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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 OowinBO MOw — Da—nraa. 

OKApna TV. 

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

itei— FAgTKimwia--P>a»~J g o y te Stnp§—Shoe», tt9. 

Obafrb Y. 

FL0OB8: Ckm^fiaiiUm--Oirdtn^WaU P l t Ua Joi«te-Btnittlng--TrtaMniag--JHigy<iiy Bo a irdtng 
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 Bld gofl C latliig 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 
W uiMiwa Fmrnu Solid— C e o ed- &nti^ hnng In dUfcrent way i Ca mmo n U r iarimg 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 Co mma B rUk 
lH§n~-Bond^Waat Jbrmlng Obhue and AmU A%gU§-Sn§ai§ vUk Spla^ Jaml» Anikm— 
Bond Timb$n H oop 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 A r r an gt mn Ua 
of 8Uni4 Stain— KoGDEX Staxbs— Parte of Voodtn ataHro—Dffforont Fonu—HoMdruOing— 
B a lm t t m t genewrf Bmatrkt on Pkmning StaWo, 

OBAPiaa XX. 
BIVBTINO : DigbroiU Forou of JUvete— Proporltone— Pttd^BiraxaD Jo uii s D yerenI 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 Q m aien f e S tu ee o -Se Un iiie 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 C W i B tpaiMtmg Otd WoHo^Pailmtlng Iron- 
wor k 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 co n veyed. 
. . . 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 inc l uded in the 
volume.*'— i< tMenamm. 



RIVINGTONS: WATERLOO PLACE, LONDON. 



NOTES 



ON 



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 



7 



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 




19 


Line from 

topofpag*. 

12 


For 
Mill HQl, 


Read 
New Mill, 






Madun. 


Madron. 


19 


15 


Do. 


Cornwall 


20 


4 


Birsmon. 


Birsmore. 


21 


8 


Torres. 


Tom's. 


94 


Footnote.— Add 


.^and sometimes 


in oversailinj 


144 


2 


228 


239 


159 


4 from foot 


181 


193 


161 


16 


74 


305 


195 


28 


162 


170 


218 


15 


is 


should be 


218 


20 


will 


should 


258 


80 


290 


804 


265 


4 


268 


262 


267 


80 


843 


355 


270 


7 from foot 


857 


355 


274 


10 


260 


832 


296 


4 


276 


290 


296 


18 


262 


276 


806 


25 


809 


323 


808 


26 


811 


825 


317 


15 


248, 249 


262, 263 


824 


15 


806 


320 


828 


1 


304 


818 


882 


10 from fool 


) 256 


270 


887 


Footnote.— 


Omit— (Bower). 




848 


13 


821 


335 


848 


20 


273 


287 


854 


Footnote 


319 


817 


422 


15 


898 


418 


59 


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. 



^1 



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 



i8 



NOTES ON BUILDING CONSTRUCTION 






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NOTES ON BUILDING CONSTRUCTION 



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GRANITES. 



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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, 



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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. 



31 





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. 

1 


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 






1 


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 


Launceston 


Cornwall. 




Maryport . 


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. 


Do. 


CULLIPOOL . 


... 




Do. 


Dalbeattie 


Do. 


Do. 


Do. 


Drumabttrn 


Perth 


Do. 


Do. 


Eabdals 


Oban 


Ai^leshire . 


Rougii- fUl of pyrites— weathen 
Wai-darkblue. 


Foudland . 


Huntly 


Aberdeenshire . 


Roofing slates. 


Gartley . 


Gartley . 


Do. 


Do. 


Glenalmond 


Perth . 


Perthshire . 


Do. 


Glbnshee . 


Do. 


Do. 


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. 


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. 



39 



PS 

< 



O 






It 
11 
if 



i-5 E 



1 



5 ^tL- 






11 










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09 



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8 



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60 

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40 



NOTES ON BUILDING CONSTRUCTION. 




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5 
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SANDSTONES. 



41 




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42 



NOTES ON BUILDING CONSTRUCTION 



1 

55 



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SANDSTONES. 



43 





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00 "« 00 -^ 



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44 



NOTES ON BUILDING CONSTRUCTION. 




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SANDSTONES. 



45 



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46 



JVOTES ON BUILDING CONSTRUCTION. 



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SANDSTONES. 



47 









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48 



NOTES ON BUILDING CONSTRUCTION. 



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05 




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. 



52 



NOTES ON BUILDING CONSTRUCTION. 






I 





i 



I 



ii 



V 

I 

=1 






n 



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III 



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a 



s 
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II 




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or 







MARBLES. 



53 



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?a II 
IJ Si 



II 



III * 
III I 
Hi % 



n 



I 



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OPQPQO 



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8 

QQ 



#^ ^ JS O « ,!^ 



54 



NOTES ON BUILDING CONSTRUCTION 



1 







MARBLES. 



55 




|l||lill^ 












1 



^^ 



^la 



I 

o 



8 



11 

i 



pq 



I 



H i 



'V3 



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I 5 



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>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. 



59 





1 
Dolo- 
mites. 


2 
Bols- 
over 
Moor. 


8 

Hud- 
dleston. 


4 

*ftoach 
Abbey. 


6 

FliTk 

Nook. 



Hans- 
field. 
Bed. 


7 
Mana. 
field. 
White. 


8 

Mansfield 

Wood- 

house. 



Fulwell 


10 

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 


100-0 


100-0 


100-0 


100-0 


100-00 


100-00 100-00 

1 


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. 



6i 



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. 



67 



oh » 

lit 




II ii 1 




to 



eq 09 






«a7 
So 



I 

o 

OS 

1 

o 
o 



^►. 



-a 2 §:§ 
;:3 o » 







I 



s 



I 



I s 



J! 

■§ 






D 

8 



I 



I I 



<5 

P 



6 



I I' 



.g 
1 






g 



§ 



? 



5 




<^ 



r 



£ 






6 

P 



I 




68 



NOTES ON BUILDING CONSTRUCTION. 



o 



I 




LIMESTONES. 



69 




ll HI i 




Inn 

P > PoS 



pp 




•|i 


•I 


Do. . 
Greenish 

Brownish 


ll 



i 



•If 




1^ 



^ 




•So 




£5 £ 



O 



ss 

O »s rj a> »/; 

5Eoig 



y 



> <5 d 

S pp 



I, 







70 



NOTES ON BUILDING CONSTRUCTION 



03 



S 

OD 
D 

S 

H 



i 

i 



o 

I 






i 



o 







IIS? Is 






00 






i 

p4 







I 






-<^ o 



■•I 



i».^ 

^Q 



2 . 






fl'S !§ . 

-g-e ^^ « 

3 V c 



o 



il 



So 



6 
P 





1 






€ 



0} o ^ o u% 



l^-"^ 



I 



I 




or 

s 




4 



3" 

M 



9>* 

Ho -n 
fc o ^ 

MM a 




LIMESTONES. 



7« 



I 

o 




iir 



J<Q 5 'pis 






1-' 



(5 JBQ^* 



^11 

Qnpa 









I 







S 5 o J 

S M N« M 

et « as H 

e« M as a 

< < •<■< 



72 



NOTES ON BUILDING CONSTRUCTION. 




► ^ "S -C .5-3 5 55 o S 2 




I 

CO 

"^ 
o 



o 






i 



I 



•f. 



SI 









s 






OPQO 






1^5 



J 






•s. 



,1' 

3 



I: 









I 






.-I 
Mi- 






^ I 



i 
li 






S 



or 

b 
O 
H 

< 



•c 






Si 



QQpqcQO 



II 






tfrjs -s 6 



1 11^^ 



I 






5.8 a 



1^1 




S 5 S 

2 go ^ 1^ iE 6 & 









Ps:i (4 o! b^ P 






a < 

O U 



LIMESTONES. 



73 




Pip 



a 



■ss 



X 









OPQPQ 



.a 
O 



'^'^ Cl^ PCpQ 



o 








if 

S4 




« & 

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. 



8i 



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. 






Cube. 




Granites. 




Inches. 




Sandstones. 




Inches. 




Aberdeen (blue) 


4-87 


U 


R 


Weak specimens, 


1-34 to 1-66 


2 


F 


Do. . . 


8-47 


1 


V 


locality notstatec 








Peterhead . 


8-7 


11 


R 


Runcorn . 


0-97 


... 


L.aark 


Do. . 


2-8 


1 


y 


Quartz rock on 


11-38 


... 


HaUet 


Comiflh 


2-84 


H 


R 


natiuulbed 








Dartmoor . 


1-64 


1 


V 


Quartz rock, 


6-25 




Do. 


Do. . 


812 






layers vertical 








Herm 


•86 


2 


B 










Moant Sorrel 
Killiney . 
Ballyknocken . 


6-74 
4-81 
1-41 


r 

1 


F 
W 
W 


Marbles. 

White statuary . 

Do. 


1-43 
2-7 


1 

H 


R 
R 


Argyleshire 


4-87 


... 


F 


Black Brabant . 


9-46 


R 


Iriah (variona) . 


1-0 to 6-0 


1 


W 


White Italian . 


9-72 


li 


R 


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 


2* 


F 


Limestones. 








maenmawr 








Compact (strong) 


8-8 


2 


F 


Felapathic 


7-68 


••• 


W 


Magnesiau, da 


8-16 


2 


F 


greenstone 








Do. (weak) 


1-86 


2 


F 


Hornblendic 


10-97 


... 


W 


Portland . 


1-66 


2 


R 


greenstone 








Da 




2-03 


U 


R 


Irish (variona) . 


3itol4i 


1 


W 


Do. 
Da 




1-5 
1-17 


2 

1 


I 

y 


Slates. 








Do. 




1-74 


2 


c 


Valencia on bed 


5 


1 


W 


Purbeck 




4-08 


1* 


R 


Do. layers 
Tertical 


4-71 


1 


W 


Ancaster 




1-04 


2 


C 








Bamack 




0-79 


2 


C 


Glanmore . 


9-58 


1 


W 


Eetton 




1-14 


2 


C 


Killaloe . 


18-71 


1 


W 


Do. (rag) . 


4-01 


2 


c 


Cahircivean 


2-76 


1 


W 


Bath (Box) 


0-66 


2 


c 










Da . . 


0-64 


1 


y 


Safidstones. 








Chalk 


0-5 


1* 


R 


Bramley Fall . 


27 


u 


R 


Bolsover . 


8-36 


2 


c 


Do. . . . 


2-5 


1 


V 


Bramham Moor 


2-64 


2 


c 


Craigleith . 


1-4 


1 


y 


Brodsworth 


2-05 


2 


c 


2-45 


H 


R 


Cadeby . . 


072 


2 


c 


Da ! ! 


8-5 


2 


C 


Chilmark . 


2-84 


2 


c 


Dundee . 


8-86 


U 


R 


HamhiU . 


1-8 


2 


c 


York paving . 


2-56 


H 


R 


Huddlestone 


1-98 


2 


c 


Binnie 


2-24 


2 


C 


Park Nook 


1-93 


2 


c 


Darley Dale 


8 16 


2 


C 


Roche Abbey . 


174 


2 


c 


Giffnenk . 


215 


2 


C 


Do. 


0-69 


1 


y 


Kenton 


2-21 


2 


C 


Tottemhoe 


0-86 


2 


c 


Mansfield (red) . 


2-27 


2 


C 


Anston . 


1-86 


... 


F 


Do. (white) 


2-84 


2 


C 


Anglesea . 


3-38 


... 


L.Clarlc 


Morley Moor . 
Park Spring 


2-21 


2 


C 


Listowel . 


8-88 




W 


8-38 


2 


C 


Longhome 


7-68 




W 


Stanley . 


2-66 


2 


C 


Ballyduff . 


4-93 




W 


Strong Yorkshire, 


4-38 


2 


F 


Moyne 


•8 -03 




W 


mean of 9 expta 








Limerick . 


3-9 


u 


R 


Irish (various) . 


•75 to 10-0 


1 


W 


Irish (various) . 


•5 to 14-0 


1 


W 



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. 

G 



82 



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 


Da 


Whinstone 








1469 


Da 


Biarble, white . 








722 


Hopkinson 


Do. 








551 


Da 


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. 



33 



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 


W 


Da do. indifferent specimens 


1 » 


w 


Do. da veiybad 


8 u 


w 


Trap and basalt . . . . 


A trace . 


w 


Da da 


Atoip.c. 




Sandstones, 






Craigleith— Very durable . 


8 per cent 


c 


Park Spring Da 




8 » 


c 


Giffiienk— Moderately durable 




10 „ 


c 


Heddon Da 




10-4 „ 





Kenton Da 




9-9 „ 


c 


Mansfield Do. 




10-4 „ 


c 


HasBock— Very bad 




20-0 „ 


w 


LimeOmes. 






Marble 


A trace. 




Portland-— Very durable 






18*5 per cent 


c 


Ancaster — Durable . 






16-6 „ 


c 


Bath (Bozground) . 






17 ,. 


c 


Ketton— Durable • 






161 „ 




Chilmark 






8-8 „ 


c 


Roche Abbey— Durable 






17-2 „ 


c 


Kent Bag Da 






li » 


w 


Banaome's stone (artificial) 




12 „ 


w 


Victoria Do. da 




7-6 „ 


w 


Apoenite Do. da 




12 ,, 


w 



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 



88 



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 


} 


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 


19 


60 




... 



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. 

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. 



97 




Fig. 4. 




Section of part of Clamp on line C D, 
Fig. 6. 



^ 


o 

r- 






























= 


l: 







Pl<m ofarrcmgemmt of 

Second Course, 

Fig. 6. 




Broken Section on Une A B. 

Bwrnt Brick shown thus 
Fig. 7. 



B.a — ^m 



H 



98 



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 


8i 


4J 


2J 


6-81 


60} 


Red Kiln . 


8i 


H 


2} 


7.-0 


68 


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) 


H 


4 


8 


9-6 


86 


Bridgewater Red Brick 


8-76 


4-8 


2-75 






Tianrashire Red Flossed Facing Brick 


9 


4i 


8 


8-9 


80 


Pressed Brick from Leeds . 


9-6 


4-5 


8-6 


10 


89 


Scotch Brick from Sandyfauld, near 
Glasgow 


9-5 


4-5 


8-5 


97 


86-6 


Bricks made from Blaize near Glasgow 


9 


4-3 


8-4 


8-6 


77 


Scotch Brick from Elgin (used for 
partitions) 


12 


6 


8 






Irish Brick from Athy 


8- 


3} 


21 






Burham Wire Cut . 


8-6 


4-0 


2-6 


6-4 


68-2 Q 


Do. Pressed . 


875 


4-2 


27 


6-1 


64-^ G 


Suffolk Brimstone . 


9 


4-6 


2-6 


6-8 


607 G 


Do. White 


9-2 


4-8 


2-6 


6-8 


66-2 G 


Staffordshire thin Paying . 


9 


4i 


8 


8-9 


80 


Do. 


9 


4} 


2 


6-1 


i56 


Staffordshire Brick-on-edge, for edge 
paving 


9 


8 


3i 


7-8 


70 


Tipton Blue 


9 


M 


8 


10 


89 


Adamantine Clinker 


6 


24 


IJ 


2 


18 


Dutch Clinker 


6i 


8 


u 


1-66 


14 



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 


4 


15 


22 


Malm Best Seoonds . 


5 


U 


20 


Malm Brown Facing Payiors 


5 


OJ 


17 


Do. Hard Paviora . 


4 


13 


94 


Washed Bright Yellow Fronts 


5 


1 


20 


Malm Shippers 


5 


n 


84 


Malm Bright Stocks . 


4 


ISi 


22 


Washed do. . . 


5 


oi 


16 


Common Shippers . 


5 


01 


9 


Common Grey Stocks 


5 





104 


Do. Hard do. . 


5 


Oi 


74 


Malm Grizzles 


4 


184 


22 


Do. Place .... 


5 


04 


21 


Common Place 


5 


04 


20 


Washed Shippers 


5 


2 


10 


Do. Hard Stocks 


4 


164 


^i 


Do. Grizzle 


5 





21 


Common Grizzle 


5 


1 


18 


Washed Place 


5 





21 


Staffordshire Dressed Bine . 


9 


5 


2-8 L 


Do. Pressed Blue . 


8 


11 


8-7 L 


Do. Common Blue . 


9 





6-6 L 


Do. Bastard 


* 9 


8 


11-8 L 


Machine-made Red . 


9 


14 


9-9 L 


Do. from Leeds . 


10 





100 


Wire-cut White Gault 


6 


8 


190 L 


Flressed Gault 


5 


12 


19-6 L 


Brown Glazed Brick . 


8 


6 

1 


8-6 L 



BRICKMAKING. 



ns 



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 


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. 


Tons. 


Tons. 






Unbnrnt Brick 


8-876 


4-876 


2-876 


38-83 


1-0 


9-0 


•23 


G 




Common Red . 


907 


4-27 


3-0 


88-7 


9-6 


67-0 


0-96 


L 




Machine-made formed 


9-8 


4-4 


8-3 


40-9 


23 


33 


•791 


L 




Red 




















Common Stock 


8-9 


4-07 


2-66 


36-2 


10 


128 


3-668 


L 




Sittingbonrne Stocks 


8-81 


4*13 


2-60 


36-36 


6-7 


33-9 


•93 


G 




Fareham Reds . 


8-50 


4*26 


2-62 


36-13 


8-42 


26-1 


•72 


G 




Da Rubbers 


10-19 


4-88 


2-94 


49-64 


1-40 


16-7 


•32 


G 




Tipton Blue 


8-76 


4-81 


2-60 


37-73 


21-26 


96*20 


•39 


G 




Exbory Best . 


8-876 


4-26 


2-76 


37-73 


21-0 


28-6 


•76 


G 




Do. Second 


8-876 


4-26 


2-76 


87-73 


210 


39-0 


-77 


G 




Do. Third . . 


8-60 


4-1 


2-6 


85 06 


11-8 


290 


-83 


G 




Suffolk Brimstone . 


9-06 


4-66 


2-69 


41-34 


61 


31-0 


•77 


G 




Da Best Whites . 


9-19 


4-66 


2-62 


41-9 


6-1 


19-6 


•47 


G 




Gault 


8-76 


4-26 


2-76 


37-18 


12-7 


36-1 


•94 


G 




Wire-cut White Gault 


9-04 


4-38 


2-72 


391 


110 


63 


1-36 


L 




Pressed Gault . 


8-9 


4-88 


2-68 


88-2 


8-0 


46-6 


1-23 


L 


|Gault Wire-cut, No. 2 


8-63 


4-0 


2-63 


84-60 


6-4 


32-90 


•96 


G 




Do. Pressed, No. 1 


8-76 


419 


2-69 


86-64 


7-4 


36-80 


1-0 


G 




Staffordshire Dressed 


9-07 


4-47 


2-97 


40-3 


15-6 


114* 


2-808 


L 




Blue 




















Staffordshire Pressed 


8-98 


4-46 


2-88 


39-8 


21-5 


73 


1-861 


L 




Blue 




















Staffordshire Common 


9-89 


4-38 


3-01 


41-1 


18-0 


39 


•964 


L 




Blue 




















Staffordshire Bastard 


9-28 


4-68 


8-21 


41-2 


27 


41-6 


1-006 


L 




Brown Glazed Brick 


9-0 


4-39 


3-39 


39-6 


16 


23 


•679 


L 




0, Grant's Bzpeii 


menta, Pnctedingt Ifu 


1 die. Efigifuen, vol. ' 


DCV. pp. 85- 


88. 








L. 


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 


17 


27 


Do. do. 


Do. 


Do. 


21 


30 


Red Bricks (machine made) 


Do. 


Do. 


20 


40 


Do. (hand made) . 


Do. 


Do. 


20 


36 


Gault Bricks . . . . 


Do. 


Roman Cement 


24 


59 


Do 


9x9 


Do. 


54 


72 


Clark's Sudbury (machine made) 


Do. 


Portland Cement 


49 


76 


Uzbridge Red (band made) 


Do. 


Do. 


44 


53 



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. 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. 




o 




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 




1 


1 


1 


i 


^ 


i 
1 


P 


% 


1 


11 


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 


-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 




10 


•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 

61 

6-9 

6-9 


9-6 
4-9 
9-9 
9-8 
6-2 


L 
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. 

2 

8 

4 

6 

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 

2 

2 

2 

2 

2 
2to8 
2to8 


Inches. 

A 1 
1 

1 
i 

J 

1 

li 

24 


Inches. 

U 

14 

If 

2 

2 

2 

2i 

24 



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 



t 



\*- 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. 


ah 


2i 


2i 


4i 


4t 


he 


8 


8 


8 


44 


cd 


2i 


^* 


4i 


4 



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 : — 



16 


X 


10 inches. 


14 


X 


» „ 


10 


X 


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 p up i u i . 



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. 



g 



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 



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. 



f 



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 



I 

a 



82 5 6 

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 

or 

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 



O ement 
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 



68 



9^6 



1*80 



Professor Bnmy 
(Gilmore). 



tths Vicat). 



Da 



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 


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 wimilft T wn ftt^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. 


29 


84 


87 


86 


99 


... 


89 


87 


89 




40 


89 


43 


41 


48 


... 



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 



a 

as 

-< 



GO 

s 

9r, 



o 

as 

< 

SB 



fi« 



n 

CO 

o .— 

-< 
>• 



'iffSi 



|a§= 



J 



^Ig* 






i 



1= 



^11 




►. 
^ 



o 
in 



^ 



Ill 



I 



SO p 00 

'^ "O '^ 









:^l 






g 



rl WCO 



5^ 






I 



<o o 

I-* f-H 00 

Si- 

lii 

ill 



Q 
H 
PS 

D 

cr 



-< 
^ 



i 

I 



lit 






OS 



Sg 



81 



o 

I 



^1 



000 

kO o 10 



o 00 
^ Sao 



t^ 



I 

QQ 



s 



11 



s 



I 



S' 






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. 


1 


Ordinary cement. Age 7 days 


59 


582 


2 


>t If }» ... 


61 


836 


8 


Fine cement sifted through sieve, ) . ^ t .i-„- 
80,976 meshes to square inch j ^^ ' "^^^ 


94 


428 


4 


»» )» *t 


57 


845 


5 


i 




65 


500 


6 


» 


„ Age 28 days 


105 


500 


7 


> 


If >f 


109 


887 


8 


» 




84 


428 


9 


) 




110 


809 


10 


> 


1 f f f 1 


86 


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 


98 

78 


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 . 


19 








Ordiziaiy tsement. 


»! >» 


24 


66 




... 


Sifted through No. 176 sieve. 


Slate (sawn) . 


49 


... 






Ordinary cement 


Portland stonu 


53 


82 




62 


Sifted through No. 176 sieTQ. 


26 


50 




... 


Ordinary. FngmentB torn out tirsur- 

fsAA 


»i »» 


29 


62 


... 


55 


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 . 


23 


6*8 




..• 


Ordinary. 


^>» , »i 


44 


66 


... 




Sifl»d through No. 176 sieve. 


Sandstone 


... 


49 


... 




Ordinary. Fragments torn out of sur- 


Polished marble 


88 




... 




Ordinary cement 


it »» 


52 


71 


... 


76 


Sifted through No. 176 sieve. 


Polished plate glass 


47 


40 


70 




Ordinary cement 


if f> 


55 


49 


51 


... 


Sifted through No. 176 sieve. 


Granite (chiseUed) 


41 


... 




... 


Ordinary. 


»t >t 


78 


97 


168 


... 


Sifted through No. 176 sieve. 


Limestone (sawn) . 


57 


78 


98 




Ordinary cement 


a it 


78 


93 


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^—^ n il I fcnaii i i . . 

» 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. 


1 


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. 

1 

4 

8 

25 


Lbe.i>er 
■qoare incb. 
358 
588 
585 
701 


Lbe. per 
square inch. 
846 
880 
469 
495 


Lbe. per 

square inch. 

75 

171 

206 

282 


Lbs. per 
square inch. 
252 
380 
858 
897 


Lbs. per 

square inch. 

81 

97 

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 



N 



178 



NOTES ON BUILDING CONSTRUCTION. 



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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. 



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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 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 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 ^ 




A 


1 


^ 


■ If 

^-■/ ii 
■"■'■-■■ '^\ 


F 


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. 


la 

88. 


la 

48. 


la 

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 


79 


49 


292 


286 


808 


828 


281 


119 


80 


124 


29 


87 



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. 


Cub. ft. 


Gallons. 


Cub. ft. 




White chalk lime in 
lump 

Do. do. . 

Portland atone lime in 
lump 


1 


2 

S 
3 


7^ 

8 
7} 


2A 
8! 


The (quantity of water 
mentioned includes that 
required for both slak- 
ing and mixing. 


Grey chalk lime in lump 




2 


n 


24 




Do. do. 




3 


84 


8 




Stone lime (Plymouth,^ 
• in lump 




8 


H 


84 




Lias (Eeynsham)^ in 
lump 




8 


7i 


2! 




Lias (Warwickshire) in 
lump 

Do. do. ground 




2 


8 


24 






2 


8 


24* 




Lias (Keynsham) ^ do. 




2 


3 


2 




Do. do. do. 




8 


4i 


24 




Lias (Lyme Regis) do. 




2 


4! 


24 




Arden lime ground 




1 


H 


lA 




Roman cement * . 




1 


5 


i| 




Portland cement ' 




1 


2 


If 




Do.« 




2 


n 


2! 




Do.« 




8 


li 


H 




Do.« . . 




4 


1! 


44 




Do.« 




5 


11 


54 





' 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 


63 


58 


78 


72-3 




Burham lime (Selea- 
! itic) 

Do. do. 

Do. do. 


165 

234 

161 


256 


340 


170 


210 
260 


Good Medwavgrey 
V lime, sold by 
Messrs. Lee. 


Halkin lime (Selen- 
itic) 


76 


128-6 


197 


99 


111 


Good hydraulic lime. 


Dolgoch lime (Selen- 
itic) 


62 


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. 


Da 


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. 


Da 


4 stone and sand 


In cutting rings of ditto. 


Da 


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. 


Da 


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. 


Da 


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 . 




Dd 


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. 


Tons. 


1 to 1 


107* 


170* 


1 ,. 2 


149 


160 


1 ,. 8 


113 


115 


1 „ 4 


103 


108 


1 » 5 


89 


99 


1 » 6 


80 


91 


1 „ 7 


75 


80 


1 » 8 


61 


76 


1 ., 9 


54 


68 


1 „ 10 


48 


48 



* 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 . 


61 


76 


Portland stone 


110 


126 


Gravel . 


74 


85 


Pottery . 


97 


118 


SUg . . . 


85 


70 


Flints . 


108 


117 


Glass . 


65 


94 



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. 


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. 


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. 


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. 


97 


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 


500 


62-0 


41-2 


46-1 


49-8 


Magneaia . 




•6 


•2 


1-0 


17 


1-6 




Alkalies . 




1-8 


1-6 


1-5 


^ 


^ 


^ 


Carbonic Acid . 




... 


6-0 


Traces. 


' 9*2 


[ 67 


■ 9-8 


Moisture and loss 




7 


1-5 


1-0 


-* 


J 


^ 


1 This cement evidently oontaina too little lim 


e. 


' Ferric 0: 


dda 


B. C. — III 














B 



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. 


I* 


ll 


1 


1 


1 


^ 






cube. 




Feet 
cube. 


Lb*. 


Oal- 
I0D8. 


BdilL 


Bundles 


Render float and 
trowel, 1 Portland 
cement, 2 sand 






6 




15 


24 




Render one coat, 
and set with fine 
stuff 


6 


... 


5 


2i 


20 






Render float, and 
set with fine stuff 


61 




6i 


3 


25 






Lath, plaster, and 
set with fine stuff 


6J 


... 


6J 


2J 


22 


... 


2t 


Lath, plaster, float, 
and set with fine 
stuff 


6} 


... 


6i 


3i 


27 




2i 



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 


70 


77 to 80 


Medina .... 


61 


68 


78 


Keene's .... 


64 


75 


82 


Parian .... 


60 


66 


77 


Plaster of Paris 


50 


Sold by weight 


64 


Whiting .... 


64 


Do. 


82 



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. 



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. 



id 



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 



ae 



Class D. 







Tons. 
26 
25 
24 



28^ 
20 J 



^21} 



li 



Percnt. 
85 
80 
22 



15^ 



► 12 



Class EL 



ill 



Ton*. 
25 
24 
23 



22-] 
19j 






Percnt 
80 
25 
18 

12^ 



Class F. 



IN 

PIS I 



Tons. 
24 
23 
22 

2n 

isj 



5 ts 



Percnt 
25 
20 
15 



^ 20 
J 17 



Class O. 



v4 



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- 

k 


J** 

II 


1^ 


li 
1^ 


II 

'i 


1^ 


9 A 

If 


U 


li 


li 
1^ 




Tons. 




Tons. 




TOHB. 




Tons. 




Tons. 






Bars round and square . 


23 


80 


24 


40 


23 


50 


24 


40 


24 


20 


Flatban 
overs' wide. 


Do. flat . 


22 


25 


28 


35 


22 


45 




... 


22 


15 


FUthan 
under5'wid€. 


Angle Iron 


22 


25 


28 


85 


22 


45 


22 


20 


22 


15 




TorH „ 


22 


25 


23 


85 


22 


45 


22 


20 


20 


10 




Plate /^^"^^^^^^^y" 

I graui crossways . 


20 


10 


22 


12 


21 


20 


21 


10 


18 


5 




17 


5 


18 


7 


19 


12 


18 


5 


... 






Sheet -('^^®°^^'^*y* 
^'^^^^l gram crossways . 


20 


10 


22 


12 


21 


20 


... 


... 




... 




19 


5 


18 


7 


19 


12 


... 


... 


... 


... 





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) 

! (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 



22 



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. 


iinch. 


B B, grain lengthways . 

„ crosswaya 
B, grain lengthways 
„ „ CTOSsways .... 


126* 
90* 
90* 
60* 


16* 

6* 

10* 


26* 

10* 

20* 

6* 


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 



C^ 




Notched and broken across to 
show quality of the iron. 



One flange cut off and bent cold, 
thus 



f 



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, 

I 



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. 



X 



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 


To 


From 


To 


Singles 


4 


20 


'289 


•085 


Doables 


20 


25 


•085 


•020 


LatteDB 


25 


27 


•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 




n 19 . 




•042 


252 


n 


) 


„ 20 . 




•086 


224 


8 in. 




„ 21 . 




•082 


206 


n 




« 22 . 




•020 


186 


ti 




.. 28 . 




•025 


166 


n 


•\ 


.. 24 . 




•022 


150 


» 


Sent to Colooies. 


„ 26 . 




•020 


112 


fi 


J 




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. 


Per Ton. 


Per Ton. 


Per Ton. 


Per Ton. 


Per Ton. 


Per Ton. 


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 

8 10 


8 2 6 


8 2 6 


5 10 

6 10 


6 

7 


5 5 


6 5 
6 15 


6 10 19 

7 10 


Do. Boiler . 




8 15 


9 12 6 


9 12 6 




7 10 


•• 


7 


7 10 2S 


Shebtb, singles . 


8 7 6 


8 16 


9 12 6 1 » 12 6 


7 5 


8 


7 10 


8 10 26 C 


Hoops (Ordinary 

Gauges) 
Akolb Iron . . 
(To 8 united in.) 
Te£ lR02f (ditto) 


6 17 6 


7 10 


8 12 6 


•• 


7 


7 10 




7 10 


8 


7 2 6 
7 12 6 


7 10 

8 


8 17 6 

9 2 6 


8 12 6 

9 2 6 


5 10 

6 10 


6 

7 


:: 


7 
7 10 


7 10 

8 


33 10 


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. 

1 




Jklivt 


ry in LivtrpooL 




Delivery in Tyw 
or Tees. 


Delivery 
in New- 
port or 
Cardiff. 


Delivery in Claa- Drftrrrj 
gou> or Leith. cf 

1 




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 


TO 


Depth. 


Width. 


Thickness. 


Depth. 


Width. 


Thickness. 




Joist Iron, Eng- 
lish 


4 


1* 


i 


8 


2* 


i 


£8:5s.to£8:15s. 


Girder Iron 


H 


Si 


A 


12 


6 


1 


£9 to £11 


Channel Iron 


2 


1 


A 


10 


8» 


i 


£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. 






1 


A 


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- 




1 


, 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. 


Per ton extra. 




Per ton extra. 


Ain. 


. 108. 


4ito4iin. . . 80s. 


1 


in. wide 


30s. 


f» . 


. 208. 


4i „ 5 „ finds, only 40s. 


1 


M »f ■ • 


20s. 


A,. 


. 808. 


5| „ 5J „ „ „ 60s. 
5i „ 6 „ „ „ 708. 


J 


»» »» • • 


lOs. 


:: » • 


.408. 


7 


>» »♦ 


10s. 


8| to 3i in 


. 108. 


6J „ 6i „ „ „ 80s, 


7i 


n n 


15s. 


3f ., 4 „ 


. 208. 




8 


•» »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. 

j f^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/ 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). 



TK 




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. 


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. 


Per ton. 




Percwt. 


Percwt. 


Ban 


£7 17 


6 


to £8 17 6 


Double shear . 


£2 5 


to £8 6 


Plates 


8 5 





,,960 


Single „ . 


1 14 


.. 


8 


„ boUer 








Borer steel 


1 8 


« 


3 15 


quality 


9 5 





„ 10 6 


Cast steel for 








Sheets 


9 





„ 10 10 




1 18 


„ 


3 5 


Hoops ^ . 


9 





„ 10 


Special die steel 


4 


„ 


5 12 


Angles . 


7 





,,800 


tool 








Tees 


8 10 





„ 10 10 


steel 


5 12 







Bulbs . 


7 10 


0- 


,,900 


Cast steel pktes 








Bulb tees 


8 





„ 10 


and sheets . 


1 


., 


2 10 


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 „ 


II 


6 „ 


25 „ 


H 


61 „ 


30 „ 


fl 


5U 


33 „ 


l» 


6 „ 


85 „ 


»l 


6i„ 


38 „ 


It 


6i« 


40 „ 


l> 


7 „ 


40 „ 


II 


7i« 


40 „ 


II 


8i., 


87 „ 


ff 


8f. 


34 „ 


II 


8|,. 


31., 


n 


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 


72 


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 


44 


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.* 



i 



1- 

S3 
&3 
ll 

ll 

JS 



i 



District 


Nsmes of ICaken or Work 
snd Brands. 


* Description. 




1 

ll 


11 

5^ 


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 


20 


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 


6-9 


Staffordshire 


Bradley & Co., fjjp S.C. 


^- *: 


24-92 


17-2 


12-5 






c. V 


22-62 


90 


6-5 


Do. 


Thomeycroft, Best Best 


' L. H" 


24-48 


12-5 


11-2 




* 


C. H" 


20-36 


4-6 


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 


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 
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. 


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 


... 


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. 


f 


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. 

1 


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. 


A 


L 

)c 


42-98 
43-37 


8-61 
8.93 


15-6 
14-8 


Shortridge and Co., puddled 
steel 


i 


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" .... 


i 


1 


L 
C 


46-80 
88-11 


4-86 
3-30 


4-6 
4-7 


Mersey Company, mild steel 


1 


1 


L 
C 


34-39 
30-22 


6-16 
6-72 


12-5 
8-5 


Mersey Company, mild steel 
(ship plates) 


1* 


L 


81-93 


8-67 


7-6, 



Tensile Strength and Ductility of Steel BARa 
Kirkaldy's Experiments.* 



Selected from Mr. 







Average 




r 


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 


97 


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 

40 
50 


In S.inches. 

23 

83 

20 

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. 

Do. do. 

Do. do. 

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 





00 











0-7 





0-7 


12-9 


7 


3-5 


2-7 


8-4 


27 


6-4 


6 


9-4 


7*7 


6-8 


50 


6-6 


7-0 


131 


8-7 


16-5 


10 



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, 






B. 


Girders .... 


Dead, 


8-6 


8. 


Do 


Do. 


6 


S. 


PlllaPB 


Do. 


6 


8. 


Water tanks .... 


Do. 


4 


& 


Crane posts or machinery 


Live. 


. 8 


8. 


Pillars subject to vibration 


Do. 


8 


8. 


Do. do. transverse shock 
Wrought Iron. 


Do. 


10 


8. R. 


Girders .... 


Dead. 


3 


8. 


Do 


Live. 


• 6 


B. 


Bridges .... 


Mixed. 


4 
in tension. 


U. 


Roofs 


Do. 


4 


8. 


Compression ban subject to 
shocks 


Live. 


6 


3. 


Compression bars not subject 
to shocks 

stea. 


Dead. 


4 


C. 


Bridges .... 


Mixed. 


4 



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 


18 

10 

8 


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 


1 


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 
186 
0-203 
0-255 


A 

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' 


d 


i 








... 


... 


•«• 


3-9 


it 


o 


i 




... 






... 


8- 


3-9 


4-8 


„ 


'S 


i 


27 


8- 


3-6 


8-9 


4-5 


4-8 


5-7 


6-0 


M 


.3 


i 


... 


,. 


... 


... 




3-6 


4.5 


6-0 


ft 


1 


4-5 


4-8 


6-1 


6-7 


6-3 


7-2 


8-4 


9-0 


»» - 


& 


1 


... 


6 


7-2 


6-1 


9-6 


11-1 


12-0 


12-9 


12^ 


li 


u 








90 


10-5 


12-0 


12-9 


150 


»t 


.11 


li 






90 


120 


14-1 


18-0 


21-0 


240 


,t 


J 5 


i| 




... 






•••. 


18-0 


21-0 


24-0 


»• . 


-1 


2 




90 


14-1 


18-0 


21-0 


24-0 


27-9 


30-0 


10 


2i 






10-8 


21-0 


25-2 


28-8 


38-6 


36-0 


n 


8 


12-6 


18-0 


24-0 


30-0 


33-6 


860 


39-0 


42-0 


ft 


3i 


16-8 


27-0 


83-6 


360 


39-0 


46-0 


480 


64-0 


„ 


4 


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 


n 


« 








51-0 


600 


70-2 


76-2 


84-0 


Number of Column 


1 


2 


3 


4 


5 


6 


7 


8 



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 

1 

11 
1^ 
2 

No. of 
column 



.Extra light Weights. 



1 


li 


2 




2 


2i 


8 




o 


81 


4 




3i 


4 


4i 


5 


4i 


5 


'ol 


6 


^ 


7 


8 




8 


9 


10 




11 


13 






2 


3 


^ 


5 



Weights suitable for sup 
ply of water under 
the heads stateil. 



50 feet 
heail 
and 
under. 


Mto 

250 feet 

head. 


n 


3 


8i 


4 


4i 


5} 


H 


6 


7\ 


8 


9 


10 


11 


124 


16 


ISi 


6 


7 



251 to 
500 feet 
head. 



H 

4i 

6 

7 

9 
12 
14 
21 



8 



Extra heavy wrigktK 

with less tin for siiyply 

of water under hvstlft 



50 feet 
head 
and 

under. 



4 

5 

7 

8 

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 



10 



21 
30 

11 



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 


1 

1 

li 

H 

2 


• -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 


n 




Lbs. 


Oz. 


Dr. 




Lbs. 


Oa. 


Dr. 


1 





1 


2 


Inch. ' 
•0018 


14 




2 


12 


Inch 
•0326 


2 





2 


4 


•0036 


15 




5 


12 


-0364 


3 





3 


7 


•0056 


16 




8 


12 


•O4O0 


4 





4 


9 


•0078 


17 




11 


11 


•0437 


5 





5 


11 


•0091 


18 




14 


11 


■0478 


6 





6 


14 


•0110 


19 


2 


1 


11 


•0509 


7 





8 





•0128 


20 


2 


4 


10 


■0581 


8 





9 


2 


•0146 


21 


2 


8 


2 


■0728 


9 





10 


5 


•0165 


22 


2 


12 


14 


•0764 


10 





11 


7 


•0180 


23 


3 


1 


1 


•0800 


11 





18 


5 


■0217 


24 


3 


6 


3 


■0896 


12 





16 


2 


•0254 


25 


8 


9 


5 


•0992 


13 


1 





15 


•0290 i 


26 


3 


18 


7 


•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 

i 
A 


7to8 
9to9J 

11 

14 


5 

8 
11 to 18 
14 to 16 
18 to 21 
28 to 26 


i 
A 

8 
J 
1 
1 


17 

28 

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. 


1 


1 


^ 


i 


1 


Iron. 


Brass, ordinary . 


2 


1 










„ forlocksanddoorhandles 


3 


1 








j 


„ „ turning and fitting . 


3 


1 




A* 




1 


„ „ engraving 


3 


1 


A little 










„ „ bushes and sockets . 


18 


1 


... 




1 






„ to bear soldermg well . 


2! 


1 












„ pot metal ^ . 


2i 






1 






1 


Bronze, hard, for bearings for 


8 




i' 










machinery 














1 


„ for stop cocks and valves 


88 


10 


2 










„ „ wheel metal for small 


10 


... 


1 








' 


toothed wheels 












1 ; 


„ „ bearings for very 


32 


1 


6 








Man- 

gaxieae. 


heavy weights 














Manganese bronze 


88 


... 


10 




... 


... 


2 


Gun metal for ordnance 


90i 


... 


H 








„ of maximum hard- 


5 


... 


1 










ness for turning 














t 


„ soft . . . 


16 


... 


1 








1 


Bell metal . 




4 




1 


LMitiMa 






i 


Muntz metal * 




3 


2 




Th 






' 


„ nails for 




87 


4 


v 










Gedge's metal 




60 


38-2 


... 




... 


1-8 




Sterro- metal 




55to60 


34 to 44 


lto2 


2 to 4 








Babbit's metal . 




4 


8 


96 










White brass 




3 




90 




7 




1 

Bis. 


i» 




1 




... 


y 


7 




muth. t 


Metal to expand in cooling . 1 


... 






9 


2 


... 


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' 


3 

6ir 


Zinc. 
773* 


Copper. 
SOOO* 


1 
607' 


1 

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 . . . 


2 

1 

1 

1 

1 

2 

4 

2 


3 

1 
1 

1 


1 
2 


'4* 

1 

3to6 

1 

1« 

1 


1 


* 

8 
2 


1 


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. 


1 


1^ 


i 


Resistance in 
tons per sq. inch. 


1 


II 


1 

cei 


j 


1 


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 


5 


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 


MO 


14-0 


60 


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 


7 


88 


17,000,000 


2700** 


•0011 


Lead, Cast . 


11-35 


709 


1-47 


8 


31 


... 


... 


•0028 


Sheet. 


11-4 


718 


1-48 


1-5 




720,000 


612* 


•0028 


Phosphor 
hronze 








26 




14,000,000 






Platinum 


21-5 


1344 


2-8 






... 


8280' 


•0008 


Steel, cast, soft 


7-8 


488 


1-01 


82 


89 


30,000,000 


8300' 


•0012 


Tin, cast 


7-3 


466 


•95 


2-0 






442' 


•0023 


Zinc, cast 


6-9 


428 


•89 


30 


... 


... 


770* 


■0029 


Muntz metal 


8-2 


611 


106 


22 











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 

tV 

A 

A 
^ 
^ 


\ 

A 



Temp. 


Lead. 


Tin. 


Temp. 


Lead. 
14 


Tin. 

4 


400 


11 


8 


490 


410 


25 


16 


500 


83 


8 


420 


7 


4 


610 


19 




430 


16 


8 


620 


25 




440 


8 


4 


690 


SO 




460 


17 


8 


640 


88 




460 


9 


4 


660 


48 




470 


10 


4 


668 


25 




480 


28 


8 


630 


1 






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. 


Vo 


0-500 


9 


0-144 


24 


0022 


39 


0*0052 


6/0 


464 


10 


128 


25 


20 


40 


48 


6/0 


482 


11 


116 


26 


. 18 


41 


44 


4/0 


400 


12 


104 


27 


00164 


42 


40 


8/0 


872 


18 


0-092 


28 


148 


48 


36 


2/0 


848 


14 


80 


29 


186 


44 


32 





824 


15 


72 


80 


124 


45 


2^ 


1 


800 


16 


64 


81 


116 


46 


24 


2 


276 


17 


56 


82 


108 


47 


20 


8 


252 


18 


48 


88 


100 


48 


16 


4 


232 


19 


40 


84 


0-0092 


49 


12 


6 


212 


20 


86 


85 


84 


50 


00010 


6 


192 


21 


82 


86 


76 






7 


176 


22 


28 


87 


68 






8 


160 


28 


24 


88 


60 







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 


7 


0-180 


18 


0-049 


29 


0^13 


0000 


0-454 


8 


0-166 


19 


0-042 


30 


0-012 


000 


0-426 


9 


0-148 


20 


0*036 


31 


0^10 1 


00 


0-880 


10 


0-184 


21 


0-082 


32 


0009 





0-840 


11 


0-120 


22 


0-028 


83 


0-008 


I 


0-800 


12 


0-109 


23 


0-026 


84 


oiwr 


2 


0-284 


13 


0-096 


24 


0-022 


85 


0-005 


3 


0-269 


14 


0-088 


26 


020 


36 


0-004 

1 


4 


0-288 


15 


072 


26 


0-018 






5 


0-220 


16 


0-066 


27 


0-016 






6 


0-208 


17 


0-068 


28 


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. 


1 


•001 


14 


-014 


34 


•084 


90 


•090 


280 


-280 


2 


•002 


15 


-016 


36 


•086 


95 


•096 


3(N> 


•800 


8 


-003 


16 


-016 


38 


•038 


100 


•100 


325 


•826 


4 


•004 


17 


-017 


40 


•040 


110 


-uo 


350 


•850 


5 


-006 


18 


•018 


45 


-046 


120 


■120 


376 


•876 


6 


-006 


19 


■019 


50 


•060 


135 


•186 


400 


•400 


7 


•007 


20 


•020 


55 


•066 


150 


-160 


425 


•425 


8 


-008 


22 


■022 


60 


•060 


165 


-166 


460 


•460 


9 


•009 


24 


•024 


65 


•066 


180 


•180 


476 


-475 


10 


-010 


26 


•026 


70 


•070 


2(X) 


•200 


500 


•600 


11 


-Oil 


28 


-028 


75 


•076 


220 


■220 






12 


-012 


30 


•030 


80 


•080 


240 


-240 






13 


•013 


32 


-082 


85 


•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. 


1 


•004 


10 


•024 


19 


•064 


28 


•120 


2 


•005 


11 


•029 


20 


•067 


29 


•124 


3 


•008 


12 


•034 


21 


•072 


30 


•126 


4 


•010 


13 


•036 


22 


•074 


31 


•133 


5 


•012 


14 


•041 


23 


•077 


32 


•143 


6 


•013 


16 


•047 


24 


•082 


33 


•145 


7 


•015 


16 


•061 


26 


•095 


34 


•148 


8 


•016 


17 


•057 


26 


•103 


36 


•168 


9 


•019 


18 


•061 


27 


•113 


36 


•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- 


of 


nesB. 


of 


ness. 


of 


ness. 


Gauge. 


Inch. 


Gauge. 


Inch. 


Gauge. 


Inch. 


7/0 


•6666 


3/0 


•6000 


2 


•3147 


6/0 


•6250 


2/0 


•4452 


3 


•2804 


5/0 


•6883 


1/0 


•3964 


4 


•2-226 


4/0 


•5416 


1 


•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. 



h 


1" 


1 


1 


1 


1 


1 


i 


i 


i 


tV 


2-3 


2 3 


2 5 


2^9 


23 


26 


2-7 


24 


Z'7 


i 


6-0 


47 


6 1 


6-8 


4^7 


6 3 


5-5 


4^8 


7-4 


A 


7-5 


7 


7-6 


8-7 


7-0 


8-2 


8-2 


7-2 


11^2 


i 


10-0 


9 4 


10^2 


11^6 


9*4 


11-0 


10^9 


9*6 


14^9 


A 


12-5 


11^7 


12^8 


14 5 


11-7 


13-7 


13^7 


12 


18-6 


J 


150 


14 1 


15-3 


17^2 


14^0 


16^4 


16^4 


14^4 


22^3 


tV 


17-6 


16^4 


17^9 


20^0 


16-4 


19^2 


19-1 


16-8 


26^0 


4 


20 


18^7 


20^4 


22^9 


18-7 


21^9 


21^9 


19 3 


29 7 


w 


22 6 


21 •I 


26 


26-7 


21 •! 


24 6 


24-6 


217 


38 4 


ft 


25-0 


23-5 


25-5 


28-6 


23^4 


27-4 


27-3 


24 1 


371 


H 


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 


H 


325 


30^5 


83-2 


372 


80^4 


85 •e 


35^0 


81-8 


48^8 


i 


35 •© 


32-8 


36-7 


400 


82 •& 


38 ^3 


88-2 


33 7 


52^0 


H 


37 '6 


35-2 


38 •S 


42^9 


86 •I 


41-2 


41*0 


361 


65^7 


1 


40 


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. 



A 



Second or Gtooo 
MmDUNO. 



« 



^^ 



I 



Third or Oohhov 

MlDDURO. 




Memel. 

(Scribed at 

end.) 



^^ 



a 



III 



^=^ 



1 



nil 



1 



Dantzic 

(Scribed at 

centre. ) 



"h: 



^^ 



) 




Stettin. 

(Scribed at 

end.) 






i 



H^ 



1 



m 



) 



' 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 



386 



NOTES ON BUILDING CONSTRUCTION. 



»&i 



»S 



♦ B8 



* 
* 




.1 






II 






+ ^ oXb ft 
M Pm ^-«5a ft 



« fa _ 
#5ft 3 
M ft 



i o 



5 



WW ^ « 



S+ +^ J+ +><ft ft 

A ^ W p^ ^-< ft 



ft h3 ;z« 
ft ft W 



6 



^6 

S« SI 



^1 










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 „ „ 

}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. 


Months. 


26 


18 


22 


11 


18 


9 


14 


7 


10 


6 


6 


3 



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