots, 136.
„ terminals, Billing's, 136.

Chinese blue, 414 ; lake, 416 ; red,
416 ; yellow, 415.

Chisels, cast steel for, 325.

Chloritic granite, 15.

Chrome green and orange, 417 ; yel-
lows, 414.

Chromium or chrome steel, 306.

Chudleigh marble quarries, 52.

Chuflfs, 105.

Churchtown limestone quarries, 72.
„ marble „ 54.

Cilgwyn slate quarries, 31.

Cinder iron, 264.

Cinders as a substitute for sand, 196.

Cinnabar, 416.

Clamp, building the, 95 ; burning
bricks, 95 ; burnt bricks, classifi-
cation of, 104, method of distin-
guishing, 111, comparative ad-
vantages of kiln and, 99 ; illus-
trations of, 97.

Clamps for burning bricks, 94 ; for
Hme, 188.

Clap boarding oak, 376.

Clare Castle limestone quarries, 72.

Claridge's patent asphalte, 251.

Clasp nails, 458 ; cut and wrought,
458 ; size and weight per lOOO,
461.

Clay, bumt^ as a substitute for sand,
195 ; defined, 232 ; digging and
weathering, 90 ; composition o^
for cements, 233, 236 ; cement
stones containing, 234 ; for mak-
ing firebricks, analysis of, 122 ;
hydraulic limes and cements con-
taining, 232 ; in limestones, hy-
draulic properties o^ 147 ; iron-
stone, 257 ; machines, dry, 94,
plastic, 93 ; nature of, for terra
cotta, 125 ; proportion of, in hy-
draulic limes and cements, 238 ;
quantity required for making
bricks, 91 ; selenitic, 180 ; slate,
24 ; used in manufacture of Port-
land cement, 160, 161 ; wares,
miscellaneous, 134.

Clays for brickmaking, 87 ; calcare-
ous, mild and strong, 87 ; pure
or foul, 87, 88.

Cleaning old paint, 436.

Clear cole, 450.

Clearing brick earth from stones, 90.

Cleavage, planes of, in slates, 24.

Clee Hill granite quarries, 18.

Clench nails, rose, 458.

INDEX.

481

Clicby white, 407.

Glifden marble qaairiee, 54 ; serpen-
tine quarries, 34.

Cliffwood sandstone quarries, 45.

Clift Hill granite quarries, 16.

Clinker from brick kilns as a substi-
tute for sand, 196.
„ Portland cement, 193.

Clinkers, adamantine, Dutch, and
terro- metallic, 109 ; size and
weight o^ 112.

Clinterty granite quarries, 20.

Clipsham limestone quarries, 68.

Clonakilty slate quarries, 32.

Clonmacnoise marble quarries, 54.

Clorhann limestone „ 72.

Cloth, glass, 457.

Clout nails, 459 ; size and price of,
461.

Clouts, countersunk, 459.

Cluster-fruited oak, 373.

Coach screws, 464.

Coal measure sandstones and grits,
quarries, 41-47, 48.

Coal tar, 454 ; pitch, 253.

Coarse stuff, 245.

Coating lead pipes to prevent poison-
ing, 343.

Cobalt blue, 414.

Cobo granite quarries, 18.

Coburg varnish, white, 434.

Cogans Field limestone quarries, 72.

Coignet's B^ton agglom^r^, 220.

Coke, from gasworks used for concrete,
211; plate, 348.

Colcerrow granite quarries, 18.

Colcothar, 408.

Cold blast and cold blast iron, 258,259.
„ extreme, effect of, on iron and

steel, 332.
„ forge tests for iron, 280, 281.
„ rolled iron, 275.
„ short iron, 276.
„ shut, 268.
„ tests for Landore steel, 311.

Cole Hill marble quarries, 52.

Collars for drain pipes, 130.

Colley sandstone quarries, 39.

Colombo breakwater, concrete used
at^ 215.
B C. — III

Coloured distemper, 256.
„ glass, 444.

„ lead paints, 420 ; paints and
pigments for, 422.

Colouring and whitening, 254.
„ bricks, 120.
„ common, cream, fawn, and

buff or stone, 254.
„ pigments for paints, 407.
413-417.

Colours and temperature for steel, 307.
„ flashed, for glass, 444.
„ for wall papers, 446.
„ pigments for common, 422 ;
for superior, 423.

Colophony or common rosin, 430.

Colton Hill sandstone quarries, 40.

Columnsof brick work,strength of, 116.

Colwich sandstone quarries, 40.

Combe Down limestone quarries, 60,
68.

Combined process of preserving tim-
ber, 396.
„ smoke and air flue, 136.

Common iron, or merchant bar, 274 ;
brands on, 298.

Compact limestone, 56 ; uses and
weight of, 56.

Comparative advantages of hot and
cold blast iron, 259.
,9 advantages of kiln and

clamp burning bricks,
99.

Compass bricks, 116.
„ timber, 365.

Composition, chemical, of stones, 2 ;
nails, 459 ; nails, size and price per
1000, 461 ; of fireclay, 121 ; of
granite, 13; of limestones, 49;
ornaments in plaster, 249; tubing,
weight of, 347, 348 ; of sand-
stones, 34; of various alloys, 350 ;
of various lime and cement stones
before calcination, 149-151 ; of
white paint to cover 100 yards,
419.

Compositions, Szerelmey's iron paint,
liquid enamels, and stone compo-
sition, 427.

Compressed steel, Whitworth's, 306 ;
2 I

482

INDEX.

tensile strength and ductility of,
323.

Compression, resistance of bricks to,
116.
„ resistance of concrete to,

221.
„ resistance of firebricks

to, 124.
„ testing by, 170.

Concrete, 210-222; aggregate for,
210; Bodmer's, 109; bricks,
109 ; Wood's patent, 110; bulk
of, produced from given quantity
of materials, 218 ; cementing mar
terial to be used for, 218 ; expan-
sion of, 219 ; experiments on the
resistance of, to compression, 221 ;
iron, 222; laying, 216; lead, 222;
matrix, 210; mixing, 214; mix-
ing machines, 225 ; plastic, 217;
proportion of ingredients for
making, 212; proportion of in-
gredients used on various works,
212,215; selenitic, 219; strength
of, 221 ; tar, 222 ; uses of, 220.

Concrete - mixers, American, 229 ;
Carey-Latham, 229 ; inclined cy-
linder, 225 ; Le Mesurier's, 227 ;
Messent's, 226 ; Ridley's, 229 ;
Stoney's, 229.

Coney Warren sandstone quarries, 41.

Cong limestone quarries, 72.
„ sandstone „ 47.

Coniston slate quarries, 31.

Connemara marble or serpentine, 34.

Continental marble quarries, 55.

Continuous system of kilns for lime-
burning, 188.

0<mtraction of wrought iron, 275 ; of
metals in cooling or casting; 355.

Conversion of timber, 396-400 ; of fir
and oak, 400.

Converter used in Bessemer process,
304.

Cook's Folly sandstone quarries, 46.

Cooling, contraction of metals in,
355 ; steel, 308.

Coolness, test for, in Portland cement^
174.

Copal, 431 ; varnishes, 433, 434.

Coping bricks, 119.

Copings for platfiMrms and wing walls,
119.

Copper, 339; aisenite of, test for,
446 ; effect of, on iron and steel,
263 ; market forms of, 340 ; nails,
459 ; nails, size and weight of,
461 ; ores of, 339 ; oxidation and
corrosion of, 340 ; properties of,
339, 354 ; sheet, 340 ; tinned,
348 ; uses of, 339 ; weight of
sheet, 340, 357 ; wire cord, 340 ;
wire-covered steel ribbon sash line,
340.

Copperas as a drier for paint, 412;
white, 431.

Coralline oolite limestone quarries, 67.

Cord, copper wire, working loads for,
340.

Cordes' patent wrought nails^ aaxe
and weight per 1000, 461.

Core for casting, 268.

Cork paint, granulated, 429.

Corkbarked elm, 379.

Comgrit, 60.

Cornice bricks, full, hollow, and
moulded, 118.

Cornish granites, 16 ; resLstanoe o^ to
crushing, 81.

Corrennie granite, 20.

Corrosion and preservation of iron
and steel, 335.
„ of copper, 340.

Corrugated sheet iron, 288.

Corrugated tiles, 1 39 ; improved, 139.

Corsehill sandstone quarries, 40.

Corsbam Down stone, 60.
„ Ridge „ 60.

Cost of terra cotta, 127.

Cotton, silicate, 457.

Countersunk clouts, 459 ; size and
weight per 1000, 461.

Countess slates, cost, sLse, and weighty
eta, of, 27 ; thickness of; 28.

Courses, damp-proof, 135.

Cove granite quarries, 20.

Cowdie or Cowrie pine, 373; ap-
pearance, characteristics, and nses,
373.

Goxbench sandstone quarries^ 41.

INDEX.

483

Craig Dhu slate quarry, 31.

Craig sandstone quarries, 40.

Craigleith sandstone, absorption, 83 ;
composition of, 38 ; colour, quar-
ries, and weight of, 42 ; resistance
of, to crushing, 82 ; tensile
strength o^ 82.

Craignair (Dalbeattie) granite quar-
ries, 20.

Crawlout sandstone quarries, 42.

Crease's paints, 429.

Creetown granite quarries, 20.

Creosote, 454.

Creoeoting timber, 394.

Cretaceous formation quarries^ 39, 67.

Crookes „ „ 42.

Crighton limestone ,, 71.

Crosdoney granite „ 21.

Crossdown limestone „ 72.

Crossland Hill sandstone quarries, 42.

Crown glass, 438; characteristics,
qualities, and sizes of, 439 ;
market forms of, quantity in
crates, and thickness of, 438.

Crucible cast steel, 303 ; brands on,
313 ; characteristics and uses
of, 304 ; Heath's, Heaton's, and
Mushef s processes of making,
304.

Crumpwood sandstone quarries, 40.

Crushed stones as a substitute for
sand, 195.

Crushing across the fibreft of timber,
resistance to, 405.

Crushing strength of cast iron, 315 ;
of firebricks, 124 ; of steel, 313 ;
of stone, 11, 81 ; of wrought
iron, 319.

Crystal varnish, 435.

CiystaUised tin plate, 348.

Cuba or Spanish mahogany, 381.

Cullipool slate quarries, 32.

Cunliffe Blue sandstone quarries, 42.

Cunliffe stone, strength of, 82.

Cupolas for burning bricks, 103.

Cupshakes in timber, 361.

Curf, 8, 60, 62 ; description of, 62 ;
position in quarry, 7, 61.

Cut nails, 457 ; clasp, 458 ; size and
weight per 1000, 461.

Cutters, bricks, 103, 104 ; price of,
105.

Cwmorthen Slate Company's quarries,
31.

Cylinder glass, 440.

Cylinder, inclined, for mixing con-
crete, 225, 226.

Cypress, 373.

Dacreback sandstone quarry, 46.
Dalbeattie granite quarries, 20 ; slate

quarries, 32.
Dalkey granite quarries, 21.
Dalmore „ „ 20.

Dammar, gum for varnish, 431.
Damp blue, 414.

„ proof courses, 135.
„ walls, how prepared for paper-
ing, 447.
Dancing Cairn granite quarries, 20.
Dangerous limes and cements, 194.
Dantzic oak, 375 ; appearance, mar-
ket forms, and uses of, 375.
,y timber, 366 ; appearance,
characteristics, and market
forms of, 366 ; different
purposes for which it is
used, 409 ; weight, strength,
etCL, of, 404.
Dark drying oil, 411.
Darley Dale sandstone, quarries, 42 ;

resistance of, to crushing, 81.
Dartmoor granite, resistance of, to

wear, 84, to crushing, 81.
Dead-burnt lime, 194.
Dead load, definition of, 467.
Deals, American, marks and brands
on, 387 ; Baltic, marks and
brands on, 385 ; cut and whole,
364 ; Russian and Finland,
marks and brands on, 385 ;
Swedish, marks and brands on,
385 ; value of, and method of
measuring, 387 ; varieties in gene-
ral use, 367.
Dean, Forest of, stone, 37.
Decay of timber, 391-393.
Defects in timber, cupshakes, heart-

484

INDEX.

shakes, and starshakes, 361 ;
doatiness, foziness, rind-gall,
twisted fibres^ and upsets,
362.

Defects in wrought iron, cold shorty
275 ; red or hot shorty 276.

Deflection, definition of term, 470.

Degree of heat for hardening steel,
308.

Delabole Slate Company's quarries,
31.

Delank granite quarries, 18.

Delicate tints, 422 ; pigments for, 423.

Delta metal, 349.

Dennett's fireproof material, 249.

Dent marble quarries, 52.

Derbyshire stone, strength of, 82.

Desiccation of timber, 390.

Destruction of timber by worms and
insects, 401.

Detection of dry rot, 393.

Devonian limestone quarries, 71.

Devonshire granite, 16.

Diamond rough plate glass, 443.

Dinas firebricks, 123 ; analysis of
clay for, 122 ; resistance to com-
pression, absorption, and weight
of, 124.

Dinorwic slate quarries, 31.

Diphwys Casson slate quarries, 31.

Dirt bed, position of, in quarry, 7,
61.

Disintegrated basalts, granites, and
schists as substitutes for sand,
196.

Distemper, 254 ; coloured, 255 ;
white, 254.

Distinction in appearance between dif-
ferent classes of wall paper, 445.

Doatiness in timber, 362.

Dod, mould for pipes, 130.

Dog nails, 459 ; size and weight per
1000, 461.

Dolomite, description of, 58.

Donaghmore sandstone quarries, 47.

Doneraile marble quarries, 54.

Dorothea slate quarries, 31.

Double, angle iron, 286 ; cant bricks,
118; headed rail, 286; junc-
tions for pipes, 132 ; roll tiles,

139 ; shear steel, brands on, 313 ;
size, 449.

Doubles or block tin, 348.

„ dates, size, weight, etc, of,
27 ; thickness of, 28.

Douglas or Oregon pine, 373.

Doulting (Old Down) limestone quar-
ries, 68.

Dowdeswell limestone quarries, 68.

Dowlais fireclay, 121, 122.

Drab bricks, 108.

Dragon's blood for varnish, 431.

Drain, bricks, 119 ; pipes, agricultu-
ral, 130.

Draw-kilns for burning lime, 18&

Drefised bricks, 94.

Dressing, granite, 15 ; ore, 257.

Drewsleighton marble quarries, 52.

Driers for paints, 407, 412 ; for var-
nishes, 431 ; patent, 413 ; pre-
cautions in using, 413.

Drogheda limestone quarries, 72.

Drop lake, 416.

Drumabum slate quarries, 32.

Drumbane sandstone „ 47.

Drumkeegan „ „ 47.

Dry clay machines, 94.
„ floated deals, 370.
„ rot, 392 ; detection o^ 393.
„ tUes, 142.

Drying bricks, 92 ; in sheds, 92 ;
out of doors, 93.
„ oil, 409 ; dark, 411.

„ oils, 409 ; for oommon work^

411; non -drying, 409;
dark, 411; pale, 41 L

Dublin limestone quarries, 72.

Duchess slates, size, weight, etc, of,
27 ; thickness of; 28.

Ductility, definition of tenn, 470 ; of
cast iron, 314 ; of cast steel, 321 ;
of iron, 314 ; of malleable iran,
318 ; of Lojidore steel, 323 ;
of steel, 319, 321 ; of steel
plates and bars, 322 ; of wrought
iron, 317, 319.

Duffield Bank sandstone quarries, 42.

Duke's sandstone quarries, 42

Dunamase limestone quarries, 72.

Dundee sandstone, strength of^ 61.

INDEX.

485

Dundoy sandstone, strength of, 68.
Dungannon sandstone „ 47.

Dungloe granite „ 21.

Dunkerrow sandstone „ 64.

Dankit limestone „ 72.

Dunmore sandstone „ 42.

Dnrabilitj of building stone, 2 ; of

terra cotta, 126.
Durable in wet positions, timber,

403.
Duramen or heart wood, 359.
Durmast oak, 374.
Dusky ant, destruction of timber by,

402.
Dust bricks, 108.
Dutch clinkers, 109 ; size and weight

of, 112.
Dutch elm, 379.

„ gold leaf, 451.

„ kiln, 98.

„ pink, 416.

„ white, 408.
Dyce granite quarries, 20.

Earth for brickmaking, characteristics
of different kinds, 88 ; composi-
tion of good, 88 ; constituents of,
85 ; practical classification of, 87 ;
preparation of, 90.
Earthenware, unglazed, 128.
Easdale slate quarries, 32.
East Kilbride cement, 159.
Eccleshill sandstone quarries, 42.
Economy of fuel with Hoffmann's

kiln, 102.
Effect of annealing steel plates, 325.
„ of carbon upon cast iron, 261.
„ of different processes and cir-
cumstances on strength of
steel and of wrought iron,
319, 324.
„ of mixing different brands of

iron, 317.
„ of fine grinding on cement,

166.
„ of rolling iron, 274.
„ of temperature on strength of
cast iron, 316.

Effect of temperature on strength of
wrought iron, 319.
„ of tempering steel, 324.
Effects caused by different degi*ee8 of
calcination of lime and cement
stones, 234.
Eiflorescence on walls, 238 ; appear-
ance, composition, causes, disad-
vantages o^ and remedies for,
238.
Elastic limit, defined, 329, 461 ; of
cast iron, wrought iron, and steel,
331 ; of cast steel, 319 ; raised
by different processes^ 330 ; raised
by stretching, 331.
Elasticity, defined, 469 ; limit of, 329,

331 ; modulus of, defined, 469.
Elemi, gum for varnish, 431.
Clland Edge sandstone quarries, 42.
Elm, 378 ; age for felling, 360; pur-
poses for which it is useful,
403; resistance of, to shear-
ing, 405.
„ Canada Bock, 379 ; weight,

strength, etc, of, 404.
„ Corkbarked, 379.
„ Dutch, 379.

„ English, common or rough-leaved,
378 ; appearance and char-
acteristics, 378 ; uses, 379 ;
weight, strength, etc, of, 404.
„ Wych, 379.
Elswick sandstone quarries, 42.
Elvan, 22.

Embossed glass, 443.
Emerald green as a colouring pig-
ment^ 417.
Emery, cloth, paper, 457.
Emperor's Bed marble quarries, 56.
Empresses slates, size, weight, etc, of,

27.
Enamel paint, 426.
Enamelled bricks, 109 ; glass, 443 ;

glass stained, 443 ; slates, 29.
Enamelling paint, Griffith's patent

silicate, 427.
Enamels, Szerelme/s liquid, 427.
Encallow, encallowing, defined, 90.
Encased pipes, lead, 343 ; weight
and strength of, 344.

486

INDEX.

EncauBtic tiles, manu&cture oi^ 141 ;

inferior, 142.
Encriual marble, 61.
Ends of timber, 364.
England, Tarieties of marble in, 51.
English elm (m0 Elm), 378.
„ granites, 18, 19.
„ papers for walls, 446.
„ quarries, granite, 18 ; lime-
stone, 67-71 ; marble^ 62 ;
sandstone, 39-47 ; slate,
31.
„ serpentines, 34.
„ slates, 30, 31.
Ennj Yale sandstone quarries, 47.
Enrichments in plaster, 248.
Essential oils, 409.
Evils of &t lime mortar, 197.
Examination of castings, 271 ; of

sand, 195; of stone, 11.
Expansion of concrete, 219.
Experiments on iron, Kirkaldy's,
277.
„ on resistance of con-

crete to compression,
221.
,, on steel by Committee

of Civil Engineers,
320.
Extract of lethirium for removing

paint, 436.
Extras charged on British iron, 291-

294 ; on steel plates, 312.
Extreme cold, effect of, on iron and
steel, 332.

Facility for working stone, 6.
Facing bricks, Lancashire red pressed,
109.

„ paviors, description and price
of, 106.
Facings, wall, 136.
Factor of safety defined, 467.
Factors of safety for cast iron, wrought

iron, and steel, 326.
Faija's testing machine, 186.
Fairbaim's remarks on hot and cold

blast iron, 269.

Falling weight or impact teat for izan,

283.
False permanent set, 330.
Fancy iron, 286.

Fareham red bricks, 108; resistance
o^ to compression, 115 ; sixe and
weight oi; 112.
Farleigh Down limestone, 60 ; quar-
ries, 68.
Farm Qate (Moyour) limestone quar-
ries, 72.
Farren limestone quarries^ 72.
Fatigue of iron, 330.
Fat lime, 154 ; mortar made from,
230, evils of, 198.
„ limes, 148, 162, 154, 230 ; cal-
cination of, 230 ; composition of,
149 ; precautions in using, 162 ;
setting o^ 230 ; should only be
allowed in inferior work, 197 ;
slaking of, 230 ; stained, 152 ;
uses of, 152.
Feebly hydraulic limes, 149; beha-
viour in slaking and setting
154.
Felling timber, age for, 369 ; oak,

time of, 376.
Feldte, 22.
Felspar in granite, 13, 14 ; weight

of, 84.
Felspathic sandstones, 36.
Felstone porphyry, 22.
Felt, 455 ; asphalted roofing, 455 ;
hair, inodorous bitumen and
sarking, 466 ; tarring and
painting, 456.
„ or silver grain in timber, 358.
Fermoy limestone quarries, 72.
Ferro-silicic acid as a preservative for

stone, 80.
Ffestiniog quarries^ 31.
Fibres, twisted in timber, 362.
Fibrous asphalte, 456.

„ plaster, 249.
Fine stuff for plastering, 245.
Fineness of grit for Portland cement,
162.
„ „ for selenitic cement,

180.
Fingask granite quarries, 20.

INDEX.

487

Finglaa limestone quarries, 72.
Finland deals, 368 ; brands on, 385.
Fir, Baldc, marks and brands on,

384 ; conversion of, 400 ; how

imported, 365 ; market forms,

364 ; resistance of, to crushing

across the fibres, 405 ; resistance

of, to shearing, 405 ; spruce, 363 ;

timber, classification o^ 363 ;

weight) strength, etc, of, 404;

white or spruce, 371.
Fire, protection of timber from, 396.
Firebricks, 120-128; absorption of,

124 ; analyses of different clays

for, 122 ; description of, 123 ;

Dinas, 123 ; Guismuyda, 124 ;

Kilmarnock, 123 ; Le Moor and

Narberth, 124 ; Newcastle, 123 ;

resistance o^ to compression, 124 ;

Stourbridge, 1 23 ; weight o^ 1 24 ;

Windsor or Hedgerly, 124.
Fireclay and firebricks, 120-128.

^ composition of, 121'; defined,
120 ; for making terra
cotta, 125 ; grain of, 123 ;
refractory, 120 ; uses of,
in building, 120 ; ware,
128 ; where found, 120.
Fireproof material, Dennett's, 249.
Fishponds sandstone quarries, 42.
Fixed oils, 409.
Flagstones, 35.
Flake white, 407.
Flare-burnt lime, 194.
Flare kilns for burning lime, 189 ;

description of, 190.
Flashed colours for glass, 444.
Fksks used in casting, 267.
Flat4ron, extras chaiged for, 291-

294.
Flat-bottomed rail, 286.
Flat-headed screws, 463.
Flaws, freedomfrom,of good bricks, 110.
Fleurs in ridge tiles, 141.
Flints for aggregate of concrete, 211.
Flitch plates, 287.
Floated deals, 370 ; diy, 370.
Flock papers for walls, 445.
Floors, term used in quarrying, 24.
„ timber useful for, 403.

Florentine lake, 416.

Flue pipes, chimney, 136.

Flues, combined smoke and air, 136.

Fluid, marvel, for removing old paint,

436 ; soldering, 353.
Fluted sheet ghiss, 440.
Flux used in melting iron, 259.
Fluxes for soldering metalB^ 353.
Foe Edge sandstone qiuirries, 42.
Foggintor (Dartmoor) granite quarries,

18.
Force, adhesive, of nails, 462; of

screws, 465.
Foreign gold leaf, 451.

„ substances in pig-iron, 260.
Forest of Dean sandstone, 37 ; quar-
ries, 42 ; where used, 38.
Foi^ iron, 263.

„ tests for wrought iron, 280.
Foi^g, 333 ; iron and steel, 333.
Forgings, form given to, 333.
Form of castings, 269.
Forms of sewer pipes, different, 131.
Forss sandstone quarries, 46.
Fottdland slate quarries, 32.
Foul clays for brickmaking, 87, 88.
Foundry iron, 263.
Foxiness in timber, 362.
Foynes limestone quairies, 72.
Fracture of sandstone, 36 ; of stone,

11.
Fractured surface of steel, to judge
quality from, 3 10.
„ „ of wrought iron,

appearance of,
282.
Frankfort black, 414.
Freeman's "non- poisonous'' white

lead, 424.
Freemator granite quarries, 18.
Freestone defined, 35.
French greens, 417.
„ nails, 459.
„ oak, 376.
„ papers for walls, 446.
„ polish, 434.
Fret lead, 344.

Frog in hand-made bricks, 94.
Fronts, bright, bricks, description and
price of, 106.

488

INDEX,

Fucata, Lycoris, 402.

Fuel, economy of, by UBing Hoflf-

mann's kiln, 102.
„ required for burning bricks,

99 ; limes and cements,

193.
Fulford sandstone qnairies, 40.
Furlough granite ^ 21.
Fusibility defined, 470.

Gaewem slate quarries, 31.
Galena, 341.
Galvanised iron, 289.
Galvanising as a means of preserving

iron, 335.
Gangue, 259.
Ganister, 304.

Gardner^s process for preserving tim-
ber, 396.
Garl bed of Kentish Bag, 65.
Garth sandstone quarries, 42.
Gartley slate quarries, 32.
Garvary Wood granite quarries, 21.
Gas threads, Whitworth's standard,

465.
Gatherley Moor sandstone quarries, 40.
Gauge, Birmingham iron wire, sheet

iron and wire, 355 ; metal, 357 ;

Whitworth's standard wire, 356 ;

zinc, 346.
Gauged stuff for plastering, 246.
Gauges for wires and metals, 355-357.
Gault bricks, 107 ; absorption of, 1 14 ;

resistance of^ to compression, 115.
Gazeby sandstone quarries, 42.
Gedge's metal, composition of, 350.
General bed, Chilmark stone, 64 ;

strength o^ 64.
General remarks on burning lime, 192.

„ „ on glass, 437.

„ „ on stone, 1.

„ „ on tests for wrought

iron, 276.
Geological position of Bath stone, 59.
German plate glass, 440.

„ steel, 306.

„ vermilion, 416.
Gifdlo Antico marble quarries, 55.

Giffneuk or Qifiiock sandstoDe, ab-
sorption of, 83 ; quarriesi 43 ;
resistance of^ to crushing 81.

Gilding ironwork, 337.

Gillogue limestone quarries^ 72.

Gipton Wood sandstone quarries, 43.

Girder iron, rolled, 285.

Glammis sandstone quarries, 46.

Glandore ^ n ^'

Glannan marble „ 54.

Glasoote (Tamworth) fireclay, analysis
of, 122.

GHasgow fireclay, analysis o^ 122.

Glass, 437-444 ; blown plate, 441 ;
British pkte, 441 ; British
polished plate, 442 ; British
sheet, 440 ; cathedral, 443
coloured, 444 ; crown, 438
cylinder, 440 ; embossed, 443
enamelled and stained enamelled,
443 ; flashed colours on, 444 ;
fluted sheet, 440 ; general remarks
on, 437 ; German plate, 440 ;
ground, 443 ; interception of light
by, 444 ; obscured, 443 ; patent
diamond and quarry rough plate,
443 ; patent plate, 441 ; per-
forated, 443 ; polished plate, 442
rough cast and rolled plate, 442
sheet, 439, 440 ; slates, 444
tiles, 444.

Glazes for clay wares, opaquei, 130 ;
transparent, 129.

Glaziers' brads or sprigs, 459.
„ putty, 452.

Glazing, clay wares, 129 ; lead and
salt, 129.

Glebe sandstone quarries, 43.

Glenalmond slate „ 32.

Glencore granite „ 21.

Glencullen granite „ 21.

Glenshee slate ' „ 32.

Glentilt marble „ 53.

Glue, 448 ; characteristics of good,
448 ; marine, 449 ; preparation
of, 448 ; uses and strength of,
449.

Glues to resist moisture, 449.

Gneiss, 22.

Godstone sandstone quarries, 39.

INDEX.

489

Gold lea^ 451 ; Dutch, foreign, and
pale, 461.
„ paint, Bessemer's, 451.
„ size, 450 ; bumiBh, 450 ; japan-
ners*, 413, 450 ; oil, 450.

Qraigue limestone quarries, 72.

Grain of fireclay, 123 ; of sandstone,
36 ; of slates, 25 ; silver, in tim-
ber, 368.

Grains, size of, in granular limestone,
66.

Granard sandstone quarries, 47.

Granite, 13-21 ; absorption of, 83 ;
bulkiness of, 84 ; characteristics
of, 15 ; chloiitic, 15 ; composi-
tion of, 13 ; Cornish and Devon-
shire, 16 ; disintegrated, 196 ;
dressing, 15; English, 18, 19;
graphic, 15 ; Guernsey, 16 ; Irish,
16, 21 ; Leicestershire, 16 ; por-
phyritic, 16 ; quarries, principal,
in Great Britain and Ireland, 18-
21 ; quarrying, 15 ; resistance of,
to crushing, 81 ; resistance of,
to wear, 84 ; scborlaceous, 15 ;
Scotch, 16, 20, 21 ; strength of,
81 ; syenitic, 14 ; talcose, 15 ;
true or common, 13 ; uses of, 16;
varieties of, in common use, 16 ;
weight, 18, 84.

Granitic paint, 427.

Grant's black, 414.

Granular limestone, absorption of, 57 ;
bulkiness of, 84 ; colour of, 56 ;
composition and structure of, 56 ;
natural bed of, 57 ; shelly, 56 ;
size of grains, 56 ; uses of, 57 ;
varieties of, 57 ; weathering qua-
lities of, 56 ; weight of, 57, 84.

Granulated cork paint, 429.

Graphic granite, 15.

Gravel used for concrete, 211.

Great and upper oolite limestone
quarries, 68.
„ Meadow limestone quarries, 72.
„ rag bed of Kentish Rag, 65.

Greaves^ Quarry sandstone quarries,
44.
„ slate quarries, 31.

Greencliff sandstone quarries, 45.

Green Rag bed of Kentish Rag, 65.
„ stains on white bricks, 107.

Greenheart, 382; appearance and
characteristics of, 382; market
forms and uses of, 383 ; weight,
strength, etc, of, 404.

Greenmore sandstone quarries, 43.

Greens for colouring, pigments, 417 ;
Brighton, Brunswick, chrome,
emerald, French, marine, min-
eral, mountain, patent, Prussian,
Scheele's verditer, Vienna, 417.

Greensand, limestone quarries in, 67.

Greenstone, 23.

Greor limestone quarries, 72.

Grey cast iron, 265 ; to distinguish
from white, 266.
„ chalk lime, 155 ; weight of,
256.

Griffith's patent silicate enamelling
paint, 427.
„ patent white paint, 424.

Grimshill sandstone quarries, 40.

Grinding clay for brickmaking, 90.

Grinding, fine, effect of, on cement,
166.

Grinshill sandstone quarries, 43.
„ stone, strength of, 82.

Grit, fineness of, for Portland cement,
162 ; for selenitic cement, 180.

Grits, 35 ; coal measure quarries, 41-
46.

Grizzle bricks, absorption of, 114;
description and price of, 105.

Grooby granite quarries, 18; slate
quarries, 31.

Grosby sandstone quarries, 39, 43.

Ground, glass, 443 ; lime, 203.

Grout, 209.

Grove Height sandstone quarries, 43.

Growth of trees, 368.

Guernsey granite, 16; resistance of,
to wear, 84.

Guismuyda firebricks, 124.

Gum, anim^, 431 ; dammar, 431 ;
elemi, 431 ; resins, 430.

Gums used for varnishes, 430.

Gun metal, 348, 350; composition
of, 350; properties of, 354;
weight of, 357.

490

INDEX.

Qunnislake granite, 18.

Qutter bricks, 119.

Guy's Cliffe sandatone quarries, 43.

Gweslye „ „ 46.

GjpBum, 242.

Hacking bricks, 93.
Hacks for drying bricks, 93.
Haematite iron ore, red and brown,
258.
„ pig iron, 296.
Haerlem blue, 414.
Haines' patent lead-encased pipes, 343.
Hair felt, 466 ; cement for attaching
to boilers, 466.
„ used by the plasterer, 246.
Half-socket pipes, 131.
Hall's hanging wall tiles, 141.
Hamburg lake, 416 ; white, 408.
Hamdon Hill limestone quarries, 68.
Hamelin's mastic, 244.
Hamhill limestone, strength of, 81.
Hand masts, 364.
„ mortar mill, 225.
„ moulding bricks, 91.
„ wrought nails, 457.
Handles, timber useful for, 403.
Handrail screws, 464.
Hard bed, Chilmark stone, 64.
„ oak varnish, 434.
„ paviors, 106 ; price of, 106.
„ putty, 462.

„ solders, 361, 362; flux for, 363.
„ spirit vamishesy brown and

white, 434.
„ steel, 306.
„ stock bricks, description and

price of, 106.
„ wood, 363, 373; classification
of; 362.
Hardening and setting Portland ce-
ment, 176.
^ and tempering steel in oil,

309.
„ case, 309.

„ defined, 470.

„ steel, 301, 307; degree

of heat for, 308.

Hardness defined, 470.

^ of slates, 26 ; of stone, im-
portance of, 5; of tem
cotta, 126.

Hardwood lacquer, 434.

Harmby limestone quarries, 70.

Hartford Bridge sandstone quarries, 43.

Harwich cement, 168.

Hassock Hill sandstone quarries, 43.
„ in Kentish Bag, 64-66 ; ab-
sorption of, 83 ; analysis
of, 66; quarries, 39; un-
fit for external work, 66.

Hawksworth Wood sandstone quar-
ries, 43.

Haydor limestone quarries, 68.

Hayter, Mr., on concrete, 214.

Haytor, or High Tor, granite quarries,
18.

Header and Headstone laying beds of
Kentish Bag, 66.

Header brick, hollow, 117.

Headington limestone quarries, 67.

Heads, tunnel bricks, 119.

Heale granite quarries, 18.

Heartshakes in timber, 361.

Heartwood, 359.

Heat, degree of, for hardening steel,
308.

Heath's and Heaton's processes, 304.

Heating steel, different methods, 308.

Heck wood granite quarries, 19.

Heddon sandstone, absorption o^ 83 ;
quarries, 43.

Hedgerly firebricks, 124 ; analysis of
clay for, 122.

Hensborough granite quarries, 19.

Herm granite, quarries, 19; resist-
ance o^ to crushing and wear, 81,
84.

High Bock granite quarries, 20.
„ Tor „ „ la

Hildenly limestone quarries, 68.

Hill o' Fare granite, 20.

Hip tiles for roofing, 141.

Hoffmann's kiln for burning bricks,
101 ; advantages and disadvan-
tages of, 102 ; economy of fuel by
using, 102 ; modifications of; 103 ;
size and produce o^ 102.

INDEX.

491

Holland white, 407.

Hollington fiandstone quarries, 40.

Hollow bricks, 117; cornice, 118.

Homogeneous metal, 307.

Honduras mahogany, 380; appear-
ance, characteristics, and uses of,
380 ; market forms oi; 381 ;
weight, strength, etc., of^ 404.

Honless Hill sandstone quarries, 43.

Honley „ „ 43.

Hookstone „ „ 43.

Hoole limestone „ 72.

Hoop iron, 289; extras charged on,
292, 293 ; price 0^ 290 ; widths
and gauges of, 292.

Hopton sandstone quarries, 43.

Hopton Wood limestone, quarries, 70 ;
strength of, 82.

Hornbeam, 383 ; appearance, charac-
teristics, and uses of^ 383 ; weight,
strength, etc, of, 404.

Hornblende, in granite, 14, 15 ; schist
or slate, 23.

Horse Bridge bed of Kentish Rag,
65.

Horse mortar-mill, 224.
„ shoe iron, 287.

Horses* teeth in porphyritic granite,
15.

Horsforth sandstone quarries, 43.

Horslej Castle „ „ 43.

Hot-air seasoning of timber, 390.
„ blast iron, 258, 259.
„ forge tests for steel, 310.
„ „ for wrought iron, 281,

282.

Hot lime for killing knots, 450.
„ shortness in iron, 276.

Howley Park sandstone quarries, 43.

Howth fireclay, analysis of, 122.
„ limestone quarries, 72.

Hoyle House sandstone quarries, 43.

Hoyston slate quarries, 32.

Huddlestone limestone, quarries, 70 ;
strength of, 81.

Humbie sandstone, tensile strength of,
82 ; quarries, 43.

Hunger Hill sandstone quarries, 43.

Hunter^sHill „ „ 43.

Hydrate of lime, 145.

Hydraulic limes, 153-155 ; artificial,
155; classification of, 154; cal-
cination of, 232 ; composition of
various, 149 - 151 ; proportion
and composition of day in, 232 ;
varieties of, 155 ; where generally
used, 198.

Hydraulic limestones, effects caused in,
by different degrees of calcination,
234.

Hydraulicity of limes and cements,
146 ; constituents of limestone
which produce, 146, 147 ;
methods of artificially producing,
180.

Hygeian . rock building composition,
455.

Idle sandstone quarries, 44.
Igneous rocks, 13 ; other than gran-
ite, 22.
Iguanodon limestone quarries, 67.
Impact test for iron, 283.
Imperial slates, size, weight, etc, of,

27.
Improved corrugated tiles, 139.
Impurities in pig iron, 262.
Inch masts, 364.
Inclined cylinder concrete-mixer,

225.
Indestructible paint, 426.
India Office tests for iron, 279.
Indian oak or teak, 381.

„ red, 416.
Indiarubber, vulcanised, 453.
Indigo, 414.
Indurating solutions, Ransome's, for

preserving stone, 78.
Inferior asphaltes, 253.
„ encaustic tiles, 142.
„ terra eotta, 127.
Ingredients in mixed paints, propor-
tions of, 418.
„ of varnish, 430.

„ proportion of, for mortar,

200.
„ „ to form con-

crete, 212.

492

INDEX.

InjuriouB effect of lead paint, 421.

Inodorous bitumen felt, 455.
„ paint, 423.

Insects, destruction of timber bj,
401, 402.

Inside painting, quantity required for,
419.

Intensity of stress defined, 468.

Interception of light by glass, 444.

Interior joinery, timbers useful for,
403.

Intermittent kUns for burning lime,
190.
„ system of lime-burning,

189.

Inverary granite quarries, 20.

Invert blocks, 136.

lona marble quarries, 53.

Ipplepen marble quarries, 52.

Ireland, fireclay from, analysis of,
122 ; quarries in, granite, 21,
limestone, 71, marble, 54, sand-
stone, 47, slate, 32 ; varieties of
marble in, 51.

Irish granites, 16, 81 ; green marble,
34 ; limestone quarries, 71-73 ;
serpentines, 34 ; slates, 28, 30,
32.

Iron, action of impurities on, 262,
263 ; amount of carbon in, 261,

337 ; angle, strength of, 318 ;
angle, tee, and other sections, 286;
bar, 274, 284 ; beading, 286 ;
Bessemer, 263 ; best Yorkshire,
283, 284 ; black oxide of, paint,
425 ; brands on, 295-300 ; cast,
264: {see Cast Iron) ; cement, cast,
452 ; chain, 287 ; channel, 285 ;
characteristics and uses of, 337,

338 ; chilled, 266 ; cinder, 264 ;
cold blast, 258 ; cold rolled,
275 ; colouring action of, on
sandstones, 35 ; common or mer-
chant bar, 274, 285 ; com-

' parative advantages of hot and
cold blast, 259 ; concrete, 222 ;
contraction of wrought, 275 ; cor-
rosion and preservation of, 335 ;
corrugated sheet, 288 ; defects in
wrought^ 275 ; description of

Iron — contintLed,

wrought, 283 ; effect of carbon
on, 261 ; effect of rolling, 274 ;
elastic limit of, 331 ; factors of
safety for, 326 ; fatigue of, 330 ;
forge and foundry, 263 ; forging,
333 ; galvanised, 289 ; grey cast^
265; hoop, 289, 292, 293;
hors&^hoe, 287 ; hot blast, 259 ;
in granite, 14 ; influence of car-
bon on, 261 ; malleable, strength
of, 318 ; malleable cast, 266,
338 ; manufacture of T, I, and
other forms of, 275 ; market
forms of wrought, 284 ; mine,
264 ; mottled cast, 264, 265 ;
nail, 287 ; nails, 461 ; oak, 375 ;
of various qualities, tensile tests
for, 279 ; ores of, 257 ; oxide of,
colouring action on bricks, 87,
89 ; oxide of, as a base for paints,
409 ; oxide of, paints, 425 ;
paints, 427 ; pig, 260-264 ; pUite,
281, 287; plates, strength of;
318; preservation of, 335-337;
production o^ 257 ; properties
of, 354 ; pyrites in brick earths,
87, in slates, 26; quadrant,
286 ; rails, price of, 290 ; rivet,
287, 318; rolled girder, 285;
sheet, 281, 287, 288, 292, 294 ;
strength of, 314-319; Swedish,
283, 300; tests for cast, 271,
for wrought, 276-283 ; to distin-
guish steel from, 309 ; toughened
cast, 266; value, relative, of
wrought) 289 ; varmsh for, 435 ;
welding, 334; white casti 264,
265; wire gauge, Whitworth's
standard, 356; weight of, 357;
working stresses for, 327;
wrought, 272-294, 296-300 («»
Wrought Iron).

Ironstone, day, 257.

Ironwork, bright, how preserved from
oxidation, 337.

Isle of Man marble quarries, 53.

Italian oak, 376.

„ or Venetian tiles, 140.

Ivory black, 414.

INDEX,

493

Jackdaw Craig limestone qaarries,

70.
Japanners' gold size, 413, 450.
Japanning, 435.
Jairah, or Australian mahogany, 381 ;

appearance, characteristics, market

forms, and uses of, 381 ; weight,

strength, etc, of, 404.
Jennings' improved drain pipes, 133.
John'sstucco cementfor pla8tering,244.
Johnson and Co.'8 process for making

Portland cement, 160.
Joiners' brads, 459.
Joinery, interior, timbers useful for,

403.
Joint, lip, in terra cotta, 126.

„ Stanford's patent, for pipes, 1 34.
Joints, moi*tar, in terra cotta, 12.
Junction blocks, 136.
Junctions for pipes, double and single,

132.

Kaolin, 16.

Kawrie, Cowrie, or Coudie pine, 373;

weight, strength, etc, of, 404.
Keate's specific gravity bottle, 167.
Eeating's cement, 243.
Keene's cement for plastering, 243;

weight of, 256.
Keinton limestone quarries, 69.
Kemnay granite „ 20.

Eenmare limestone „ 72.
Kennack Cove serpentine, 34.
Eentish Rag, 64 ; absorption of, 83 ;

analysis of, 66; beds of, 64;

quarries, 66 ; weight of, 84.
Eenton sandstone, absorption of, 83 ;

quarries, 44; resistance of, to

crushing, 81.
Kerb bricks, 119.
Kerf, 8.

Kerr sandstone quarries^ 40.
Ketton limestone, absorption of, 83 ;

quarries, 69 ; strength o^ 81.
Ketton Rag limestone, quarries, 69 ;

strength of, 81.

Kilbride, East, cement, 159.

„ lime, 155.
Kilkenny marble, quarries, 54 ;

strength of, 89.
Killaloe, Imperial Slate Co.'s quarries,

32, slates, strength of, 81.
Killamey limestone quarries, 73.
Killea sandstone „ 47.

Killey Park marble quarries, 52.
Killin serpentine, 34.
Kilmallock limestone quarries, 73.
Kilmarnock firebricks, 123; analysis

of clay for, 122.
Kiln-burning bricks, 98 ; comparative
advantages of clamp and, 99.
9, burnt bricks, classification of,
106; method of distinguish-
ing, HI.
Kilns for burning bricks. Bull's patent
semi -continuous, 103; cupolas
or ovens, 103 ; Dutch, 98 ;
Hoffmann's, description of, 101 ;
other forms of, 103 ; Scotch, 98.
„ for burning cement, Michele-
Johnson, 192; Portknd, 191;
Roman, 192.
„ for burning lime, continuous and
draw, 188 ; flare, 188, 189 ; in-
termittent, 1 88, 1 89 ; perpetual,
running, sow, and tunnel,
188.
Kilrush sandstone quarries, 47.
King's yellow, 415.
Kingstown granite quarries, 21.
Kingswell „ „ 20.

Kingsteary „ „ 20.

Kintail marble „ 54.

Kirby Ireleth slate „ 31.
Kirkaldy's, Mr., experiments on iron

and steel, 277, 282.
Kirkstall sandstone quarries, 44.
Knockly „ „ 46.

Knockroe slate quarries, 32.
Ejaotting, hot lime, 450 ; ordinary

and patent, 450.
Kremnitz or Krems white, 407.
Kuhlmann's process for preserving

stone, 78.
Kyan's process for preserving timber,
395.

494

INDEX.

La Moye granite quarriefl, 19.
La Perruque „ „ 19.

Lac for yamish, 431 ; seed, shell,

and stick, 431.
Lacquer for brass and hardwood,

434.
Lacquers, or spirit varnishes, 432.
Ladder poles, 364.
Ladies slates, cost, size, weighty etc.,

of, 27 ; thickness of, 28.
Lakes, as colouring pigments, 416 ;

Brazil wood, drop, carminated,

Chinese, Florentine, Hamburg,

Roman, scarlet, Venetian, 416 ;

yellow, 415.
Laminated lead, 342.
Lamoma granite quarries, 19.
Lampblack, 413.
Lancashire red pressed facing bricks,

109 ; size and weight of, 112.
Land rag bed of Kentish Bag, 65.
Landore Siemens-steel, 313.

„ steel. Admiralty tests for,
310 ; brands on, 312 ;
tensile strength and duc-
tility of, 323.
Lanesborough limestone quarries, 73.
Langdale slate quarries, 31.
Lanrick slate quarries, 32.
Larch, 372 ; age of, for felling, 360 ;

appearance, characteristics, and

uses, 372 ; weight and strength

of, 404.
Larches, American, Hacmatack or

Tamarak, 372.
Lath nails, 460.
„ work, selenitic plaster for, 246.
Latham's, Mr. Baldwin, directions for

forming bends and junctions,

132.
Laths, 453 ; plasterers', market forms

and thickness of, 453 ; metal, 453 ;

slate or tiling, 453.
Latt sandstone quarries, 47.
Launceston slate quarries, 31.
Layers of sandstone, thickness o^ 36.
Laying asphalte, 250.
„ concrete, 216.

Lazonby sandstone quarries, 40.
Lead, 341-345; acetate of, 412;
action of water upon, 342 ; and
tin, melting points of alloys of,
355 ; cast, 341 ; concrete, 222 ;
encased pipes, Haines's patent,
343; fret, 344, 345; genuine
dry white, 407; glazing, 129;
laminated, 342 ; market forms
0^ 341; miUed, 341; old
white, 408 ; ores o^ ^ena,
341 ; oxide of, 412.
„ paint, 418; injurious effect of,
421 ; mixing, 421 ; white and
coloured, 418.
„ pipes, 342; coating of, to pre-
vent poisoning, 343 ; size and
weighto of, 343, 344.
„ pipes, encased, 343 ; weight and

strength of, 344.
„ properties and uses o^ 341, 354.
„ red, adulteration of, tests for and
uses o^ 408; as a base, 408 ; as
a drier, 41 3 ; as a pigment, 416.
„ sheets, 341 ; weight and thick-
ness of, 341.
„ sugar of, 412, 431.
„ weight of, 357.

„ white, adulteration of, 407; as
a base, 407 ; markets forms of,
407; old, 408; uses, advan-
tages and disadvantages o^ 408.
Le Mesurier's concrete machine, 228.
Leaf, gold, 451 ; Dutch, foreign, and
pale, 451.
„ wood, 373 ; classification of^ 362.
Lecarrow limestone quarries, 73.
Lee Moor firebricks, 124; absoip-
tion, resistance to com-
pression and weight of,
124.
„ granite quarries, 19.
Leicestershire granite, 16.
Leigh Carr, strength of, 82.
Lemon chrome, 414.
Lersdip limestone quarries, 73*
Lethirium, extract o^ 436.
Letterfrack serpentine, 34.
Lettemaphy marble quarries, 54.
Lias cement^ 244.

INDEX.

495

Lias lime, 156; strengtli o^ 181, 201.
,y limestone, quarries, 60 ; weight

of, 84.
„ sandstone quarries, 39.

lichens, action of, on stone, 10.

Lidded pipes, 133.

Light, interception o^ hy glass, 444.
„ red, as a pigment, 416.

Lime, air-slaking o^ 146 ; amount of,
in fireclay, 122 ; and cement
burning, 188 ; artificial hydrau-
lic, 155 ; calcination of, 145, 230;
carbonate of, 146 ; caustic of quick,
145; dangerous, 194; dead-
burnt, 194; description of,
to be used in mortar, 185;
effect of, on day for brickmaking,
86 ; flare-burnt, 194 ; grey
chalk or stone, 155 ; ground,
203; hot, for killing knots,
450; hydrate of, 145 ; hydraulic,
to be used for important works,
198 ; hydraulicity of, 146 ; kilns,
classes of and operation of burning,
188-191; lias, 155; mixture of
cement and, 208. Mortar made
from fat, 230, evils of, 197,
made from selenitised, 206.
Nature of, for selenitic cement,
180 ; quantity required for mor-
tar, 205 ; selenitic mortar made
with ordinary, 207 ; rough tests,
151 ; slaking and setting of, 145,
146 ; superphosphate of, for pre-
serving stone, 80; varieties of, in
common use, 154.

Limes and cements, analysis of, 239 ;
classification of, 148 ; dangerous,
194 ; how produced, 145; weight
of, 256.

Limes, calcination of pure or &t, 230;
fat, 154; fat, should only be
used for inferior work, 197 ; fat,
stained, 152 ; hydraulic, 153-
155, classification of, 154 ; action
of, 232 ; i>oor, 152, composition
of, 149; rich or fat, 152, 232;
composition of, 149.

Limerick limestone, quarries, 73 ;
marble quarries, 54 ;8trengthof, 81.

Limestones, 49-73 ; absorption of,
83 ; action of foreign constituents
in, 230; carboniferous, 155;
classification of, 50 ; colour of,
67-73 ; compact, 56 ; composi-
tion of various, 149-151 ; consti-
tuents of, 146, 147 ; granular, 56 ;
magnesian, 57, 69, 155 ;
manufacture of Portland cement
from, 161 ; quarries, principal, in
Great Britain and Ireland, 67-
73 ; shelly, 57 ; strength of, 81 ;
weight of, 67-73, 84 ; where used
for building, and remarks, 67-73.
Limit, elastic, defined, 451; of cast
iron, wrought iron, and steel,
331.
Limit of elasticity defined, 329-331.
„ to increase of strength with
age of Portland cement, 179.
Limner asphalte, 253.
Limnoria terebrans, 401.
Lincrusta Walton, 447.
Lindrop sandstone quarries, 44.
Lingenfield sandstone quarries, 44.
Lining paper for walls, 446.
Linseed oil, 410; boiled, 411, and
raw, 410 ; boiling, 431 ; uses of,
410.
Lioch sandstone quarries, 46.
Liquid asphalte, Bamett's, 253.
„ enamels, Szerelmey's, 427.
„ petrifying, as a preservative

for stone, 80.
„ process of laying Val de Tra-

vers asphalte, 252.
„ stains, 435.

„ Szerelmey's stone, as a pre-
servative for stone, 79.
Lisbury limestone quarries, 73.
Lismore „ „ 73; sand-

stone quarries, 47.
Lisnaskea sandstone quarries, '47.
List brands on iron, 290.
Listowel limestone, quarries, 73 ;

strength of, 81.
Litharge as a drier, 412, 431.
Little Island limestone quarries, 73.
live and moving loads, 331, 332.
„ load defined, 467.

496

INDEX,

Live oak, 373.

Liver rock, 35.

Lizard serpentine, 34.

Llanfair Bojal Slate Co.'s quarries, 31.

Llangollen Slate Co/s „ 31.

Llechwedd slate quarries, 31.

Lloyd's tests for steel, 311.

Load Bridge limestone quarries, 69.

Load, defined, 467 ; breaking, dead,
and live, 467 ; proof and work-
ing, 468 ; set caused by con-
tinued, 330.

Loads, live and moving, 331 ; re-
peated, 332 ; repeated or falling,
test for steel rails, 311.

Loam, castings in, 268.

Loams for brickmaking, 87, 89 ;
analysis of, 88.

Lochee sandstone quarries, 46.

Log of timber, 364.

Longannet sandstone quarries, 44, 46.

Longford „ „ 47.

Longhaven granite „ 20.

Longridge sandstone „ 44.

Longwood Edge „ „ 44.

Lougb granite „ 21.

Luminous paint, 429.

Lundy Island granite quarries, 19.

Lycoris fucata, 402.

Machine-made bricks, method of dis-
tinguishing, from clamp and
kiln-burnt. 111.
„ moulding bricks, 93.
„ wrought nails, patent, 458.
Machines for brickmaking, dry clay,
94 ; plastic clay, 93.
„ for mixing concrete, 225-
230 ; American, 229 \
Carey - Latham, 229 ;
inclined cylinder, 225 ;
Le Mesurier's, 227 ;
Messent's patent, 226 ;
Ridley's and Stoney's,
229.
„ for mixing mortar, 223-
225 ; hand mill, 225 ;
horse mill, 224; mill

driven by steam power,
223; portable mill, 224.
Machines for testing cement, 182-
187; Adie's^ 182, 183;
Michaelis's, 184; Mi-
chele's, 184, 185; Reid
and Bailey's, 186 ; Thur-
ston's, 187.
y, for testing iron, 279.

Madrepore marbles, 51.
Maenoflfem slate quarries, 31.
Magnesia, carbonate of, 148, 156,
237 ; colouring action of^ on
bricks, 89 ; in brick clays, 88
in fireclay, 122.
Magnesian limestones, analysis of, 58
colour of, 69, 70; composition
of^ 57 ; crushing weight of, 81
hydraulic limes from, 155 ; quar-
ries, 69, 70 ; structure of, 58
weight o^ 69, 70, 84; where used,
and remarks on, 69, 70.
Magnetic iron ore, 258.

„ paint, Pulford's, 425.
Mahogany, 380; African teak, or,
376 ; Cuba or Spanish,
381.
y, Honduras, 380; appear-

ance, characteristics,
and uses o^ 380 ;
market forms oi^ 381.
^ Jarrah or Australian, 381.

„ Marks and brands on,

387.
„ Mexican, Nassau, and St

Domingo, 381.
„ purposes for which it is

useful, 403.
„ resistance to cmahing

across fibres, 405.
„ stain, 436.

„ weight, strength, etc, of^

404.
Main Bridge bed of Kentish Bag,

65.
Majolica tiles, 143.
Malachite, 417.
Malleability defined, 470.
Malleable cast iron, 266 ; character-
istics and uses of, 338.

INDEX.

497

Malleable iron, tensile strength and
daetility of variouB d&-
flcriptiona, 318.
„ nailfi, 457.
Mallet's buckled plates, 287.
Mallow limestone quairies, 73 ; sand-
stone qnarries, 47.
Malm, 88 ; preparation of^ 91.
^ bricks, 9 1 ; absorption of, 11 4 ;
price o^ 106.
Manganese, effect o^ on cast iron, 862.
„ oxide and sulphate of, as

driers, 413.
Manger bricks, 120.
Manley sandstone quarries, 40.
Mansfield stone, 38 ; absorption o(
83 ; quarries, 39 ; red,
white, and where used,
38; strength o^ 81.
^ Woodhouse limestone, 66 ;
chemical composition,
uses, and where used, 66.
M yellow, limestone, 66 ; quar-
ries, 70.
ManuiiEU^tare of Portland cement from
chalk and clay, 160 ;
jfrom limestone and
clay or shale, 161.
„ of T and I irons, 275.

Marble, absorption of, 83 ; artificial
247 ; description of, 50 ; different
forms of 51 ; quarries^ 52-
55 ; Rust's vitrified, 76 ; tensile
strength of, 82 ; uses of, 51 ;
weight of, 84.
Marbles, 50-55; ancient, encrinal.
Madrepore, and shell, 51 ; arti-
ficial, 247, 248 ; continental, 55 ;
English, 52 ; Irish, 54 ; Scotch,
53 ; resistance of, to crushing, 81.
Marcaaite, in granite, 14; in slates,

26.
Marchionesses slates, cost, weight, etc,

of, 27 ; thickness o^ 28.
Marezzo marble, 248.
Mai^gary's process for preserving tim-
ber, 396.
Marine glue, 449.
„ green, 417.
Markfield granite quarries, 19.
B. C. — m

Marks and brands on iron, pig, 295,
wrought,296-
300.
^ „ on steel, 312, 313.

„ ^ ou timber, 383-

387.
Marls for brickmaking, 87, 89.
Martin's cement, 243.
Marvel fluid, 436.
Maryport slate qaarriee, 31.
Masons' tools, tempering, 307.
Massicot, 412.
Mastic, 250 ; asphalte, 253.
„ for varnish, 431.
„ Hamelin's, 244.
Mastics, 244.

Masts, hand and inch, 364.
Material, cementing, to be used for
concrete, 217.
„ Dennett's fireproof, 249.
Materials used by plasterers, 242 ;
for ordinary plastering, 244 ;
quantity requii«d for plastering
and rendering, 255.
Matheson's, Mr., remarks on tests for

cast iron, 272.
Matlock Moor sandstone quarries, 44.
Matrix for concrete, 210.
M'Dougal's patent for coating lead

pipes, 343.
M'Neile's process for seasoning timber,

390.
Mealoughmore slate quarries, 32.
Mealwood limestone „ 73.
Mean Wood sandstone „ 44.
Means for testing tensile strength of

cement, 182.
Measuring timber deals, method of,

387.
Medina cement, 158 ; strength of,

159, 201 ; weight o^ 256.
Medullary rays in timber, 358.
Meelick limestone quarries, 73.
Melting points of alloys of lead and
tin, 355.
„ „ of solders, 353.

Memel fir, weight, strength, etc, of,

404 ; deals, 367 ; timber, 366.
Mento marble quarries, 54.
Merchant bar iron, 274.

498

INDEX.

Merlin Park marble quarriea, 54.

Meirivale granite quarries, 19.

Meiryfield sandBtone quany, 44.

Mersey Company's steel, strength and
ductility o^ 322.

Messent's concrete-mixer, 226.

Metal, Babbit's, 350 ; beU, 350 ; bronze,
349, 350; Delta, 349; gauge,
Birmingham, 357 ; Qedge's, 350;
gun, 350, homogeneous, 307 ;
Muntz, 349, 350, 354; screws
for, 464; sterro, 350; work,
black varnish for, 435.

Metals, 257-357 ; coiltraction of, in
cooling, 355 ; fluxes used for,
353 ; pot, 444 ; properties of
useful, 354; weight of different,
357 ; welding, 333.

Metallic cement for plastering, 244.
„ oxides, 148.

Metamorphic sandstones, 36.

Methylated spirits of wine in vamiBh,
431.

Metropolitan Main Drainage Works,
cement used on, 163-166 ; com-
position of concrete used at, 215.

Mexican mahogany, 381.

Mica in granite, 13, 14; schist or
slate, 23.

Micaceous sandstones, 36.

Michaelis's double cement testing
apparatus, 184.

Michele-Johnson kiln for cement, 1 92.

Michele's cement-testing machine, 1 85.

Micklefield limestone quarries, 70.

Middle chrome, 414.

Midland brands on iron, 298.

Mild clays fur brickmaking, 87.
„ steel, 306.

Mill Hill granite quarries, 19.

Milled lead, 341.

Minard sandstone quarries, 47.

Mine iron, 264.

Minera sandstone quarries, 44.

Mineral green, 417.
„ pitch, 253.
„ tar, 454.

Mirror-iron, 304.

Misshapen bricks, 103, 104.

Mitis wrought iron castings, 289.

Mixing lead painty 420.

„ materials for concrete, 214 ;

for mortar, 203,
„ Portland cement, 177.
„ Seyssel asphalte, 252.
„ Yamishes, 432, 433.

Mixture of lime and cement for mor-
tar, 208.

Moderately quick cements, 150.

Modulus of elasticity defined, 469.

Moisture, glues to resLst, 449.

Molluscs, action o^ on stone, 10.

Mona marble quarries, 53.

Moneen limestone quarries^ 73.

Money Point sandstone quarries^ 47.

Monte marble quarries, 54.

Montrotier asphalte, 253.

Moor Quarry sandstone quarries, 44.

Mora, 383 ; appearance, characteris-
tics, market forms, and uses of,
383; weight, strength, etc^ of^404.

Mordant 436-

Morley sandstone quarries, 44.

Morley Moor sandstone quarriei^ 44 ;
strength o^ 81.

Mortar, 197-209 ; bulk of, produced
from given quantities of materialB,
204, 205 ; cement, 197 ; compo-
sition of, 197; effect of different
proportions of sand in, 201 ; evils
of fat lime, 197 ; grout, 209 ; in
brickwork. General Scotfs pro-
portions- for, 201 ; joints for
terra cotta, 126 ; made from £st
lime, 230, from given quantities
of lime, cement, and sand, 205,
with ordinary lime, 207, lime or
cement to be used with, 198;
mill for preparing selenitic^ 206 ;
mills for mixing, driven by steam
power, 223, hand, 225, horse
and portable, 224; mixing
machinery, 223-230 ; mixed
separately for concrete, 213 ; mix-
ing, 203; ordinary, 197; pre-
cautions in using, 209 ; prepara-
tion and mixing of, 202 ; pro-
portion of in<rreilierit8, 200 ; sand
to be used in, 198; substitutes
for sand in, 199; selenitic, 206,

INDEX,

499

Mortar — eonttnuecL

made with selenitised lime or
selenitic cement, 206, with ordi^
nary lime, 207 ; strength of, as
compared with bricks in a wall,
200 ; sugar in 206 ; uses o^ 197 \
water to be used in, 199.

Mortars made from various cements,
sho¥dng effect of different
proportions of sand in, 200.
„ pozzuolana, 180.

Mosaic paving slabs, uses o^ 143.

Moas and Gamble's cast steel, strength
and ductility of, 322.

Mottled cast iron, 265 ; pig iron, 264.

Mould presS) cement, 182.

„ split cement, 182.

Moulded bricks, 109; cornice, 118.

Moulding bricks, hand, 91 ; ma-
chine, 93 ; sand and slop, 92.

Mountain green, 417.

Mount Mado granite quarries, 19.

Mountmellick sandstone „ 48.

Mountsorrel granite, quarries, 19;
strength of, 81«

Moving and live loads, 331.

Mubb Hill limestone quarries, 73.

Mulgrave's cement, 159.

Mullaghglass granite quarries^ 21.

Munlochy sandstone quarries, 46.

Muntz metal, 349 ; composition of,
350 ; properties of, 354.

Mushefs process, 304.

Mylnefield or Bingoodie sandstone
quarries, 46.

Nail iron, 287 ; rods, price of, 291.

Nails, 457 ; adhesive force of, 462 ;
cast, 457 ; clasp, 458 ; clout,
composition and copper, 459 ;
Conies' patent wrought, 461 ; cut,

457 ; cut clasp, 458 ; dog, 459 ;
French, 459 ; hand-wrought, 457;
lath, 460 ; maUeable, 457 ; mis-
cellaneous, 460 ; patent machine-
wrought, 458 ; pound, 460 ; rose,

458 ; slating and steel, 460 ; table
of size and weights of different

kinds per 1000, 461, 462 ; ten-
penny, holding power of, 462;

varieties o( in conunon use, 458 ;

weight 0^ 460, 461 ; wire or

French, 459 ; wrought clasp, 458.
Nairn sandstone quarries, 47.
Naples yellow, 414.
Naphtha for varnish, 410.

„ parafifin dissolved in, as a pre-
servative for stone, 77.

„ wood,as a solvent for varnish,
431.
Narberth firebricks, 124.
Nassau mahogany, 381.
Natural bed of granular limestones, 57.

„ beds of stone, 9.

„ cements, 156-168.

„ pozzuolana, 196.

„ seasoning of timber, 389.

„ steel, 306.
Naylor's and Vickers' steel, strength

and ductility o^ 321, 322.
Nettlefold's patent screw, 464.
New Leeds sandstone quarry, 44.
New Red sandstone quarries, 40.
Newbiggin sandstone quarry, 40.
Newbridge sandstone quarries, 41.
Newcastle firebricks, 1 23 ; analysis of
clay for, 122 ; resistance
to compression, weight
and absorption of, 124.
„ white, 407.
Newfoundland red pine, 372.
Newington Cleaves bed of Kentish

Bag, 65.
Newport sandstone quarries, 48.
Newry granite quarries, 21.
Nidderdale limestone quarries, 71.
Nodules or cement stones, 157.
Noir Antico marble quarries, 55.
Non-drying oils, 409.
Nooaff limestone quarries, 73.
North Auston limestone, analysis of,

59.
North of England brands on iron,
295, 299.
,, M extras charged for

iron, 294.
„ Owram sandstone quarries, 44.
Northamptonshire pig iron, 295.

500

INDEX.

Northern pine, 365.

Northfield sandstone quarrieB, 40.

Norway timber, 367.

Norwegian deals, 368; marks and

brands on timber, 386.
Nottingham patent bricks, 108.

„ white, 407.

Nut oil, 411.
Nuts and bolts, 466.
Nyland deals, 368.

Oak, 373 ; age for felling, 360 ; ap-
pearance, characteristics, com-
parison of the different varie-
ties, and uses of, 374.

„ African teak or mahogany, 376.

„ American WhiteorP&sture, 375;
appearance, characteristics,
market forms, and uses o^ 375.

„ Baltimore, 375.

„ British, 373 ; cluster-fruited or
bay, 373 ; Durmast, 374 ;
stalk-fruited or old English,
373.

„ Canadian or red, 375.

„ dap boarding, 376.

„ conversion of, 400.

„ Dantzic, 375 ; appearance, mar-
ket forms, and uses o£^ 375.

„ Durmast, 374.

„ felling o^ 375.

„ French, 376.

„ how supplied to H.M. Dockyards,
364.

„ iron, 375.

„ Italian or Sardinian, 376.

„ live, 375.

„ purposes for which it is usefril,
403.

„ resistance to crushing across
fibres and shearii^, 405.

„ Riga, 376.

„ stain, 436.

„ varnish, 434.

„ wainscot, 376.

„ weight and strength of, 404.
Oakeley slate quarries, 31.
Oban granite „ 20.

Obscured glass, 443.

Ochil Hills serpentine, 34.

Ochre, brown, 415 ; chrome and
orange, 417; Oxford, 415;
Spanish, 417 ; spruce, stone, and
yellow, 415.

Oil, as a preservative for stone, 77 ;
boiled, for zinc paint, 411; dark
drying, 411 ; drying for common
work, 411 ; gold size, 450 ; hard-
ening and tempering steel in,
309 ; linseed, 410; boiled, 411,
431, raw, 410 ; of turpentine^
409, 411 ; nut^ pale drying, and
poppy, 411.
„ varnishes, 431 ; mixing, 438 ;
receipts for, 433.

Oils as a vehide for paints^ 409;
drying and non- dryings 409;
fixed and volatile, or essential,
409.

Old English oak, 373.
„ paint, cleaning, 436.

Old Red sandstone quarries^ 46-48L
„ white lead, 408.

Oligodase, 13.

One Ash marble quarries, 58.

Oolitic limestone „ 67-69.
„ sandstone „ 39.

Opaque glazes, 130.

Opercular or lidded pipes, 133.

Orange chrome, 414, 417 ; ochre and
red, 417.

Oranges^ colouring pigments for,
417.

Ordinary building bricks, 103, 104,
116.
„ iron pyrites in slates, 26.
„ lime, selenitic mortar made

with, 207.
„ mortar, composition o^ 1 9 7.
„ tarring, 428.

Ore, magnetic iron, 258 ; spathic,
258.

Oregon or Douglas pine, 373.

Ores, 257 ; blackband and brown hie-
matite, 258 ; clay ironstone, 257;
of copi>er, 339 ; of iron, 257 ;
of lead, galena, 341 ; of metal^
257 ; red haematite and spathic,

INDEX.

501

86d; smeltiiig of, 258; of tm,

347 ; of zmc, 345,
Oreston marble quarries, 52.
Organic matter in brick clajs, 88,
Ornamental bricks, Pether'S) 100.
Ornaments, plaster, 248; composi-
tion, 249.
Orpiment, yellow, 415.
Orthodase, 13.
Osborne and Company's steel, tensile

strength and ductility of, 321.
Osmoiherley sandstone quarries, 40.
Oughterard granite „ 21.

Outside painting, quantity required

for, 419.
Overbumt limes and cements, 194.
Overbeating foigings, 333.
Oxalate of alumina as a preservatiye

for limestone, 80.
Oxford ochre, 415.
Oxidation of copper, 340.
Oxide of iron as a base for paints,

409; colouring action of^ 87,

89 ; in brick clay, 68 ; paints,

425, black, purple, brown, and

silicate^ 425.
Oxide of lead as a drier, 413.

„ of manganese as a drier, 413.

„ of zinc as a base for paints,
uses o^ 409.
Oxides, metallic, in limestones, 148.
Oxygen, action of^ on stones, 3.
Oxy- sulphide of sine in painty

409.

Packing for concrete, 212.

Painswick limestone quarries, 69.

Painty anti-corroeion, 426 ; as a pre-
servative for stone, 77 ; Bessemer's
gold, 451 ; black oxide of iron,
425 ; cleaning old, 436 ; enamel,
426; granitic, 427; granulated
cork, 429 ; Griffith's patent sili-
cate enamelling, 427; Griffith's
patent white, 424 ; indestructible,
426 ; injurious effect of lead, 421;
inodorous, 423 ; lead, 418 ; mix-
ing lead, 421 ; Pulford's magnetic,

425 ; silicate oxide, 425 ; tar,
428 ; titanic, 426 ; wash for re-
moving, 436 ; white lead, 420 ;
white, quantity required to cover
100 square yards, 419 ; Wolston's
Torbay, 425; zinc, 421.
Biinter's putty, 452.
Painting as a preservative for iron,
336 ; for timber, 394.
„ felt for exterior work, 456.
„ wall papeis, 447.
Paints and vamiahes, 406 ; Asbestos,
428.
,y bituminous, 428;coloured,429;
coloured lead, 420; iron,
Szerelmey's, 427 ; mixed, pro*
portion of ingredients in, 418;
oxide of iron, 425 ; pigments
for coloured, 422; silicate,
426 ; specia], 423-429.
Pale amber vamish, 435 ; drying oil,
411.
„ leaf gold, 451.
Pallas Kenry marble quarries^ 54.
Pallette bricks, 109.
Panelling, timbers useful for, 403.
Ptotiles, 139.

Paper, lining for walls, 446.
„ ghiss, 457.
„ varnish for, 435.
Paperhanging, 446-447; useso( 447.
Paperhangings, washable, 447.
Papers for papering walls, 445, 446 ;
colours used for, 446 ; common
or pulp, 445 ; different classes of,
distinction in appearance, 445 ;
English, 446; flock, 445; French,
446 ; market forms o^ 446 ;
printing, 445 ; satin, 445 ; vai^
nishing and painting wall, 447.
Papier-mach^ 249.
Paraffin as a preservative for stone,

77.
Parchment size, 450.
Parian cement, 243 ; weight o^ 256.

„ marble quarries, 55.
Paris, plaster of, 242.
Park sandstone quarries, 48.

„ Nook limestone, quarries, 70;
strength 0^ 81*

502

INDEX.

Park Quany (New Malton) sandfltone
quarries, 39.
„ Quarry (Toxall) sandstone quar-
ries, 40.
n Spring sandstone, absorption o^
83 ; quarries, 39 ; resistance
of, to crushing, 81.
Parkfield sandstone quarries^ 40.
Parker's or Roman cement, 167.
Parsonstown limestone quarries, 73.
Paste, 451.
Pasture oak, 375.
Patent knotting, 450 ; size, 449.
Patterns, timbers useful for, 403 ;

used in castinf^s, 267.
Paving bricks, 118.

„ slabs, mosaic, 143.
„ tiles, 138.
Paviors, hard and facing, description

and price of, 105.
Payne's process for preserving timber,

396.
Pegs, tile, 460.

Pelsea bed of Kentish Rag, 65.
Penmaenmawr stone, 23.
Penrioca slate quarries, 31.
Penrith sandstone „ 40.
Penrhyn slate quarries, 31.
Penryn granite quarries, 19.
Pensber sandstone quarries, 44.
Pen-yr-Orsedd slate quarry, 31.
Percy's, Dr., remarks on influence of car-
bon in iron, 267.
„ y, on vibration, 332.

Perforated air bricks, 134.
„ bricks, 117.
„ glass, 443.
Permanent set, false, 330.
Permian, Upper, sandstone quarries,

41.
Perpetual kiln for lime burning, 188.
Persian red as a colouring pigment,

416.
Persley granite, 20.
Perthshire serpentine, 34.
Peterhead granite, colour, weight of,
and quarries, 20 ; resistance of, to
crushing, 81 ; resistance of, to
wear, 84.
Pether's ornamental bricks, 109.

Petit Tor marble quarries, 52.
Petrifying liquid as a presenrstive

for stone, 80.
Petworth marble quarries, 52.
Pew Tor granite „ 19.
Pewter, 357.

Pholas dactylus mollusc, 10.
Phosphor bronze, 351 ; properties of,

354.
Phosphorus, effect of^ on iron, 262.
Physical structure of stone, 4.
Pickling iron, 336.
Pierre, carton, 249.
Piers, brick, strength of^ 116.
Pig iron, 260-264, 266, 295 ; brands
on, 295 ; classification of^ 263 ;
descriptions o^ for castings, 266 ;
different materials produced from,
260 ; foreign substances in, 260 ;
hflematite, 295; impurities in,
262, 263 ; Northamptonshire and
Staffordshire, 295.
Pigments for coloured paints, 422,
„ 423, for colouring, 407, 413-
417.
Piles, timber useful for, 403.
Pillough sandstone quarries, 45.
Pine, 363.
„ American, 368; red, 368; ap-
pearance characteristics, mar-
ket forms, uses, and where
found, 369.
„ American yellow, 369 ; appear-
ance, characteristics, market
forms, and uses of, 369 ; cUs-
sification of^ 370.
„ Canada red, 368.
„ Eawrie, Cowrie, or Cowdie, 373 ;
appearance, characteristica^ and
uses of, 373.
„ Newfoundland red, 372.
„ Northern, 365.
„ Oregon or Douglas, 373.
„ pitch, 370 ; appearance, charac-
teristics, and uses of, 370 ;
market forms of, 371.
„ Quebec yellow, 370.
„ resistance to crushing across
fibres and to shearing,
405.

INDEX.

503

Pine — eomivM^L
f, weight) strength, etc^ of, 404.
„ irood, 362, 365 ; eharacteruBtics
and examples of, 362.
Pink, blown, 415 ; Dutch and rose,

416.
Pipes, 130 ; agrieultnral drain, 131 ;
capped, 133 ; cast iron, examina-
tion of castings, 271 ; channel,
137; chimney flue, 136; Jen-
nings' improved patent drain, 1 33;
junctions for, 132 ; lead, 342 ;
lead, coating to prevent poison-
ing, 343 ; lead, size, weight, and
strength of, 342, 343; lead-en-
cased, strength and weight of, 343,
344 ; opercular or lidded, 133 ;
sewer, socket, and half socket,
131 ; taper, 132 ; test for sewer,
134.
Pisolites, 56.
Pit sand, 195.

Pitch, 253 ; coal tar and mineral, 253.
y, pine, appearance, characteris-
tics, and uses, 370 ; mar-
ket forms o^ 371 ; weight,
strength, eta, of, 404.
Place bricks, description and price of,

105.
Plain tiles, 139.
Plane tree, 377 ; weight, sti^ngth,

etc., of, 404.
Planes of cleavage in clay slates, 24.
Planks, Baltic, marks and brands on,
385 ; market forms of, 364 ; of
oak, how supplied to H.M. Dock-
yards, 364 ; size o^ 364 j varie-
. ties of, 367, 368.
Plaster, fibrous, 249.

„ of Paris, 242 ; weight o^ 256.
„ ornaments, 248.
„ selenitic, 246.
Plasterers' laths, thickness and market
forms of, 453.
y^ materials used by, 242.

putty, 246.
„ tab for mixing selenitic
mortar, 207.
Plastering, materials used in ordinary,
244,

Plastering on lath work with selenitic
plaster, 246.
M outside work with selenitic

plaster, 247.
„ quantity of materials re-
quired for, 255.
Plasters, cements used for, 242.
Plastic clay machines, 93.

„ clays for brickmaking^ 87.
„ concrete, 217.
Plate, charcoal, 287, 348.

„ coke and crystallised tin,

348.
„ gauge, 357.
„ glass, British, 441 ; advantages

of, 441.
„ „ 9, polished, 442.
„ „ German, 440.
„ „ patent or blown, 441 ;
colour, quali-
ties, sizes, thick-
ness, and weight
of, 441.
„ „ „ diamond and quar-
ry, rough, 443.
„ „ polished British, 442 ;
qualities, sizes, thick-
ness, and uses of,
442.
„ „ rough rolled, 442 ; plain
and fluted, 442 ; sizes
and thickness o^ 442.
Pkte iron, 287.

„ forge tests for, 281.
„ price of, 292 ; extras
charged for, 287, 292,
294.
Plate, teme, 287 ; tin, 348.
Plates, boiler, extras charged for, 292,
294 ; flitch, 287 ; iron, strength
of, 318; Mallet's buckled, 287;
steel. Admiralty tests for, 310,
311, effect of annealing, 325 ;
extras charged for, 312, tensile
strength and ductility o^ 322 ;
tin, 287.
Platforms, copings for, 119.
Platinum, properties of, 354.
Plerry, 24.
Pliability defined, 469.

504

INDEX.

Plinth bricks, 118.

Plumbers' solder, melting points of,
proportion of ingredients and pur-
poses for whicb used, 353.

Plymouth marble quarries^ 52.

Pooombe ,, ,,52.

Pointed screws, patent, 464.

Poisoning by lead pipes^ coating to
prevent, 343.

Poles, scaflfold and ladder, 364.

Polish, French, 434.

Polished bricks^ 94.

„ plate glass, British, 442.

Pomphlet limestone quaxiies, 71 ;
date quarries, 32.

Poor limes, 152.

Poplar, 380; appearance, character-
istics, and uses of, 380 \ weight,
strength, etc., of^ 404.

Poppy oil, 411.

Porphyries, 22.

Porphyritic granite^ 15.

Porphyry, felstone and qnartziferous,
22 j characteristics of, 22.

Port John granite quarries, 19.

Port St Mary sandstone quarries,
53.

Portable mortar mill, 224.

Portland cement, 160; adulterations,
187; breaking weights of, on
▼arious works, 169; briquette,
method of making, 172 ; shape
of, and nature and proportion of
water for, 178; clinker, 193;
colour of^ 168 ; coolness, testa
for, 174; fineness of grit, 162;
hardening and setting, 1 75 ; kilns,
191 ; limit to increase of strength
with age, 179 ; manufacture from
chalk and day, 160; manufacture
from limestone, day, or shale,
161 ; from slag, 161 ; market
forms of, 179 ; method of weigh-
ing, 167; mixing and using, 177;
quality, tests of, 162; storing,
176; strength o^ 176, 182, 200;
stucco, 244 ; tensile strength, test
for, 168 ; tests for, 163-175 ; used
for plastering, 242 ; weight o^
165, 256.

Portland oolite limestone quarries^ 67.
„ screw, 62.

M stone, 8, 60-63 ; aheorption
0^ 83; basebed, 8, 63;
basebed roach and baalard
roach, 8, 62 ; buildings in
which used, 63 ; diemical
composition of, 60; curf,
or kerf^ 8, 62 ; lime, weight
of, 242 ; quarries 63, 67 ;
quany, section of, 7, 61 ;
strength of^ 81 ; true roach
and whitbed, 8, 62.
Portmadoe granite quarries^ 19.
Portsoy serpentine, 34.
Portumna limestone quamea^ 73.
Portwash marble „ 53.

Position, geological, of bath stone, 59.
M of a stone in a building, 4 ;
in a quarry, 7.
Posts^ timbers useful for, 403.
Pot metals, glass, 444.
Pots, chimney, 136.
Potter Newton sandstone quarries, 45.
Power, adhesive, of screws, 465.
Pozzuolana, 180, 196, 237 ; artifidd
and natural, 196.
„ mortars, 180.

PreeautionB in using driers, 413.
„ „ fat lime, 1 62.

„ „ mortar, 209.

Preparation of glue, 448.

,, malm for brickmaking,

91.
„ mortar, 202.

PreparatioDs for preserving sUrne^ 77,

80.
Preservation of iron and steel, 335-
387.
„ of stone, different me-

thods of, 76-80.
^ of timber, 394-396;

from fire, 396.
Press, cement mould, 182.
Pressed bricks^ method ef making,
94.
„ fadng briok% Lancadiire red,
109.
Princesses slates, area covered, aiie
and weight (^, 27.

INDEX.

50s

PrintiBg wall paper, 446.
Production of iron from ores, 257.
Proof load defined, 468.
„ strength „ 468.
„ stress y, 468.
Protection of timber against the white
ant and worms, 408.
^ temporary, of stone sor-
ilBbces, 80.
Pnidham sandstone quarries^ 45.
Prussian blue, 414 ; deals, 867 ;

green, 417.
Psammites, 196.
Puddle balls, 273.
Puddlecote limestone quarries, 60.
Puddled bars, 273, 274.

„ steel, 306.
Puddling iron, 273.
Pulford's magnetic paint, 426,
Pulp paper for walls, 445.
Purbeck, beds of limestone, 67 ; lime-
stone quarries, 67 ; marble quar-
ries, 63 ; strength o^ 81.
Pure clays for brickmaking, 87, 88.
^ or fiit limes, 230 ; calcination
o( 230; mortar made from,
230 ; slaking and setting o^
230.
Purple brown as a colouring pigment,
415.
„ n oxide for paint, 425.

Purpose-made bricks, 116.
Putty, 452; hard and soft, 452;
painters' and glaziers', 452;
plasterers', 246; thermo-plaatic,
452.
Pyotdykes sandstone quarries, 47.
Pyriteis, iron, in brick clays, 87.
^ in slates, ordinary and white,
86.

Quadrant iron, 286.

Quantitative analysis of a brick earth,

144.
Quarella sandstone quarries, 44 ;

strength of, 82.
*« Quarries," flooring tiles, 138.
Quarries Bath stone, 59.

Quarries, granite, 18-21.

„ Kentish Rag, 66.

„ limestone, 67-73.

„ marble, 52-55.

„ sandstone, 39-48.

„ slate, 31, 32.

„ Portland stone, 63.
Quarry, Portland, section o^ 7, 61.

„ position of stone in, 7.

„ rough plate glass, 443

„ sap, 8, 15.
Quarrying Bath stone, 69.

„ granite, 15.

„ remarks on, 12.
„ slates, 24.
Quartz, crushing weight of, 81; in

granite^ 13 ; weight of, 84.
Quartziferous porphyry, 22.
Quebec yellow pine, 370.
Queens slates, area covered, cost,

weight, etc, 27.
Queensberry sandstone quarries, 46.
Quick cements, 150, 151.

„ setting rust cement, 452.
Quicklime, 145 ; weight of, 256.

Bace, 90.

Rag, Kentish, 64-66 ; Rowley, 24, 76.

Rags slates, area covered, cost, and
weight, etc., of, 27.

Ragstone bed of Kentish Rag, 64 ;
uses of, 65.

Rail bars, 282 ; bridge, double-headed,
tram and Vignoles or flat-bottom-
ed, 282.

Rails, iron and steel, price of, 290.

Ransome's artificial stone, 74; ab-
sorption of, 83 ; cement,
161 ; characteristics of,
74 ; uses of, 75.
„ indurating solutions, 78.

Rathdrum skte quarries, 32.

Raihfriland granite „ 21.

Ravaccione marble „ 55.

Raw linseed oil, 410.
„ sienna, 415 ; umber, 415.

Recipes for varnishes, 433-435.

Red bricks, 108; Fareham, 108;,

5o6

INDEX.

Lancaahire pressed facing, 109;
size and weight of, 112.
Red Corsehill sandstone, strength of,
82.
„ Cow limestone quairies, 73.
„ hsBmatite, 258.
„ lead, adulteration and tests, 408 ;
as a base for paint, 408 ; as a
colouring pigment, 416 ; as a
drier, 413.
„ Mansfield stone, 38.
yy or Canadian oak, 375.
„ pine, American, 368 ; Newfound-
land, 372.
„ shortness in iron, 276.
„ stain, 436.
Redgate sandstone quarries, 45.
Reds for colouring pigments, bright,
carmine, Chinese, Indian, light,
Persian, and Venetian, 415.
Refining iron, 273.
Refractory clavs, 120.
Reid and Bailey's cement- tester, 187.
Remedies for efflorescence on walls,

239.
Remeltings, repeated, effect of, on

strength of cast iron, 316.
Removing paint, wash for, 436.
Rendering, quantity of materials re-
quired for, 255.
Repainting old work, 420.
Resilience defined, 470.
Resins as an in^^edient of varnish,

430 ; gum, 430.

Resistance to compression, of bricks,

115; of concrete, 221 ;

of firebricks, 124; of

stones, 11, 81, 82.

„ to crushing and shearing,

of timber, 405.
„ to wear, of granites, 84.
Retire granite quarries, 19.
Rhiwfachno slate „ 31
Rhosydd „ „ 31.

Ribbon sash line, breaking strain, 340.
Rich or fat limes, 152, 154 ; calcin-
ation of, 230; composition of,
various, 149 ; slaking and setting
of, 230.
Rickers, 364.

Ridge tQes, 141.
Ridley's concrete-mixer, 229.
Riga deals, 372 ; fir, weight, strength,
etc, of, 404 ; oak, 376 ; timber,
366.
Rigidity defined, 469.
Rimpton limestone quarries^ 69.
Rind-galls in timber, 362.
Ringby sandstone quarries, 45.
Ringoodie sandstone quarries, 46.
River sand, 195.

Rivet iron, 287; price of, 294;
extras charged on, 294 ; tensile
strength and ductility o^ 318.
Rivets, steel, 311.

„ tests for, 282.
Roach, 8, 60, 62 ; bosebed, bastard,
and true, 8, 60, 62 ; position of^
in quarry, 7, 61.
Roasting ore, 257.
Robin Hood sandstone quarries,

45.
Robinson's cement, 244.
Roche Abbey limestone, absorption
of, 83; crushing weight of, 81;
quarries, 70.
Rock asphalte, Brunswick, 253.
„ concrete tabes, 221.
„ ekn, Canada, 379.
„ liver, 35.
Rockhill sandstone quarries, 46.
Rocks, igneous, other than granite,
22.
„ trap, 23.
Roestones, 56.
Roll tiles, double, 139.
Rolled bars, tensile strength and duc-
tility of, 318.
„ girder iron, 285.
„ glass, cathedral, 443; plate,

442.
„ iron, cold, 275.
Rolling iron, 273 ; effect o^ 274.
Roman cement, 157 ; for plastering,
243 ; kilns, 192 ; market forms,
storing, and uses of, 158 ; weight
and strength of, 157, 159, 201,
256.
Roman lake, 416.
Roofing felt, asphalted, 455.

INDEX.

So?

Boofing tiles, 138; Broomhall Ck>m-
pany's or Taylor's patent^
140 ; corrugated and double
roll, 139 ; hip and valley,
141 ; pan and plain, 139 ;
Venetian or Italian, and
Wade and Cherr/s, 140;
wire-wove, 467.
Bose nails, 458; clench, flat and
sharp, 458 ; size and weight
per 1000, 461.
„ pink, 416.
Rosin, common, for varnish, 430.
Ross of Mull granite quarries, 20.

Rosso Antico marble

55.

Rot in timber, 392; dry, 392; de-
tection of, 393 ; wet, 393.
Rouge Royal marble quarries, 55.
Rough-cast and stucco, 247.

„ cast and rolled plate glass,

442.
„ leaved elm, 378.
„ plate glass, diamond and quarry,

443.
„ timber, oak, 364.
Rough tor granite quarries, 19.
Round-ended bricks, 118.
„ headed screws, 463.
„ and half round iron, 284 ;
extras charged for, 291-294.
Rowley Rag basalt, 24 ; used in mak-
ing Chance's artificial stone, 76.
Royal blue, 414.

Rubbers, 103, 104 ; characteristics of
good. 111 ; should be avoided for
exposed work, 104.
Rubislaw granite quarries, 20.
Runcorn sandstone, crushing weight

of^ 81 ; quarries, 41.
Running kilns for lime-burning, 188.
Ruskington limestone quarries, 69.
Russian deals, 367 ; marks and brands

on, 386.
Rust cement, 452 ; quick and slow

setting, 452.
Rust's vitrified marble, 76.

S
S. Tauton marble quarries, 53.

Sabicu, 379; appearance of, 379;
characteristics of, 380.

Saddles for pipes, 132.

Safety, factors of, defined, 467.
„ „ for iron and steel,

326.

Salt glazing, 129.

Salt in clay for brickmaking^ 87.
„ waterobjectionableinmortar,199.

Salted bricks, 109.

Samel bricks, 104.

Sand, 195 ; casting in, 267 ; descrip-
tion o^ to be used in mortar, 198 ;
examination of, 1 95 ; in limestone,
147; in mortar, substitutes for,
199 ; in mortars, effect of differ-
ent proportions of, 201 ; moulding
bricks, 92; pit, river, and sea,
195 ; quantity requbed for mor-
tar, 205 ; screening, 195 ; size of
grit, 183; substitutes for, 195;
washing, 195.

Sandarach, 431.

Sanded sheet cathedral glass, 443.

Sandstones, 34-48, 83, 84; absorption
of, 36, 83; Brard's test for, 11,
36; calcareous, 36; Cambrian,
47 ; cretaceous, 39 ; classification
of, 35; coal measure quarries, 41-
46; colour of, 35, 39-48; com-
position of, 34; felspathic, 36;
from cretaceous formation, 39 ;
grain o( 36 ; Irish quarries, 47,
48 ; metamorphic, 36 ; micaceous,
36 ; New Red quarries, 40 ; Old
Red quarries, 47, 48 ; oolite and
lias, 39; quarries, 39-48 ; Smith's
test for, 11, 36 ; strength of; 81,
82; tests for, 36; thickness of
layers, 36 ; transverse strength
of, 82 ; Upper Permian quarries,
41 ; uses of, 36 ; varieties of, in
common use, 37 ; weight of, 36,
39-48, 84 ; Yorkshire, 37.
Sapwood, 359.
Sudinian oak, 376.
Sarking felt, 455.
Sash iron, 286 ; price of, 290.
Sash line, copper wire covered steel,
340.

So8

INDEX.

Satin wall paper, 446.

Saxicava mollusc, 10.

Saxon blue as a colouring pigment,

414 ; green, 417.
Scaffold poles, 364.
Scagliola, 248.
Scarlet lake, 416.
Scarlett marble quarries, 53.
Scheele's green, 417.
Schist, hornblende, and mica, 23.
Schists, disintegrated, sand from, 196.
Schorlaceous granite, 16.
Schwartz's patent for coating lead

pipes, 343.
Scintling bricks^ 93.
Sdattie granite quarries, 20.
ScorisB as a substitute for sand, 196.
Scotch brands on iron, 296, 300.
„ bricks, size and weight o^

112.

„ fir, 366 ; age for felling, 360.

„ granite, quarries, 20, 21 ;

varieties in common use,

16.

„ kilns for burning bricks, 98,

99.
„ limestone quarries, 71.
„ marble „ 63.

„ serpentine, 34.
„ slates, iiregularity of thick-
ness, 28, 30 ; quarries, 32.
„ wrought iron, extras charged
for, 292.
Scotgate Ash sandstone, 37 ; quarries,
46 ; strength, 82.
„ Head sandstone quarries, 46.
Scott bed of Chilmark stone, 64.
Scott's cement, 179 ; selenitic, 179 ;
strength of, 201.
^ processes for making cement,

179.
„ proportions for mortar in brick-
work, 201.
Scrabo sandstone quarries, 48.
Scrap bars, 276.
Screening sand, 196.
Screw, Nettiefold's patent, 464.
„ pktes, 466.

„ thread, Whitworth's standard,
466.

Screws, 463-466; adhesiye power of,
466; brass, 464; coadi, 464
flat-headed, 463 ; for metal, 464
handrail, 464; making, 466
patent pointed, 464 ; round-
headed, 463 ; stoTe, 465 ; wood,
46a
Sea sand, 196.

Seacombe limestone quarriee, 67.
Seasoning stone, 8 ; Bath, 59.

„ timber, 388-391 ; boiling
and steaming, 390 ; hot
air, 390 ; M'Neile'a pro-
cess, 390 ; natural, 389;
second and smoke dry-
ing, 391 ; time required
for, 389, 891 ; water,
390.
Seatings, boiler, 119.
Second seasoning of timber, 391.
Seconds, bricks, description and price

of; 106.
Sections of wrought iron, market,

286 ; miscellaneous^ 285.
Seed lac, 431.
Seggars, 130, 142.
Segmental sewers, 137.
Selection of timber, 388.
Selenitic cement^ Scott's, 179 ; fine-
ness of grit and
nature of lime
for, 179; propw-
tion of sulphate,
179 ; strength,
and where used,
179.
^ „ for making selen-

itic mortar, 801.
„ clay, 180; finish for plas-
ter, 247.
„ concrete, 219.
„ mortar, 206 ; made with
ordinary lime, 207.
„ M breaking weights o^

208.
„ plaster, 246.
Selenitised lime for iwAln'iig selenitic

mortar, 206.
Semi-continuous kiln, Bull's patent,
103.

INDEX.

509

Serpentine, 33, 34 ; ancient, 34 ;
eharacteristics and colonr of, 33 ;
compoeitionof, 33 ; English, Irish,
and Scotch, 34 ; nses of, 33 ;
Tarietiee in common use, 34.
Set defined, 330; caiued by con-
tinued load, 330 ; fJEdse perma-
nent, 330.
Setting and slaking of bnmt cement
stones^ 167,
236.
M „ of pure or i&t

limes, 230.
„ coat of selenitic plaster, 246.
„ of lime defined, 146.
Sewer pipes, 131; different forms of,

131; tests for, 134.
Sewers, segmental, 137.
Sejssel asphalte, 261 ; mixing, 262 ;

qualities of, 261.
Shale and limestones, manufacture of

Portland cement from, 161.
Shandon limestone quarries, 73.
Shankill sandstone „ 48.
Shap Fell granite „ 19.
Shaw Lane sandstone „ 46.
Shear steel, brands on, 313.

„ „ double and single, 303.
„ „ forging, 333.
Shearing, resistance of various woods
to, 406.
I, strength defined, 469.
ly yy of wrought iron,

319; of steel,
324.
„ stress for steel, 329.
Sheds for drying bricks, 92.
Sheep Hill limestone quarries, 73.
Sheet copper, 340 ; weight of,
340.
y, glass, 439 ; British, 441 ; cha-
racteristics of, 442 ; cathe-
dral, 443; fluted, 440; mar-
ket forms and sizes of, 440 ;
qualities, thickness, and
weight of; 439.
ft iron, 287 ; corrugated, 288 ;
forge tests for, 281 ; gauge,
thickness and weight, etc.,
of, 288, 366, 357 ; price of,

292 ; extras charged on,
292, 293.
Sheet lead, thickness and weight of,

341.
Sheets of lead, cast and milled, 341.
Sheffield granite, 19.
Sheldon marble quarries, 63.
Shell lac, 431.
Shell marble, 61.
Shelly granular limestone, 66 ;

weight of, 84.
Shelly limestone, 67 ; absorption o^

67 ; colour, structure, and uses

of, 67 ; weight of, 67, 84.
Sheppy cement, 168.
Shepton MaUet limestone quarries,

69.
Shetland Isles serpentine, 34.
Shingle for concrete, 211.
Shingling iron, 273.
Shipley sandstone quarries, 46.
Shippers, bricks, absorption of, 114 ;

description and price of, 106.
Shortness in iron, cold, 276 ; red or

hot, 276.
Shropshire brands on pig iron, 296.
Shut, cold, in iron, 268.
Siccative, Xerotine, 413.
Sicilian marble quarries, 66.
Sided timber, 364.
Side-wedge bricks, 116.
Siemens'-Martin process, 306.
Siemens' process, 306 ; modification
o^ 306.

„ steel, Landore, 306.
Sienna, burnt, 416.

„ marble quarries, 66.

„ Terra de, and raw, 416.
Sieves, wire, gauge of, 164.
Signal Staff Hill serpentine, 34.
Silica in clay for brickmaking, 86,
88 ; in fireclay, 122.
„ soluble, as a preservative for

stone, 78.
„ „ in limestones, 147.

Silicate enamelling paints, 427.

„ cotton, 457.

„ oxide paint, 426.

„ paints, 426.

„ Zoppisa, 428.

510

INDEX.

Silicated stone, 75.
Silicates, alkaline, as a preservative
for stone, 78.
„ „ assists hydrauli-

city, 180.
Silicon as an impurity in pig iron,

262.
Sill bricks, 120.
Sills, window, timbers useful for,

403.
Silurian formation, dates from, 30.
Silver solder, 352.
„ white, 407.
Single junctions, 132.
Sink bricks, 119.

Sir William Bumef s system of pre-
serving timber, 396.
Size, 449; bumidi, gold, and clear
cole, 450 ; double, 449 ; gold,
450 ; japanners* gold, 413, 450,
as a drier, 413 ; oil gold, 450 ;
parchment, 450; patent^ 449.
Skerries limestone quarries, 73.
Skibbereen sandstone „ 48.
Skull cap, position of, in quarry, 7,

61.
Skye marble quarries, 53.
Slabs, mosaic paving, 143.

„ slate, 29.
Slag, 259 ; as a substitute for sand,
196 ; bricks, 110 ; from iron
furnaces for concrete, 211.
„ Portland cement made from, 161.
Slaked lime defined, 145.
Slaking and setting of burnt cement
stones,157,234.
„ „ „ of true or fat

limes, 230.
„ defined, 145; influenced by
proportion of clay, 234 ;
of lime, 146; lime for
mortar, 202.
Slate, blocks, 29 ; day, 24 ; differ-
ent forms of, 29 ; enamelled, 29 ;
hornblende, 23 ; mica, 23 ; laths,
437 ; quarries, 31, 32 ; quarry-
ing, 24; slabs, 29; strength of,
82 ; weight of, 84.
Slates, 24-33 ; absorption of, 25 ;
Cambiian and Silurian, 25, 28,

30 ; characteristics and oolonr
of^ 25 ; cost of, 27 ; crushing
weights of, 81 ; Englidi, 30, 31 ;
glass, 444 ; grain of, 25 ; hard-
ness and toughness of, 25 ; Irish,
28, 30, 32 ; pyrites in, 26 ;
quality o^ 28 ; quarrying, 24 ;
Scotch, 28, 30, 32 ; sizes of vari-
ous, 26, 27 ; stone, 33 ; table of
area covered, cost, size, and wei^t
of different, 27; tests for, 28;
thickness of, 28 ; varieties in
use, 29 ; veins in, 26 ; weight
of, 27, 84; Welsh, 29, 31.

Slating nails, 460; size and weight
per 1000, 461.

Sleeper blocks, 135.

Sleepers, timbers useful for, 403.

Slieve Gullion granite quarries, 21.

Slop-moulding bricks, 92.

Slow-setting cements, 150.
„ rust cement, 452.

Smalls slates, area covered, cost, size,
and weight, etc, o^ 27.

Smalt as a colouring pigment, 414.

Smawse limestone quarries, 70.

Smelting ore, 257, 258.

Smith's, Dr. Angus, process for coat-
ing cast-iron pipes, 336.

Smith's, Mr. C. H., test for stone, 11.

Smoke and air flues combined, 136.

Smoke-drying timber, 391.

Soaps, bricks, 118.

Socket and half socket pipes, 131.

Soft putty, 452.
„ soldering, 353 ; solders, 351,

352.
„ wood, 363-373.

Softening steel, 309.

Softness defined, 470.

Softsoap as a preservative for stone^
77.

Solder, 351 ; silver and spelter, 352.

Soldering, 351 ; fluid, 353 ; fluxes
for hard and soft, 353; soft,
353.

Solders, coarse and fine, 352 ; bard
and soft, 351, 352; proportions
of ingredients, melting points, and
purposes for which used, 353.

INDEX.

51*

Soluble oxalate of alumina as a pre-
servative for limestone, 80.
9 silica as a preservative for

stone, 78.
„ „ in limestones, 147.

Solution of baryta as a preservative

for stone, 80.
Solutions, Bansome's indurating, 78.
Solvents, 406, 431.
Sorel stone, 75.
Sough bricks, 119.
South Owram sandstone quarries, 45.
Sow kilns for ]ime-buming, 188.
Spanish brown, 415.

„ mahogany, 381 ; weighty
strength, etc, of, 404.
Sparkford limestone quarries, 69,
Spars or poles, 364.
Spathic iron ore, 258.
Special paints, 423-429.
Spelter, 346 ; solder, 352.
Spiegeleisen, 304.
Spikes, 459 ; weight of, 460.
Spinkwell sandstone quarries, 45 ;

strength of, 82.
Spirit varnishes or lacquers, 432.
„ „ mixing, 432; re-

ceipts for, 433 ;
white and brown,
434.
Spirits of wine, methylated, as a sol-
vent, 431.
Splay bricks, 118.
Split mould for cement^ 182.
Splits, bricks, 118.
Sprigs, glaziers', 459; size and weight

per 1000, 461.
Spring steel, 303.
Spruce, 363 ; age for felling, 360.
„ American, 372 ; appearance,
characteristics^ and uses,
372.
„ Baltic, 371.
„ ochre, 415.

„ weight, strength, and resist-
ance to shearing, 404, 405.
„ white fir or, 371 ; appearance,
characteri8tics,and uses, 371.
Squaring timber, 360.
St Austell granite quarries, 19.

St. Bees and Corby sandstone quarries,

41.
St Blazey granite quarries, 19.
St Domingo mahogany, 381.
St Giles limestone quarries, 69.
St John*8 Hole sandstone quarries,

48.
Staflfordshire bar iron, 285.

„ blue bricks, 108 ; ab-

sorption o^ 114 ;
resistance o^ to com-
pression, 116 ; size
and weight of, 112.
„ brands on iron, pig, 295 ;

wrought, 296.
„ fireclay from, 121.

„ iron, extras charged for,

291.
Staffordshire pig iron, 295.
Stain, black, black walnut, mahogany,

oak, red, and walnut, 436.
Stained enamelled glass, 443.

„ felt limes, 152.
Staios, 435 ; liquid, 435.
Stainton or Stenton sandstone quar-
ries, 45.
Stair treads, timbers useful for, 405.
Stalk-fruited or old English oak, 373.
Standard screw thread, Whitworth's,
465.
„ wire gauge, Whitworth's,

356.
Stanford's patent joint for pipes, 134.
Stanley sandstone, quarries, 41 ;

strength of^ 84.
Staningley standstone quarries, 45.
Stanton „ „ 45.

Starshakes in timber, 361.
Staverton marble quarries, 53.
Steaming timber, 390.
Steel, 300-339 ; Admiralty tests for,
310, 311; action on, of copper,
263, of manganese, phosphorus,
silicon, and sulphur, 262 ; amount
of carbon in, 261, 301 ; an-
nealing, or softening, 309 ; bars,
tensile strength and ductility of,
322; Bessemer, brands on, 312;
Bessemer's process of making,
304 ; blister, 302 ; brands on,

Sia

INDEX.

312-314 ; cast, 303, 380, 321 ;
cast, for chisels, 325 ; character-
istics and uses of, 301, 337, 339 ;
chromium or chrome, 806 ; colours
and temperatures of, for diflPerent
tools, 307, 308; corrosion of,
335; crucible cast, 303, 304,
313, Beaton's, Heath's, and
Mushet's processes, 304; crush-
ing strength of^ 324 ; definitions
of, by Grenier, Percy, Siemens,
and Whitworth, 300, 301 ; de-
gree of heat for hardening, 308 ;
double shear, 303, 313 ; ductility
of; 320-325 ; effect of different
processes and circumstances upon
strength o^ 324 ; elastic limit of^
331 ; factor of safety for, 326,
328 ; forging, 333 ; fractured
surface, to judge quality by, 310;
German, 306 ; hiird, 306 ; har-
dening, 301, 307 ; hardening
and tempering in oil, 309 ; in-
fluence of carbon upon strength
of, 325; Landore,brand8on, 313,
tests for, 311, Siemens, 305,
strength and ductility of; 323,
Lloyd's tests for, 311, market
forms of, 311 ; methods of mak-
ing, 302 ; mild, 306 ; nails, 460 ;
natural, 306 ; plates. Admiralty
tests for, 310, effect of annealing,
325, price and extras charged
for, 312, strength and ductility
of, 320; properties o^ 354 ; pud-
dled, 306 ; rails, price of; 290 ;
relative value of different kinds
of, 311 ; ribbon sash line, break-
ing strain, 340; rivets, 311;
safe or working stresses for, 326-
330 ; shear, 303, 313 ; shearing
strength of, 324 ; spring, 303 ;
strength of, 320-325 ; temper-
ing, 301, 307, effect of, 324, in
oil, 309 ; temperatures and col-
ours for different tools, 307,
308 ; tensile strength and duc-
tility of, 320; tests for, 309,
310 ; tilted, 303 ; to distinguish
from iron, 309 ; Tungsten, 306 ;

varieties of, 302-306 ; wdght oC;
357; welding, 333; Whitworth'i
oompreesed, 306, tensile strength
and ductility of, 322; working
stresses for, 328.

Steetley limestone, analysis o^ 69.
„ „ - quarries, 70.

Sterro-metal, 350; composition of,
351.

Sticklac, 431.

Stifhiess or rigidity defined, 469.

fitirlinghill granite quarries, 2a

Stock board, 92.

Stocks, bricks, 105 ; absorption of,
114 ; hard, 106 ; description and
price of, 105 ; resistance of; to
compression, 115.

Stoke Ground Bath stone quany, 60.

Stone, 1-84 ; absorption of, 11, 83;
acid test for, 1 1 ; agents which de-
stroy, 3, 4, 10 ; appearance of, 6;
artificial, 74 ; atmospheric influ-
ence on, 3 ; Brard's test for, 11 ;
cement, 157; characteristics of
building, 2 ; chemical compod-
tion of; 2 ; classification of, 12 ;
crushed as a substitute for sand,
195 ; crushing weights o( 11,

81 ; durability of, 2 ; ezanuna-
tion of, 1 1 ; facility for working,
5 ; fracture of, 11 ; granites, 13-
22 ; hardness of, 5 ; igneous, 22-
24 ; limestones, 49-73 ; liquid,
22 ; natural beds of, 9 ; ochre as
a colouring pigment, 415 ; phy-
sical structure of, 4 ; positicHi of,
in a building, 4, in a quarry, 7 ;
preservation of, by various pro-
cesses, 76-80 ; properties of dif-
ferent, 80-84 ; quarrying, 12 ;
Ransome's artificial, 74 ; resist-
ance of, to crushing, 11, 81 ;
sandstone, 34-48 ; seasoning, 8 ;
serpentine, 33; silicated, 75;
slates, 24-33 ; Smith's test for,
11 ; strength of, 6, 81, 82, 84;
tensile and transverse strength o(;

82 ; surfaces, temporary protec-
tion of, 80 ; tests for, II ; Tis-
bury, 63 ; weathering qualities

INDEX.

513

oi; 18 ; wdght 6^ 6, 18, 39, 67,

83,84.
Stoneware, 128, 1S9.
Stoney's conciete-mixer, 829.
Storing Portland cement, 176 ; Bo-
man eement, 158.
Stourbridge firebrickfl^ 123 ; analysiB
of ckys for, 128 ; absorption,
crashing strength, and weight of,
124.
Stonrton sandstone qnanies, 41.
Stove screws, 465.
Strength of bricks, 115, 116.
„ cast iron, 315, 316.
n cement^ means of testing,
182; Portland, 168,
176, 177; Roman, 157,
159 ; selenitic, 180.
„ Chilmark stone, 64.
„ columns of brickwork,

116.
n concrete, 221, 222.
„ defined, 468.
„ firebricks, 124.
„ glue, 449.
„ iron, cast, 314, 315 ;

wrought, 317-319.
„ lead pipes, and lead-en-
cased pipes, 344.
„ mortar, as compared with
bricks in a wall,
200.
„ proof, defined, 469.
„ shearing, defined, 469.
„ steel, 320-324 ; cast, 320 ;

Landore, 323.
„ stones^ various, 6, 81,

82.
„ tensile, defined, 468.
„ terra cotta, 126.
y, timber, 403-405.
„ to resist bearing and
crashing, defined, 468,
469.
„ torsional, defined, 469.
„ transverse, „ 468.
„ ultimate „ 314,

469.
„ woods, varioas, 404.
M working, defined, 314.
B. C. — III

Stress and strain defined, 468.
„ intensity of, ultimate or break-
ing and workings defined,
468.
n working, for steel, 328, 329.

Stresses defined, 468.

„ working, 327 ; for cast and
wrought iron, 326.

Streteher, brick, hollow, 117.

Strike used in brickmaking, 92.

String-course bricks, 118.

Strong clays £or brickmaking, 87.

Strontian granite quarries, 21.

Structure of compact and granular
limestone, 56 ; of shelly lime-
stone, 57 ; of magneman lime-
stone, 58 ; physical, of stone, 4.

Stub on pantiles, 139.

Stucco, 247 ; bastard and common,
247 ; John's cement, 244 ; Port-
land cement, 244 ; rough, 247 ;
tioweUed, 246, 247.

Stuff for plaster, coarse, 245; fine,
245 ; gauged, 246.

Substances, foreign, in pig iron,
260.

Substitutes for sand, 195 ; in mortar,
199.

Sufiblk white bricks, 107 ; resistance
o^ to compression, 115 ; size and
weight o^ 112.

Sugar of lead, 412, 431.
„ use of, in mortar, 206.

Sulphate of baryta, test for, 408.
„ of manganese as a drier,

413.
„ of zinc „ 413.

„ proportion of, in selenitic
cement, 180.

Sulphates, action of^ on limes and
cements, 148, 238.

Sulphide of antimony, 408.

Sulphur, action of, on iron and steel,
262 ; as an impurity in pig iron,
262.

Sunderland Road sandstone quarries,
45.

Superior colours, pigments for, 423.

Superphosphates of lime as a pre-
servative for stone, 80.

2 L

514

INDEX.

Sutton limeBtone qnairies, 69.
Swedish bars, tests for, 279.

„ deals, 368 ; uses o^ 368.
„ iron, 283; how marked, 300.
„ timber, 367 ; appearance
and market forms of^
367 ; marks and brands
on, 385.
Swithland sandstone quarries, 47.
„ slate „ 32.

Sycamore, 377 ; appearance, charao-
teristics, and uses, 377 ; weight
and strength of, 404.
Syenite and syenitic granite, 14 ;

true, 14 ; characteristics oj^ 16.
Syphon traps, 133.
Szerelmey's compositions, 427 ; iron
paints and liquid enamels^ 427 ;
stone liquid, 79*

T irons, 285 ; forge tests for, 880 ;

manufiEurture of, 275 ; price o^ 290.

Tables. Granite quarries, principal, in

Great Britain and Ireland,

18-21.

„ Slates, area covered, cost, size,
and weighty etc!, o^ 27;
principal quarries of, in
Great Britain and Ireland,
31, 32.

n Sandstone quarries, principal,
in Great Britain and Ire-
land, 39-48.

„ Marble quarries, principal.
Continental, 55 ; in Great
Britain and Ireland, 52-54.

„ Analyses of principal mag-
nesian limestones, 59.

„ Limestone quarries, principal,
in Great Britain and Ire-
land, 67-73.

„ Resistance of stones to crush-
ing, 81.

„ Tensileand transverse strength
of stone, 82.

„ Absorption of stones, 83.

„ Weight and bulkiness of vari-
ous stones, 84i

Tables. Analysesof somebrickday8,88.

„ Size and weight of different
varieties of bricks, 112.

„ Absorption of different varie-
ties of bricks, 114.

„ Resistance of Inicks to eom-
pression, 115.

„ Analyses of different days for
firebricks, 122.

19 Resistance to compveaaioo^
weight, and abeorptioiiy of
firebricks, 124.

n Dimensions and thickneaa of
stoneware, fireclay, and
other day pipes, 131.

n Composition of various lime-
stones^ cement stones, etc,
before calcination, 149-
151.

„ Classification of hydiaulic
limes^ 154.

I, Experiments on strength of
Roman and Medina cement,
159,

y, Breaking weights of cement
at different works, 169.

„ Comparison of adhesive and
cohesive strength, 171.

^ Comparative oementitioua
strength o^ sifted and
unsifted cement, 171.

n Strength of adhesive Portiand
cement to various materially
172.

^ Increase of strength of Port-
land cement with age, 176.

I, Proportion of dean pit sand
to 1 cement, 177.

II Cement ooarsdy ground and
sifted, etc^ 177.

ji Tensile strength of various
limes, cements, etc, 178.

I, Compressive strength of limes
and cements, 178.

11 Force necessary to tear apart
bricks cemented together,
181.

19 Effect of different proportions
of sand in mortars made
from various oemente^ 201.

INDEX,

515

Tables. Bulk of mortar produced from

given quantities of lime,

cement, and sand, 206.
I, Breaking weights of briquettes

made from various limes

and cements, 208.
„ Showing the proportions of

the concrete used in various

works, 216.
„ Strength of concrete blocks,

221, 222.
,9 Proportion and composition

of day, degree of calcina-
tion and settingpropertiesof

various limes and cements,

236.
f^ Analyses of Portlaud and

Roman cement, 241.
„ Quantity of materials used in

plastering, rendering, etc,

266.
„ Weight of limes and cements,

266.
n Scale of tensile tests for iron

of various qualities, 279.
^ Classification of sheet iron as

to thickness, 288.
„ Thickness and weights of

corrugated sheet iron, 288.
,y Relative value of different

kinds of wrought iron, and

extras charged on, 290-294.
,, Temperatures and colours for

Bt^ 307, 308.
ff Relative value of different

kinds of steel, and extras

charged on, 311.
„ Crushing and tensile strength

of different descriptions of

cast iron, 316.
„ Tensile strength and ductility

of various descriptions of

malleable iron, 318.
n Effect of different processes

and circumstances upon the

strength of wrought iron,

319.
I, Tensile strength, elastic limits

and ductility of cast steel,

320.

Tables. Tensile strength and ductility
of steel, plates, bars, Lan-
dore and Whitworth'8,323,
324.

„ Cast steel for chisels, 326.

„ Influence of carbon upon
strength of steel, 326.

„ Factors of safety for cast iron,
wrought iron, and steel, 326.

, , Effect of overheating wrought
iron for forgings, 333.

„ proportion of carbon in dif-
ferent varieties of iron and
steel, 337.

„ Weight of sheet copper, 340.
„ and thickness of sheet
lead, 341.

„ Size and weights of lead pipes,
343.

„ Weight and strength of lead
pipes and lead-encased
pipes, 344.

M Sizes of fret lead, 346.

„ Weight of zinc gauges, 346.
„ of tin and composition
tubing, 348.

„ Composition of various alloys,
360.

„ Proportions of ingredients in
solders, melting points of,
and purposes for which
used, 363.

„ Properties of useful metals,
364.

„ Contraction of metals in cool-
ing, 366.

„ Melting points of alloys of
lead and tin, 366.

„ Birmingham wire gauge,
366.

„ Whitworih's standaid wire
gauge, 366.

„ BirminghammetalgaQge,366.

„ Weight of different metals,
367.

„ „ strength, etc, of

various woods, 404.

^ Resistance of timber to crush-
ing and shearing, 406.

„ Oompoflition of the different

5i6

INDEX.

Tables — conHnued.

coats of white paint, and
quantity required to cover
100 square yards, 419.
„ Quantity of glass in crates,

439.
„' Thickness, weight, and size

of sheet glass, 440.
„ Thicknessandweightofpatent

plate glass, 441.
„ Size and weight per 1000 of
different kinds of nails,
461.
9, Holding power of wrought
iron tenpenny nails, 462.
„ Adhesive force of nails, 462.
„ Whitworth's standard screw
and gas threads, 465.
Tacks, 459 ; size and weight per

1000, 461.
Tadcaster Umestone quarries, 70.
Tainton limestone „ 69.
Talacre sandstone „ 45.

Talc, 15.

Talcose granite, 15.
Taniemouth slate quarries, 32.
Taper pipes, 132.

Tar, 454 ; coal, 454 ; concrete, 222 ;
mineral, 454 ; paint, 428 ; pitch,
coal, 253 ; wood, 454.
Tarradale sandstone quarry, 47.
Tarring felt, 456.

„ ordinary, 428.
Taylor's patent roofing tiles, 140.
Teak, African, or mahogany, 376.
„ or Indian oak, 381 ; appearance
and characteristics of, 381 ;
market forms and uses of,
382 ; weight, strength, etc.,
of, 404.
Temperature, effect of, on strength of

cast iron, 316.
Temperature, effect of, on strength of

wrought iron, 319.
Temperature of burning lime or

cement stone, 192.
Temperatures and colours for steel,

307, 308.
Tempering clay for brickmaking,
90

Tempering defined, 470.

„ masons' tools, 307 ; very

small tools, 307.
„ steel, 801, 307 ; and har-
dening in oil, 307 ;
effect o^ 324.
„ tests for lAndore steel,
810.

Temporary protection of stone sur-
faces, 80.

Tenacity or tensile strength defined,
468.

Tenpenny nails, holding power of,
462.

Tensile strength defined, 468 ; of
bricks, 116 ; of cast iron, 315 ;
of cast steel, 320; of cement,
means of testing, 182 ; of Landore
steel, 310 ; of malleable iron, 31 7 ;
of steel, 320-323 ; of stone, 82 ;
of Whitworth's compressed steel,
323 ; of wrought iron, 817, 318.

Tensile tests for iron of various
qualities, 279 ; for Landore steel,
310 ; for Portland cement, 168 ;
for steel, 309 ; wrought iron, S79.

Terebrans, Chelura and Limnoria, 401.

Terebine, 413.

Teredo navalis, 401; destruction of
timber by, 401.

Terminals, Billings' chimney, 136.

Teme plate, 287.

Terra cotta, 124-129 ; advantages,
126 ; disadvantages o^ 127;
blocks, 125; building, 126;
colour and cost of, 127 ; dura-
bility, hardness, and lightness of,
1 26 ; for pipes, 1 29 ; inferior, 127;
making and nature of clay for,
125 ; porous, 127 ; strength of,
126; where used, 127.

Terra de Sienna as a colouring pig-
ment, 415.

Terro-metallic clinkers, 109.

Tenyland limestone quarries, 73.

Tesserse, 143.

Tester, Reid and Bailey's cement,
186.

Testing machines for cements, Adie's
Nos. 1 and 2, 182, 184.

INDEX.

517

Testing Machinefli Faya'fl» 186.
„ 9, Michaelit's, 184.

„ „ Beidaad Bailey's,

186; Thnxstoii's,
187.
Testing machines for iron, S79.
„ wrought iron, different meth-
ods of, 279.
Tests, Admiralty, for iron and steel,
880, 310.
„ chemical,187 ; forhydraulidty

of limes and cements, 239.
M for anenite of copper, 446.
^ for bricks, 113.
„ for cast iron, 271, 278.
,9 for Landoie steel, Admiralty,

310.
M for Portland cement : for cool-
ness, 1 74 ; quality, 1 62; ten-
sile strength o^ 168; other
tests, 175.
M for sandstones, 36.
M for slates, 28.
M for steel, 309, 310.
t, for stone : absorption, aeid.
Braid's, resistance to crush-
ing, and Smith's, 11.
« for sulphate of baryta, 406.
9, for Termilion, 416.
M for wrought iron, 276-884.
,» for red lead, 408.
», for sewer pipe^ 134.
„ ioTfg^ for iron, 280; hot^ for

Landore steel, 310.
„ impact or falling weight, 283.
„ Lloyd's, for steel, 311.
„ rough, for finding hydraulidty

in limestones, 151.
„ „ for wrought iron, 280.
„ simple, without machines, 187.
„ tempering^ for Landore steel,
310.
Texture of good bricks, 111 ; of

limestones, 49.
Thermo-plastic putty, 450.
Thick stuff, oiJc, how supplied to

H.M. Dockyards, 364.
Thinnings, 420.

Thornton's sandstone quarries^ 45.
Thrang Crag slate quarries^ 82.

Threads, Whitworth's standard for

gas and scrow, 465.
Thurston's testing machine, 187.
Tilberthwaite slate quarries, 32.
Tile pegs, 460.

Tiles, 138-143 ; common, 138 ;
dry, 142 ; encaustic, 141, in-
ferior encaustic, 442, uses of,
143; glass, 444; nujolica,
143; mosaic paving slabs,
143 ; paving, 138; wall, 141.
M roofing, 138 ; Broomhall Com-
pany's, 140; corrugated, and
improved corrugated, 139 ;
double roll, 139 ; Halls, 141 ;
hip and valley, 141 ; pan and
plain, 139; ridge, 141 ;
Taylor's patent^ 140; Yen-
etian or Italian, 140 ; Wade
and Cherry's, 14a
^ Tessera, 143.
Tilestones, 35.
Tiling kths» 453.
Tillyfourie granite, 21.
Tilted steel, 303.

Timber, 358-405 ; balk, 364, 366 ;
characteristics of good, 360 ;
charring, 394 ; classification of,
362-364 ; compass, 366 ; con-
version o^ 396-400 ; Dantzic^

366 ; deals^ value t/i^ and method
of measuring, 387 ; decay oi^ 391-
393 ; defecto in, 361, 362 ; de-
scriptions of different kinds, 365-
383 ; destruction o^ by worms
and insects, 401, 402 ; felling,
time for, 359, 360 ; fir, classifica-
tion dt^ 363 ; market forms of,
and how imported, 364 ; marks
and brands on, 383-387 ; Memel
366; Norway, 367; preserva
tion ol^ 394-396, ftom fire, 396
Riga, 366; rough and sided,
364; seasoning, 388-391; selec-
tion of, 388; squaring, 360
strength of, 403-405 ; Swedish,
appearance and market forms of,

367 ; varieties in general use,
366 ; varieties useful for differ-
ent purposes, 403 ; waney, 365.

5i8

INDEX.

Time of bumiDg bricks, in dampe, 96 ;
in Scotch kilns, 99.

Tin, 347, 348 ; action of^ on wrought
iron, 263 ; as an impurity in pig
iron, 263 ; block, 348 ; crystal-
lised plate, 348 ; melting points
of alloys of lead and, 366 ; ores
of, 347 $ plate, 348 ; plates, 287;
properties .of, 364 ; tubing and
weight of, 348, 367.

Tinned copper, 348.

Tintagel Slate Company's slate quar-
ries, 32.

Tints, delicate, 422 ; pigmentsfor, 423.

Tipton blue bricks, 108; size and
weight 0^ 112 ; strength of^
116.

Tiree marble quarries, 63.

Tisbury limestone, 63 ; quarries, 67.

Titanic paint, 426.

Titanium as an impurity in pig iron,
263.

Tools, masons' and very small, tem-
pering, 307.

Top cap, position in quarry, 7, 61.

Torbay paint, Wolston's, 426.

Torres Forest granite, 21.

Torsional strength defined, 469.

Tottenhoe limestone quarries, 67.

Toughened cast iron, 266.

Toughness defined, 470.
„ of slates, 26.

Tram rail, 286.

Transparent glazes, 129.

Transverse strength defined, 468.
„ „ of bricks, 116.

„ „ of stone, 82.

Trap, absorption of, 83 ; weight of^
84.
„ rocks or whinstone, 23 ; descrip-
'tion and varieties of, 23.

Traps, guUey and valve, 137 ; syphon,
133.

Trass, 196.

Treads of stairs, timbers useful for,
403.

Trees, growth of^ 368.

Trethwy granite quarries, 19.

Trewamet slate „ 32.

Triuidad asphalte, 263.

Trowlesworthy granite, 19.
Trough bed^ Chilmark stone, 64.
Trowelled stucco, 246, 247.
Tubes, rock concrete, 221.
Tubing composition, and tin, 347 ;

weight o^ 348.
Tubular bricks, 117.
Tullamore limestone quarries, 73 ;

marble quarries, 64.
Tungsten, action o^ on cast steel,
263.
„ steel, 306.

Tunnel heads, bricks, 119.
Tunnel kilns for burning lime,

188.
Turin slate quarries, 32.
Turpentine as a solvent, 431 ; cha-
racteristics and qualities
of, 412 ; French, 412 ;
oil of, 411 ; spirits of,
411 ; uses of; 412 ;
Venice, 412. ^
„ varnishes, 432-436 ; mix-

ing, 432, 433.
Turps, 411.
Turton and Sons' steel, strength of;

321, 322.
Twisted fibres, defect in timber,

362.
Tyn-y-Gwm sandstone quarries, 47.
Tjme sandstone quarries, 46.
Tyre bars, price of, 291.
Tyrebagger granite quarries^ 21.

Ultimate strength defined, 469.

„ stress defined, 468.
Ultramarine as a colouring pigment,

414.
Umber, burnt and raw, as colouring

pigments, 416.
Underbumt bricks, 103, 104.

„ limes and cements, 194.

Unglazed earthenware, 128.
Uniformity in quality of wrought

iron, 278.
Unsoiling brick earth, 90.
Upper Moor sandstone quarries, 46.
Upsets in timber, 362.

INDEX.

519

Using and mixing PorUand eement,
177.

Val de Tiavers asphalte, 252 ; hoi,
compressed, and liquid processes,
252.

Yale granite quarries, 19.

Valencia slate „ 32.

Valley tiles, 141.

Value of timber deals, etc, 387.

Vandyke brown as a colouring pig-
ment| 415.

Varnish, 429-436; application of,

433 ; best body copal, 433 ; black,
for metal work, 435 ; brown and
hard spirit, 434 ; crystal, 435 ;
different kiiids of, 431 ; for iron-
work and paper, 435 ; ingredients
of, 430 ; oak, 434 ; pale amber,

434 ; second carriage, 434 ; uses
of, 434 ; wainscot, 434 ; water,

435 ; white Cobuxg, 434.
Varnishes: copal, 433; mixing, oil,

spirit, and turpentine, 432, 433 ;

oil, 431, 433 ; receipts for, 433 ;

spirit, 432, 434 ; turpentine,

432-434; water, 432, 434.
Varnishing and painting wall papers,

447.
Vegetable black, 414.
Vehicles for paints, 406, 409.
Veins in slates, 26.
Venetian lake, 416*

„ red, 416.

„ taes, 140.
Venice white, 408.
Verde Antique marble quarries,

55.
Verdigris as a colouring pigment,

417 ; as a drier, 413 ; on copper,

349.
Verditer, 414 ; green, 417.
Vermilion, as a colouring pigment ;

German ; tests for, 416.
Vert antique, 34.
Vibration, effect of, on iron and steel ;

Dr. Percy's remarks on, 332.
Vicat's needle apparatus, 176.

Vietoria sandstone quarries, 45.

„ Slate Company's quarries, 32.

„ stone, 75 ; absorption of,
83 ; characteristics, uses,
and where used, 75.
Vienna green, 417 ; whiter 407.
Vignoles rail, 286.
Viney Hill sandstone quarries, 45.
Viscountesses slates, area covered, size

and weight of^ 27.
Vitrified marble. Rust's^ 76.
Volatile oils, 409.
Vulcanised indiarubber, 453.

Wade and Cherry's roofing tiles, 140.
Wainscot oak, 376.

„ varnish, 434.
Wales, manufacture of iron in, 299.
Wall facings, 135 ; tiles, 141.
„ papers, varnishing and painting,

447.
„ strength of mortar and brick-
work in, comparison, 200.
Walls, damp, how to prepare for paper-
ing, 447.
„ efflorescence on, 238.
„ wing^ copings for, 119.
Walnut stain, 436 ; black, 436.
Waney timber, 365.
Warden sandstone quarries, 45.
Wardour limestone quarries, 67 ; stone,

63.
Ware, fireclay, 128.
Wares, miscdOaneous clay, 134.
Warsdill sandstone quarries, 45.
Warwick „ „ 45.

Wash for removing paint, 436.
Washable paperhangings, 447.
Washed bricks^ 91, 105; absorption

of, 114.
Washing sand, 195.
Watehill sandistone quarries, 45.
Water, action of, upon lead, 342.
„ amount of, in fireclay, 122.
„ description o^ to be used for

mortar, 199.
„ nature and proportion of, for
cement briquette, 173.

520

INDEX.

Water, quantity required to abike
lime for mortar, 208.
,y flalt, objectionable in mortar,

199.
„ seasoning of timber, 390.
„ vamiflhes, 432 ; light-colouied
and ordinary, 435.
Waters which act upon lead, 342.
Wax varnish isx preserving marble

and statues, 78.
Wear of various granites, resistance

to, 84.
" Weather," meaning of, as applied to

stone, 2.
Weathering day for brickmaking, 90.
„ of Bath stone, 59.

„ qualities of granular lime-

stone, 56.
„ N ^ stone, to as-

certain, 12.
Weetwood sandstone quarries, 46.
Weighing Portland cement, method

of, 167.
Weight, breaking^ of selenitic mortar,
208.
„ crushing, for various stones,

81.
„ of bricks, 111, 112.
„ of compact limestone, 56, 84.
„ of varieties of stone, 84.
„ of falling or impact test for

iron, 283.
„ of firebricks, 124.
„ of granular limestone, 57, 84.
„ of lead pipes, 343 ; encased,

344.
„ of limes, cements, etc., 256.
„ of metals, 357.
„ of nails per 1000, 460, 461.
„ of Portland cement, 1 65, 256.
„ of Boman cement, 157, 256.
„ of sandstones, 36, 39-43, 84 ;

tests for, 36.
M of sheet copper, 340; lead,

341.
„ of shelly limestone, 57.
„ of stone, 6, 18, 39, 64, 83, 84
„ of tin and composition tubing,

347.
,1 of various woods, 404.

Weight per 1000 of various kinds of

nails, 461.
Weldability defined, 470.
Welding, 333; steel, 334; steel to
wrought iron, 334 ; wrou^t iron
a&d other metals^ 334.
Welsh brands on pig iron, 295.
M firebricks, absorption, resist-
ance to compression, and
weight of, 124.
„ elates, 28, 29 ; quarries, 31.
„ witought iron, brands <m, 299 ;
extras charged for, 292.
Westwood Down quarries, 60.
Wet rot in timber, 393.
Whinstone, Baltic, resistance to wear
of; 84.
^ description o^ and where

found, 23.
„ strength o^ 81, 82.

Whitbed and Whitbed roach, 8, 60,
62 ; positions of; in quany, 7, 61.
Whitby cement, 159.
White ant, destruction of timber by,
402 ; protection against,
402.
„ brass, 360; oompoaitiiCNi of,

351.
„ bricks, 106 ; green stains on,

107.
„ cast iron, 265 ; how to distin-
guish from grey, 265.
„ chalk lime, strength of, 181 ;

weight o^ 208.
„ Clichy, 407.
„ Coburg varnish, 434.
„ copperas as a drier, 431.
„ deal, 372.
„ distemper, 254.
„ Dutch or Holland, 407.
„ fir or spruce, 371.
„ flake and Fiench, 407.
„ Hamburg, 407.
„ hard spirit varnish, 434.
„ iron pyrites in slates^ 26.
„ Erems, 407.

„ lead, 407; adulteration o^
407 ; different names and
market forms o^ 407 ; old,
40&

INDEX.

521

White lead paint, 420; quantity
required to cover 100
yards, 419 ; uBes, ad-
vantages and disad-
vantages, 420.
„ „ nses, advantages and dis-
advantages of, 408.
„ Mansfield stone, 38 ; where

used, 38.
„ oak, 375.
„ paint, Griffith's patent, 424;

silver, 407.
„ pig iron, 264.
„ Rag bed of Kentish Bag, 66.
„ Venice and Vienna, 407.
Whitechurch sandstone quarries, 48.
White Gate limestone „ 73.
Whiteland Bridge bed of Kentish Bag,

65.
Whitening, 254.
Whitewash, 254.
Whiting, 254 ; weight of, 256.
Whitland Abbey slate quarries, 31.
Whitworth's compressed steel, 306 ;
tensile strength and ductility of,
323.
Whitworth's standard threads, gas and
screw, 465.
„ „ wire gauge, 356.

Whole deals, 364.
Wideopen sandstone quarries, 46.
Wilderness stone, strength of, 82.
Willesden fabrics^ 456 ; canvas, 456 ;

paper, 456.
Willow, weight, strength, etc, of, 404.
Wilmcote limestone quarries, 69.
Wilton marble quarries, 53.
Wimberry sandstone quarries, 46.
Window sills, timber useful for, 403.
Wine, methylated spirits of, as a sol-
vent, 431.
Windrush limestone quarries, 69,
Windsor firebricks, 124.
Wing walls, copings for, 119.
Wirchscombe slate quarries, 32.
Wire cord, copper, working loads for,
340.
,y covered steel ribbon sash line,

breaking strain of, 340.
w g&uge, Binningham, 355.

Wire gauge Whitworth's standard,
356.
„ nails, 459.
Wolston's Torbay painty 425.
Wood beetles of Ceylon, destruction
of timber by, 403.
„ cinders not suitable as a sub-
stitute for sand, 196.
„ hard or leaf, 362, 363, 373-

383.
„ naphtha as a solvent, 431.
„ pine or soft, 362, 363, 365-

873.
„ screws^ 463.
„ tar, 454.
Woodhouse limestone quarries, 70.
Woodland slate „ 32.

Wood's patent concrete bricks, 110.
Woods, strength and weights of vari-
ous, 404.
Working Chilmark stone, 64.

„ load and stress defined,

468.
„ stone, &cility for, 5.
„ stress in compression for
steel, Mr. Stoney's remarks
on, 328.
„ stresses of cast and wrought
iron, 327; for steel, 328;
Board of Trade rule for,
328.
„ tensile stress for steel, Mr.
Stone/s remarks on, and
opinion of Committee ap-
pointed by Board of Trade,
328.
Worcestershire, fireclay from, 121.
Worms, destruction of timber by,
401 ; protection against, 402 ;
varieties of, 401.
Worms or molluscs which destroy

stones, 10.
Wrought clasp nails^ 458.

„ iron, 272-294, 296-300,

826, 327, 338.
„ „ Admiralty tests, 280.

^ „ action on, of anti-

mony, arsenic, and
copper, 263 ; of
manganese and sili-

522

INDEX.

Wrought iron, strength and ductility

con, 262 ; of phoB-

of, 317, 319.

phornBand sulphur,

„ tests for, 276-283;

262 ; of tin, 263.

different methods

amount of carbon in,

of testing^ 278;

261, 272, 337.

falling weight or

appewance of frac-

impact, 283 ; foige,

tured aurface of.

280; general re-

282.

marks on, 276 ;

brands on, 295-300.

Eirkald/s experi-

characteristics and

ments, 277, 278;

uses of; 338.

rough,for,280; ten-

contraction o^ 275.

sile, for, 279.

corrosion of, 335.

„ weight 0^ 357.

»>

crushing and shearing

„ weldings 334 ; weld-

strength of, 319.

ing to steel, 334.

defects in, 275 ; cold

„ working stresses for,

shorty 275 ; red or

327.

hot shorty 276.

Wrought nails, hand, 457 ; machine

descriptions of, 283.

patent^ 458.

effect of different pro-

Wrysgan slate quarries, 31.

cess, etc., on strength

Wyborg deals, 368.

oi; 319.

Wych elm, 379.

elastic limit o^ 331.

factor of safety for,
326.

forging, 333.

Xerotine aicoative, 413.

India Office tests for.

279.

Eirkaldy's experi-

ments on, remarks

Yellow ant| destruction of timber by.

on, 277, 278.

402.

Eirkaldy's remarks on

„ Uke, 416.

fracture o^ 282,

„ Mansfield limestone, 6a

283.

„ pine, American, 369.

market forms and sec-

„ „ Quebec, 370.

tions of, 283-289.

„ rag bed of Kentish Bag, 65.

painting of, to pre-

Yellows, colouring pigments for, 414 ;

serve, 337.

arsenic^ Chinese, chrome, king's,

pickling, 336; pud-

lake, Naples, ochre, oipiment,

dling 273.

414.

Yeolmbridge date quarries^ 32.

refining, 273.

Yeovil limestone „ 69.

relative value of dif-

York pavings strength o^ 81.

ferent descriptions

Yorkshire bar iron, uses of^ 284.

and forms of, 289-

I, brands on pig iron, 295;

294.

on wrought iron, 299.

rolling, 273; effect of

„ fireclay, 121.

rolling, 274.

a iron, 283, 284; extras

shingling, 273.

charged on, 294.

INDEX

5«3

Yorksliire sandBtones, 37.
Yoaghal aondstone quarries, 48.

Zincy 346-847 ; g»iige (BelgianX 346.
Zinc, market forms o^ 346.

„ nails, size and weight per 1000.
461.

„ ores o^ 345.

Zinc, oxide o^ as a base for paint,

409.
„ ozy-snlphide of, as a base for

paint, 409.
„ paint, 421 ; characteristics and

uses o^ 421.
„ properties and uses of, 345,

354.
„ sulphate o^ as a drier, 412.
„ weight of, 357.

IND 07 PABI m.

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "Notes on building construction, arranged to meet the requirements of the syllabus of the Council on Education, South Kensington"

See other formats