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Full text of "Architectural pottery; bricks, tiles, pipes, enamelled terra-cottas, ordinary and incrusted quarries, stoneware mosaics, faïences, and architectural stoneware"

.189. 




ARCHITECTURAL POTTERY 



ARCHITECTURAL 
POTTERY 



BRICKS, TILES, PIPES, ENAMELLED TERRA-COTTAS, 

ORDINARY AND INCRUSTED QUARRIES, 

STONEWARE MOSAICS, FAIENCES, AND 

ARCHITECTURAL STONEWARE 



BY 

LEON LEFEVRE 

INGE"NIEUR (E. i. R.) 

PREFACE BY 
M. J.-C. FORMIGE 

ARCHITECT TO THE GOVERNMENT AND TO THE CITY OF PARIS 



WITH 5 PLATES, 950 ILLUSTRATIONS IN THE TEXT, AND NUMEROUS ESTIMATES 

TRANSLATED FROM THE FRENCH BY 
K. H. BIRD, M.A., AND W. MOORE BINNS 



LONDON 
SCOTT, GREENWOOD & CO. 



(pofferg <Baseffe," " ecorafors' tomtit anb (pfum6er' (gevtetv 
ani> "0tf anb 



19 LUDGATE HILL, E.G. 
1900 

[The sole right of publishing this work in English rests with the above Jirm] 

COMPANY. 



L 



PREFACE. 



M. LEFEVRE's work on the use of pottery in architecture 
appears at a fortunate moment, for natural building materials 
such as wood and stone already show signs of exhaustion in 
those districts where they formerly existed in abundance. 

The rapid exhaustion of quarries from which we have drawn 
for years obliges us to get supplies from greater and greater 
distances, and so to raise inordinately the price of building- 
stones. We can only replace them by calling to our aid artificial 
materials, such as iron, brick, terra-cotta, cement, etc. 

Ancient examples of the substitution of terra-cotta for stone 
are frequent in Persia. Jules Laurens and Dieulafoy have shown 
them to us in the imposing buildings which they have sketched 
and reproduced from the remarkable ruins excavated on the sites 
of ancient cities like Suse. 

In the Milan district, in Italy, the cloisters of the Carthusian 
Monastery at Favia, the Milan Hospital, and many other fine 
buildings, present splendid examples of the use of bricks and 
terra-cotta decoration. 

Even while the sculptors of the Renaissance were carving 
from stone the lacework, arabesques, and statues which make 
the buildings of that period gems of architecture, the genius of 
the Delia Robias, that family of artists, was achieving a triumph 
for decorative pottery. 

But generally, it is those countries which lack building-stone 
and possess clay, that especially offer us interesting edifices 
constructed of artificial materials. 



(126760 



vi PREFACE. 

Of all those substances, terra-cotta is undoubtedly the one 
best adapted for elegant work, and the architect should never 
lose sight of it, even in the simplest constructions. 

Besides the artistic effect given by the use of terra-cotta 
materials, and due to their preparation and colour, cheapness is 
undoubtedly a strong argument in their favour. 

The resource of the future, then, is incontestably a judicious 
use of pottery. But we must not content ourselves with copying 
ancient objects ; we must adapt the shapes and decoration of 
terra-cotta materials to the requirements and taste of our own 
period. For that purpose it will be necessary to thoroughly 
understand the infinite resources which pottery offers to builders. 

A description of the processes of manufacture will therefore 
be of undoubted interest. This M. Lefevre appreciates, and in 
his book he studies step by step the manufacture and applications 
of all the ceramic products used in architecture. ' From the 
common brick, to terra-cotta enamelled in brilliant colours, and 
including tiles, quarries, etc., everything is carefully described in 
detail. 

This book will, without any doubt, be profitably studied by 
manufacturers, builders, and architects, in a word by all who 
are interested in architecture. 

J.-C. FORMIGE, 

Architect to the Government and 
to the City of Paris. 



TRANSLATORS' PREFACE. 



THE principal difficulty in the translation of a work which abounds 
in technical details is the correct interpretation of technical terms. 

In " La Ceramique du Batiment " there occur several names for 
which there is no English equivalent, that is to say, no technical 
expression generally used and understood by the English potter. 
Among such may be mentioned the terms " Enfumage," "Petit 
Feu," and " Grand Feu " in the description of kilns. We have 
preferred to leave these and most similar names in the original 
French rather than to attempt an English rendering which could 
only be clumsy and inaccurate. 

Some machines and processes have different names in differ- 
ent districts but no definite designation common to the whole 
trade ; to these we have endeavoured to give names which, while 
not perhaps strictly technical, will sufficiently explain their nature 
to all readers. 

Thus to the machine called a " Tailleuse " in French we have, 
on the advice of a leading firm of brick-makers, affixed the name 
" Mixing Mill." 

To mark the distinction between a " Tuile " and a " Carriere " 
we have translated the latter as a " Quarry," although the term 
" tile " would be equally applicable to it as to the former. 

Similarly " vernis " has been translated " varnish " to distinguish 
it from other glazes, notwithstanding the fact that the word would 
not be commonly used in this sense. 



Vlll TRANSLATORS PREFACE. 

We are indebted to several firms of brick and tile makers for 
kind advice, which we hereby gratefully acknowledge. 

The work of M. Lefevre is, however, so comprehensive and of 
such magnitude that it has not been possible for us to obtain 
information as to all the processes described in it, and there 
may be some terms which might have been rendered with more 
technical accuracy. 

In spite of such shortcomings, we shall venture to hope that 
our translation may prove as clear and readable as the subject- 
matter undoubtedly is instructive. 

K. H. B. AND W. M. B. 



THE METRIC AND BRITISH SYSTEMS. 



TABLE OF COMPARISON. 

MONEY. 

= 25 francs. I franc = 9id., about, 
i franc = 100 centimes. 



WEIGHT. 

I gramme = 15.43 grains. 
28^ grammes = I ounce av. 
I kilogramme = 1000 grammes = 2.20 Ibs. av. 

LENGTH. 

I metre = 100 centimetres = 39.37 inches 
Roughly speaking, I metre = a yard and a tenth. 

I centimetre = four-fifths of an inch, 
i kilometre = 1000 metres = five-eighths of a mile. 



Metres. 


Deci- 
metres. 


Centi- 
metres. 


Milli- 
metres. 


Inches. 


Metres. 


Deci- 
metres. 


Centi- 
metres. 


Milli- 
metres. 


Inches. 


.OOI 


.OI 


. I 


j 


039 


.06 


.6 


6 


60 


2.362 


.002 


.02 


.2 


2 


.079 


.07 


.7 


7 


70 


2.756 


.003 


03 


3 


3 


.118 


.08 


.8 


8 


80 


3.150 


.004 


.04 


4 


4 


157 


.09 


9 


9 


90 


3-543 


.005 


05 


5 


5 


.197 


.1 


i 


10 


IOO 


3-94 


.006 


.06 


.6 


6 


.236 


.2 


2 


20 


200 


7.87 


.007 


.07 


7 


7 


.2 7 6 


3 


3 


30 


300 


11.81 


.008 


.08 


.8 


8 


.315 


4 


4 


40 


400 


15-75 


.009 


.09 


9 


9 


354 


5 


5 


50 


500 


19.69 


.OI 




i 


10 


394 


.6 


6 


60 


600 


23.62 


.02 


.2 


2 


20 


.787 


7 


7 


70 


700 


27.56 


03 


3 


3 


3 


1.181 


.8 


8 


80 


800 


3i-5o 


.04 


4 


4 


40 


1-575 


9 


9 


9 


900 


35-43 


05 


5 


5 


50 


i 


1 


10 


IOO 


1000 


39-37 



CONTENTS. 



PAGE 

TABLE OF COMPARISONS OF THE METRIC AND BRITISH SYSTEMS ix 



PART I. 
PLAIN UNDECORATED POTTERY. 

CHAPTER I. 
CLAYS. 

i. CLASSIFICATION, GENERAL GEOLOGICAL REMARKS. Classification, origin, 

locality ......... I 

2. GENERAL PROPERTIES AND COMPOSITION : physical properties, contraction, 

analysis, influence of various substances on the properties of clays . . 14 

3. WORKING OF CLAY-PITS. I. Open pits: extraction, transport, cost. 

II. Underground pits. Mining laws . . . . . 24 

CHAPTER II. 
PREPARATION OF THE CLAY. 

Weathering, Mixing, Cleaning, Crushing, and Pulverising. Crushing cylinders 
and mills, pounding machines. Damping : damping machines. Soaking, 
Shortening, Ptigging: horse and steam pug-mills, rolling cylinders. Parti- 
culars of the above machines . . . . . . 41 

CHAPTER III. 
BRICKS. 

I. MANUFACTURE (i) Hand and machine moulding. I. Machines working by 
compression: on soft clay, on semi-firm clay, on firm clay, on dry clay. - 
II. Expression machines: with cylindrical propellers, with screw pro- 
pellers. Dies. Cutting-tables. Particulars of the above machines. 
General remarks on the choice of machines. Types of installations. 
Estimates. Planishing, hand and steam presses, particulars. (2) Drying, 
by exposure to air, without shelter, and under sheds. Drying-rooms in 
tiers, closed drying- rooms, in tunnels, in galleries. Detailed estimates of 
the various drying-rooms, comparison of prices. Transport from the 
machines to the drying-rooms, barrows, trucks, plain or with shelves, lifts. 



Xl'i CONTENTS. 



I'AGE 



(3) Firing. I. In da nips. 1 1 . In intermittent kilns. A. Open : i. using 
wood ; 2. coal ; (i) in clamps ; (2) flame. B. Closed : I. direct flame ; (i) 
rectangular; (2) round; 2. reverberatory. III. Continuous kilns : A. With 
solid fuel : round kiln, rectangular kiln, chimneys (plans and estimates). 
B, With gas fuel, Fillard kiln (plans and estimates), Schneider kiln (plans 
and estimates), water-gas kiln. Heat production of the kilns . . 94 

DIMENSIONS, SHAPES, COLOURS, DECORATION, AND QUALITY OF BRICKS. 
Hollow bricks. Dimensions and prices of bricks, various shapes, 
qualities. Various hollow bricks, dimensions, resistance, qualities . . 244 

APPLICATIONS. History. Asia, Africa, America, Europe : Greek, 
Roman, Byzantine, Turkish, Romanesque, Gothic, Renaissance, Architec- 
ture. Architecture of the nineteenth century: in Germany, England, 
Belgium, Spain, Holland, France, America. Use of bricks. Walls, 
arches, pavements, flues, cornices. Facing with coloured bricks. 
Balustrades . ... 257 



CHAPTER IV. 

TILES. 

i. HISTORY ......... 285 

2. MANUFACTURE. (i) A/oulding, by hand, by machinery: preparation of 
the clay, soft paste, firm paste, hard paste. Preparation of the slabs, 
transformation into flat tiles, into jointed tiles. Screw, cam, and 
revolver presses. Particulars of tile-presses. (2) Drying. Planchettes, 
shelves, drying - barrows and trucks. (3) Firing. Divided kilns. 
Installation of mechanical tileworks. Estimates .... 287 

3. SHAPES, DIMENSIONS, AND USES OF THE PRINCIPAL TYPES OF TILE. 
Ancient tiles: flat, round, Roman, Flemish. Modern tiles. With 
vertical interrupted join : Gilardoni's, Martin's ; hooked, Boulet's, villa ; 
with veitical continuous join: Muller's, Alsace, pantile. Foreign tiles. 
Special tiles. Ridge tiles, coping tiles, border tiles, frontons, gutters, 
antefixes, membron, angular. Roofing accessories : chimney-pots, mitrons, 
lanterns, chimneys. Qualities of tiles. Black tiles. Stoneware tiles. 
Particulars of tiles . . . . . . . 3 T 9 

CHAPTER V. 
PIPES. 

I. CONDUIT PIPES. Manufacture. Moulding: horizontal machines, vertical 
machines, worked by hand and steam. Particulars of these machines. 
Drying. Firing. II. CHIMNEY FLUES. Ventiducts and " boisseaux," 
"wagons." Particulars of these products ..... 341 

CHAPTER VI. 

QUARRIES. 

i. Plain quarries of ordinary clay. 2. Of cleaned clay. Machines, cutting, 
mixing, polishing. Drying and Firing. Applications. Particulars of 
quairies ......... 357 



CONTENTS. Xlll 

CHAPTER VII. 
TERRA-COTTAS. 

PAGE 

HISTORY. MANUFACTURE. Application: balustrades, columns,pilasters, capitals, 
friezes, frontons, medallions, panels, rose-windows, ceilings. Appendix: 
Official methods of testing terra-cottas ..... 363 



PART II. 
MADE-UP OR DECORATED POTTERY. 

CHAPTER I. 
GENERAL REMARKS ON THE DECORATION OF POTTERY. 

DIPS. Glazes: composition, colouring, preparation, harmony with pastes. 
Special processes of decoration. Enamels, opaque, transparent, colours, 
under -glaze, over -glaze. Other processes: crackling, mottled, flashing, 
metallic iridescence, lustres . . . . . . 383 

CHAPTER II. 
GLAZED AND ENAMELLED BRICKS AND TILES. 

HISTORY : GLAZING. ENAMELLING. Applications: ordinary enamelled bricks, 

glazed stoneware, enamelled stoneware. Enamelled tiles . . . 404 

CHAPTER HI. 

DECORATED QUARRIES. 

I. PAVING QUARRIES. i. Decorated with dips. 2. Stoneware: A. Fired 

stoneware; a. of slag base. Applications; b. of melting clay. Applica- 
tions. B. Plain or incrusted stoneware ; I. of special clay (Stoke-on- 
Trent). Manufacture. Application. 2. Of felspar base. Colouring, 
manufacture, moulding, drying, firing. Applications . . .413 

II. FACING QUARRIES. i. In faience. A. Of limestone paste. B. Of silicious 

paste. C. Of felspar base. Manufacture, firing. 2. Of glazed stoneware. 

3. Of porcelain. Applications of facing quarries .... 443 

III. STOVE QUARRIES. Preparation of the pastes, moulding, firing, enamelling, 

decoration. Applications. Faiences for fireplaces .... 454 



PAGE 



XIV CONTENTS. 

CHAPTER IV. 

ARCHITECTURAL DECORATED POTTERY. 
i. FAIENCES. 2. STONEWARE. 3. PORCELAIN . . . .461 

CHAPTER V. 

SANITARY POTTERY. 

STONEWARE PIPES: Manufacture, firing. Applications. Sinks. Applica- 
tions. Urinals, seats, and pans. Applications. Drinking - fountains, 
washstands ......... 472 



BIBLIOGRAPHY 
PLATES . 



492 



PART I. 

PLAIN UNDECORATED POTTERY. 



POTTERY IN ARCHITECTURE. 

CHAPTER I. 

CLAYS. 

I. CLASSIFICATION GENERAL GEOLOGICAL REMARKS. 

Definition. -Clays are mineral substances, very extensively 
found in nature, soft to the touch, yielding under slight pressure, 
and of very varied colours : white, yellow, red, green, blue, grey, 
or black, according to the nature of the impurities contained in 
them. They possess as common and distinctive characteristics : 
first, their plasticity, which causes them to preserve received 
impressions this quality varies with the nature of the clay ; 
second, their property of forming with water a tenacious paste, 
with a peculiar smell, which paste can be modelled, and hardened 
by drying. The clay then clings to the tongue, and if it is again 
suitably moistened, becomes plastic once more ; but if it is 
exposed to a high temperature, its nature completely changes ; 
it can no longer be diluted with water, it undergoes a consider- 
able contraction, and, at the same time, acquires occasionally 
a very great degree of hardness ; for certain clays, when highly 
baked, will give a spark on being struck by steel. 

Chemical Composition. Pure clay, which is white and 
refractory, is composed of silica, aluminium, and water, this 
latter being in a state of combination and not as a hydrate. The 
proportions of these three substances are very variable, and lie 
within the following limits : 

Silica . . . . . . . . 45 to 75 per cent. 

Aluminium . . . . . . . 38 to 16 

Water in combination . . . . . 6 to 19 ,, 

I 



2 POTTERY IN ARCHITECTURE. 

These pure clays are very rare. Ordinary clays, such as are 
found in great profusion, contain other substances in more or 
less quantity ; especially iron oxides and sulphuret (pyrites), 
salts of lime, particularly the carbonate (limestone) and the 
sulphate (gypsum), magnesium, alkalies (potash and soda), 
organic substances, etc. We shall refer later on to the pro- 
perties given to clays by the presence of these ingredients. 

Classification of Clays. The difficulty of this classification 
is due to the different aspects in which their chemical com- 
position, physical characteristics, and geological origin may be 
considered. 

Authors generally follow the classification suggested by 
Brongniart about I 840 ; by it clays are thus divided : 

1 . Kaolin Clays. White, yellowish or greyish, refractory, 
thin to the touch, and not easily forming a paste with water. 

2. Plastic Clays. Refractory, dense and greasy to the touch, 
forming with water a tenacious, supple, and dough-like paste. 

3. Smectic Clays or Fullers Earths. Full and greasy to 
the touch, frothing when beaten up with water, of variable 
colour, fusible in the porcelain kiln, absorbing oils easily, hence 
used in cloth-fulling. 

4. Figuline Clays or Potters Earths. Same physical pro- 
perties as the plastic clays, but coloured and much more 
fusible. 

5. Marls or Effervescent Clays. Not very stable, but very 
fusible, forming with water a brittle paste which effervesces 
under acids. 

6. Ochreous Clays. - - These contain a large quantity of 
oxides of iron, yellow and red, and are used as colouring- 
matter. 

Several objections may be made to this nomenclature : the 
kaolins are badly defined ; to make a special class of plastic 
clays is to infer that plasticity exists little, if at all, in other 
clays ; whereas, as a matter of fact, potter's earths possess 
this property to as great a degree as the plastic clays ; also 
there is no mention in the list of a clay, or clay-like earth, 
which is very extensively found on the surface of the globe, 



CLAYS. 3 

and, wherever it exists, is used in the manufacture of bricks ; 
this is the " lehm " or tableland slime, a mixture of clay and 
very fine quartz, coloured with an oxide of iron. Another 
classification has been proposed by M. le Chatelier. This 
savant has affirmed that, when clays are heated, they undergo 
molecular changes; one of these, dehydratation, manifests 
itself by an absorption of heat which takes place at different 
temperatures according to the nature of the clay. Moreover, 
some of them show, at about 1000 C., a peculiar phenomenon 
attended by a sudden elevation of temperature. Combining 
these two facts, M. le Chatelier has found that the great 
majority of clays can be assigned to five very distinct classes 
which do not generally overlap one another. These are : 

Absorb. Set free 

heat at. heat at. 

1. Allophanous . . SiCX, A1 2 O 3 . Aq 220 (noticeable) 1000 (sharp). 

2. Kaolin . . 2SiO 2 , A1 2 O 3 , 2H 2 O 770 (very marked) 1000 (slight). 

3. Halloyshe 2 SiO 2 , A1 2 O 3 , 2 II 2 O. Aq{ 

4. PyrophyUite . / . 4 SiO 2 , Al^ 

[ 2OO (very important) } 

5. Montmorillonite . 4SiO 2 , A1 2 O 3 . Aq- 770 (less marked) -Not at all. 

^950 (doubtful) J 

However interesting these facts may be scientifically, it seems 
to us difficult to adapt them to the technical point of view 
from which we are looking. We shall content ourselves with 
modifying Brongniart's classification as follows : 

1. Kaolin Clays. White, generally crystallised, refractory, 
undergoing no contraction in firing. 

We must not confuse with these very characteristic sub- 
stances certain white refractory clays, wrongly called kaolins, 
which may in the last resort be used for making china, but 
which have not the well-defined properties of the true kaolin. 

2. Refractory Clays. Yellowish or greyish white, usually 
soft and greasy to the touch, and forming with water a paste 
which is often tenacious, dough-like, and supple. 

3. Figuline Clays or Potters Earths. Plastic like the fore- 
going, but coloured, becoming generally red in baking, and 
much more fusible than the preceding classes. Some contain 



4 



POTTERY IN ARCHITECTURE. 



no limestone, the rest a small quantity which does not at the 
most exceed 2 or 3 per cent. 

4. Clayey Marls or Effervescent Clays. Of variable plasticity, 
very fusible, and characterised by the presence of a large quantity 
of limestone ; according to the amount of this limestone, they 
are called clay marls or calcareous marls ; it is to it that they 
owe their property of effervescing under the action of acids. 

5. Lehm, Tableland Slime, or Brick - earth. An intimate 
mixture of clay and very fine quartz, coloured yellow or reel 
by oxides of iron. When the lehm is calcareous, it takes the 
name of loess. 

6. Smectic Clays or Fuller s Earths. 

7. Ochreous or Ferruginous Clays. 

The latter two kinds are not used in pottery. 

Geological Origin of Clays. 1 Clays are usually found in 
fairly regular seams in nearly all stratified soil which has been 
formed in the midst of fresh or sea water ; for there are 
frequently found in them the fossil remains of sea or fresh 
water shells, as well as other fossil organic debris. The clays 
are formed by the deposit of substances formerly in suspension 
within a liquid in motion. 

These substances come from the destruction of primitive 
volcanic rocks by the combined action of the atmospheric 
agents : wind, water, air, heat, cold, etc. Nevertheless, we 
shall see that other more complex agencies, of a chemical 
nature, must have had a share in the formation of certain 
clays, especially of the enormous deposits of kaolin like those 
of Limousin in France and Cornwall in England. 

The majority of volcanic rocks contain a common ingredient 
called felspar, which is a combination of silica with different 
metals : aluminium, potassium, sodium, calcium, etc. Such are 
the pegmatites (Haute-Vienne, Pyrenees, Cornwall), formed of 
quartz (crystallised silica) and felspar, the granites and gneiss, 
which are both composed of quartz, mica, and felspar. 

1 The following description and figures are borrowed from that excellent work by 
M. de Lapparent, Traite de Geologic, 3rd ed., Paris, 1893, Masson et Cie. The 
eminent geologist has been kind enough to revise this summary, and I thank him 
heartily for doing so. L. L. 



CLAYS. 5 

The typical felspar contains 

Silica , . . . . . . . 65 per cent. 

Aluminium . . . . . . . . 18 ,, 

Potassium . . . . . . . . 17 ,, 

Under the influence of water charged with carbonic acid, 
the alkaline silicates existing in felspar are decomposed into 
alkaline carbonates or earthy alkalines, and give up silica, 
which remains in veins in the dry rock, where the current of 
filtering water is too slow to carry it off in suspension. The 
aluminium silicate which remains engenders a product resemb- 
ling kaolin, hence the name of kaolinisation has been given 
to this mode of disintegration of felspar rocks. When the 
rock contains grains of quartz, these are not affected, and as 
the water draws from them the clay element formed by the 
kaolinisation of the felspar, it follows that, under the sole 
influence of the filtering water, the majority of granitic rocks 
are changed into sand. In our climates, this change can be 
effected down to fifteen or twenty metres below the surface. 
What proves conclusively that it is the work of the moist air 
assisted by variations of temperature, is that it does not occur 
to an appreciable extent in Egypt, where the equable and 
dry climate leaves granite almost intact after the lapse of 
centuries. 

If the kaolinisation of felspar rocks, caused by meteoric 
water, has yielded here and there some veins of clay pure 
enough to be called kaolin, this superficial action has not 
been capable of forming great layers of kaolin like those of 
Limousin, and we must therefore find another explanation of 
their existence. 

Origin of Kaolin. Kaolin is almost always found in the 
neighbourhood of tin deposits ; but, with tin ore, there always 
appear either quartz and granite with white mica, or pegmatite 
invariably accompanied by fluorine compounds. 

This coincidence has led people to think that tin ore is 
formed by the action of a powerful mineralising agent which 
might be fluorine. As this metalloid violently attacks the 
silicates, it has been concluded that its appearance has reacted 



6 POTTERY IN ARCHITECTURE. 

upon the rock containing them, that is to say, the pegmatite, so 
as to transform it into kaolin. This theory, suggested by Buch in 
1824, with reference to the kaolin at Halle in Prussia, has been 
taken up by Daubree, and definitely adopted by de Lapparent 
in his Geology, 

Fig. i represents a section of the tin deposit of Weisse 
Andreas in Saxony. The containing rock is formed by a mica 




Fig. I. Stanniferous Deposit at Weisse Andreas (Saxony). 
i, miscaschiste ; 2, tin ore ; 3, stockscheider. 

schist (quartz and mica more or less mixed with felspar) which, 
in the neighbourhood of the tin ore, has become transformed into 
granite, the felspar being kaolinised and the crystals of quartz 
imbedded at right angles in the schist, reaching a length of 
several decimetres. This granite has received the name of 
Stockscheider, and is worked for the manufacture of porcelain. 

Refractory clays other than kaolin, such as those of Bray and 
in the neighbourhood of Vierzon (France) and Andenne (Belgium) 
are usually connected with deposits of fresh-water sand, in the 
midst of which the clay forms not seams properly so called, but 
nests, accumulations, and veins. Opinion is divided as to their 
origin ; some see in them the action of meteoric waters on vol- 
canic rocks ; then the transportation or mechanical displacement 
of the kaolin so formed, which, at that period, was more 
or less adulterated with foreign substances. Other authors, 
and these. not less numerous, attribute the formation of these 
clays to the influences of temperature acting either on granitic 
masses at a considerable depth, or on sediments of the Primary 
Epoch. 

The other clay deposits are the result of the agglutination of 
substances which have been in suspension for a long time, in the 
form of a more or less impalpable slime, and which came from 
the destruction of pre-existing rocks by the action of sea or river 
water or atmospheric agencies. The deposits were made during 



CLAYS. 7 

the period of the formation of sedimentary soil, therefore clays 
are found in all stratified ground. 

Origin of Lehm or Brick-earth. Lehm, which dates from 
the quaternary or modern epoch, covers large surfaces, especially 
in the neighbourhood of large uneven masses. 

According to de Lapparent (Traite de Geologic], the trickling 
of rain-water, when very abundant, degrades the neighbouring 
slopes and carries down, according to the strength of the flow, 
sometimes fine soil and sometimes fragments of stone ; this would 
be sufficient to account for the formation of lehm, which is there- 
fore also called tableland slime. This trickling, many times 
repeated, was produced by streams of water thin enough to allow 
free access to the air ; that is to say, the formation of the slime 
took place in an oxidising atmosphere, whence this peculiarity 
that the clay contains no organic substances, and that the iron in 
it is, for the most part, in the form of peroxide, as is shown by 
the yellow colour of the mass. 

We know that glacier-earths and river-mud, which are similar 
to lehm, but are formed without access of air, have a bluish grey 
colour, due to the organic matter and the nature of the iron-salts 
contained in them. 

As for the red slime which, showing signs of having been 
hollowed out by water, covers the deposits of lehm, and forms the 
beetroot soil of the North, it is also employed for the manufacture 
of brick, but opinions are divided as to its origin. It contains 
no limestone, but in many places contains angulous splinters of 
white oxidised flint. 

According to Wood, the red slime with splintered flint is the 
result of the alternation of frost and thaw on the surface of 
the earth; the changes of temperature lightened the crust and 
splintered the flints, which, being situated in a frequently muddy 
mass, acquired the white oxidisation, a sign of change. This 
transformation, taking place at different depths, must have 
produced those signs of hollowing which are observed on the 
horizontal parts, while on the inclined parts there was a real 
hollowing-out, due to the slipping of the slime which was reduced 
to pulp by its mixture with snow. 



8 



POTTERY IN ARCHITECTURE. 



Geological Situation of Clays. It is known that sedimentary 
rocks are divided Jnto four groups according to the age of their 
formation : primary, secondary, tertiary, and quaternary or 
modern period. Each group is subdivided into systems which 
form stages, according to the age of their deposit. 

Quaternary. 



GROUPS : 


Primary, 


Secondary. 


Tertiary. 


SYSTEMS : 


Precambrian 


Triassic 


Eocene 




Silurian 


Jurassic 


Neocene 




Devonian 


Cretacian 






Carboniferous 








Permian 







In all these systems clays are found, even in the primary. 
We will point out to which geological stages the principal clay 
deposits belong. 

Primary Epoch. PERMIAN SYSTEM. Large deposits of 
clays and variegated marls in Russia. 

Secondary Epoch. TRIASSIC SYSTEM. The Keuper stage 
of this system is represented by the variegated marls of the 
Vosges and Moselle ; these are clayey marls of strongly contrasted 
colours, in which red and green predominate. 

JURASSIC SYSTEM. In France, in the liasic. system, are 
found the Bayeux clays which are used in the manufacture 
of fired china, and reach a height of 1 5 to 20 metres. In 
England the Bradford clays belong to the mediojurassic series, 
and to the suprajurassic^ Oxford clay, which is tenacious, of a 



Oare de Gournay 



Villers Hannaches 



Wambez Gerberoy 




Eig. 2. Section of the Bray District between Gournay and Gerberoy. 
I, lower clays (upper Kimeridge) ; 2, lithographic limestone ; 3, upper clays (upper 
Kimeridge) ; 4, sand, sandstone, and limestone marls ; 5> clay (Portland) ; 6, sand- 
stone ; 7, lower cretaceous earth ; 8, chalk ; F, excavation. 

dark blue colour, sometimes bituminous, and reaches a thickness 
of 150 to 200 metres. The clay is also found in the Calvados, 
in France, where, mingled with fine sand, it serves as support to the 
rich pasturage of the Auge country. At Honfleur it is 20 metres 



CLAYS. 9 

thick. At Villequier (Seine- Inferieure) an excavation to a depth 
of 40 metres brings to light the so-called Kimeridgian clay situated 
a little higher, which is worked for brick and tile manufacture. 

The Bray country possesses clays, little worked, however, 
belonging to the suprajurassic system {Portland and Kimeridge 
stages) and arranged as in Fig. 2. 

CRETACEOUS SYSTEM. The neocomian stage of the same 
infracretaceous series includes considerable deposits of clay which 
are of great industrial importance. 

In England is found the blue or brown Weald clay, whose 
thickness reaches 300 metres. 

In France, the very interesting clays of the Bray country 
belong to the same stage, but have very different properties 
according to the position they occupy. . The section in Fig. 3 
shows their arrangement. 

In the middle neocomian are found the stone clays, called in 
the Bray district terre a pots or terre a gres^ which have been 
worked from time immemorial at la Chapelle-aux-Pots (Oise), 
Saint-Germain-la-Poterie, Savignies (Oise), for the manufacture of 
stoneware articles, chimney-pots, fountains, bonbonnes, ink bottles, 
etc. They are extracted from open pits or by means of shafts. 



s.o. 



Dots cLe C 



N.E. 




Fig- 3- Transverse Section (i in 10,000) from the Northern Outskirts of Bray, 

near Glatigny. 

i, lower Portland and Kimeridge; 2, upper Portland ; 3, white sands and refractory 
clays ; 4, ferruginous sandstone and potter's clays ; 5, streaked clay ; 6, green sands ; 
7, gault and gaize ; 8, cenomanian chalk ; 9, turonian chalk; 10, senonian chalk ; 
F, excavation. 

The refractory clays, found in the Bray country from Forges to 
Gournay, belong to the lower neocomian. They are more or 
less mixed with white sand, and are especially abundant in the 
neighbourhood of Forges. The best variety is of a bluish silver- 
grey, which whitens on exposure to air. The seams are very 



10 



POTTERY IN ARCHITECTURE. 



irregular, and the products of different pits are extremely diverse. 
The masses of clay, in the midst of sand, take often the shape 
of isolated balls. At Forges these masses are large and numerous, 
while at Serqueux, only two kilometres distant, the sand contains 
hardly any clay. 

The upper neocomian presents, also in the Bray district, a 
considerable outcrop of streaked loam, or marbled pink clay, 
worked for the manufacture of tiles, pipes, and paving squares. 
This is also an ingredient of the mixtures used for the manu- 
facture of stoneware. 

The most important pits are on the road from Auneuil to 
Beauvais and on that from Forges to Rouen. 

At Desvres (Pas-de-Calais) is also found a layer of clays 
20 metres thick, some grey and violet, others streaked with red 
and grey, which are often refractory, and appear to correspond 
to the Fnglish Weald deposit. 

To the albian stage of the loiver cretacian series belong 
30 or 40 metres of green sand found in the Bray district, and 
worked for brick-making. 

Tertiary Epoch. --The tertiary rocks contain numerous 
deposits of plastic clays, which are especially abundant in the 
Paris basin, where they are found above the chalk. 

EOCENE SYSTEM. Eocene Series. The Thanet stage of this 
system presents, at Lille, a bed of grey or black plastic clay, I 5 
to 20 metres thick. But it was particularly after the invasion of 
the Thanet Sea (from the Thanet promontory to the mouth of the 
Thames) that the plastic clays were formed in consequence of a 
period of lagoons and estuaries which forms the sparnacian stage. 

Meudon Auteuil Arc de Triomphe "MonLtnartre 




Fig. 4. Diagram showing the Tertiary Deposits under Paris (l in 10,000). 

I, chalk and pisolithic limestone ; 2, plastic clay ; 3, limestone gravel ; 4, Beauchamp 

sands and Saint-Ouen limestone ; 5, gypsum and green clays ; 6, Fontainebleau sands. 



CLAYS. I I 

At Varengeville, near Dieppe, a plastic grey clay is worked 
for the manufacture of tiles and bricks ; in Artois, in Flanders, in 
Picardy, in Hainault, plastic clay is often found collected in holes 
and irregular veins in the midst of sand. These clays bear signs 
of the conflict between the fresh water and the sea at the 
sparnacian period ; but when we come to the Paris basin, there is 
no longer anything but fresh-water deposits. The thickness of 
the plastic clays of this district is very diverse ; it is slight at 
Meudon, but below Saint-Denis extends to 50 metres. 

At the base there is found a bed of clay streaked with red 
and grey, then the true bluish grey plastic clay divided into two 
strata by a fine, clayish, and ligneous quartz sand, called Auteuil 
sand. Everywhere in the neighbourhood of Paris these clays are 
worked for tiles, bricks, pipes, etc. 

At the extremity of the Ile-de-France, in the Gatinais country, 
a plastic clay, variegated with bright tints, occupies pockets in 
the chalk ; it is used in the neighbourhood of Montereau for the 
manufacture of porcelain. 

West of the Paris basin, on the Eure plateaux, there are 
found white sands streaked with yellow and red with veins of 
clay which are frequently red and usually form pockets in the 
chalk. In these pockets, peculiar chemical reactions have taken 
place which in certain places have caused the formation of 
halloysite (a variety akin to kaolin), and this is employed at 
Breteuil - sur - Iton for the manufacture of stoneware. The 
refractory clay of Abondant, near Dreux, also forms part of the 
sparnacian stage. 

After this stage follows the ypresian (from Ypres in Flanders), 
which includes the London clay, a brown or brown-grey clay 
reaching a thickness of 250 metres, and known in Flanders by 
the name of Ypres clay or Flanders clay. Its thickness is about 
100 metres; it is plastic and of a bluish grey colour, like the 
Roubaix clay which appears to belong to the same stratum. 

As type of the eocene series, we will mention also they?/;// 
clay of le Perche. It is a conglomerate of natural flints coming 
from the chalk, and encrusted in a red and white clay which 
appears to have a chemical origin. This conglomerate is found 



I 2 POTTERY IN ARCHITECTURE. 

also in the Sologne and Blaisois districts, where it extends in 
places to a thickness of 30 metres. In the forests of Chateau- 
neuf and Senonches, the conglomerate of plastic clay passes 
under quartz sands with lustred sandstones mingled with coarse 
kaolin sands and white or variegated pure clays. This variety 
of the plastic clay stage is continued in the neighbourhood of 
Chateaudun and round Evreux, where the clay sometimes becomes 
refractory, while the lustred sandstones are accompanied by iron 
ore formerly worked in the valley of the Iton. 

Oligocene Series. To this series belong the clays or green 
marls of the Paris basin, the depth of which does not exceed 4 
to 5 metres. They extend to the neighbourhood of Etampes and 
Ferte-Alais, and are worked everywhere for brick and tile manu- 
facture at Fresne-lez-Rungis, Sannois, and Orgemont. They 
contain no pyrites, and consequently give out no sulphurous 
acid in baking like certain plastic clays from the western side 
of Paris. This is what distinguishes the Vaugirard brick-earth 
from the clay called Menilmontant or Belleville. 

To the oligocene series are attached the Marseilles clays, the 
order of which is as follows : 

Aquitanian . . Yellowish Marseilles clays with pudding-stones. 
Stampian . . Red clays of Saint-Henri and Lestaque. 

/'White lacustrine limestone, 
bannoisian . . ; ,,, , . , .. 

^ Blackish ligneous clays. 

The refractory clay of Andenne (Belgium) is also of the same 
series,as is too the sometimes sandy,sometimes clayey, deposit which 
covers a large part of North Germany to a height of I 60 metres. 

Some clays of special formation belong to the oligocene period. 
Under the plain of la Bresse at Bourg (Ain) they form a continuous 
layer of 28 metres thick and of various colours: white, yellow, 
marbled, red, blue, or green. They are of siderolithic origin and 
are found above iron ore. 

NEOCENE SYSTEM. Miocene Series. -The sands and clays 
of la Sologne are of this series ; they reach a thickness of 40 
metres on the right bank of the Loire, and join the so-called 
kaolin sands of the Eure plateaux, which are formed of grains 
of quartz, combined by means of a clay cement easily loosened 



CLAYS. 



by water. In company with plastic clays, chemically very pure, 
they fill cracks or funnels. 

Pliocene Series. This is represented, in the Morbihan, by 
blue or grey clays found at Saint- Jean-la-Poterie, Redon (Ille- 
et-Vilaine), Saint-Gildas-des-Bois (Loire-Inferieure). 

In the neighbourhood of Chalon-sur-Saone, fluvial sands are 
found mingled with variegated clays, which are often refractory, 
and are worked at Saint-Leger-sur-Dheune and Montchanin 
(Saone-et-Loire). 

Quaternary or Modern Rocks. Pleistocene Epoch. 
To this period belongs the lehm (brick-earth or tableland slime), 



Plateau. 




Fig. 5. Normal Section of the Valleys in the North of France. 

gig*^", gravels at the bottom of the different levels ; a,a f ,a", lehm ; 

/,/V r/ , red ooze with splinters of flint. 

and the loess (calcareous lehm). Generally these alluvial deposits 

are in terraces of different heights from the bottoms of valleys 

to the highest points of a watershed, as can be seen from Fig. 5. 

The sands and gravels accompanying the lower alluvions become 

rarer as one ascends ; but 

more or less angular flints 

are always to be met with. 3 *?< : -' : - 

The ooze is hollowed out, 

or sometimes covered with 

another reddish brown 

slime, the formation of 

which we have explained. 

On lower ground the Fig . 6 . -Section of the Alluvions of the 

composition of the alluvions Somme Valley. 

is fairly Constant (Fig. 6). r chalk J 2 > sands and gravels ; 3, rich sand ; 

4, brown ooze with angular splinters of flint ; 

The distribution of the 5) brick-earth. 




14 POTTERY IN ARCHITECTURE. 

lehm is independent of the altitude, and is found from the level 
of the sea to a height of 1500 metres in Europe, and in China to 
a height of 3500 metres. 

In Europe it is especially abundant in the valleys of the 
Rhine, Danube, and their tributaries. 

Hainault, Brabant, and Limburg are completely covered with 
it. Although less thick in the north of France, it is found over 
a large part of the tablelands between the valley of the Loire 
and Flanders, where it reaches its maximum of thickness. It is 
found in Hungary, Moravia, and Roumania ; but not in Russia, 
or on the Baltic or North Sea coasts. 

The pampas of la Plata and the basin of the Mississippi are 
covered with it, and, finally, in China it attains a thickness of 
400 to 500 metres. 

Wherever it exists, lehm is used in the making of bricks, as 
also is. loess when it is not too calcareous. 



2. GENERAL PROPERTIES OF CLAYS COMPOSITION. 

Physical Properties. Plasticity. That is to say that clays 
are able to preserve the shape which is given them ; a valuable 
quality utilised in the manufacture of ceramic productions. This 
property varies with the nature of the clays, being highly developed 
in some, such as potter's earths, and slight in the thin or lime- 
stone clays and lehm. 

It is generally admitted that the plasticity of clays varies 
with the proportion of combined water which they contain. This 
water enters into the very composition of the clays, which contain 
as much as 1 8 or 19 per cent, of it, and only leaves them 
at a red heat, while the hygroscopic water, or quarry water, 
which does not play the same part in the properties of the 
clays, mostly leaves them when dried in the air. The 2 or 3 per 
cent, remaining after this drying are expelled by a heat of 100 C. 

But the clay, so heated and deprived of its hygroscopic water, 
recovers its properties when suitably moistened, whereas, if 
deprived of its water of combination, it acquires new properties : 



CLAYS. 1 5 

hardness, sonorousness, and inability to regain its former 
plasticity. 

The testing of the plasticity of a clay is not an easy matter ; 
daily practice alone can teach it. 

Experience shows the quantity of cleansing matter required, 
in order to leave a good paste which will mould well and dry 
without losing shape. 

For plastic clays cannot be worked alone on account of their 
adhesiveness and of the change of shape, accompanied by 
cracking, which they undergo while being dried. 

Contraction. Clays as they come from the pit contract 
when dried ; if warmed, they continue to contract more or less 
sensibly according to their nature. The contraction becomes 
considerable when the clay has been made into a paste with 
water, and may be as much as a quarter of the linear dimensions. 
Usually, in the case of brick-clay, the total shrinkage, in drying 
and firing, amounts to 5 to 15 per cent, of the linear 
dimensions. Shrinkage takes place twice : during the air-drying, 
and during firing. It varies according to the mode of the latter 
process, and the method of manufacture. 

Plastic and fusible clays undergo most contraction, but for 
different reasons ; the former because they contain a great 
deal of water. They experience the greatest shrinkage at the 
moment when they lose this water ; that is to say, at about 
1 10 C. A higher temperature causes little contraction, because 
the infusible molecules cannot get closer to one another. Fusible 
clays, on the other hand, undergo shrinkage at that period of 
the firing, because the molecules weaken and approach one 
another to form a homogeneous whole, of a more or less close 
texture according to the temperature. 

The shaping of the paste plays an important part in the 
shrinkage. Thus articles made of soft clay, that is to say of 
clay soaked in water, undergo more contraction than those 
formed from hard or semi-hard clay, that is to say from clay 
merely moistened with water. 

Articles made by expression undergo more contraction than 
those manufactured by simple compression. In the latter, 



1 6 POTTERY IN ARCHITECTURE. 

inequalities of pressure cause inequalities of shrinkage, hence 
there is warping when the pieces are fired. This is especially 
noticeable in tiles and other articles which have a large surface 
in comparison to their thickness. 

Shrinkage takes place perpendicularly to all the surfaces of 
the pieces ; that is to say, they shrink simultaneously in length, 
breadth, and thickness. But sometimes it happens that it acts 
unevenly in consequence of pressure on the piece when being 
baked. Thus pieces placed in the lower part of the kiln, and 
resting one upon another, so supporting the weight of all the 
upper layers, may increase in length and breadth while diminishing 
in height. These deformations are especially noticeable in 
highly baked bricks ; they bear no trace of external fusion, but 
their fracture has a compact texture resembling that of stone- 
ware, and evidently due to the drawing together of the molecules 
under the action of heat and pressure. 

A thorough knowledge of the shrinkage of clays is of great 
importance in the manufacture of pottery, not only to give 
the proper dimensions to moulds and dies, but also with 
regard to the adhesiveness of glazes, as we shall show later on. 
Experience alone can teach us, since contraction varies with the 
clay. In expression-machines we allow an average of 10 per cent, 
difference between the brick issuing from the die and the same 
brick when baked. For the moulds in presses, working with 
unblended clay, only 5 per cent, is allowed. 

Fusibility. A clay is said to be refractory when it supports 
without melting a temperature of about I 800 C., which is that 
borne by china-clays. The most refractory clays are those 
which most resemble pure unadulterated silicate of alumina. The 
presence of metallic oxides, such as the oxide of iron, lime, 
potash, soda, etc., makes clays fusible by reason of the formation, 
at high temperatures, of complex silicates, which are all more or 
less fusible. Lime, which when pure is very refractory, makes 
an infusible clay fusible if mixed with it. The carbonate of lime, 
or limestone, added to a clay in the proportion of one-half or 
three-quarters, renders it fusible. 

The oxides of iron which colour clays with various tints, 



CLAYS. 17 

make them fusible by reason of the formation, during baking, of 
silicate of iron. 

To summarise, then, foreign bodies in clays tend, at a high 
temperature, to combine with the silicate of alumina, the base 
of clay, to form with it complex silicates which are generally 
more fusible. Hence the necessity of never subjecting ordinary 
pottery to too high a temperature. Nevertheless the heat must 
be sufficient to form complex silicates, yet not great enough to 
melt them. In this way 1 we obtain an impervious, hard, 
compact substance, similar to stoneware. 

If the temperature is pushed too high, the complex silicate 
melts like glass, and binds together the different articles being 
fired. Sometimes, in a badly managed kiln, a sudden access 
of heat softens the pieces and binds them into one single mass, 
which has to be removed from the kiln with the tongs. In a 
continuous kiln, the walls of which are not made of refractory 
substances, we have seen a part of the vault become welded to 
the pieces being fired under a tremendous access of heat, and 
break away from the arch under the action of shrinkage; these 
are accidents easily avoided by careful watching and regular 
stoking. 

Chemical Composition. -Analysis of Clays. We have 
already shown the limits within which the different ingredients 
of clay vary. In the following tables we have collected a certain 
number of analyses of the best-known clays. These analyses 
have usually been made with pure clays which in most cases 
have been cleaned. 

They do not show, therefore, the impurities which may be 
contained in clays, and hence have more interest for the savant 
than for the manufacturer. 

We must also not forget that they can only serve as a rough 
guide, since the composition of clays varies from one place to 
another, even in a distance of a few metres. Hence, whenever a 
manufacturer wishes for information as to the chemical composition 
of his clays, he should take, with every precaution, a sample from 
each bed, the physical appearance of which seems different from 
the others. 
2 



i8 



POTTERY IN ARCHITECTURE. 





o 


Composition of Clays when dried at i to" C. 




d* 

o ^ 




Physical 


Locality. 




\S ! c: : c 


ID C ^ b/) 


A 


Properties 
and 




>? 


a O's\ u s s 

cj g! ~ 1,3.5 


^2 -5 rt '~ "^ 


Applications. 




E 




X >"* H^ ^=H OJ . 1 








'J3 


O > c j < 












I. REFRACTORY ULAYS. 


A. Kaolins. 


FRANCE 


i 


Brittany 13.0048.003600 


. ... ... ... 2.0O 


Limousin . . ; ... 13.1048.0037.00 


... 2.50 


Nievre . . .... 12.6049.0036.00 


... i ... ; ... j 1. 60 


Pyrenees . . | ... 11.5048.0034.60 


traces/ 0.84; ... '2.15 


ENGLAND 






Cornwall 13.0048.35 


36.00 


0.75 ... 


0.96 


GERMANY 








Dolau (near Halle) ... 12.7648.15 
RUSSIA 12.6048.00 


37. 03 ! 0.60 0.27 0.30 0:82 
36.00! ... ... ; ... 2.40 


CHINA 11.2050.00 


3370 


i 1-90 


B. Various Clays. 


GERMANY 








' 




Eifel . 


3-50 


13.0046.60 39.30 








Refractory. 


Gr os sal me rode 


















(Duchy of Hesse) 


0-43 


14.0047.5034.37 


1.2^ 


0.50 


I . OO ... 


Grey and plastic, be- 




















low the ligneous 




















earths, very pure. 




















Mixed with quartz 




















sand, is used for 




















Hessian crucibles, 




















which bear sudden 




















changes of tempera- 




















ture without crack- 


Lautersheim 


















ing. 


(Prussia) . 




I3-56 


49.0033.00 


2. IO 


2 OO 0.2O 




White and plastic. 


















Fine pottery of Mett- 


















lach and Sarresue- 


Loshhayn (near 














mines. 


Meissen, Saxe) . 


2.70 


ii. /o 


61.52 20.92 


0.50 


traces. 


4-97 


Blackish, mixed with 


















quartz. Saggers > 
(Meissen Manufac- 


















tory). 


ENGLAND 


















Devon . 




11.20 


49.60 


37-40 










Grey, plastic, base of 


















English flint-ware. 


Stourbridge . 




17-34 


45-25 


28.77 


7.72 


0.47 






Black, not very plas- 




















tic, comes from coal- 




















field, infusible. 




















Crucibles for melt- 




















ing steel, and refrac- 


AUSTRIA 
















tory bricks. 


Gottweith (near 












1 




I 


Krems) 


I.OO 


10.00 


65.60 


20.75 


2.00 


1. 5 5 traces. 




Dirty green with red 




















spots. Saggers 




















(Vienna Manufac- 




















tory). 


Theuberg( Bohemia) 


0.49 


IO.OO 


58.39 


27.74 traces. 


o. 74 i . oo 




Plastic, grey, below 










1 










the lignite clays. 




















Saggers (Elbogen 




















Manufactory). 


BELGIUM 


















Andenne 




19.00 


52.0027.00 


2.OO 








White plastic. Glass- 


















ware pots, crucibles, 




















faiences. 


Angleur 


8.30 


14.3046.3039.50 








Refractory. 



CLAYS. 





'5. 


Composition of Clays when dried at i to C. 






o c 




Phvsical 


Locality. 


X 


||| 


. 


j^ 


o . 


<u 



tic c 


^ Properties 
and 




K 




CO 


|.| 


'* >i 


J 


11 


M 


Applications. 






' 






O 






< 




Antragues 




9.00 


7I.OO 


19.00 ... 






Grey and plastic. 
















Glass-ware pots, gas 




















retorts, refractory 




















bricks. 


DENMARK 




















Isle of Bornholm . 


0.27 


5.9272.50 


19.50 i.oo 


0.50 


0.50 




Plastic, grey, superior 


















to chalk. China 








J. 












saggers (Copenhagen 


FRANCE 


















Manufactory). 


Abondant (near 


















Dreux, Eure-et- 


















Loir) . 




13. 10 


5O.6O 


35.201 0.40 








White, plastic, very 


















refractory. Cruci- 


















bles for melting steel, 
















china saggers. 


Belin (Ardennes) . 




1.27 


63.57 27.45 


0.15 


0.551 


traces. 


Plastic, grey, infusible. 


Boulogne (Pas-de- 


















Faiences (Douai). 


Calais) . . . 


2.24 


6.28 


69.42 


18.00 


0.95 


2.00 


3-27 




Hard, greyish brown, 
infusible. Fine fai- 




















ences and pottery. 


Breteuil (Eure) 


12.50 


14.30 


48.30 


35-60 










Refractory. Bricks 
and refractory pieces. 


Dourdan (Seine-et- 




















Oise) . . : 




920 


60.60 


26.39 


2.50 


0.84 






Plastic, infusible. 


Echassieres (Allier) 


... 


16.40 


49.20 


34-oo 








... 


Plastic, white. Hard 
porcelains. 


Etrepigney (Jura) . 




9.96 


70.00 


18.50 


0.50 


0.75 


traces. 




Rich, greenish grains 
of quart/, infusible. 




















Faiences (Doubs). 


Forges - les - Eaux 




















(Seine-Inferieure) 




I I.OO 


65.00 


24.00 


traces. 


... 






Plastic, grey. Stone- 




















ware articles, glass- 




















ware pots, refractory 




















products, fine fai- 




















ences, common fai- 




















ences. 


Gaujacq (Landes) . 


0.42 


14.50 


46.50 


38.10 




traces. 






Plastic and white. 
China saggers (Ville- 




















dieu). 


Hayange (Moselle) 




7.50 


66. 10 


19.80 


6.30 








Yellow, sandy. Re- 
fractory bricks. 


Huelgoat(Finistere) 


5.10 


14.30 


47.90 


38.00 










Refractory. 


... 








Klingenberg ( Vosges ' 




16.00 


48.32 


32.48' 1.52 


1.6 4 


... 




Plastic, grey. Glass- 
ware pots, glass pots. 


Labouchade ( Allier) 




12.00 


55-40 


26.40 


4-20 






... 


Hard, yellowish white. 
Glass-ware pots. 


La Malaise (Haute- 




















Yienne) 


i-55 


15.00 


52.55 


26.50 


0-55 


3.00 


1.50 




Plastic, with red veins, 
infusible. China 




















saggers (Limoges 




















Manufactory). 


Laumede (Dor- 




















dogne) 


4.00 


13.60 


48.7036.50 










Refractory. 


Leyval (Charante- 










{ 










Inferieure) . 




12.00 


52.00 


31.60 


4-40 








White, marbled with 
red. Glass-ware 




















pots. 


Miglos (Ariege) 


6.50 


14.00 


46.30 


36.70 










Refractory. 











2O 



POTTERY IN ARCHITECTURE. 



Montereau (Yonne) 



Provins (Seine-et- 
Marne) 



Retourneloup 

(Seine -et-Marne) 



Salavas (Ardeche) . 



Savignies (Oise) 



RUSSIA 
GloukoflF 



Valendar 



ENGLAND 
Longport 

FRANCE 
Arcueil (Seine) 



Livernon (Lot) 
Yaugirard (Seine) . 



2.27 



i-45 



2.71 



Composition of Clays when dried at 110 C. 



' 



10.0064.40 24.60 



0.3057.00 



16.9642.0038.96 



58.76 25.10 



65.0031.00 



16.5046.3537-00 



Oxid 

Iro 



4.00 1.70 



0.85 1.04 



0.17 



2.50 ... 2.51 



2.OO traces. 



0.15 



0.52 6.7565.27124.19 1. 00 ... | 2.02| 

H. POTTERY CLAYS. 

I | | 
.. 10.6054.5016.50 3.13 3.37 ... 

II.Ol62.I4!2200 3.09 1. 68 traces. 
18.0049.0024.00 6.26 2.00 ... 



14.58:51.8426.10 4.91 2.25 0.23 



Physical 
Properties 

and 
Applications. 



Plastic, light grey, very 
variable in com- 
position. Used for 
Knglish faience clay. 



Plastic, whitish. Re- 
fractory bricks, china 
saggers. 



Plastic, grey, with red 
veins. Sevres sag- 
gers. 

Plastic, rose-coloured, 
turning grey in the 
kilns. --Crucibles for 
smelting steel. 

Plastic, black, above 
chalk. Native pot- 
tery. 



White, plastic. Base 
of St. Petersburg 
china. 



Plastic, greyish. 



Plastic, violet-coloured. 

S t aff ordshire 
bricks. 



Plastic, black, below 
coarse limestone. 
Paris pottery. 

Red. Pottery, imi- 
tation of Etruscan 
pottery. 

I Plastic, blackish, vein- 
I ed. Paris pottery. 



FRANCE 
Grandpre 

Saint - Henri (near 
Marseilles) . 



III. MARLY CLAYS. 



U-^SS-SO^-S 8 -33 5-*9 1-35 Tiles and pottery. 



21.7038.0024.00 4.5011.00 0.8o' ... Tiles and pottery. 



Xonllingen . 



IV. LEHM (Vegetable Mouhi). 
ii 5566.0712.90 5.27 2.60! 1.61 ... 



Reddish and sandy. 
Bricks. 



CLAYS. 2 1 

Influence of Various Bodies on the Properties of Clays. - 

Potash and Soda. These exist nearly always in clay, sometimes 
as mere traces, sometimes in quantities of as much as 2 or 
3 per cent. 

Washing does not remove alkalies from the clay, and it is 
probable that these substances come from the felspar or mica 
parts scattered in the clay in excessively fine particles which 
remain, like the clay itself, in suspension in the water. 

At a moderate temperature the alkalies have no effect, but 
at the temperature of china-kilns they act as fluxes ; hence 
ordinary brick paste, fired at a high temperature, should only 
contain a small proportion of alkalies, otherwise they would be 
too fusible. But it is very different with stoneware and porcelain 
pastes. Alkalies (felspar, pegmatite, etc.) are added to the former 
in order to weld together the particles of the substance, and to 
give it that peculiar appearance characteristic of stoneware, and 
to the latter in order to obtain the characteristic transparency of 
porcelain. 

Lime. The presence of this substance increases the fusibility 
of clays, and consequently diminishes the value of the refractory 
earths. But in those products which are fired at a less high 
temperature, if the lime does not exist in too large a proportion, 
it forms silicates which do not effervesce, and which play a part 
in the transparency of certain chinas. In the hard French china 
we find 3 to 6 per cent, of lime, a quantity which is increased 
to 10 or 14 per cent, in soft porcelain. 

Side by side with this chemical action, lime plays an 
important physical part in faiences. Its presence is indispensable 
for the adhesion of the stanniferous glaze with which faience 
pastes are coated. Moreover, in fai'ences intended for stoves, it 
prevents cracks and increases their resistance to fracture. The 
proportion of lime in faience pastes varies from 14 to 22 
per cent. 

The lime is always introduced in the form of more or less 
pure limestone. In the case of common pottery the quantity of 
limestone contained in the clay may rise as high as 10 or 12 
per cent, without their workability being much affected, but it is 



22 POTTERY IN ARCHITECTURE. 

inconvenient to use more calcareous clays alone, because the 
products obtained split up under atmospheric influences. They 
are therefore used as antiplastics in combination with rich clays. 

Magnesium. Like lime and potash, traces of this occur in 
almost all clays, but those which contain it in appreciable 
quantity are rarely employed for pottery. 

Oxides of Iron. White clays contain none ; these are the 
most uncommon (kaolins, refractory clays), the rest owe their 
yellow colour to the hydrated ferric oxide, and their red colour to 
the same oxide anhydrous. In firing it acts in two ways: it 
colours the pastes, and makes them fusible according to its quantity. 
Thus, common ferruginous stoneware contains from 5 to 8 per 
cent, of it. Above that proportion, the firing of the pastes 
becomes a delicate operation which must be stopped at the 
proper moment, otherwise the pieces will be deformed. The 
colour of pottery is not always proportioned to the quantity of 
iron contained in it ; it depends upon the substances introduced 
into the paste, and especially on the state in which the iron is, a 
state which varies with the temperature and the atmosphere in 
which the firing took place. 

Thus the same china paste containing oxide of iron some- 
times bakes white and transparent, sometimes yellow and opaque, 
according to the atmosphere of the kiln. If the atmosphere is a 
reducing one, especially at the moment when the glaze begins to 
melt, the iron remains as an almost colourless silicate ; if the 
atmosphere is an oxidising one, the iron may free itself in the 
form of ferric oxide ; the quantity of oxide of iron being the 
same, the more silicious the paste is, the less is the coloration. 

The influence of temperature is evidenced by this fact, that 
porcelains which are red when slightly heated, are transformed 
at a high temperature into transparent products, the oxide of iron 
becoming ferrous silicate. 

In common faiences, charged with oxide of iron, a too great 
coloration of the biscuit, a coloration which would afterwards 
have to be hidden by a thick coat of opaque enamel, is avoided 
by firing in a reducing atmosphere (smoked). 

The colour of the biscuit wares disappears superficially when 



CLAYS. 23 

they receive a glaze containing borax, because this latter dissolves 
the oxide. This is the case with English flint-ware, which is 
slightly coloured as biscuit, but becomes white on the application 
of the glaze. 

In firing bricks, differences of colour are sometimes noticed 
depending upon their position in the kiln ; these differences are 
caused by the varied oxidising and reducing power of the 
atmosphere due to the state of the fire. 

Sulphuret of Iron (Pyrites). This occurs in many clays, 
sometimes in the form of lumps or grains, sometimes scattered 
through the mass in an impalpable state ; it is probable that the 
colour of certain plastic clays is caused by its presence. 

In firing, the sulphuret of iron is decomposed into sulphurous 
acid which escapes, and into an oxide which, by attacking the 
surrounding parts, forms hollows in the products. Several clays 
in the neighbourhood of Vaugirard contain such large quantities 
of sulphuret of iron that their use has had to be forbidden on 
account of the volumes of sulphurous acid given out by the 
brickworks. 

Sometimes there are found in these clays beautiful crystals of 
iron sulphate caused by the oxidisation of the sulphuret. This 
chemical decomposition is sometimes so pronounced that in the 
Soisson district these clays are worked to extract from them the 
sulphate of iron, and the double sulphate of aluminium and 
potassium (alum). The latter is produced by the sulphuric acid in 
excess formed in the oxidisation of the sulphuret attacking the clay. 

Organic Substances. These are of different kinds, and their 
quantity is very variable. Although non-existent or occurring in 
very small amounts in most clays, they are sufficient in others to 
colour them grey, brown, or black ; and then in the firing these 
substances produce charcoal, or leave hollows within the products. 

Finally, certain clays contain considerable quantities of matter 
resembling coal, and produce black pottery, which is rendered 
very refractory by the infusibility of the charcoal. Such are 
plumbago crucibles. - 



POTTERY IN ARCHITECTURE, 



3. WORKING OF CLAYS. 

This includes the extraction of the clay and its transport to 
the place where it is to be manufactured. Arrangements for 
working differ according as the pits are open or underground. 



I. Open-air Pits. 

Extraction. In the majority of brickworks using the 
plateau-slime, this extraction is of the most simple character. 



HIHMMttbHHitatti 





Fig. 7. Workings of Plastic Clay at Arcueil. 

If hand-machines are used like those in the neighbourhood of 
Paris (Fig. 89), they are placed near the beds of clay. With a 
special tool, resembling a wheelwright's spokeshave but with a 
blade higher and more curved, the workman cuts the earth in 
tiers, the earth when cut falling to the foot of the machine; 
it is used as it is, with a little moistening if too dry. When the 
distance between the bed of clay and the machine becomes too 
great, that is to say every week or fortnight, the latter is brought 



CLAYS. 2 5 

nearer. When the bricks are hand-moulded (Flemish method) 
the clay is extracted beforehand, in order that it may undergo 




Fig. 8. Workings or Plastic Clay at Arcueil. 

weathering. If ordinary brick-earth (lehm) is used, the shovel 
and pick are sufficient ; if rich clays, however, are used, the 
process is as follows : 



26 POTTERY IN ARCHITECTURE. 

The bed is opened by removing the vegetable earth or any 
other layer likely to injure the working. Sometimes these layers 
are fairly thick and entail somewhat heavy expense, and it is 
necessary in that case that the thickness of the bed should be 
great enough to repay this outlay. The bed is attacked in tiers 
(Figs. 7 and 8) ; the clay is extracted by means of two special 
tools, kinds of pointed hoe with edged sides ; one with a short 
handle, the other with a longer one. With the first, the work- 
man makes, in the perpendicular face of a tier, vertical then 
horizontal incisions which will form two dimensions of the slab. 
When a certain number of these incisions are made he cuts the 
clay mass vertically with the long-handled tool in a line parallel to 
the face of the tier and at about I 5 "centimetres (6 inches) from 
that face. In consequence of the previous cuts the slab of clay 
comes away, and the workman lays it down near him. Some 
may be seen to the left in Fig. 8. 

By reason of its plasticity rich clay sticks to the tools and 
would prevent all working if care were not taken, to avoid this 
inconvenience, to dip the tool frequently into a bucket of water. 

Transport. Except in the case we have mentioned above, 
clay is rarely used at the place where it is extracted. It has 
always to be transported from the pit to the manu- 
factory. If the distance is very short, or if local conditions 
prevent other means, the classic wheelbarrow is used. The 
English model is the best ; the slope of the sides and their 
slight projection above the bottom place the centre of gravity 
much lower, relatively to the shafts, than in the French wheel- 
barrow, and thus render it more stable and easier to move. 

Another important advantage is that the contents may be 
discharged by turning the barrow through an angle of 45, 
resting it still upon the wheel, and without the man being 
obliged to move or let go the shafts ; the discharge is therefore 
quick, and can take place on a narrow plank, which is an advan- 
tage in certain cases (Brabant, Portefeuille de ringenieur de 
chemin de fer). As the wheel of the barrow, by passing con- 
tinually over the same line, would soon make a rut, especially in 
rainy weather, and would thus make wheeling difficult or even 



CLAYS. 27 

impossible, it is run upon deal planks 22 centimetres (9 inches) 
wide and of different lengths. These planks are imbedded in the 
ground in order not to hamper the walking of the men. Some- 
times plates of sheet-iron are substituted for these planks. In 
damp weather the clay, which always gets deposited on these 
wooden paths, makes them very slippery and even dangerous if 
on a slope. This inconvenience may be remedied by occasionally 
strewing some sand on them. 

Transport by Tramway. A. DRAWN BY MEN. The trans- 
port of clay by means of wheelbarrows is certainly the most 
onerous method. In all cases where it is possible to do so, a 
portable tramway should be substituted for them. These tramways 
(the best-known type of which is the Decauville) are now com- 
paratively cheap. (The 40 centimetre gauge costs 3 fr. 10 c. 
per metre, and the 50 centimetre gauge 3 fr. 20 c.) 




0e* 

-V -" 

Fig. 9. Earthwork Waggon. 

For man traction, which is the simpler method if the distance 
is not too great, a waggon is used containing 250 litres for the 
40 cm. gauge or 300 litres for the 50 cm. gauge, making the 
volume of about five or six wheelbarrows. 

The waggon is emptied very simply by tipping it over on 
one side as shown in Fig. 10. These waggons, which are made 
entirely of iron, cost about 100 francs (1897). 



28 



POTTERY IN ARCHITECTURE. 



B. HORSE TRACTION. If the distance from the place of 
extraction to the manufactory is somewhat great, and if the clay 

is worked on a slope, it is politic to use 
horse traction. Waggons like that in 
Fig. I I are then used, furnished with 
a central buffer and couplings. The 
waggons contain 500 litres. A number 
of them, varying according to the in- 
clination of the line and the strength of 
the horse, are coupled together. The 

Fig. 10. -Earthwork Waggon horse SQon gets accust omed to his 
Tipped. 

\vork. It is well to make it easier for 

him by adopting a special (Fig. i 3) harness, which permits him 
to develop the maximum of power. The swing-bar (Fig. 12) 





Fig. II. Earthwork Waggon with Central Buffer. 

shown at the left of the figure is furnished with a leather cover 
to the coupling to prevent the horse's tail from being caught 
in it. 

For the information of our readers we will calculate the 
net cost per cubic metre of the extraction of the clay and its 
transport over a certain distance by man and horse traction. 
This cost is evidently variable, depending upon the price of 



CLAYS. 29 

labour and the difficulty of extraction. We will assume an 
ordinary clay easily dug and loaded. 

Net Cost per Cubic Metre of the Extraction of Clay and its 
Transport by Waggon. This net cost is made up of three parts : 




Fig. 12. Whipple-tree with Coupling-cover, 
ig- ! 3- Horse with Special Set of Harness for Waggon Traction. 



one fixed, i.e. the cost of extraction, the two others varying 
according to the distance, and including the cost of traction, 
depreciation, repairs, maintenance, and interest on capital. We 
will estimate them in turn. 

C. HAND TRACTION. Cost of Extraction. The extraction 
includes digging and loading. In ordinary brick - earth 
(lehm), a good digger can do 15 cubic metres per day of 10 
hours, provided that he uses Fabattage\ that is to say, digs below 
the mass to be removed, and when it only holds by cohesion, 
drives into the top of it, at a certain distance from the edge, 
stakes armed with iron points. The excavated mass falls away, 
and becomes lighter in falling ; a few blows with the flat of a 
mattock make it fit to be shovelled. 

The shoveller can treat 20 cubic metres in his day's work, 
but we will suppose that, being entrusted with the maintenance 
and displacement of the line, he only loads 15. We will take 
40 centimes an hour as the cost of labour ; that is to say, 
4 francs per day of I o hours. 



30 POTTERY IN ARCHITECTURE. 

The cost of a cubic metre of clay loaded on the waggon will 
therefore be . . . . . . 0.533 fr. 

Cost of Traction. A man of medium strength will push a waggon of .3 cubic 
metres at an average speed of 4 kilometres an hour on a straight road. If we 
take a distance of 100 metres, we shall have : 

Journey loaded ......... 2 mins. 

Return empty . . . . . . . . . 2 ,, 

Unfastening, emptying, etc. . . . . . . . 2 ,, 



Total for a return journey . 6 mins. 

That is to say, 10 journeys an hour; 100 journeys a day to transport about 
30 cubic metres. The man pushing the waggon is paid about 3.50 fr. a day ; 

that is to say, per cubic metre : 2ll_l!=Q.n6 fr. . . . . . . o. Ii6fr. 

Depreciation of Plant, Interest ', etc. 
' 100 metres of rails of .5 metres gauge 

15 ,, ,, ,, for shunting 

115 at 3 fr. 20 ernes. 1 . . 368 fr. 

3 crossings ,, 45 ,, . . . . 135 ,, 

I turn-table ,, 60 ,, . . . . 60 ,, 

8 waggons of 300 litres (Eig. 9) ,, 94 ,, .... 752,, 



1315 fr- 
Discount or rebate 



Total . 

Depreciation 10 per cent, per annum on 1315 fr. . . . 131.50 fr. 

Interest at 4 per cent, on 1315 fr. .... 52.60 

Oil and maintenance, taken at 2 per cent. . . . . 26.30 

Total . 210.40 fr. 

Taking 300 working days and a daily output of 120 cubic metres, the annual 
output would be 300 x 120=36,000 c.m. If we suppose a less large extraction, 
or, as often happens, a stoppage of work in the winter for four months, we may 
reduce this estimate by a third, leaving 24,000 cubic metres. 

In the first case, the cubic metre would cost ?i9-'4 fr. =.oo<;8 fr., and in 

36,000 



the second, = .oo87 fr. 

24,000 

We will take the latter and higher price ....... o.ooS fr. 

The cost of extracting and transporting a cubic metre of clay to a distance 
of 100 metres on a level road thus comes to ...... . 0.657 fr. 

If there are any inclines, the cost is at once increased, and it 
is better to use horse traction. 

HORSE TRACTION. The cost of extraction and loading does 
not change, and is always, per cubic metre . . 0.533 fr- 

Cost of Traction. Ahorse of medium strength, walking beside the track 
and pulling with a chain, can haul on a level road of .5 m. gauge 8 waggons of 

1 We have taken the prices from the catalogue for September 1895 of the Decauville line and plant. 



CLAYS. 3 1 

Brought forward O-533 fr- 

.5 cubic metres each ; that is to say, 4 cubic metres. His speed is about 4 kil. 
per hour ; taking a distance of 500 metres, we shall have 

Journey loaded . . . . . . . .8 mins. 

Return empty . . . . . . . . . 6 ,, 

Unfastening, coupling and uncoupling of waggons, shunting, 

etc., per journey . . . . . . . . 6 ,, 

Total duration of return journey . 20 mins. 
That is to say, 3 journeys per hour carrying 12 cubic metres 

30 ,, ,, day ,, 1 20 ,, 

A horse costs in food and maintenance about, per day . . 4 fr. 

Driver, 50 fr. a fortnight, per day . . . . . 4 ,, 

Total . 8 fr. 

o 

Which makes per cubic metre : = .066 fr. . . .066 fr. 

120 

Depreciation of Plant, Interest, etc. 
500 metres of .5 m. gauge. 
35 ,, ,, for shunting. 

535 at 3.20 fr 1712 fr. 

4 crossings at 45 fr. . . . . . . . . 180 ,, 

i turn-table at 60 fr. . . . . . . . 60 ,, 

1 6 waggons of 500 litres with buffers and couplings (Fig. 11), 

at 1 50 fr. . . . . . . . . 2400 , , 

i set of harness for horse, with chain . . . . 90 , , 

I horse (approximate price) ...... 1200 ,, 

5642 fr. 
Discount or rebate 



Total . 5642 fr. 

Depreciation at 10 per cent, per annum .... 564. 20 fr. 

Interest at 4 per cent, per annum ..... 225.68 ,, 

Oil and maintenance, 2 per cent, per annum . . . 112.84 . , 

Total . 902. 72 fr. 
Supposing as before an annual extraction varying from 24,000 to 36,000 cubic 

metres, each metre will cost from 9 2 ' 72 or .037 fr. to 9 2 -'7? O r .025 fr. ; 

36,000 24,000 

we will take the higher estimate '. .. . . .. , . . 0.037 fr. 

Thus the cost of extraction and carriage for a distance of 500 metres ts, per 
cubic metre of clay . . . . \ . ._. . . . 0.636 fr. 

that is to say, is less, for a distance five times as great, than 
that of man-power ; but naturally the cost is greater if there are 
inclines. In this case, the amount carried per journey sinks. 

On a slope of 2 centimetres per metre to 3 cubic metres (6 waggons) 

4 2 (4 ) 

7 i (2 >. ) 

10 A (i ) 

The cost of extraction and loading are the same, also the depreciation, and, the 
daily output being fixed at 120 cubic metres, we have: 



POTTERY IN ARCHITECTURE. 



Incline of 2 c. Incline of 4 c. Incline of 7 c. Incline of 10 c. 

Cost of extraction . 0.533 fr. 0.533 fr. 0.533 fr. 0.533 fr. 

,, depreciation . 0.037 ,, -37 >, -37 -37 ?> 

,, traction . 0.082,, 0.132,, 0.264,, 0.528 ,, 



0.652 fr. 



o. 702 fr. o. 834 fr. 



It is therefore evidently advantageous to have only slight 
inclines ; when the slope is more pronounced, traction by cable 
and inclined plane must be used. 

Traction by Locomotives. It may happen that the distance 
between the pit and the manufactory is such that it will be 
advantageous to replace horse by steam traction. 

This occurs, for example, when a manufactory, in order to 
make use of an economical means of transport such as a river or 
canal, is installed on its banks, while the clay-pit is at some 
distance and a large daily output is required. 

In this case a 
railway is laid down 
the gauge of which 
will depend upon 
the importance of 
the factory and its 
distance from the 
P^. Usually the 
60 centimetre gauge 
will be sufficient, 
and wooden wag- 
gons will be em- 
ployed of the type 
used for large earthworks, containing about a cubic metre and 
emptying by side-tip. 

The framework is of oak and the body of poplar. A waggon 
of this kind costs 190 francs. 

If the amount of clay to be carried daily is very great, 
waggons measuring two cubic metres and of the type represented 
in Fig. 14 can be used. The sides are wood, the base sheet 
iron resting on T-shaped iron bars. The price of a waggon of 
this type is 600 francs. 




Fig. 14. Waggon of the Couvreux System Tipped. 



CLAYS. 



33 



The side door is automatic and shuts itself when the waggon 
is raised by pulling down the other side. 

The installation of locomotive traction is always expensive on 
account of the rails, which must weigh at least 9.5 kils. per metre. 

To give some idea of the expense, we add an approximate 
estimate of the plant necessary for such a system. 

A small locomotive like that represented in Fig. 1 5 weighs 




Fig. 15. Three-ton Locomotive for .60 metre gauge. 

3000 kilos (three tons nearly), and can haul a weight of 40 to 
50 tons on the level at a speed of 10 to 12 kilometres an hour. 

8.85ofr. 

7.600 ,, 



It costs 

20 waggons (Fig. 14) of 2 cubic metres at 600 fr. each . 
or 40 waggons of I cubic metre at 190 fr. 



8.850 fr. 

I2.OOO ,, 



Fixed outlay varying from 16.450 fr. to 20.850 fr. 
There must be added for each kilometre : 

For the permanent way at 7. 15 fr. a metre 7. 150 fr. 
Sundries 5 per cent. , about . . . .350 ,, 



7.5cofr. 
Which makes for I kil. of line, with rolling-stock, from 



7-5oofr. 7-50ofr. 

23.950 fr. to 28.350 fr. 

26.000 fr. 
31.450 fr. to 35.850 fr. 

33.000 fr. 
38.950 fr. to 43.350 fr. 

41.000 fr. 



Average about 

,, for 2 kil. of line, with rolling-stock, from 

Average about 

,, for 3 kil. of line, with rolling-stock, from 

Average about 
,, for 4 kil. of line, with rolling-stock, from 46.450 fr. to 50. 850 fr. 

Average about 48.000 fr. 

These figures are sufficient to show under what circumstances a system of traction of 
such a kind becomes economical. In fact the annual expense for each distance will be 

3 



34 



POTTERY IN ARCHITECTURE. 



i kil. 


2 kil. 


3 kil. 


4 kil. 


2600 fr. 


3300 fr. 


4100 fr. 


4800 fr. 


1040 ,, 


I3 20 


1640 ,, 


1920 ,, 


520 ,, 


660 


820 ,, 


960 



Depreciation . . 10 per cent. 
Interest . . . 4 ,, 
Oil and maintenance .2 ,, 

4160 fr. 5280 fr. 6560 fr. 7680 fr. 

Fixing, according to the distance, the maximum cost of amortisation for each cubic 
metre carried at 0.075 fr -? - l 5 fr -> and - 22 5 fr< respectively, it will be seen that the 
minimum annual bulk carried should be respectively 

55.400 c.m. 35. 200 c.m. 29. 100 c.m. 25.600 c.m. 

Transport by Aerial Railway. This system is used when 
the manufactory is situated below the level of the pit, and is 



Fig. i 6. 




Fig. 17. 

Fig. 1 6. Suspension Pulleys. 
Fig. 17. Sketch showing the Working of Two-way Aerial Railway. 

separated from it by an excavation. This occurs in the neigh- 
bourhood of Paris where, above the plaster-stone, brick-clay is 
often found. Under these circumstances, as the working of the 
plaster-stone leaves great hollows, and the brickworks are situated 
at the bottom of the hill, we want to pass the clay over the 
excavation by a simple and cheap method. The object is 
attained by the installation of a cable system. The full waggon 
suspended below a cable causes an empty waggon, which is 
suspended below another parallel cable, to ascend. The sketch 
in Fig. I 7 explains the working of this aerial railway. 

Two iron cables, C and C', firmly attached at their extremities 
to fixed points, are stretched over the space to be crossed. On 
these cables run tw r o grooved pulleys, which support beneath 
them the body of a waggon. The system of pulleys (Fig. 1 6) 
is joined by means of a cross-bar, B, to two other cables, C and 
C'. One of these, C', passes over a return pulley, R, and joins 
the bar B' of the descending waggon W' ; the other, C, is turned 



CLAYS. 



35 



several times round the windlass T, and joins the bar ft' of the 
waggon W'. 

When the loaded waggon W' is 
hung in its place, the system is set in 
movement by giving a few turns to 
the windlass T, so as to start the 
empty waggon W ; and as soon as the 
apparatus has gained a certain speed, 
it is left to itself, the difference of 
weight causing the empty waggon to 
ascend. The next time, the windlass 
T is turned in the opposite direction 
so as to pull the empty waggon W', 
and so on. 

On the arrival of the waggons, 
they are placed on their framework, 
which has remained on the rails, and 
are taken, the full ones to the fac- 
tory, the empty ones to the clay- 
pit. 

Transport by Inclined Plane. 
When there is no excavation to be 
crossed, and the manufactory is sepa- 
rated from the clay-pit by a gradual 
slope, or one that can be made 
gradual, it is advantageous to use 
inclined planes if the inclination is 
more than 8 or 10 in 100. 

There are an infinite number of 
ways in which inclined planes can 
be arranged. The best and the most 
economical is that by cables where 
the apparatus is self- working, i.e. 
where the descending load pulls up 
the empty cars. 

The installation comprises a pulley or a windlass, roller- 
frames, rollers, and a cable. In the one we describe, the pulley 



36 POTTERY IN ARCHITECTURE. 

over which the cable passes is furnished with a lever friction- 
brake (Fig. i 8) ; it is placed between the uprights of a wooden 
frame which is fixed firmly into the ground, at the top of the 
incline, with stout piles, the axis of the pulley being quite 
vertical. After the pulley is placed the roller - frame with its 
four return rollers ; two of these, with vertical axes, help to give 
the two branches of the cable their necessary distance and 
direction ; and the two others, which have horizontal axes, are 
placed at the beginning of the slope, at the point where the 
plane changes from horizontal to inclined. 

The rollers, which support the cable and prevent it from 
rubbing on the ground, are placed in a straight line at distances 
of from 5 to 10 metres according to the girth and tension of 
the cable. 

The latter may be metallic (steel or iron), or of vegetable 
fibres (hemp, manille, agave) ; its length is that of the incline 
with 10 or 15 metres extra to enable it to go round the pulley 
and pass the roller-frame. 

II. Underground Clay-pits. 

When the bed of clay is covered by a quantity of foreign 
substance too great to be removed, or if it occurs in strata, it is 
cheaper to work it by shafts and galleries. Previous soundings 
will have informed us as to the thickness and probable extent of 
the bed. This is highly necessary, because the extraction by 
shaft being always expensive, it is evidently necessary that the 
outlay should be redeemed in a certain number of years. 

The situation of the shaft is fixed by local circumstances, 
position of the bed, communication with the manufactory, etc. 
The size depends upon the method of extraction. In a large pit, 
a railway of 40 or 50 centimetres gauge will be used, hence 
the shaft must be square and large enough for two cars to pass 
one another ; one ascending loaded, the other descending empty. 

The square form also facilitates shoring up the shaft : for 
that purpose, by means of four beams, a square is formed, called 
" trousse," of the same size as the shaft. 



CLAYS. 37 

The trousses rest against the earth ; they are separated from 
one another by pieces of wood placed at the four angles, and if 
necessary in the middle of the bearing; these are called bearers. 
The distance from one trousse to another is more or less great 
according to the nature of the ground. 

Shoring, properly so called, is carried out by introducing, 
between the trousses and the side of the shaft, oak planks 
of length equal to the vertical distance between the trousses. 
Behind these planks clay is heaped to prevent the entrance of 
water. 

On reaching the bed of clay, a large reservoir is placed at 
the bottom of the shaft to collect the water coming from the 
galleries, which are bored through the whole thickness of the 
clay if it is not too great. 

As a gallery is extended, it is lined by placing planks across 
it on the ground ; on the ends of each plank two beams rest 
against the vertical sides of the gallery, and are joined at their 
upper ends by a strong oak plank, which thus forms a support 
to the roof. 

These stays are placed more or less close together according 
to the consistence of the soil : in good ground they are placed 
at every metre, but in ground subject to landslip this distance is 
diminished, and the stays are joined by planks which support the 
soil. 

The slope of the galleries will always be arranged so as to 
facilitate the flow of water towards the shaft reservoir. This 
reservoir will be emptied by pumps, or, better still, by using the 
water-tight bodies of waggons. The operation of emptying the 
reservoir is carried out every morning and evening before and 
after work. 

A pit of this kind requires the same care as a mine : ventila- 
tion of the galleries, testing woodwork, etc. etc. The owner 
and manager must conform to the Mining Law of 2ist April 
1 8 10, the articles of which referring to clay - pits we add 
below. 

For the transport of clay through the galleries, a portable 
tramway will be used whenever possible, with waggons the bodies 



38 POTTERY IN ARCHITECTURE. 

of which have rings riveted to the four corners. The loaded 
waggon is brought under the hoisting - gear, the hooks on the 
four cable extremities are attached to the rings, and the car is 
raised. The descending empty car is put on the waggon-frame 
in its place. The same operation takes place at the surface. 

This is evidently the most economical system, and there are 
very few cases of large extraction to which it is not applicable. 

Note. Extracts from the Mining Law of 2 1st April 1810, modified by the laws of 
9th May 1866 and 2;th July 1880. 

Extract from the Mining Law of 2ist April 1810. 

I. MINES, ORE-PITS, AND QUARRIES. 

ARTICLE I. Masses of mineral or fossil substances, contained within the earth or on 
its surface, are classed, for purposes of regulation, under the titles of mines, ore-pits, and 
quarries. 

ART. 2. Shall be considered as mines those known to contain in lodes, seams, or 
masses, gold, silver, platinum, mercury, lead, iron in lodes or seams, copper, tin, zinc, 
calamine, bismuth, cobalt, arsenic, manganese, antimony, molybden, plumbago, or other 
metallic substances, sulphur, earth or stone coal, fossil wood, bitumens, alum, and 
sulphates of metallic base. 

ART. 3. Ore-pits comprise the ores of iron called alluvial, pyrite earths convertible 
into sulphate of iron, aluminous earths, and peats. 

ART. 4. Quarries contain slates, sandstones, building and other stones, marbles, 
granites, limestone, plaster-stone, pozzalana, trass, basalts, lavas, marls, chalks, sands, 
flints, clays, kaolins, fuller's earths, potash earths, earthy matters and pebbles of all 
kinds, pyrite earths used as manure, all worked in the open air or with underground 
galleries. 

Y. OF THE SUPERVISION OF MINES BY THE GOVERNMENT. 

ART. 47. The engineers of the mines shall, under the orders of the Minister of 
Public Works and of the Prefect, exercise police supervision for the preservation of 
buildings and security of the soil. 

ART. 48. They shall observe the manner in which the workings are carried out, in 
order either to point out to the owners its inconveniences, and how it may be improved 
upon, or to inform the Government of defects, abuses, or dangers which may exist. 

ART. 49. If the working is reduced or suspended in such a way as to affect the public 
safety or the needs of consumers, the Prefect shall, after hearing the views of the owners, 
make a report to the Minister of Public Works in order that proper measures maybe 
taken. 

ART. 50 (altered l>y the law of 27/4 July 1880). If the experimental or after- 
working of a mine be such as to endanger public safety, the preservation of the mine, 
the safety of the miners, the preservation of the lines of communication or of the mineral 
waters, the solidity of dwellings, the use of springs which supply towns, villages, 
hamlets, and public institutions, the Prefect shall take proper measures. 



CLAYS. 39 

VII. REGULATIONS AS TO THE OWNERSHIP AND WORKING OF ORE-PITS. 
SECTION I. Ore-pits. 

ARTS. 57 and 58 (replaced by Article 3 of the law ofqth May 1866). 

ART. 3. The Articles 57 and 58 of the same Act are modified as follows : 

ART. 57. If the working of the pits is to be in the open air, the owner must, before commencing 
work, make a declaration to that effect to the Prefect. The Prefect gives an official certificate of such 
declaration, and the working proceeds without any other formality. This arrangement is applicable to 
iron-ores in seams and lodes, in the case in which, in accordance with Art. 69, they are not concessible. 
If the working is to be underground, it can only proceed with the permission of the Prefect. The permit 
states the special conditions to which the manager must conform. 

ART. 58. In the two cases foreseen in the preceding Article, the manager must observe the general 
or local regulations referring to public safety and health which are binding upon ore-pit managements. 
Articles 93 to 56 of the present Act apply to offences committed by managers of ore-pits, to the regulations 
of Art. 57, and to the general and local regulations referred to in the present Article. 

SECTION III. Pyrites and Aluminous Earths. 

ART. 7 1 - The working of pyrites and aluminous earths will be subjected to the 
formalities prescribed by Arts. 57 and 58, whether it is carried on by the owners, or by 
others who have obtained their permission to do so. 

ART. 72. If the pits are worked by non-owners, they will have to pay an indemnity 
to the proprietors, the amount of which shall be settled by agreement or expert 
arbitration. 

VIII. 
SECTION I. Quarries. 

ART. 8 1 (modified by the Act of 2.*] th July 1880). The working of open-air quarries 
requires a simple declaration made to the Mayor of the Commune, and forwarded to the 
Prefect. It takes place under supervision of the Government, and must conform to the 
laws and regulations. The general regulations shall be replaced by regulations made in 
the form of State Council decrees, in departments where these are in force. 

ART. 82 (modified by the Act of 2"]th July 1880). When the workings are carried on 
in subterranean galleries they are under the supervision of the mining administration as 
foreseen in Arts. 47, 48, and 50. In Paris the working of underground quarries of any 
kind is forbidden. The two decrees, with force of law, dated 22nd March and 4th July 
1813, and the decree of general regulation dated the 22nd March 1813, relating to the 
working of quarries in the departments of Seine and Seine-et-Oise, are repealed. 

ART. 83. Peat can only be worked by the owner of the land, or with his consent. 

ART. 84. A proprietor who wishes to work the peat-beds on his land cannot do so, 
under penalty of 100 francs, unless he has previously made declaration at the sub- 
prefecture and received a permit. 

ART. 85. A Government regulation will fix the direction of the works of extraction 
in the land where the peat is situated, that of the drying-trenches, and in fact all the 
measures for facilitating the flow of water in the valley, and the deposit of the peat 
cuttings. 

ART. 86. The owners working the peat, whether private individuals, commonalties, 
or public institutions, must conform to the above under penalty of being obliged to cease 
working. 



40 POTTERY IN ARCHITECTURE. 



IX. OF EXPERT ARBITRATION. 

ART. 87. In all cases foreseen by the present law, and in other cases arising from 
special circumstances in which expert arbitration is necessary, the regulations of Cap. 14 
of the Code of civil procedure, Arts. 303 and 323, shall be carried out. 

ART. 88. The experts shall be chosen from among mining engineers, or men eminent 
and experienced in mining matters. 

ART. 89. The Imperial Procurator shall always be heard, and shall give his opinion 
on the reports of the experts. 

ART. 90. No plans shall be admitted as evidence in a contested case, unless sub- 
mitted or approved by a mining engineer. The verification of plans shall always be 
made gratis. 

ART. 91. The expenses and fees of experts shall be assessed and fixed, according 
to circumstances, by the courts ; also the honoraria of mining engineers ; all being in 
accordance with the scale fixed by a Government regulation. Nevertheless, there shall 
be no honoraria for mining engineers when the operations have been conducted either 
in the Government interests or in consequence of police supervision. 

ART. 92. The deposit of the sums considered necessary for paying the expenses of 
expert evidence may be required by the court from the party who seeks such evidence. 

The Act of 2 1st April 1810, from which we have given extracts referring to the 
industry we are discussing, was completed by the Act of 27 th April 1838, relating to the 
draining and working of mines, which, when several mines situated in different con- 
cessions are attacked or threatened by a common inundation which is likely to imperil 
their existence, public safety, or the needs of consumers, gives the Government power to 
oblige the grantees of those mines to carry out, jointly and at their own expense, the 
works necessary either for draining the whole or part of the flooded mines or to check 
the progress of ihe inundation. As this Act has only a limited interest, we think we 
may forbear from printing the text of it here. 



CHAPTER II. 

PREPARATION OF CLAYS. 

THE preparation which clays must undergo with a view to 
their use in pottery depends upon their nature, the process of 
manufacture, and the kind of article to be made from them. We 
shall only give here a few general remarks, as we intend later on 
to refer in a more detailed manner to this preliminary work, when 
we speak of the manufacture of the various products. 

We have said that the preparation which clays have to 
undergo depends upon their properties and the process of manu- 
facture. If, for instance, brick-earth (lehm) is used for what are 
called native bricks, it is an exceptional case ; all other products 
are usually made of mixtures of different clays or even of foreign 
substances which have to be incorporated in them to make a 
homogeneous whole. The physical nature of clays enters into 
the choice of mixtures ; rich clays must be thinned by the 
addition of antiplastic or thinning bodies, sand, thin clays, 
cinders, etc., while, on the other hand, thin clays must, for 
certain products, be enriched by loams, etc. 

In fact, with the exception of the above-mentioned case, clays 
coming from the pit require to be treated, in order to remove 
the hard portions and foreign matter contained in them. Besides 
this, they have to be mixed with water uniformly, and the whole 
must be well mixed to form a sufficiently homogeneous paste, 
well fitted for moulding, drying, firing, and consequently for 
making good products. 

Dry clays also are treated by reducing them to dust in order 
to mix them with others, or even to use them as they are by 
compressing them under powerful pressure followed by firing at a 
high temperature. 



42 POTTERY IN ARCHITECTURE. 

These various operations may be summarised under two 
heads 

1. Disintegration and division of the mass by cutting and 
crushing ; separation of the hard bodies or their crushed remains 
so that they may mix with the rest of the clay. 

2. Addition of foreign substances necessary for the forma- 
tion of paste, water and antiplastics if necessary ; and making a 
close mixture by pugging or blending. The processes by which 
these results are obtained are 

c Weathering and decomposition. 

. T / by hand. 
Disintegration and division of the mass . -! & I by machine. 

Washing and removal of stones. 
V. Crushing and pulverising. 
( Soaking and moistening. 
Addition of foreign substances. -Pugging J Thinning, and treatment with antiplastics. 

. f by hand. 
I Pugging \ , . . 

b I by machine. 



WEATHERING. 

In order to disintegrate the clay after it comes from 
the pit, it has been customary for ages to extract it in the 
autumn and to spread it in heaps of various heights on a flat 
surface. If there are several kinds of clay, they are placed in 
alternate heaps, so as to make a mixture when the heaps are 
demolished. 

Winter and its climatic changes rain, snow, frost, thaw 
cause a physical alteration which breaks the hard pieces and 
splits up the mass throughout all its thickness. 

Weathering, always a costly operation, has almost entirely 
disappeared with ths introduction of machinery, except for 
manufacture by the Walloon method, and even for that it has 
been abandoned in many works. 

Decomposition. Certain plastic clays experience, besides the 
disintegration caused by winter changes, another phenomenon 
called decomposition. These clays take a grey then a black 
colour, setting free sulphuretted hydrogen. On contact with the 
air the black colour disappears, carbonic acid is given out, and 



PREPARATION OF CLAYS, 43 

sulphate of iron is formed. The presence of organic matter 
appears to be one of the causes of decomposition, for it can 
be hastened by sprinkling the clay with liquid manure, marsh 
water, etc. 

This special phenomenon gives rise, in the midst of the mass 
of clay, to complex chemical reactions which last for several 
years. It is then quite different from what is called weathering. 

And besides, it is independent of weather changes, since it 
can take place in a covered space, provided the clay is kept 
constantly damp. Water and certain substances are thus 
indispensable for the decomposition of clays, and so is time. 
Also, experience seems to show that the oldest pastes are the 
best. The decomposition of clay is peculiar to the porcelain 
manufacture, and even for that purpose many important factories 
have abandoned the process, so we will not lay stress upon it. 

We will bear in mind only that decomposition and weathering 
are different processes, and that both of them, although they 
have useful effects on the physical qualities of the clay, are being 
more and more neglected under new economical conditions. 

MIXING. 

Hand-mixing". This is done to reduce to shavings the 
vegetable mould (lehm or limon) used for the manufacture of 
so-called native bricks. The earth is scraped vertically with the 
round knife of -which we have spoken, and which the workman 
holds by two handles, one in each hand. Layers of about 60 to 
80 centimetres high are taken in turn ; the earth falls to the foot 
of the bed, splitting up and becoming sufficiently granulated to 
be put as it is into the press-moulds. 

Machine-mixing". This process is applied to non-calculous 
loams which are treated as they come fresh from the pit. As 
they are compact and in large lumps which cannot be crushed 
between cylinders, they are cut up into small pieces which absorb 
water more easily. For this purpose special machines called 
mixing mills are used, the principle of which is the same as 
that of chaff-cutters ; rotating steel knives meet the motionless 



44 



POTTERY IN ARCHITECTURE. 



mass of clay and cut it into regular shavings. Cylindrical 
and conical mixing mills are manufactured. 

Cylindrical Mixing Mill. This consists of a cast-iron frame- 
work in the middle of which is a cylindrical pan with movable 
bottom. The base is a cast-iron plate pierced with oblong holes 
in the direction of the radii. Each of these openings is furnished 
with a steel blade which acts as a knife and is fixed with bolts to 
the plate and projects from it. The plate is fixed to the end of 




Fig. 19. Mixing Mill with Horizontal Tray (Pinette). 



a strong shaft which is moved by bevelled gear. The pan is 
divided into two parts by bars or by a plate fixed against its 
sides (Fig. 19). 

When the machine is set in motion, the plate with the knives 
begins to turn with a speed of 60 to 70 revolutions a minute. 
The clay is introduced into the pan, and, the fixed bars preventing 
it from following the rotation of the plate, the steel blades cut it 
below. The slices so formed pass through the openings between 
the blades and the plate and fall to the ground, their size being 
greater or less according to the dimensions of these holes. 



PREPARATION OF CLAYS. 



45 



The machine is strong enough to stand shocks caused by 
little stones being broken by the knives. If the stone is too 
large the driving-belt slips, and the machine must be thrown 
out of gear in order that the stone may be taken out by the 
hand. 

The yield of a mixing mill depends upon the amount of 
moisture in the clay and the size of the machine. 

Conical Mixing Mill (Fig. 20). The principle is the same 




1 1 ;, H P 



Fig. 20. Conical Mixing Mill (Lacroix). 

in this, but the knives are fixed on the surface of the frustum 
of a cone. The clay, being thrown into the frustum, is kept 
motionless by a fixed partition as in the flat-bottomed machine. 

Usually the mills are placed immediately above the soaking- 
trenches (Fig. 21). It is easy to so arrange the machine that it 
shall supply several trenches by placing it at a certain height, 
and guiding the clay into the more distant ditches by means 
of inclined planes kept damp by a slight stream of water. 



46 POTTERY IN ARCHITECTURE. 

Sometimes an endless band is placed under the mill, as in 
Fig. 19. 

SEPARATION OF FOREIGN SUBSTANCES. 

It is preferable, for many reasons, not to use clays which 
contain too much foreign matter, stones, sands, pyrites, etc., 
but there are cases in which one cannot do otherwise, and then 
the foreign substances have to be removed. 

Cleaning by hand is only suitable for expensive clays like 




Fig. 2i. Conical Mixing,Mill (Boulet). 

the kaolins ; generally washing is used to remove the sand and 
gravel, and stone-removing machines for the larger stones. 

Washing of Clays. This is an excellent but a costly process 
for freeing clays from the heavy products contained in them. 
It is used with kaolins, and for preparing the fine pastes used 
in decorative terra-cottas and certain kinds of pottery. 

The substances which clays deposit, when washed with 
water, are pyrites or quartz sands (silicious), with felspar or 
mica. 



PREPARATION OF CLAYS. 



47 



The apparatus used depends upon situation and the quantity 
of water available. In works where both are satisfactory, the 
process is carried out in large walled ditches, through which a 
current of Avater is passed over the clay. When there is a 
sufficient quantity of water, the clay is stirred up so as to make 
a kind of clear pulp, while the dense substances remain at the 
bottom ; when all the clay is in a state of pulp, it is passed into 




P'ig. 22. Filter Press for Clay (Wegelin and Hiibner). 

reservoirs, where it falls to the bottom. The remaining water 
is removed by decantation, and for this purpose the reservoirs 
are arranged in cascades. 

In order to prevent the current of water from carrying with 
it part of the foreign substances, the pulp may be passed over 
a kind of filter which retains them. When the deposit, which 
has been exposed to the air, is firm enough to be handled, it is 
taken out to be compressed by different methods, the quickest 
and least cumbrous of which is the filter press (Fig. 22). 

The use of deposit-reservoirs necessitates a very large space 
and considerable cost of installation, when the output is large ; 
therefore it is desirable in certain cases to substitute for them 
a system of diluting the clay in sheet - iron tanks with sieve 
bottoms which retain the foreign bodies and let the pulp pass. 
The latter is forwarded by means of a pump to the filter press. 
The apparatus is easily moved complete, and sometimes is 
combined with a motor which works the pump for transferring 
the pulp to the filter press. This latter contains a certain 



48 POTTERY IN ARCHITECTURE. 

number of compartments which communicate with the pipe 
bringing the pulp under pressure. The water runs off, and 
when the filter press is full of clay, the entrance tap is turned 
off and the pulp conducted into another filter. The clay is 
thus obtained in the form of a paste still containing much 
water, which is removed by compressing the plates strongly 
by means of a fly-wheel moved by a central screw. The pump 
(Fig. 23) has an elastic membrane which separates the piston 




Fig. 23. Membrane Pump for Filter Press (Wegelin and Hiibner). 

from the muddy liquid to be raised. There is therefore no 
damage from the hard bodies to be feared. 

To make the production continuous, it is sufficient to con- 
stantly remove the stones. This is done by using a rotating 
sifting cylinder slightly inclined. 

The pulp is prepared in a tub, A, and flows with the foreign 
substances into a perforated rotating cylinder, C. The pulp falls 
into a reservoir, D, while the impurities, drawn by the rotatory 
motion of the cylinder, are poured into the waggon, W, which is 



PREPARATION OF CLAYS. 



49 



changed when full. The pulp is drawn up by the pump and 
sent on to the filter press F. 

We must not forget that the washing of clays only removes 
certain impurities such as sands and stones, foreign bodies like 
limestone, pyrites in an impalpable condition, oxide of iron, 




Fig. 24. Arrangement of an Installation for continuous Washing of the Clay. 

etc., becoming shaken up with the clay and remaining in 
suspension with it. 

Mechanical Stone-removing. This process is not as perfect 
as the foregoing, but it allows of the expulsion of stones or 
other hard bodies of a certain size. The apparatus used 
is composed of two conical rollers placed according to their 
generating lines (Fig. 25), and moved by a conical gear. 
The machine is fed without interruption like the other 
rolling- machines. The foreign substances advance automati- 
cally and are expelled by a gutter which may be seen on 
4 



50 POTTERY IN ARCHITECTURE. 

the left of the figure. The clay afterward passes between the 
rollers and undergoes a first flattening. The machines made 
by Messrs. Jager (Fig. 25) treat in 10 hours a quantity varying 




Yig. 25. Stone-removing and Rolling Machines (Jager). 

according to their size, from 10,000 to 70,000 bricks, and 
require from 3 to 7 horse -power. Their weight varies from 
1500 to 4000 kilos (i| to 4 tons). 

Another machine of the same kind is shown in Fig. 26. 




Fig. 26. Stone-removing Machine (Penfield). 



PREPARATION OF CLAYS. 5! 



CRUSHING AND PULVERISING. 

Crushing 1 . This is done, in fresh clays, in order to destroy 
hard lumps and to crush the foreign substances contained in 
them : limestone, schists, quartz, flint, etc. Dividing and 
crushing cylinders are used. 

Dry crushing is used with dry clays which are reduced to 
powder, either for use as they are or for mixture with others. 
Finally, substances are crushed for use as antiplastics, such as 
sands, slag, fragments of pottery, etc. 

Damp Crushing. Dividing Cylinders. When the clays are 
too hard or in pieces difficult to treat with the mixing mills, 
special cylinders are used to split them up. Some carry tempered 
steel points (Fig. 27) to catch the large pieces of clay which 




Fig. 27. Crusher and Divider with Inlei changeable Points (Jager). 

might slip over smooth cylinders. The fragments of clay thus 
obtained are sent on for rolling or soaking. 

In the machine shown in Fig. 28, the diameter of the 
cylinders plays the same part as the steel points of the fore- 
going machine. This machine, which is very strong, is supplied 
direct from waggons, and the large pieces or unseparated parts 
of the clay are reduced to the size required for a satisfactory 
soaking. 

Crushing Cylinders. These are used to crush hard bodies, 
such as limestone or flint, which may be contained in the clays. 
They should be very hard, and the whole of the machine 



52 POTTERY IN ARCHITECTURE. 

extremely strong in order to resist the violent shocks. Usually 
two or three pairs of cylinders are placed one over the other, 
the distance between them decreasing, and the clay falling from 
one pair to another. 




Fig. 28. Large Dividing Cylinders (Boulet). 

The cylinders are smooth or fluted, and their diameter varies 
from 35 centimetres to i metre, the length being always 60 
centimetres. The clay is brought to the cylinders by endless 
bands, or poured in direct from waggons, or thrown in with the 
shovel. 

The cylinders represented in Fig. 29 are also used to crush 
the clays, but have also this peculiarity, that by the addition 
of one or two extra pieces of machinery, they can be easily 
employed for the crushing of dry substances such as fragments 



PREPARATION OF CLAYS. 



53 



of tiles and pottery ; they can thus in a certain measure take 
the place of the grindstone apparatus generally used for that 
work. 

The extra pieces comprise a lever with counterpoise and an 
oscillating grating to separate the powder from the large pieces. 
To increase the effect of this kind of machine, a differential 
speed is sometimes given to the rollers, so as to add to the 
crushing action a powerful rubbing. The crushing cylinders 




Fig. 29. Crushing Cylinders (Joly). 

of the machine shown in Fig. 30 are arranged in this manner, 
and so are those of the Whittaker machine (Fig. 31). 

As shocks are numerous in these machines, automatic 
belting is used to avoid breaking the gear-wheels ; the move- 
ment is transmitted by means of a friction pinion, and a catch 
which can be put in or out of gear by a lever. 

In the foregoing machines the rollers are furnished with 
scrapers as in flatting-machines, but instead of leaving a layer 
of clay on the cylinders, these are always kept clean. As the 
rollers wear out rather quickly, they have to be brought closer 



54 



TOTTERY IN ARCHITECTURE. 



together in order to keep them at the required short distance 
apart. 




Fig. 30. Differential Speed Crushing Cylinders (Johnson). 

A time comes when the gear-wheels transmitting the motion 
work deep into one another, in spite of their long cogs, and 




- 31- Differential Speed Crushing Cylinders (Whittaker). 



PREPARATION OF CLAYS. 55 

this will infallibly cause their fracture. To avoid this accident, 
then, we must have an extra wheel of the same speed but less 
diameter and substitute it in good time. The one removed is 




Fig. 32. Crushing Cylinders with Arrangement for Throwing Out of Gear (Whitehead). 

not useless, for it will serve again when the worn-out rollers 
are replaced by new ones. 

Dry Crushing. This process is used in certain cases when 
the clays are dried, and also to pulverise bodies for use as anti- 
plastics. 

Drying of Clays. The manufacture of pottery with dry clay 
only flourishes in warm countries where the extreme dryness 
permits of easy desiccation of the earths. In other climates the 
cost of drying prevents a general use of this method. Neverthe- 
less certain clays are worked in a dry state by leaving them for 
a long time in the air under covered sheds. 

For artificial drying, large hot-air ovens are used ; the clay 
is placed in layers of 15 or 20 centimetres thick, and moved 
from time to time. For large works, continuous kilns are used. 
The clay is thrown into an upper hopper, and thence falls into 



56 POTTERY IN ARCHITECTURE. 

the oven itself, which is heated by coke furnaces giving a 
moderate heat to a large extent of air. This air, loaded with 
water vapour, issues by means of openings made in the arch 
supporting the hopper, and passes into two longitudinal conduits, 
whence it goes into a chimney. A kiln 7 metres high, 2 broad, 
and 4 long dries in 24 hours about I 5 cubic metres of clay con- 
taining i 3 per cent, of water, and uses 400 to 500 kilos of coke. 

Pulverisation. This is done by grindstone mills in the 
case of clays and in general for substances of medium hardness. 
In the case of very hard and bulky substances, it is advisable to 
use pounding mills and special crushers. 

Crushing" Mills. These consist of vertical grindstones of 
varying weight, and circular cast-iron pans into which the 
substances to be crushed are placed. Sometimes these pans are 
fixed, sometimes they are movable. The separation of the 
pulverised portions from the coarser ones is effected in several 
ways : either by a central inclined sieve, on to which an 
automatic feeder throws the substance ; or by the bottom of the 
pan itself being perforated with a number of holes, whose size 
depends upon the coarseness of the powder to be produced. 

Crushing Mills with Central Sieve and Automatic Feeder. 
The pan is of cast-iron and has in the middle a hollow covered by 
a sloping sieve, the fineness of which varies with that of the pro- 
duct required. The vertical shaft which works the grindstone 
carries with it a chain of buckets supported by a shaft per- 
pendicular to the first one, and rotated by means of a bevelled 
gear as shown in Fig. 33. The buckets pick up the pulverised 
matter into a wooden gutter which guides it on to the sieve ; 
the portions which are too large to pass it fall back again into 
the pan, and the powder is received into a lower receptacle, 
whence it is removed by various means according to the locality. 

If it has to be carried to a higher level, a kind of shaker is 
used, moved by a belt, and constructed to throw the pulverised 
substance into a trough from which it is carried by a bucket- 
chain to the required height. 

The apparatus here represented may have two grindstones 
instead of one. The weight of these stones varies according to 



PREPARATION OF CLAYS. 



57 



their size from 350 to 3500 kilos (6 cwt. to over 3 tons), and 
as they are hollow, this weight is increased by bricking them 
inside. Thus a simple grindstone like that in Fig. 33 weighs 
350 kilos; filled with bricks like that in Fig. 34, it weighs as 





Fig. 33. Crushing Mill with Central Sieve 
and Automatic Feeder (Jannot). 



Fig. 34. Crushing Mill 
(Luce). 



much as 850 kilos. The crushing mill of Fig 34 differs very little 
from the preceding one. 

Crushing Mills with Perforated Pans. These may either 
have fixed or movable pans. The one in Fig. 35 has a fixed 




^'g- 35- Crushing Mill with Fixed Pan (Groke). 



58 POTTERY IN ARCHITECTURE. 

pan pierced with a series of holes ; the grindstones set in motion 
by the bevelled gear crush by their weight and speed the 
substance to be pulverised. The powder is collected in a closed 
space, whence it can be raised by a bucket-chain to be distributed, 
if required, to other machines. In other mills the pan is 




Fig. 36. Crushing Mill with Movable Pan (Johnson). 

movable and the grindstone is fixed on an axis which is held 
between slides and so can be raised or lowered. The grinders 
thus follow the level of the substance to be crushed, and turn 
round on their axis in consequence of the friction caused by 
the pulverisation. 

The arrangement of the pans naturally depends upon the 
makers. Figs. 37 and 38 show us the different arrangements. 
In the machines represented the motion of the pan is trans- 
mitted from above by means of a vertical shaft which passes 
through, but with slight friction, the axis of the tw r o grind- 
stones. On the other hand, in the mill represented in Fig. 
39 the pan carries a cog-wheel, and the motion is transmitted 
below. 

The perforated bottom of the pans is made up of several 
segments which can easily be replaced when worn out, the parts 
being interchangeable. 

A special crushing mill, represented in Fig. 40, is used to 
reduce agglomerated sand to powder. The peculiar shape of 



PREPARATION OF CLAYS. 



59 



the grindstones or rather of the fluted cylinders allows of easy 
crushing of the lumps. 




ig- 37- Crashing Mill with Movable Pan (Whitehead). 



Universal Pounder and Crusher. These are used to reduce 
hard bodies to small fragments. They are composed (Fig. 41) 




. 38. Crushing Mill with Movable Pan (Whittaker). 



6o 



TOTTERY IN ARCHITECTURE. 




Fig. 39. Crushing Mill with Movable Pan (Ja'ger). 




Fig. 40. Crushing Mill for Sand (Luce). 




Fig. 41. Pounder for Hard Bodies (Borner), 



PREPARATION OF CLAYS. 



6l 



of movable cheeks between which the material is broken and 
reduced to larger or smaller fragments according to the distance 
between the cheeks. These regular fragments are afterwards 
passed under the wheels of mills to reduce them to powder. 

Another machine used to crush these bodies direct is Carr's 
universal crusher. It is composed of a certain number of 




Fig. 42.-Carr Universal Crusher the Cages separated (Jager). 

concentric barred cages fixed upon a rotating plate. Other 
cages, also concentric and of diameter intermediate to the 
preceding ones, are fixed to another plate which revolves in 
the opposite direction. This second plate and its shaft are 
mounted on a support which can slide longitudinally, so that 
the cages fit one within the other (Fig. 43). 

When the machine is working, the cages being thus fitted 
together, two contrary movements are produced. The whole 







Fig. 43. Carr Universal Crusher the Cages together (Groke). 



62 POTTERY IN ARCHITECTURE. 

is contained in a sheet-iron cover, shown on the right of the 
sketch, and the substances to be crushed are thrown in by the 
hopper fixed to it. They receive a shock against the bars of 
the first cage, and after passing through those bars, meet those 
of the second cage, which are turning in the opposite direction, 
then those of the third, and finally those of the fourth, each being 
opposite in direction to the preceding. At last they fall outside 
in the form of a powder the fineness of which depends upon 
the number of turns of the cages. These latter, rotating 
within the cover, act as ventilators, and prevent dust in the 
workshop. 

The production of this machine is much greater than that 
of any other used for the same object, but it requires a con- 
siderable motive power. 

ADDITION OF WATER TO CLAYS. 

Clays coming from the pit very rarely contain enough 
water to be worked as they are, especially in summer ; it is 
necessary to moisten them. This operation is called soaking 
or moistening according as the clay is rich or thin. 

Moistening. Moistening differs from soaking in this : thin 
clays absorbing water much more easily than rich ones, do not 
require to be placed under the water ; it is sufficient to sprinkle 
them when they come from the pit, and leave them to absorb 
the moisture uniformly, or to accelerate the equal partition of 
it by mechanical means. Moistening is also suitable for 
powdered earths which have to be damped in order to be trans- 
formed into ceramic products. 

The moistening of clays requires much attention, for on it 
depends their satisfactory manufacture. The amount of moisture 
which a clay should contain depends upon its nature ; never- 
theless, we must not forget that, in the mechanical part of manu- 
facture, if the clay is too damp the products lose shape and cannot 
be handled ; if, on the other hand, the clay is not sufficiently 
damped, the products do not hold together, and fall to pieces. 
We must then choose a suitable intermediate state so as to get 



PREPARATION OF CLAYS. 63 

a fairly firm paste resisting manipulation and at the same 
time giving the maximum production, for the power used in 
working increases with the hardness of the clay. There is 
then a happy mean to be found, which only experience can 
indicate. 

The uniformity of damping has of course no less importance 
than its amount ; if there are in the clay some parts softer than 
others, the products will be defective. 

To attain good results, the clay coming from the pit is 
spread, after being reduced to small fragments by some process 
or other, in a thin layer, then damped more or less according 
to the natural moisture it contains, which varies with the season 
and weather. Another layer will then be spread over the first, 
and if clays of different nature are used, they will be placed 
alternately, each layer being sprinkled in turn. The clays will 
now be left for at least twenty-four hours to become uniformly 
damped. A longer period will not be injurious if the surface is 
prevented by a covering from getting dry. 

In order to work it, the heap will be cut vertically, so as to 
make a first mixture of the different layers. The clay will be 
placed in a pug-mill, either with a shovel, if the heap is 
near the machine, or by an endless band if it is far off, or 
by any other means. The clay may be laid in ditches, instead 
of on the earth. 

Moistening Machines. The uniform moistening of the clay 
is effected by means of special machines, the object of which is to 
cause a complete mixture of the clay with water. These machines 
are especially useful in the case of powdered earths, but they can 
also be used for clay from the pit. They consist principally of a 
cast-iron or sheet-iron trough, in which is a shaft furnished with 
curved pallets or mixing blades according to the clay to be 
worked, and moved by a belt-wheel. 

Above the trough is placed a pipe pierced with holes through 
which the water falls on to the clay while it is being stirred by the 
knives (Fig. 44). 

These knives, something like screw - propellers, cause a 
motion of translation which carries the clay from the front of 



6 4 



POTTERY IN ARCHITECTURE. 



the machine, where it is introduced, to the back while mixing 
it closely with the water. 

The discharge is effected either direct on to the ground 
(Fig. 45) or through an aperture in the lower part of the trough 




Fig. 44. Moistening Machine (Whittaker). 

(Fig. 44) or in the vertical wall. The clay, thus uniformly moist- 
ened, is afterwards transferred to other machines for working. 

The belt-wheel of the machine is either placed in a separate 
frame, as in Figs. 45 and 46, or fixed directly on to that of the 
machine, as in Fig. 47. 




^ig- 45- Moistening Machine (Groke). 

The transmission of motion is effected by conical and 
cylindrical gear-wheels. 

Instead of a single shaft there may be two turning in opposite 
directions. A machine of this kind is shown in Fig. 48. 



PREPARATION OF CLAYS. 




Fig. 46. Moistening Machine (Jager). 




Fig. 47. Moistening Machine (W. Johnson). 







Fig. 48. Moistening Machine (Boulet). 



66 



POTTERY IN ARCHITECTURE. 



When the machines are constructed to moisten powdered 
substances, the useless knives are replaced by curved pallets 
which stir the powder better and facilitate the incorporation of 
the water. 

Moistening and Crushing Machines Combined. When the clays 
have to be crushed before damping, instead of having two 
machines they are combined in one. All that is required is to 
arrange the framework of the moistening machine to receive 
crushing cylinders as we see in Fig. 49. 




Fig. 49. Moistening Machine with Supports to receive Cylinders (Jacobi). 

The cylinders may be conical or cylindrical, and two or four 
in number, as required. The machine represented in Fig. 50 
has a pair of spiked crushers and another pair of conical rollers. 

The machine in Fig. 51, called damping trough, is also 
provided with flatting friction cylinders to which is attached an 
automatic distributing tray. 

In the trough are arranged two horizontal shafts furnished 
with screws crossing one another in their motion. The water 
is thrown on the clay by means of percolators. 

Soaking. Rich clays are damped with difficulty. Simple 
moistening as used for thin clays is not sufficient to damp them 
enough for working ; a long stay in water is required in ditches 
as water-tight as possible. 



PREPARATION OF CLAYS. 



6 7 



This process, called soaking, is carried out after cutting 
or crushing, but before blending with shortening substances. 
Generally the ditches are situated below the cutting or crushing 
machines ; when they are at some distance the clay must be 
carried to them by means of inclined planes or endless bands. 




Fig. 50. Moistening Machine fitted with Crushing Cylinders (Ja'ger). 

The size of the ditches depends upon the importance of 
the factory and the manner in which it is arranged. 

In some cases, their capacity is as much as 20 or 30 cubic 
metres ; the depth of the clay in the ditches is as much as I to 2 J 
metres, not more. As twenty-four hours are required for uniform 




Fig. 51. Moistening Machine (Damp Trough) fitted with Rolling 
Cylinders (Lobin). 

and complete soaking, it is arranged that the total volume of the 
ditches should represent double the daily consumption of clay. 
To avoid waste of time the ditches are sometimes made with 
removable ends, so that, if one end is removed, it is only necessary 
to cut the mass, and put the clay into the pug-mill close by, 



68 POTTERY IN ARCHITECTURE. 

mixing it with antiplastics which are also placed near at hand. 
This being so, only just enough water should be added to give 
the paste a sufficient consistency without making it too soft. 
When the local conditions and the nature of the clay are 
favourable, this is undoubtedly an economical arrangement. 

In other manufactories the clay is submerged for twelve or 
twenty-four hours, and then the water is drawn off; the clay 
is then taken from the ditches and placed on slightly sloping 
ground in thin layers between which is put the necessary 
quantity of thinning matter. When the heap reaches a certain 
height, it is drained until it reaches the required degree of 
dampness, then it is cut in vertical slices and put either into 
the pug-mill or straight into the hopper of a machine. Finally, 
in other factories the clay, or clays if there are mixtures, and 
the thinning substances are put together for damping. 

Soaking is equally important for rich clays as for thin ones, 
therefore it must be watched with great care ; on it depends 
successful manufacture. 



SHORTENING. 

Rich clays cannot be used alone on account of their eminently 
plastic properties. They stick too much to the moulds or 
cylinders of machines, and the paste they form with water falls 
in and loses shape after working. Its very tenacity prevents 
equal drying in all parts of the mass, hence cracks are formed 
going from the drier surface to the damper interior. If the 
pieces have parts of different dimensions, the less thick parts 
dry more quickly than the thinner ones, causing deformations. 
Firing increases these faults still more. 

The only way to avoid these accidents is to mix closely with 
the rich clays, substances which will thin them sufficiently to be 
easily worked, uniformly dried, and satisfactorily baked. These 
substances are called antiplastics, shortening, or thinning materials. 

Antiplastics. Their function is to diminish the plasticity of 
rich clays. When mixed closely with the latter, they form 
within the mass a kind of skeleton which has two uses : to 



PREPARATION OF CLAYS. 69 

support the plastic paste and prevent it from losing shape, and 
afterwards to assist drying by acting as a system of drainage. 
Thus unequal drying and warping are avoided, for the anti- 
plastic skeleton is so identified with the clay that it follows its 
contraction and maintains the regular shape of the piece. 

Natural Antiplastics. First of these substances is sand, 
which is an excellent shortening matter. According to its nature 
it will communicate special properties to the paste : if it is 
silicious (quartz) it will diminish the fusibility of fusible clays ; it 
will, on the contrary, increase it if of a felspar, iron, or limestone 
nature. If the sand contains large grains, it will be passed 
through a sieve, and if necessary crushed. 

The pulverisation of sandstone gives a sand which may 
advantageously be substituted for ordinary sand, but which is 
naturally dearer on account of the cost of pulverisation. 

Carbonate of lime and chalk may be used as shorteners, but 
with great care. In fact, if in firing, the lime formed by de- 
composition of the limestone does not combine entirely with 
the silicate of alumina, and in order to attain that object a 
temperature is required not usually reached in firing, it will be 
found scattered about in the mass, and by its abundance will 
make the products fall into powder. In faience pastes it is used 
for reasons which we explain on p. 2 I . 

The clay marls, and in general thin clays, are all indicated 
for shortening potter's clays ; the reverse is equally true, and 
the addition of a certain amount of rich clay to a thin one 
assists the working of it noticeably. A marl clay should not 
contain more than 10 to 20 per cent, of limestone to be used 
direct, but if used as an antiplastic, this proportion may rise to 
30 per cent., as long as it does not exceed equal parts in the 
mixture. 

Cinders, Coke Dust. These substances have a double use ; 
like sand they are excellent antiplastics, but they have this 
additional advantage, that they burn in firing in the heart of 
the mass, thus spreading the heat evenly, and economising fuel. 

They are most commonly used in the manufacture of bricks 
and pottery ; the products obtained are less dense in consequence 



7O POTTERY IN ARCHITECTURE. 

of the numerous hollows contained in them ; but if well baked 
they are not porous, ring well, and have excellent qualities which 
cause them often to be preferred to other better-looking pieces. 

Too large cinders are taken out by the sieve. The coke dust 
has the same properties as cinders and is used for the same 
purpose. 

Cements. These are formed from the pulverisation of frag- 
ments of bricks, tiles, and pottery, and possess antiplastic properties 
similar to those of sand. They would be too expensive for use 
with ordinary products on account of the cost of pulverisation, 
but they are commonly used in working refractory substances 
and other ceramic products of fairly high price. Naturally 
fragments are also used of out-of-date or defective pieces such 
as bricks, crucibles, glassware, retorts, saggers, etc. 

Antiplastics of vegetable origin such as sawdust, husks, and 
straw can only be employed occasionally on account of their 
high price in our countries. As they disappear in firing and 
leave large hollows, they are used for objects which require great 
porosity, like water-coolers, or those intended to resist sudden 
changes of temperature, like enameller's plates. 

Artificial Antiplastics. Slags, dross, scoria. When pulverised 
these substances form excellent shorteners ; they are, however, 
less economical than cinders in spite of their lower cost, because 
their pulverisation is difficult, and they have little or no calorific 
power. The machines used to pulverise these substances for 
use as shorteners vary according to their hardness. For some, 
like sand and cinders, crushing mills such as we have described 
suffice ; but for hard and large bodies like fragments of pottery, 
Carr machines are necessary. 

BLENDING OR PUGGING. 

This is one of the most important processes in the manufac- 
ture of pottery ; its object is to change the clay or mixture of 
clays and antiplastics into a homogeneous paste without break 
in continuity. Pugging is done by hand or machines ; the former 
is peculiar to brick-making by the Flemish method. Besides 



PREPARATION OF CLAYS. 71 

the ease of working given to clays by pugging, it gives the 
products a remarkable resistance. 

An experiment made by Colonel Gallon of the Engineers 
shows the influence of this process on resistance. 

A brick made with clay once pugged, and another made 
with the same kind of clay twice pugged, after having been fired 
under similar conditions were broken under weights of 34 kilos 
and 64 kilos respectively, applied at the ends, the bricks being 
placed up on edge and supported in the middle. 

Hand-pugging. Pugging was formerly effected by treading, 
workmen called treaders trampling on the clay with a sufficient 
quantity of water in tanks. This primitive process has now 
been abandoned, except perhaps in the manufacture of certain 
porcelains. 

In the very numerous brickworks where hand-power is used, 
this is how the pugging is done. 

A hoe and a flat wooden shovel (Figs. 52, 53, 54) are the 



Fig. 52- 




Fig. 52. End view of Hoe. Fig. 53. Side view of Hoe. 

Fig. 54. Wooden Shovel. 

tools used. The latter is slightly concave, and is about 40 
centimetres high by 25 broad; it is made of a single piece of 
wood. The workman attacks the heap of clay with the hoe ; he 
brings down and spreads evenly on the ground a certain amount, 
then sprinkles it with water, and generally scatters cinders over 
it. Afterwards he lets fall on this layer another which he waters 
and covers with cinders like the first. He thus prepares two or 
three cubic metres to a thickness of 40 or 50 centimetres. This 
heap is cut for the first time with the hoe, the workman pulling 
the clay towards him so as to disturb it, and more water is 



72 POTTERY IN ARCHITECTURE. 

sprinkled on it. The second time the workman beats it with the 
heel of the hoe ; when this beating is completed the shovel comes 
into use. The workman cuts the heap from top to bottom and 
throws his shovelful violently to the side to form a new heap. 
From time to time he dips his shovel in a bucket of water to 
prevent the clay from sticking to it. This shovelling is followed 
by another beating ; and when these processes have been repeated 
several times the pugging is complete. The workman arranges 
his heap in the form of a large round slab, which he smooths over 
with a well-damped shovel to prevent the surface from getting 
dry. 

Pugging is better performed by two men ; one of them brings 
the water and the cinders while the other beats the clay and cuts 
it with the hoe. Afterwards one of them throws it with the 
shovel under the hoe of the beater. If the pugged clay is not 
used at once it is kept from the sun by straw matting. 

This mode of preparing the clay is, as we can see, long and 
troublesome, and it has been rendered easier by the use of 
pugging machines, which are the same as those we shall describe 
under the head of mechanical pugging, except that they are 
worked by hand or horse power. 

Mechanical Pugging. This is done with special machines 
called pug-mills, but mills similar to crushing mills and cylinders 
are also used. Each of these machines produces a special kind 
f P u gg m g> and one cannot be replaced by another because their 
effects are different. For clearness' sake we shall subdivide the 
three classes of pug-mills according to their construction, as 
follows : 

I. Grindstone pug-mills. 
II. Pug- mills ^vith knives. 

(A. With gearing above $ " Worked b >' animal power. 
' ^rtical U. Worked by steam power. 

\B. With gearing below. 
2. Horizontal. 

III. Pug-mills with cylinders. 

(A. Vertical. 

IV. Pug-mills with crushing cylinders *,fi. Horizontal. 

I C. With two cylinders. 



PREPARATION OF CLAYS. 73 



I. Grindstone Pug-mills. 

Generally speaking, these resemble grinding mills, except 
that the pans are not perforated, and that there is no central 
sieve. This kind of pugging is, we believe, not very extensively 
practised. The special arrangement in Fig. 40 shows the 
application of fluted cylinders to this kind of machine. 

II. Pugging with Knives. 

i. Vertical. A. WORKED FROM ABOVE. a. Moved by 
animal power. As their effect does not differ from that of 
those worked by steam, we will postpone a description of the 
inner mechanism till we refer to the latter. The only difference 
consists in the way in which the shaft is rotated. On the beam 
is fixed a pole 3 to 4 metres long (Fig. 55), having two vertical 
shafts at the end. 

It is better to substitute for these shafts a semicircular piece of 
iron movable about an axis passing through the pole ; in this 
way the motion is more free, and the horse feels shocks less 
(Fig. 56). 

The pans of these pug-mills are of sheet-iron (Fig. 55) or of 
cast-iron (Fig. 56). 

Double-pan pug-mills (Fig. 57) are also made, each pan 
being furnished with a knife-shaft. Their advantage is that they 
pug rapidly and well, and thus give a large output. 

b. Worked by steam. Like the foregoing, these are essentially 
formed of a sheet or cast iron pan, in the centre of which moves 
a shaft fitted with screw-shaped blades to cut the clay (Fig. 58). 
Upon these blades are fixed steel knives so arranged as to cut 
the clay again in a direction perpendicular to the first. At the 
bottom there is a strong blade of 10 or 15 centimetres in height, 
and shaped like a reclining CO, the use of which is to facilitate the 
expulsion of the clay through the orifice in the side of the pan. 

The shaft is rotated in such a direction that the blades make 
the clay descend by pushing it in front of them. 



74 



POTTERY IN ARCHITECTURE. 




- 55- Pug-mill worked by a Horse (Boulel). 




Fig. 56. Pug-mill worked by 
a Horse (Whitehead). 



PREPARATION OF CLAYS. 



75 



The blades are arranged so as to form a kind of endless 
screw, hence the clay driven downwards by one blade is taken on 
by the second before the effect of the first ceases, and its motion 
is thus continuous. When it reaches the bottom of the machine 
the CO-shaped blade expels it by the orifice made for that purpose. 

This orifice is provided with a door, the opening of which is 




Fig. 57- Pug-mill with two Pans worked by a Horse (Joly). 

regulated at will. Another much larger opening is used for 
cleaning the interior of the machine ; it also is closed with a 
door. 

Sometimes the orifice of issue is placed in the cleaning-door 
itself, sometimes it is on the opposite side (Fig. 60) or 
underneath (Fig. 61). 



POTTERY IN ARCHITECTURE. 





Eig. 58. Vertical Sheet- iron Pug-mill 
worked from above (Joly). 



Eig. 60. Vertical Cast-iron Pug-mill 
worked from above (Joly). 




Eig. 6 1. Vertical Sheet-iron Pug-mill worked from above (Boulet). 



PREPARATION OF CLAYS. 77 

The arrangement of the pug-mills in Fig. 62 is intended 
to facilitate the introduction of the clay by diminishing the 
height. 

To make the machines lighter the pans are made of sheet- 
iron instead of cast-iron. But it must not be forgotten that, if 
we are working with hard paste, the wear is much more rapid in 
the case of sheet-iron in consequence of its thinness. 




Fig. 62. Veitical Cast-iron Pug-mill worked from above (Sachsenberg). 

The prism of earth expelled from the pug-mill, if it is not 
immediately cut (Fig. 57), or absorbed by another machine, is 
driven forward by the clay behind it ; but as its weight causes 
friction on the horizontal surface, there comes a moment when 
this friction and the pushing of the clay cause equilibrium, the 
prism advances no further, and the supply from the pug-mill is 
stopped. This inconvenience must then be prevented by cutting 
the prism as soon as it attains a certain length. The mode in 



78 POTTERY IN ARCHITECTURE. 

which the shaft of the blender is moved varies with the 
manufacturer ; an examination of the figures will show these 
differences. 

/>. VERTICAL PUG-MILLS WORKED FROM BELOW. In certain 
installations it is sometimes advantageous to use pug-mills worked 
from beneath. The upper orifice is thus quite free, which facilitates 
feeding, especially when this orifice can be so placed that the 
moistened clay can be poured direct into it 

The arrangement of these machines varies with the maker 




Eig. 63. Vertical Cast-iron Pug-mill worked from below (Jager). 

(see Figs. 63, 64, 65). The pug-mill in Fig. 63, however, 
having its upper orifice completely free, seems to exemplify most 
thoroughly the advantage of this type of machine, that is to say, 
ease of feeding. 

The Boulet pug-mill (Fig. 65) is specially reserved for the 
mixing of hard clay, which, owing to the work entailed, requires 
strong and well-constructed apparatus. 

Horizontal Pug-mills. These are made in different ways, 
and are used advantageously for clays difficult to mix. The 



PREPARATION OF CLAYS. 



79 



height of vertical pug-mills cannot exceed a certain limit, while 
the great length possible with horizontal machines facilitates the 





Fig. 64. Vertical Cast-iron Pug-mill 
worked from below (Joly). 



Fig. 65. Vertical Cast-iron Pug-mill 
worked from below (Boulet). 





Fig. 66. Horizontal Pug-mill 
(Jager). 



Fig. 67. Horizontal Pug-mill with attached Gear 
(Jager). 



incorporation of one clay with another. The introduction of the 
clay takes place above and the expulsion below (Fig. 66), or on 
one side (Fig. 67). The gearing is either fixed to the pug-mill 
or separated from it. 



8o 



POTTERY IN ARCHITECTURE. 



The issue of the clay is regulated as in the vertical machines 
by a movable door by which the opening may be varied at will ; 
it is held in position by a rod fixed to it (Fig. 68). 




Fig. 68. Horizontal Pug-mill with attached Gear (Sachsenberg). 



III. Pug-mills witJi {Flatting} Cylinders. 

We have seen that cylinders are used for crushing 
the hard bodies contained in clays. For this purpose the 
cylinders, which are of equal diameter, are fairly distant from 
one another, and turn with the same velocity. But if different 
speeds are given to them, or if, while making the same number 
of turns, their diameters are unequal, the velocities at the cir- 
cumference will be different and a tearing of the clay will ensue 
which will effect a mixture. Care is taken to leave between 
the rollers some clay to the thickness of a few millimetres by 
placing scrapers to remove the excess. This layer of clay sticks 
to that contained in the hopper and draws it between the 
cylinders, where it is united by pressure at the same time as 
it is being drawn out by the differential speed; this causes a 
special pugging different in its effects from that produced by 
the ordinary pug-mills. 



PREPARATION OF CLAYS. 



8l 



Several arrangements are utilised to arrive at the desired 
result. 

1. Use of cylinders with equal diameters and unequal speed, 
or equal speed and unequal diameters. 

2. Use of cones. 

3. Use of fluted cylinders. 

4. Use of perforated cylinders. 

Cylindrical Roller Pug-mills. -- These machines, which are 
not very complicated, consist of two solid cast - iron supports 
fixed upon wooden joists or a block of masonry. Between 




Fig. 69. -Pug-mill with Rolling Cylinders (Jacobi). 



these supports are placed two cast - iron rollers, one of which 
receives the motion direct and transmits it to the second by 
means of a differential gearing (Fig. 69). Over the two rollers 
is placed a hopper into which the clay is put. 

At a certain distance (which can be regulated at will) from 
each roller is a steel blade acting as a scraper. Above the 
rollers is the hopper, as can be seen in Fig. 70. 

Cone-roller Pug-mills. These differ from the foregoing only 

in the conical form of the crushers and their arrangement. The 

smaller diameter of the one being placed in front of the larger 

diameter of the other, an unequal speed at the circumferences 

6 



82 



POTTERY IN ARCHITECTURE. 



is caused for the same number of turns ; hence blending occurs 
(Fig. 71). 

The use of cones would be more advantageous, from the 







Fig. 70. Pug-mill with Rolling Cylinders ((iroke). 



point of view of output, than that of cylinders of the same 
diameter. To regulate the speed a flywheel is attached to the 
gear-shaft (Fig. 71). 




Eig. 71. Pug-mill with Rolling Cones (Jager). 

Rolling Machines with Fluted Cylinders or Cones. The 
blending of the clays is increased by the use of fluted rollers ; 
the projections of one roller enter the depressions of the other. 
The shape of these flirtings is, however, variable (see Figs. 72 



PREPARATION OK CLAYS. 




Fig. 72. Rolling Machine with Fluted Cylinders (Groke). 




Fig- 73- Rolling Machine with Fluted Cones (Boulet). 



84 POTTERY IN ARCHITECTURE. 

and 73). The speed of the rollers being the same, there is a 
difference of speed between the surface of a hollow and the 
surface of a projection which produces a tearing apart of the 
clay simultaneously with the flattening. 

By using fluted cones this effect is increased. Thus it 
is that with the Boulet machines (Fig. 73) a single passage 
through it turns a mixture of differently coloured clays into 
a paste of uniform colour. 

The flutings get filled with clay during the operation, but 
scraping combs, placed above, constantly clean them. 

Rollers with Perforated Cylinders. -- These machines are 
specially constructed for blending hard clays. They were 
invented by M. Dumont, and are now built by M. Lacroix. 
They consist of strong cylinders pierced with holes which are 
very close together and have a diameter of from 1 2 to 13 




Fig. 74- Dumonl Perforated Cylinders (Lacroix). 

millimetres (Fig. 74). The two cylinders touch one another, 
and the one receiving motion transmits it to the other by 
contact. 

After the clay has been passed between ordinary cylinders, 
it is thrown by means of the hopper between the perforated 
cylinders, and as they press one against the other it is forced 
to pass through the holes when drawn down by the rotation. 



PREPARATION OF CLAYS. 85 

Thus it penetrates into the interior of the cylinders in the form 
of endless curls, splitting up into small pieces which roll round 
one another before reaching the ground. This process develops 
the plastic qualities of the clay. 



IV. P ttg-mills with Crushing Cylinders. 

A. VERTICAL PUG-MILLS. When the clays contain small 
impurities such as limestone, lumps of hard clay, etc., it is 
important that they should be mixed to avoid accidents in 




Fi g- 75- Vertical Pug-mill with Crushing Cylinders (Pinette). 

baking. As pugging would be insufficient to remove them, 
the pug-mill is fitted with a pair of cylinders whose function 
is to crush these bodies. Fig. 75 shows a machine of this kind. 

The cylinders and the pug-mill are worked separately ; the 
latter is moved from below, and does not differ from an ordinary 
pug-mill. The clay having been introduced by the hopper 
above, is crushed by the cylinders and falls into the pug-mill, 
whence it issues by the lower door. 

B. HORIZONTAL PUG-MILLS. The two crushers are placed 
over the entrance to the pug-mill ; they may be cylindrical 



86 



POTTERY IX ARCHITECTURE. 



(Fig. 76) or conical (Tig. 77), and are driven from the belt- 
wheel of the pug-mill by means of intermediary cog-wheels, or 
are worked separately (Fig. 77). 




Fig. 76. Horizontal Pug-mill \\illi 
Crushing Cylinders (Whitehead). 



'''to- 77- Horizontal Pug-mill with 
Crushing Cones (Jager). 



C. Doui'.LE CYLINDERS. - - These are placed one over the 
other, the use of the first pair being especially to crush and 




Eig. 78. Cone Rolling Machine with Dividing Apparatus above (Jager). 



divide the masses of clay, to break up the little hard bodies, 
and thus to facilitate rolling by the second pair of cylinders. 
When it is required to split up the clay, the rolling machine 



I'KKI'ARATION OF CLAYS. 




Fig. 79. Rolling Machine with Crushing Cylinders above (Jager). 




Fig. 80. Rolling Machine with Fluted Cones above (Boulet). 



88 



POTTERY IN ARCHITECTURE. 




. Rollin Machine with Joined Cones above (Groke). 




Fig. 82. Perforated Cylinders with Crushing Cylinders above (Lacroix). 



TRKPAKATION OF CLAYS. 89 

is surmounted by a special apparatus consisting of curved 
blades fixed to two shafts turned in opposite directions. These 
blades pass through the intervals of a kind of comb fixed to 
the sides of the machine. The clay, having been thrown from 
above on to a doubly inclined plate, spreads between the blade 
and the comb, and being drawn down by the rotation, is split 
up while passing through the hollows and falls between the cones 
of the roller (Fig. 78). 

If the clays contain large lumps, crushing cylinders with 
points (Fig. 79) are used. 

The double roller represented in Fig. 80 has a pair of fluted 
cones and a pair of cylinders. 

The position of these may be inverted, as in the double 
roller of Fig. 81, which comprises a pair of cones and another 
pair of cylinders. 

Finally, above the Dumont granulating cylinders are placed 
crushing cylinders to break up the hard lumps in the clay 
(Fig. 82). 



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CHAPTER III. 

BRICKS. 

IN i of this chapter we shall study the different phases 
of the manufacture of bricks : moulding, drying, and firing ; 
2 will be reserved for the examination of the shapes, 
dimensions, and decoration of bricks ; and in 3 we shall 
point out their uses and their applications as well as their 
history. 

I. MANUFACTURE. 

(i) Moulding. - - From the most distant antiquity this 
moulding has been performed by hand by methods which 
probably differ very little from that which is called Flemish or 
Walloon. The simplicity of this process, the few tools required, 
its small cost, the absence of large expenses of installation, and 
the great output which it allows, were calculated to cause it 
to be considered as the only one possible. And in fact it is 
admirably suited for the manufacture of bricks which are 
intended for large buildings distant from centres of production 
but near beds of clay. The work is carried on on the spot. 
Small brickworks, and even large ones, have employed and 
still employ this process to a great extent, but it is no longer 
the only one. Nearly a hundred years have passed since 
those hand machines appeared which produced bricks by 
pressing the clay in moulds when it came from the pit. In 
this way the extraction of clay for weathering was avoided, 
and a considerable economy effected. No doubt the bricks 
so made are not .as good as those made by hand, but for what 
are called native bricks the difference was not very noticeable. 

94 



BRICKS. 95 

Another valuable advantage was that the work and the presses 
were no longer so much subjected to the inclemencies of the 
summer. We know in fact that everything in the Walloon 
method is done in the open air, and thus a rainy summer 
causes frequent stoppage of work and consequent loss. We 
have no precise documents as to the invention of machines 
for making bricks by expression, and we do not know who 
recommended the use of die machines, but we may say that 
these discoveries date from the beginning of the century. 
For a long time the use of machines was very little extended ; 
but the invention and the increasing use of hollow products and 
mechanical tiles, the manufacture of which requires machines, 
have considerably augmented the number of factories using 
machinery. This extension has been encouraged by the con- 
stantly increasing consumption of bricks, and the facility of 
transit which allows the distribution of the goods even outside 
the sphere of action of the factory. 

Finally, the requirements of customers, who have gradually 
become used to fine machine-made productions and will have 
no others, have something to do with the fact that in large 
towns and in factory buildings hand-made bricks are no longer 
to be seen. 

But in a great number of local works the primitive method, 
especially for the so - called native bricks, is the only one 
employed on account of its simplicity. 

There are then two quite distinct processes of brick manu- 
facture 

i . The process by hand carried out in the open air ; 
2. the process by machinery carried out in the open air 
or in factories. 

The latter, as we shall see later on, is subdivided under 
several headings according to the way in which the machines 
work, and according as they are driven by hand, by animal 
power, or by steam. 

Hand-moulding. The installation of a manufacture of this 
kind requires plenty of room, for the bricks, which are laid singly 
on the ground, must have the time to harden before being put 



POTTERY IN ARCHITECTURE. 



into hacks. The first thing to be done is to choose a situation. 
A piece of ground is chosen, near the heap of clay which has 
already been weathered, and on a slope, in order that the rain- 
water may run off easily. This water, collected in a pool, may 
be used to moisten the clay. The ground is afterwards scraped 
with a shovel to remove inequalities, and is then smoothed by 
means of a scraper (Fig. 84$), a tool composed of a board of 
about 0.50 metres long, and o.io to 0.15 metres broad, furnished 
with a handle placed at right angles to the board. 

Tools. We have mentioned those used in preparing the clay ; 
for moulding there are required: a special square table, a sand- 
box, also called a " minette," two double moulds, a " plane " or 
strike, a bucket or tub, and finally some wheelbarrows for trans- 
porting the clay from the heap to the moulding-table, and the 
bricks from the ground to the hack. 

Fig. 83. 




r 



m 



Eig. 84. 



Eig. 84^. 



Fig. 85. 



Fig- 83. Sand-box. Eig. 84. Moulding-table. Eig. 840. Double Mould. 

Eig. 84/7. Scraper. Fig. 85. Bricks laid on the Ground. 

The moulding-table (Fig. 84) has four legs and is about 0.80 
metres high, and has about one square metre of surface. At one 
corner a part of the board has been cut off, of slightly larger 
dimensions than the mould laid flat. This portion is covered 
with a plate of thin iron to prevent wearing away, for it is here 
that the moulding is done. 



BRICKS. 97 

This protected piece of wood is fixed to the upright of the 
table by means of two hinges on which it turns ; and in order 
that it may lie flat in its normal position, a chain is fixed to it, 
with a mass as counterpoise generally a stone. 

The sand-box or " minette " (Fig. 83) is a square wooden 
tray placed at the same height as the table, and about 0.20 
metres deep. It is filled with fine and very dry sand, or, more 
economically still, with crushed and sifted terra-cotta. 

The mould (Fig. 840) is double and made of beech-wood of 
the best quality of about I centimetre thick ; it is covered at the 
edges with plates of sheet-iron to prevent wear. Sometimes it is 
furnished with a bottom, to make one of the faces of the brick 
smoother. 

The use of the single mould is a waste of time, as the moulder 
can easily take at one time the quantity of clay required for two 
bricks. The dimensions of the moulds must be calculated accord- 
ing to the amount of contraction which the clay will undergo in 
drying and firing. 

If the brick is to be stamped, the mould must be higher than 
for an ordinary brick. Contraction is generally estimated at 
from 5 to 10 per cent. that is to say, in order to have a brick 
0.22 x 0.105 x 0.05 after firing, a mould of about 0.23 x o.i i 5 X 
0.052 must be used, contraction acting principally on the breadth 
of the brick on account of its position in firing. But the 
contraction of clays is very variable, and experience alone can 
guide us. 

The " plane " or strike (Fig. 84) is a plain oak board, well 
finished, and having one end shaped as a handle. Sometimes a 
steel blade is used. 

Moulding. This kind of work is mainly done by people of 
Picardy and Flanders. They go in gangs during the summer to 
the place of manufacture, and return home in the autumn. 
There are also some moulders of settled habitation. The number 
of workmen forming a " brick-table " is variable. For regular 
and constant work four are required : a moulder, a separator, a 
barrow-man, and a mould-carrier. But it happens sometimes, if 
the moulder is an active worker, that the barrow-man cannot keep 
7 



98 POTTERY IN ARCHITECTURE. 

up the supply of clay and at the same time stack the bricks. In 
this case a fifth man is required ; as his work, however, is irregular, 
many gangs prefer to manage with four, and when the stacking 
of the bricks is in arrears, the moulding is stopped, and all assist 
in carrying the bricks to the stack. 

The moulding is done in this way : the moulder takes with 
both hands a sufficient quantity from the heap of clay which the 
barrow-man has placed at his feet, rolls it into a ball, and raising 
it over his head throws it with force into the mould ; he then 
completes the forming of the mass by a vigorous kneading, which 
he begins at the side farthest from him. Afterwards he takes 
his strike, which is lying in a bucket of water on the table, and 
holding it in both hands passes one of its angles along the edges 
of the mould, afterwards taking off the excess of clay, which he 
throws with one hand back on to the heap while with the other 
he replaces the strike in the bucket. 

The mould-carrier then seizes the mould by its two ends, and, 
resting lightly upon it, he swings over the movable board so as to 
turn the bricks up on edge, and carries them away, resting them 
slightly against his body. When he arrives at the ground where 
they are to be laid, he proceeds to demould them by placing the 
mould on the ground, still up on edge, quickly inclining it, and 
then laying it flat ; then, by a slight jerk, he removes the mould 
cleanly. 

In this way the brick is laid on the ground without loss of 
shape ; some practice is required for doing this well, but the boys 
soon learn the knack. The workman then goes to the sand-box 
which stands near the table, plunges the mould into the sand, and 
returns for another, which the moulder has filled during his 
absence. When the mould is taken from the table, the moulder 
throws a little sand on the iron plate, takes the mould from the 
sand-box, and places it upon the plate (a stop prevents it from 
going too far), and proceeds as before. From time to time the 
moulds are cleaned with a wooden knife and washed ; the whole 
installation is moved if the rows of bricks come too near the 
table. 

The moulder need not move during his work ; everything is 



BRICKS. 99 

within reach of his hand. A good mould-carrier can nearly 
always keep up with the moulder, but he must be active and per- 
form all his work promptly. 

The bricks are left lying until they have become sufficiently 
firm to be handled without loss of shape ; this is tested by press- 
ing upon them with the finger, which should leave no mark. 
Naturally this period is variable according to the weather, and 
may be from twelve to forty-eight hours. When once the proper 
firmness is acquired, the bricks are edged off by removing the 
seams with a wooden knife, and they are placed on edge without 
being moved from the ground by turning them on one corner. 
They are then put on barrows and wheeled to the place where 
they are to be stacked. 

If rain threatens, care must be taken not to leave the bricks 
up on edge, for in that position rain deforms them more easily 
than when they are laid flat. 

Production and Net Cost. The production depends upon the 
skill and strength of the moulder. When he can make 500 to 
600 bricks per hour without trouble he may be considered to be 
a good workman. 

Hand moulding is paid by the piece, and the price varies with 
the country. In the North of France and in Belgium the pay is 
from 2 fr. to 2 fr. 50; in the neighbourhood of Rouen and Paris, 
it averages 4 to 5 fr. per 1000. It rose to 6 fr. during the 
great boom which preceded the crisis in the building trade in 
1882. 

This pay includes the preparation of the clay (but not its 
extraction), the moulding of the bricks, the shaving of the seams, 
and stacking, and also superintendence up to the time when the 
bricks are taken away for firing. 

The sand is prepared by the gang but provided by the manu- 
facturer. 

Space Necessary. The space necessary for a " brick-table " 
is rather large. There must be an area of at least 600 square 
metres for laying down the bricks ; besides this there must be 
room for the clay-heap, stacks for drying, kilns, paths, and the 
place where the clay is extracted during the winter. 



IOO POTTERY IN ARCHITECTURE. 

A factory for making bricks by hand must then consist of 
two distinct portions : the space where the moulding, drying, and 
firing are carried on, and the place of extraction. The arrange- 
ment of these spaces depends upon locality and facilities of com- 
munication, but the kiln should be placed as near as possible to 
the exit. 

For the life of the pit, it is calculated that 1.250 cubic metres 
of virgin soil, which give 1.500 to 1.750 cubic metres of 
excavated clay, furnish about 1000 bricks (0.22 x 0.105 
X 0.06). According to the thickness of the bed of clay, it 
will be easy to calculate the surface necessary for the annual 
output. 

It sometimes happens that, in the same works, the upper 
stratum of the clay, called weak clay^ is made into bricks by hand- 
presses, while the lower stratum, called strong clay, which cannot 
be treated in the press, is hand-moulded. In this case the hand- 
moulders begin work when the upper stratum has been taken 
away. 

Hand-moulding- after Mechanical Preparation of the Paste. 

There are some brickworks whose annual production is as 

much as ten millions, and which are worked by hand. This 

large quantity of bricks requires a daily consumption of vast 

quantities of material. 

It is advisable, in order to reduce as far as possible the cost, 
to prepare the paste mechanically, and to transport it cheaply to 
the place of manufacture. The plan and section in Fig. 86 
show an installation of this type, furnished with two pug-mills 
similar to those represented in Fig. 63. 

The clay when extracted from the pit is loaded on little 
waggons and taken to the pug-mills by an inclined plane //. 
This inclined plane is easily removed and, with a sufficiently 
long cable, covers a large radius. It may be replaced by an end- 
less belt sloping downwards, on which the clay brought by the 
waggons is thrown. In front of, and at the same height as, the 
issuing orifice of the pug-mills are flat cars which run on rails 
from the mills to the place of moulding. Each car carries 
enough to make from 100 to 150 bricks ; they follow one another 



BRICKS. 



IOI 



without interruption, and are so arranged that the moulding is 
carried out on the platform of the car itself. 

The pug-mills are worked by a stationary engine, and produce 
per hour a sufficient quantity of paste to make 2000 to 2500 
bricks. The net cost, extraction not included, which is the same 
in both cases, is estimated as follows ; it may be remarked, 



BRICK-MAKING INSTALLATION FOR A DAILY PRODUCTION OF FROM 
4O,OOO TO 5O,OOO HAND-MADE BRICKS. 





-HI- -II- -li-li- HI,- 



Fig. 86. Section and Plan. 



however, that the cost of labour, which is put down as 30 to 50 
centimes an hour, is capable of reduction. 

The economy which may be realised amounts to the differ- 
ence between 4 or 5 francs, price for piece-work, and the sum 
mentioned below, that is to say, i or 2 francs per 1000, and 
from 10,000 to 20,000 francs for the 10,000 manufactured 
annually. 



IO2 



POTTERY IN ARCHITECTURE. 



Material A 20 horse-power engine 
2 pug-mills, at 2500 fr. . 

1 windlass and cable . 

8 waggons for transport, at 100 fr. 

30 waggons with platforms, at 60 fr . 

Transmission of power and belting 

500 metres of rail, .50111. gauge, at 3 fr. 20 

2 sets of points ....- 
12 turn-tables, at 40 fr. 

Structure and inclined plane 

Moulds and tools, barrows 

Sundries ..... 

Francs. 

Interest at 4 per cent. . 1000 

Sinking-fund at 10 per cent. 2500 



3500 

3,500 
Per thousand : = ofr.35 

Labour ; etc. 9 moulders, at 5 fr. 
9 boy mould-carriers, at 3 fr. 
4 boys to push waggons, at 3 fr- 
4 men to stack the bricks, at 4 fr. 
4 boys to edge off the bricks, at 3 fr. 
I engine-driver .... 
Coal, 400 kil. at 25 fr. per 1000. 
Oil, repairs, etc. 



Francs. 
II,OOO 

5,OOO 
300 
800 

i : 8oo 
300 

i, 600 
1 80 
480 

2,500 
840 

200 
25,OOO 



45 fr- 
27 

12 

16 

12 

5 

10 

5-50 



132^.50 
That is to say per thousand : - = 2 fr. 65 

The cost of manufacture, with interest and depreciation, conies then to 



132.50 



Francs 
0.35 



2.65 
3.00 



Machine-moulding of Bricks. -The increasing demands of 
trade have caused, in brick-making as in so many other manu- 
factures, the substitution of machine for hand work. 

The invention of the Hoffmann continuous kilns, by perfect- 
ing to such a degree the firing processes, has also been one of 
the causes of the development of machinery in brickworks. 
Economy cannot be a factor favourable to the development of 
machinery, for if, in works having a large output, the cost of 
mechanical manufacture is no larger than that by hand, in works 
of moderate size, where there is a long cessation of work in the 
winter, interest and sinking-fund are factors to be taken into 
consideration. But what has gained the day for machines is 



BRICKS. IO3 

that they allow of the manufacture of articles impossible to make 
by hand. 

Thus in the great centres of consumption, England, Germany, 
America, where millions of bricks are used annually, they are 
nearly all made by machinery. In France also numbers of 
brick and tile works produce by machinery. 

The machines that have been invented for the mechanical 
manufacture of bricks, are as numerous as they are varied ; but 
if we consider how a parallelepiped, regular like a brick, can be 
made out of clay, we must come to the conclusion that two 
processes only can be utilised : the first consists of compressing 
a certain quantity of clay by some means or other in moulds of 
the required shape ; this is the principle of machines working by 
compression. The other process consists of forming out of clay 
suitably prepared a long prism having two of the dimensions of 
the brick, and of cutting it afterwards at regular intervals to get 
the third dimension. It is in this way that machines working by 
expression act. 

In practice these principles may be applied in many different 
ways, hence we have a variety of machines possessing one 
common principle. 

In classifying machines we must note the manner in which 
they carry out one of these principles, and also the degree of 
dampness of the paste used ; it is evident that machines intended 
for treating firm or semi-firm clays are not suited for treating 
hard clays, and vice versa. 

This being so we have the following classification : 

II. On soft clay. 
2. On semi-firm /By gradual pressure, 
or firm clay V By shock. 
3. On dry clay. 

( With semi - firm f ^ P ro P ellin S cylinders. 
II. Machines working ) or fi rm c i ay 1 B Y pug-mill with expelling j Vertical. 

by expression 1 screws \Horizontal. 

I With hard clay. By piston. 



IO4 



POTTERY IN ARCHITECTURE. 



DESCRIPTION OF MACHINES FOR MAKING BRICKS. 

I. Machines Working by Compression.--!. ON SOFT 

CLAY. These machines, which imitate hand work, operate upon 

soft clay previously prepared by a vertical or horizontal pug-mill 
attached to them. The wooden mould, which has six or seven 
compartments, is placed under the press, and when it is full is 
automatically expelled ; a workman smooths the surface of the 
bricks with a scraper and passes the mould to the demoulder ; 




Fig. 87. Horizontal Machine for Soft Paste Fig. 88. Vertical Machine for Soft Paste 
worked by Steam. worked by Horse-gear. 

the latter places the bricks on a board, which is carried to a 
drying ground or room. The empty mould is dipped in water 
and put under the press again. These machines, largely used 
in America, are suitable for thin clays which draw badly. 

With a horse the machine in Fig. 88 (2800 fr.) produces 600 
to 900 bricks per hour; with two horses (2500 fr.) from I2OO 
to 1800 bricks. The machine (Fig. 87) which is worked by 
steam power (6300 fr.) produces from 3000 to 5000 bricks. 

2. ON SEMI-FIRM OR FIRM CLAY. Lever Gradual Pressure 
Mac/lines. The oldest of these, and the one always used in a 



BRICKS. 



105 



large number of works which make bricks of vegetable mould 
(lehm or tableland ooze), is composed (Fig. 89) of a low and very 
thick wooden table, pierced with a square hole at one end. Into 
this hole a copper double mould (Fig. 90) is introduced and 
fastened to the table by bolts which pass through the thickness of 
the table. The bottom of each mould is closed with a T-shaped 
piece of wood (Fig. 91) called chandelle, the top of which is 
covered with a copper plate. The two pieces are moved up and 
down smoothly in the mould by rack-work connected with two 
pinions worked by a winch. This motion is guided by an iron 
rod 'passing through each of the two T-pieces and resting on a 
strong cross-bar which joins the two uprights of the machine. 




Fig. 90. 



Fig. 91. 



jpj$^5$P^^ 



Fig. 89. Lever Press for moulding Vegetable Moulds. 
Fig. 90. Cap and Double Mould. Fig. 91." Chandelle." 

A first lever, movable round an axis, is connected by a chain 
to another lever, which is attached at one end to one foot of the 
table. This chain holds the lever by a collar which slides on an 
iron guide fixed to the lever. A wooden counterpoise called a 
mouton, which is pivoted on an axis, rests on the horizontal lever 
and keeps them both raised. 

The working of this machine is simple and requires two men, 
at the most three. The clay is prepared as we have said. The 
workman who manages the lever takes a shovelful of this clay 
and throws it into the two moulds ; the latter must not only be 
full but must overflow. He puts aside his shovel quickly, and, 
with the aid of his comrade, compresses the clay by striking it 
with his fists ; then with a quick motion he takes the excess off 



IO6 POTTERY IN ARCHITECTURE. 

the moulds, one corner of which he discloses in order that the 
man who takes the cap (Fig. 90) may be able to see the place 
where he is to put it. Meanwhile the other man has placed 
himself at the end of the lever and leans upon it. The pressure 
is transmitted to the clay by the lever called brebis. After 
having given two or three pulls, the moulder quits the lever, 
which is drawn back by the counterpoise called mouton. The 
demoulder takes off the cap and turns the winch ; the bricks 
come out of the mould, and the demoulder takes away the one on 
his side and puts it on a barrow with a platform which contains 
about fifty of them. His comrade puts his on the brebis, whence 
the other takes it to place it on the barrow. Meanwhile the 
moulder has taken a handful of powder from the table and has 
sprinkled the moulds, -the winch, left to itself, having been re- 
turned to its first position by the weight of the movable pieces 
forming the bottom of the moulds, then he throws another 
shovelful of clay into these latter, and the process continues as 
before. 

When a barrow is full the moulder pushes it forward a few 
metres and substitutes an empty one. The other workman has 
meanwhile been bringing as near as possible to the machine the 
clay which has been drawn in advance to replace that used. 
When the second barrow is full, the two moulders expose their 
productions in drying-places, generally open-air ones. Sometimes 
this part of the work is done by a third man who, in the intervals, 
prepares and draws the clay. These three men are able to make 
from 300 to 400 bricks an hour. 

The length of the chain is so adjusted that the end of the 
lever touches the ground when the strongest pressure is used. 
This method of manufacture, simple as it is, requires a certain 
skill to be quickly carried out. Especially is this the case in 
putting on the cap, for it must at first trial be placed just over 
the moulds, and this is difficult owing to the excess of clay on 
the table. If it is put on badly one corner of the plates will strike 
against the mould, and compression cannot take place ; it will 
have to be readjusted, and time will be lost. The moulder, too, 
must have the knack of putting the same quantity of clay in each 



BRICKS. 



107 



shovelful, in order that the bricks may have a uniform thickness. 
The fulling of the clay should be uniformly done, otherwise the 
bricks will be thicker at one end than the other. Bricks made 
in this way require to be fired thoroughly to acquire cohesion, 
and never, even when restamped, have the tenacity or the quality 
of blended bricks. 

The machine above described has been modified in different 
ways. The framework is made of cast-iron (Fig. 92), the cap 




Fig. 92. Lever Press with Cast-iron 
Frame (Boulet). 



- 93- Lever Press with Cast-iron 
Frame (Dupuy). 



is hinged and held by a stirrup ; the pressure instead of acting 
from above acts from below. The adjustment of the cap is 
thus simplified, and can be done by a young man. 

In the Dupuy machine also (Fig. 93) the cap is movable 
about a hinge. The lever by its special position makes the 
operation more rapid, for the workman, instead of having to go 
from the moulds to the end of the lever, has only to turn round, 
and thus output is increased. 

Another improvement is in the demoulding. In ordinary 



IO8 POTTERY IN ARCHITECTURE. 

machines, in order to keep the bottom of the moulds at the level 
of the platform, the workman is obliged to hold with his knee the 
winch which controls the pinions. 

In the Dupuy machine the demoulding is done by the lever 
which, in the figure, the workman is holding in his hand. The 
bottom of the moulds is held by a special catch, and when the 
bricks are taken out the assistant, by means of the little lever at 
his side, releases the catch and the bottom falls into its place 
again. The moulds are of bronze, as also are the plates of the 
cap and bottom. As these latter wear out rather quickly in 
consequence of the friction, a hollow is formed between them and 
the sides of the mould, through which a little clay is forced under 
compression, and this makes seams in the bricks. It would be 
troublesome to be always renewing the plates. Therefore they 
are made of malleable bronze, and every two or three weeks they 
are beaten on an anvil to lengthen and broaden them, then they 
are fixed to the mould by screws or bolts. 

The moulds also get worn ; the only inconvenience of this is 
the progressive increase in the dimensions of the brick ; when it 
becomes too large, the moulds are renewed. 

Price and Output. The wooden machine in Fig. 89 costs from 
350 to 400 francs; the Dupuy machine costs 600 francs and 
weighs 400 kilos that is to say, nearly the same as the other. 
The output, as we have said, is from 300 to 400 bricks per hour ; 
labour is always paid by piece-work, at an average of 4 to 5 
francs per thousand. 

This kind of machine is extensively used in the neighbour- 
hood of Paris, Rouen, Amiens, Saint-Quentin, etc., as well as 
abroad. But it must not be forgotten that all kinds of clay cannot 
be used with them. Weak vegetable moulds only can be treated, 
as the strong clays and potter's clays stick to the moulds and 
cannot be demoulded. 

Machines Working by Shock. To a certain extent the 
stamping presses, which we shall describe in connection with high- 
class bricks (Figs. 158-166), may be used for moulding certain 
raw clays coming from the pit. The clay is prepared as in the 
case of the preceding machines. It should be as fine as possible, 



BRICKS. IO9 

without lumps, and neither too damp nor too dry. The press- 
mould is movable. By means of a handle it is brought forward 
in front of the table, there it is filled, then returned to its former 
position, and with a rapid, violent blow the lever is depressed ; 
the cap falls sharply and compresses the clay. The latter flies 
back and brings the lever forward again. The workman takes 
hold of it and replaces it in its former position. During this 
movement the movable bottom of the mould is taken away and 
the brick comes out. The output hardly reaches 200 to 250 
bricks per hour. 




Fig. 94. Hand Press for moulding Coarse Clay (Chambrette Bellon). 

This inconvenience does not exist in the perfected press 
shown in Fig. 94. The moulds, three in number, are fixed on a 
plate which revolves round one of the uprights of the machine. 
Compression is no longer exerted by the action of the cap only, 
but the lever acts simultaneously on the movable bottom and 
the cap, and so the two faces of the brick are equally pressed. 
The motion of the lever produces at the same time an automatic 
demoulding by means of a cam and jointed lever. The plate is 
kept by gear in its position of compression. 

The working of the machine is simple. While a boy takes 



I IO 



POTTERY IN ARCHITECTURE. 



away the brick which has just come from the mould, another fills 
the empty mould, and a third workman turns the plate and works 
the lever. 

The remarks we have made on these lever presses apply to 
the preceding machines, the use of which can only be interesting 
in certain special cases. 

For complete description of these machines see paragraph on 
Stamping of Bricks (p. 1 6 1 ). 




Fig. 95. Press for making Bricks from Dry Clay (Johnson). 

3. MOULDING POWDERED CLAY. -The machines used in 
this kind of moulding are of American or English construction ; 
they act by strong compression in moulds on dried, pulverised, 
and moistened clay. 

The pressure on each brick exercised by the pistons is as 
much as i 2 5 tons ! Therefore these powerful machines, a model 
of which is represented in Fig. 95, are constructed in a very solid 
manner. They absorb much power, and for a production of 



BRICKS. 



I I I 



2500 to 3000 bricks an hour a 25 horse-power steam-engine is 
required. 

The number of moulds varies from 2 to 6, and the bricks go 
from the machine straight to the kiln. 

In the Whittaker machine (Fig. 96) the pressure is also 
exerted by a piston, but each brick receives two compressions 
successively. 

Fig. 97 represents a section of the machine. The powder 




Fig. 96. Press for making Bricks from Dry Clay (Whittaker). 

arrives from the upper storey by a conduit furnished at its lower 
end with a hose which takes the clay into a mould. The mould 
when full is pushed under a piston, which makes a first compression ; 
then the brick is pushed under the second piston while the first 
mould is filled with clay. The second compression completes 
the brick, which, when demoulded, is placed on an endless band 
by the same motion which brings the clay to be pressed under 
the first piston. 



I 12 



POTTERY IN ARCHITECTURE. 



The bricks thus formed by great pressure require no drying; 
they are taken direct to the kiln. 




Fig. 97- Section of the Parts of the Whittaker Press. 

The mechanism moving the different parts of the machine is 
easily understood by the annexed figures. 




Fig. 98. Press for making Bricks from Dry Clay, with Revolving Plate (Boulet). 

The Boulet machine (Fig. 98) differs from the foregoing in 
the arrangement of the moulds which are placed in pairs on a 



BRICKS. 



I I 



movable table. They are filled by hand ; during the compres- 
sion the table is motionless, then it turns automatically, and the 
pressed bricks are at the same time removed from the moulds. 

Another machine with a turning table is represented by Fig. 
99. A special arrangement in this machine permits of bricks 
with hollows perpendicular to the surface being made by it. 

II. Machines Working by Expression or Wire-drawing". 
The principle of these machines consists in the compression of 




Fig. 99- Press with Revolving Table (Bernhardi Sohn). 



the clay, which has been suitably prepared and made into a more 
or less firm paste, into a space one end of which is formed of a 
special piece pierced with a hole and called a die. Through 
this opening, which has various shapes and sizes, the clay issues 
in the form of a continuous smooth-faced prism, and is received 
on to a special waggon, where it is cut into the required lengths. 

There are three essential parts in these machines : I . The 
machine proper, simple or with attached apparatus for the 
previous preparation or crushing of the clay. 
8 



I! 4 POTTERY IN ARCHITECTURE. 

2. The die, a very important instrument, which gives the 
shape to the bricks. 

3. The cutter, which divides the prism of clay into bricks 
when it comes from the die. 

Each of these parts requires a special description, for the 
parts and their arrangement, although the same result is aimed 
at, are different with different makers. 

I. Description of the Machines. 

Expression Machine with propelling Cylinders. General 
Remarks. It is difficult to say under what circumstances 
machines of this kind are preferable to screw machines ; but 
we can state in what cases they can not be used. If it is true 
that clay can be used for these machines just as it comes from 
the pit, after having undergone a suitable moistening, the work 
will nevertheless be facilitated and the production increased by 
a previous pugging. This pugging is even indispensable for 
rich clays which have to be thinned ; the mixture of the rich 
and the shortening matter is thus rendered a close one. 

It is equally evident that if the clays contain stones or 
foreign matter they must undergo crushing before the 
pugging. 

Personal experience has shown us that vegetable moulds 
(lehm or loess), which are always thin, cannot be worked alone 
by the powerful screw machines, as a too strong pugging makes 
the products brittle and unfit to be cut, while the same clay 
treated with a cylinder machine, even without previous pugging, 
gives fairly good results. 

We may say then that, in questions like this, experience 
alone can guide us, according to the nature of the clays, and we 
must not hesitate, when circumstances require it, to abandon the 
screw machines, and replace them by cylinder machines with 
pug-mills attached. The Vaugirard brickworks in Paris, which 
use plastic clays, employ cylinder machines. 

The principal parts of a machine with propelling cylinders 
(Figs. 100 and 101) are a solid cast-iron frame, X, supporting 



BRICKS. 115 

two hard cast-iron cylinders, G and H, of different diameters, 
which are moved by the gear-wheels B and E, themselves moved 
by the pulleys C D. The upper cylinder, H, turns between 
movable iron wedges in slide - bars the height of which is 
regulated by the screws F F. Behind the cylinders is a mov- 
able hopper to receive the clay. In front is placed an open 
cast-iron box, O, which has one orifice turned towards the two 
cylinders, and the other closed by a cast-iron plate held in place 




Fig. 100. Section of a Cylinder Expression Machine (Joly). 

by cotter-hooks, and pierced in the centre with a square hole, S, 
through which the clay passes. 

This plate is called a die. At the bottom of the box A 
are two blades, I and J, furnished with two oval openings for 
the bolts which fix them to the sides of the box ; these blades, 
called scrapers, can then be moved nearer to the rollers as they 
wear away. 

The prism of clay when it issues is received on a table 
furnished with rollers and called the cutting - table. We shall 
give a description of this in a special chapter. 

The machine works as follows : the clay introduced into the 



Tl6 



POTTERY IN ARCHITECTURE. 



hopper, K, is drawn along by the cylinders, which, in consequence 
of their difference of diameter, crush and blend it. It accumu- 
lates in the space O, and is gradually compressed there. When 
the pressure is sufficient, it issues by the opening, S, in the form 
of a regular prism, which is cut up on the table. 







Fig. 101. Machine with Expression Cylinders (Joly). 

All cylinder machines are based on the same principle, the 
dimensions and shape of the parts only being different. Thus 
the Joly machine is so constructed that it can also be used for 
pottery (Fig. 575). If the size of the machine be reduced, it 
can be worked by hand (Fig. 102), but we cannot recommend 
this unless unavoidable. 

The model in Fig. 103 is the preceding machine made 
stationary ; this simplifies the construction and consequently 
reduces the price (see table, p. 146). 

When the propelling cylinders have the same diameter, as in 
the Sachsenberg (Fig. 104) and Groke (Fig. 105) machines, they 
have a different speed, so that friction may be produced for 
pugging the clay and driving it towards the die. 

The Jager machine (Fig. 106) possesses the same parts as 



BRICKS. 



117 




Fig. 102. Hand Cylinder Machine with Movable Frame (Joly). 




Fig. 103. Cylinder Machine with Fixed Frame (Joly). 



i8 



POTTERY IN ARCHITECTURE. 




Fig. 104. Cylinder Expression Machine (Sachsenberg). 




Fig. 105. Cylinder Expression Machine (Groke). 




Fig. 1 06. Cylinder Expression Machine (Jager). 



BRICKS. 



119 



the foregoing machines, but the space in which the clay is com- 
pressed is reduced to a minimum ; the clay passes straight to 
the die from the cylinders. These latter are sometimes fluted 
instead of smooth, the flutings being angular or straight like 
those of the Johnson machine (Fig. 107). This machine has 




Fig. 107. Expression Machine with Fluted Cylinders (Johnson). 

three rollers : two to compress the clay and placed one over the 
other ; the third passes the clay to the two first. 

Cylinder Machines combined with Pug-mills. Except 
in a few cases it is preferable to submit the clay to a previous 
pugging before sending it to the cylinder machine. Thus 
a good installation is one in which the two machines are so 
arranged that the clay passing from the pug-mill is at once 
absorbed by the moulding machine. 



I2O 



POTTERY IN ARCHITECTURE. 



Fig. 1 08 represents an installation of this kind composed of 
a pug-mill (Fig. 60) and the cylinder machine of Fig. 101. 

Another installation of the same kind (Fig. 109) combines 
the pug-mill of Fig. 62 and the machine with propelling cylinders 
of Fig. 104. 

Any kind of clay can be treated by an installation of this 
type, provided it is friable and contains no very hard particles 
which would require special crushing. The mixture of rich and 




Illlli 

Fig. 108. Cylinder Expression Machine combined with Pug-mill (Joly). 

shortening clays is carried out in the pug-mill, as are any other 
mixtures required. 

Brick - making Machines with Pug - mill and Screw 
Expresser. We stated, when speaking of pug-mills, that the 
clay underwent, by the action of the knives in those machines, 
a certain pressure which drove it through the orifice of issue, this 
expulsion being facilitated by the presence near that orifice of 
screws of various forms. 



BRICKS. 



121 



This being so, if the orifice is provided with a die and the 
parallelepiped of clay is received on a cutting-table, we have a 
brick-making machine. This is a most simple machine, giving 
good results with clays which are free from all foreign substances, 
and easily worked. These machines are called vertical or 
horizontal according to the position of the pug-mill. 

Machines with Vertical Pug-mill. A. WORKED BY ANIMAL 
POWER. These machines do not differ from pug-mills of the 
same type (see p. 74). The orifice of issue is provided with a 




Fig. 109. Cylinder Expression Machine combined with Pug-mill (Sachsenberg). 

die, and a cutting-table is joined to the machine. Theoretically 
any pug-mill can be made into a brick-making machine ; practi- 
cally, as we said above, special clays are required to get good 
results under these conditions. 

Fig. 1 1 o represents a Whitehead pug-mill with two issues, 
transformed into a brick-machine, and worked by a horse-gear 
fixed to the shaft of the mill. In this way power is more 
economically applied, but it must not be forgotten that the 
supply of clay and removal of bricks are rather difficult in these 
machines on account of the horses. 



122 POTTERY IN ARCHITECTURE. 

B. WORKED iw STEAM. These are the same machines but 
more powerful and of greater output. 

In the Whitehead machine (Fig. I I i) the gearing is separate, 
but there are simpler arrangements in which the pug-mill supports 
the driving-gear. 

Screw Machines. These consist of a horizontal pug-mill, 
in which are screws of various shapes and sizes. At the end 
of the pug-mill is placed the die through which the prism of 
clay passes. Above are usually fixed one or several rollers for 
different purposes; some serve to supply clay regularly to the 
screws and for crushing the hard portions in it. The others, 
when used, are true rolling machines like those we have 





Fig. no. Vertical Pug-mill worked by P^ig. ill. Vertical Pug-mill worked by 

Horse-gear. Steam. 



described under the head of Preparation of Clays. They are 
used for clays which require to be crushed before being pugged. 

The working of the screw machines is easily understood. The 
clay comes to the pug-mill in a regular and continuous stream, 
is seized by the blades of the screws, mixed, triturated, divided, 
and finally driven towards the outlet as would be the nut of a 
turning screw fixed at its two ends. The treatment of the clay 
is more or less severe according to the dimensions of the mill. 
In the French machines the screws are two in number and turn 
in opposite directions. 

In order to simplify the description of the numerous screw 
machines, which are, besides, all based on the same principle, we 
shall classify them according to the number of cylinders attached 
to them. We shall have then 



BRICKS. 123 

1 . Simple screw machines. 

2. Screw machines with distributing cylinders. 

3. Screw machines with rollers and distributing cylinders. 

i. SIMPLE SCREW MACHINES. These are not desirable, as 
they can only treat pur clays or those having already undergone 
preliminary working. Moreover, they have to be fed by hand, 




Fig. 112. Simple Screw Machine (Ja'ger). 

as, having no feeding cylinders, the clay is not drawn up by the 
screws; therefore their use is not recommended. 

2. SCREW MACHINES WITH ONE OR TWO DISTRIBUTING 
CYLINDERS. To make sure of regular distribution and con- 
tinuous flow of clay to the pug-mill, it has been found advisable 
to join to it one or two cylinders whose rotation, opposite in 
direction to that of the screws, assures a constant supply. 

The arrangement of these machines is similar to that of the 
preceding ones. The gear which transmits motion to the screws 




Fig. 113. Screw Machine with a Distributing Cylinder (Laeis et Cie.). 

is fixed on the framework itself of the machine (Fig. 113) or 
separate from it (Fig. 1 1 4). 

When there are two cylinders, as is usually the case, they 
crush small stones and lumps which may be contained in the 
clay, without, however, producing as thorough effects as rolling 
machines specially constructed for that purpose. 

Fig. 1 1 5 represents a machine with two distributing cylinders 



124 



POTTERY IN ARCHITECTURE. 



whose axes are in the same plane. It is fixed on a cast-iron 
framework in such a way that the die is on the level of the 




Fig. 114. Screw Machine with a Distributing Cylinder (Bcrnhardi Sohn). 

cutting-table. At the foot of the framework in the figure may 
be seen a die with water-face so that the brick may come out 
flat. 




Fig. 115. Machine with two Screws and two Distributing Cylinders (Joly). 

The Boulet machine (Fig. i i 6) does not sensibly differ from 
the last. 

The Lacroix machine (Fig. 117) is also similar to the preced- 
ing ones. In the figure one of the workmen is throwing clay 
between the cylinders while the other cuts off the hollow products 
as they come from the die. 

In other machines, notably those made by the Johnsons 
(Fig. i 1 8), a special arrangement for bringing up the clay is 
observed. At the side is placed a windlass worked by the 
machine and set in motion by means of a gear lever which is 



BRICKS. 



125 




- rsa :..; 

Fig. 116. Screw Machine with two Distributing Cylinders (Boulet). 




Fig. 117. Screw Machine (Lacroix). 




Fig. 118. Machine with Screws and Distributing Cylinders, furnished 
with a Windlass (Johnson). 



126 



POTTERY IN ARCHITECTURE. 



seen in front of the machine. This windlass brings up the 
waggons full of clay close to the hopper of the machine by 
means of a chain ; then they have only to be overturned. 
The distributing cylinders are arranged in different ways ; 




Fig. 119. Screw Machine with Distributing Cylinders (Bonier). 

sometimes their axes are in the same plane (Figs. 115, I i 6, 117), 
sometimes they are not (Figs. 119, 121). 

It may be seen from the figures that the dies have 
different shapes and appearance ; we shall refer to them in a 




Fig. 120. Screw Machine with Distributing Cylinders (Jacobi). 

more detailed manner in the paragraph relating specially to 
them. 

In certain powerful machines, the output of which is consider- 
able, the pan of the pug-mill is in two parts joined by bolts. 
This arrangement facilitates cleaning (Figs. 122, 123) and 
taking to pieces. 



BRICKS. 



127 




28 



POTTERY IN ARCHITECTURE. 



Fig. 1 2 2 represents a strong American machine producing 
5000 to 8000 bricks an hour with a motive force of 75 horse- 
power. 

The Chambers machine (Fig. 123) is similar to the last- 
named in arrangement and production. 




- 



Fig. 123. Screw Machine (Chambers Brothers). 

Instead of cylinders, cones can be used, and act as rollers 
as well as distributors. 

Screw Machines with Rollers and Distributing 1 Cylinders. 
We have stated that the distributing cylinders of screw machines, 




Fig. 124. Screw Machine with Distributing Cones (Jager). 

the principal aim of which is to stuff the pan of the pug-mill with 
clay, could to a certain extent act as crushers. But when the 
crushing has to be severe it is preferable to substitute a pair 
of conical (Fig. 124) or cylindrical rollers (Fig. 125) which 
are placed above the distributing cylinder or cylinders. These 



BRICKS. 



I2 9 



rollers are worked direct from pulleys (Figs. 125, 128) or else 
receive their motion from the gearing of the machine by means 
of cog-wheels (Fig. 126). 




Kig. 125. Screw Machine with Rollers and Distributing Cylinders (Laeis et Cie.). 

If the clay is difficult to hold, cylinders with points are used 
like those we have described (Fig. 27). 




Fig. 126. Screw Machine with Rollers and Distributing Cylinders (Johnson). 

The machine represented in Fig. 127 is so made. One or 
two pairs of rollers, cylindrical, conical, or fluted, are placed over 
it, according to the nature of the clay to be treated. 
9 



1 3 o 



POTTERY IN ARCHITECTURE. 



Finally, if there is a difficult mixture to be made, or a 
perfectly homogeneous paste is desired, a pug-mill is added to 
the screw machine. 

Fig. i 29 shows an installation of this kind. 




Fig. 127. Screw Machine with Rollers, Distributers, and Cylinders with 
Points (Whitehead). 

As can be seen from the numerous figures above, which do 
not by any means represent all the types of machines constructed, 
the manufacturer of pottery has a large choice, which cannot 




Fig. 128. Screw Machine with Rollers and Distributing Cylinders (Groke). 

fail to embarrass him. The composition of the clay to be 
treated, and the way in which it is to be treated according to the 
articles to be made from it, are the only things which should 
influence him ; in the last resort experience is the only guide. 



HRICKS. 



Screw machines are intended for treating clay in the state 
of a semi-firm paste, the most suitable state for getting the 
maximum of output with the minimum of motive power. 




Fig. 129. Screw Machine with Distributing Cones and Vertical Pug-mill (Ja'ger), 

Piston Machines. These machines are intended for treating 
clay when in a state of firm paste. It will be understood that 
the firmer the clay to be worked upon is, the greater is the 
effort required to force it through the die. Hence machines with 
propelling cylinders or pug-mills with expression screws are un- 
suitable for this kind of work. They are replaced by machines 
which compress the previously pugged clay into boxes with a piston. 

One of the ends of these boxes forms a die. The piston 
has an alternating motion, therefore the production is not 
continuous, but in order not to lose the return motion the 
machine is double and furnished with two cutters. In machines 
with large output like that of Fig. 37 the feeding is done by 
hoppers into which the clay is thrown during the return journey 
of the piston. 

In small machines (Fig. 564) the clay is placed in two 
boxes, the upper part of which form lids : while one is emptied 
under the pressure of the piston the other is being filled with clay. 

Large piston machines are called " galettieres " ; they are 
used for the preparation of slabs for tiles ; the others are specially 



132 POTTERY IN ARCHITECTURE. 

employed for the preparation of hollow products and especially 
pipes. We shall describe them when we speak of the manu- 
facture of these. 



1 1 . Description of Dies. 

Dies are the orifices by which the clay escapes when com- 
pressed by the motion of the screws or cylinders. These dies 
are movable, and are fitted to the machines either by collar-bolts, 
or nuts and bolts, or any other means. As the shape of the 
orifice is variable, it may be seen at once that brick-machines 
working by expression can make bricks of any dimensions or 
shape. Let us consider how clay issuing from a die behaves. 
According to Schlickeysen (experiments made in 185 6) 

1. Well prepared and ductile clay driven vertically through 
a rectangular orifice in sheet-iron with narrow walls, comes out 
without cohesion ; the prism opens out at the four angles as far 
as the centre. 

2. If the thickness of the walls is increased so as to make 
a cylindrical pipe, the prism acquires cohesion, but breaks 
perpendicularly at short intervals. 

3. If the thickness of the walls, or the breadth of the 
pipe, is still more increased, the prism of clay then splits into 
two in a plane passing through the angle of pressure. This 
separation is due to a slackening of the speed of the exterior 
particles, due to their friction against the sides of the pipe. The 
two pieces curve outwards. If this effect is produced in con- 
sequence of the thickness which must be given to the face-plate, 
the influence of friction can be reduced by piercing conical holes 
from the outside to the inside, which diminishes the surface of 
friction. 

4. If the piping is conical from inside to outside, so that 
the largest section is towards the machine, the cohesion of the 
prism is increased, but the surface is covered with flutings and 
the edges are jagged. 

The effects above described are very variable according to 
the richness of the clay. With a paste of a proper degree of 



BRICKS. 



133 



dampness and plasticity there is no tearing at the angles when 
it comes through the die. If the clay is too damp, or if it 
changes from less to more moist, the prism is deformed and 
increases in volume as it issues. Finally, thin clays require 
special dies called hydraulic. 

To summarise, what must be avoided is the friction caused 
by the walls of the piping, especially at the angles, which tends 

Fig. 130. Fig. 131. 



Fig. 
132. 



Fig. 
133- 




Fig. 
134. 



Fig. 
135. 



Fig. 136. Fig. 137. 

Figs. 130-138. Various Dies. 



to produce a slackening of speed of the outer molecules as 
compared with that of the inner ones. If this slackening occurs 
the prism of clay undergoes one of the above-mentioned deforma- 
tions. This inconvenience is less to be feared with rich clays, 
which glide more easily ; it is otherwise with thin clays, and for 
them hydraulic dies are required (Figs. 136, 137, 138). Inside 
a hydraulic die, on the four faces, is placed a pervious skin 



134 POTTERY IN ARCHITECTURE. 

fitting closely to the prism of earth. This skin is surrounded 
by an empty space bounded by the sides of the die. This space 
is furnished with a pipe to which is attached a tap communicating 
with a water-conduit or reservoir frequently placed above the 
machine over the die (Figs. 120, 121, 124, 129). The water 
passes into the die, percolates through the skin, and lubricates 
the clay, thus facilitating its expression. The flo\v of water is 
regulated by the speed of the prism. 

The shape of dies varies with the maker, as can be seen by 
an examination of the different machines we have described 
(Figs, i oo to 128); but in all of them arrangements are made 
to ensure that the prism shall issue with smooth faces and clear- 
cut edges. We give sketches of some dies for hollow bricks 
(Figs. 130, 132, 134), for solid bricks with water-face (Figs. 136, 
!37> J 38) or without water-face (Figs. 131, 133, 135). When 
several thicknesses of brick are to be expressed, well stretched 
threads are placed in front of the die and divide the prism of 
clay (Figs. 130, 135). The tube of the die has the dimensions 
and shape (Figs. 133, 138) of the brick to be manufactured. 
In calculating these dimensions, allowance must be made for 
the contraction which the clay will undergo in drying and firing ; 
I o per cent, is usually allowed for semi-firm pastes. 

Several cases present themselves according to the position 
in which the brick comes out. 

i. The prism forms one brick. 

A. Flat (Figs. 131, 132, 136), o. 105 x 0.06 = (x- contraction) (y- contraction). 

B. Up on edge (Figs. 137, 138), 0.220 x o. 105 = (c - contraction) (x - contraction). 

The dimensions of the die will then be found by 



2. The prism forms several bricks 

A. Flat (2 bricks) : (0.105 x 2 xo.o6) = (.v 1 -contraction) (j 1 -contraction). 

B. Up on edge (3 bricks) (Figs. 130, 135): (0.105 xo.o6x 3) = (^-contraction) 
} -contraction). 



BRICKS. 135 

The dimensions are therefore found by 



/- =.06 .-./=. 20 

It must be noted that bricks being placed on edge in firing 
contract more in height than in the other two dimensions ; thus, 
we must increases but diminish y and especially z. For example, 
we shall take 

x = .\2Q instead of .116 
^ = .065 ,, ,, .066 
z = .240 .244 

Whenever it is possible to judge by experiments made with 
moulding clay, we should not fail to do so ; they give the most 
accurate information. 



III. Description of Cutting. Machines. 

These are divided into two classes according as they are 
worked by hand or automatic. In the first class we shall make 
a distinction between cutting machines with trolleys and those 
without, also between those cutting obliquely and those cutting 
perpendicularly. 

'(i) Simple 

-(a) Cutting ob- 



CA. With movable threads -j ,( 

1(2) With trolley \ ( 

1.^9. With fixed threads 



pendicularly. 
vvjiii uxeu uireaus 

2. Automatic cutters. 

i. Hand-cutters. A. WITH MOVABLE THREADS. The 
principal parts of these machines are : a framework, rollers, 
wire-carrier, and a stop-pallet : we shall describe them in 
turn. 

The Framework is composed of two cast-iron brackets joined 
by cross-pieces (Figs. 140, 141), or of a cast-iron frame resting 
on four legs (Figs. 101, 102, 103), or simpler still, of a frame 
resting on one support and one leg (Fig. 1 04). " The four legs 
generally have adjustment screws (Figs. 101, 140, 142), so that 



I ^6 POTTERY IN ARCHITECTURE. 

%J 

the table can be raised at will and placed in a perfectly horizontal 
position. 

The Rollers are of wood covered with chamois leather, or of 
plaster ; this is because certain clays adhere to the plaster and 
slip on the leather. The rollers are movable about an iron 
axis whose ends rest on notches made in the sides of the frame- 
work. The rollers made of wood covered with chamois are 
supplied all ready mounted by the makers ; when the leather is 
worn out it is renewed. 

To make the plaster rollers, a bronze mould (Fig. 139) is 
used, divided into two parts, which are slightly conical in exterior 
shape, and are held together by two rings. The inside of the 
two parts is greased, they are fixed together by means of the 
rings, and the iron axis is placed through the middle, one end 
resting in a hollow in the lower part of the mould. The axis 
is held quite vertical, and plaster in a fairly liquid condition is 
poured round it. When it becomes solid it is taken out of the 
mould and dried. The plaster rollers get quickly worn out, but 
it is easy to remake them ; the cost of plaster is small. 

The Wire-carrier consists of a frame of variable shape, across 
which are stretched steel wires of excellent quality. One end 
of these wires is fixed to a socket movable on one of the sides 
of the frame ; the other end is fixed to a screw and hook fitted 
with a fluked nut. A special arrangement allows these hooks to 
slide along the rod which holds them. They are fixed by means 
of the nut. These wires can therefore be moved at will and 
placed at any desired distance from one another : care must of 
course be taken that they pass between the rollers. This wire- 
carrier swings on an axis fixed to the frame of the machine 
(Figs. 1 01, 140). 

Stop -pallet. This is a movable piece placed at the end 
of the trolley; its object is to fix the thickness of the first 
brick, the thickness of the following ones being given by the 
distance between the wires. The work of this pallet is very 
important, for on it depends a good or a bad division. In certain 
cutting machines its motion is linked to that of the wire-carrier 
(Fig. 142); in others it is independent of it (Figs. 101, 102, 140). 



BRICKS. 137 

(i) Simple Cutting- Machines. We shall describe a small 
cutting machine (Fig. 102), which gives good results in cutting 





Fig. 139. Bronze Mould for making Plaster Rollers (Chavassieux). 

bricks, especially hollow bricks, in a flat position. It is composed 
of the same parts as the previous ones, but has no trolley. 

The pallet is movable round a cylindrical rod ; it is kept 
in position by two rings fixed by bolts to the rod itself. On the 
rod also slides the wire-carrier ; this is fixed by bolts pressing 
on the rod as in the case of the movable rings. The distance 
between the pallet and the first wire is equal to that between 
the wires. In the ordinary position this pallet rests on the 
rollers (3, Fig. 140), and, by sliding the rod through two sockets 
fixed to the framework, it may be dropped on to a stop ; it is then 
in the position of Fig. 102. To cut, the pallet is raised, the wire- 
carrier is pushed to the left, and the pallet is allowed to fall 
upon the rollers. When the prism of clay reaches it, the wire- 
carrier is quickly lowered, and to raise it again a slight pressure 
to the right is exerted in order to follow the motion of the clay, 
and bring the wires back through the same path. As soon as 
the wires are freed, the frame is pushed to the right ; the pallet 
follows this motion, and falls on its stop. The cut bricks are 
taken away, the pallet is replaced on the rollers by pushing the 
wire frame, and the same process is repeated. 

The cutter represented in Fig. 140 is similar in arrangement 
to the preceding one : it carries at the entrance a wire the use 
of which is to cut the prism horizontally in the case, in which it 
has the thickness of two bricks. 

(2) Trolley Cutting Machines consist of the same parts as 
the preceding ones, but a certain number of rollers are mounted 
on a trolley which runs by means of flanged wheels on rails 



'38 



POTTERY IN ARCHITECTURE. 



forming the edges of the frame. Sometimes these flanged wheels 
are inside the frame and are consequently invisible, sometimes 
they are visible. In other cutting machines (Fig. 142) the trolley 
is double. 

According to the manner in which the wire attacks the prism 
of clay, we shall have 

(a) Angular Trolley Cutting Machines. These machines act as 




Fig. 140. Small Cutting-table (Joly). 

follows. The movable trolley being pushed against the two 
rollers of the fixed frame, and the stop-pallet being raised, the 
prism of clay advances over the rollers, which turn and thus 
facilitate its motion. Having reached the pallet, it draws on by 
its motion the trolley, which begins to move along on its wheels ; 
it is then that the wires are brought into use. 



BRICKS. 



139 



In the Joly machine (Fig. 101) the wire-carrier swings on 
one of its sides 5, 5. The stop-pallet is fixed to an axis fitted 
with two counterpoises which keep it raised. In order to pre- 
vent the prism of clay when it strikes it from turning it over, 
one of the counterpoises is held with one hand, and with the 
other the wire-carrier is brought forward. The prism is -cut; the 
pallet is released and falls (Fig. 101), the bricks are removed, 
the pallet is raised, and the trolley is pushed back again. The 
same movements are repeated, the wire-carrier being success- 
ively pushed backwards and forwards. In those cutting machines 
where the wire frame is fixed to the trolley (Fig. 141) the 




Fig. 141. Trolley Cutting-table, cutting at an Angle (Ja'ger). 

motion of the former is connected with that of the pallet, 
which, during the operation of cutting, is held by a piece fixed to 
the arms of the wire frame, and released as soon as the cutting 
is done. 

The Groke cutter (Fig. 142) has two trolleys ; the wire frame 
has a spring and returns automatically to its first position. 

We call the preceding cutters angular because the wires 
attack the prism at a certain angle : others are made in which 
this attack takes place perpendicularly to one face of the prism ; 
such are 

(b} Perpendicular Trolley Cutting Machines. The wire frame, 



I4O POTTERY IN ARCHITECTURE. 

which is placed parallel to the rollers, is guided in its motion by 
two rods fixed to each side of the trolley. An arrangement of 
levers allows of its being brought down on to the prism of clay. 
In another system (see Fig. I 20) the wire frame is fixed to the 
framework of the machine and not to the trolley. 




Fig. 142. Trolley Cutting-table, cutting at an Angle (Gioke). 

The Borner (Fig. 144) cutting machine is arranged for 
making special corner cuts for arch bricks ; it also cuts per- 
pendicularly. It can be regulated to all dimensions, as the wires 
run between guides which can be moved at will. 

B. FIXED WIRE-CUTTERS. -In the preceding machines the 
wires are movable and the prism of clay is fixed ; in the follow- 
ing ones the arrangement is reversed. The movable table is 
preceded by rollers, which facilitate the gliding motion of the 
clay. When the latter has attained a sufficient length (8 to 10 
bricks) it is cut by a single wire, then the piece is pushed back 
from the wires against a square board. By means of the lever 
seen on the Ijft in Fig. 146, and which is moved forward, the 
block meets the stretched wires and is divided into regular pieces, 
while the bricks so formed are placed on a movable tray, which 
has only to be taken up and placed on the barrow without 



15KICKS. 





U 



142 



POTTERY IN ARCHITECTURE. 



the bricks being touched (Figs. I 1 8, 126). Fig. 145 shows 
the arrangement of the rack-work and toothed segment, which 
give the backward and forward motion to the table ; at the left is 
seen the square stop which checks the end of the prism. In 
these machines there is always a certain waste, owing to the 
difficulty of so cutting the prism that it may contain an exact 
number of bricks. The excess of clay beyond the last wire is 
useless, and must be thrown back into the machine. 




Fig. 145. Cutting-table with Side Discharge (Whitehead). 




Fig. 146. Cutting-table with Side Discharge (Johnson). 



2. Automatic Cutting 1 Machines. -- It has naturally been 
thought that the motion of the prism of clay might be utilised 
to work a cutter which would require no separate mechanism. 
It is on this principle that automatic cutters are based. 

A small machine of the kind is manufactured by Chavassieux, 
and is shown in Fig. 147. The clay issues on a special endless 
band which rests on rollers and passes over drums. The clay 
by its weight and adhesiveness draws the band on in its motion, 



BRICKS. 



143 



and the band turns the drum round as it passes. The rotation 
of the drum is communicated by means of a pulley and belt to 
a kind of star-shaped wheel whose branches are joined by the 
steel wires which cut the clay. The length of the arms of the 
wheel and the position of the wires are calculated according to 
the dimensions of the bricks required. 




Fig. 147. Automatic Cutting-table (Chavassieux). 

We give (Figs. 148, 149, 150, 151, 152) sketches of auto- 
matic cutting machines of American make. The complicated 
mechanism of these machines may be seen. The arrangements 
made for assuring a quite perpendicular cut will be noticed : in its 
passage under the wheel the prism of clay is bent in order to 
counteract the curvature of the cut caused by the rotation of the 
wire, and, in order to disengage the latter when the cut is made, 
the endless band does not pass over the place where the cutting 
is done ; there is a system of drums for the return and motion of 
the endless band. 

In Fig. 149 the prism is seen passing under the wheel, and the 



144 



POTTERY IN ARCHITECTURE. 



AUTOMATIC CUTTER (I'enfield). 



Fig. 148. 




Eig. 148. Back View Fig. 149. Side View. Fig. 150. Front View 




Fig. 151. Automatic Cutter (Chambers). 



BRICKS. 



'45 



cutting-wire is just about to meet it. Fig. 148 shows the 
operation of cutting, and Fig. 150 shows the cut bricks 
advancing over the front part of the table. 

The Chambers cutting machine (Fig. 151) has a similar 
arrangement, and, as in the preceding machine, the motion of the 
endless band is produced by a horizontal shaft which is worked 







_ " . 



Fig. 152. Automatic Cutter. 

direct from the machine by means of cog-wheels. The great 
length of the tables of these .cutters is necessary owing to their 
large output. 

Instead of cutting the bricks endways, the wheel may be so 
arranged as to cut them lengthways. Such is the arrangement 
of the machine represented in Fig. 152. 



[TABLE. 



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POTTERY IN ARCHITECTURE. 







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148 POTTERY IN ARCHITECTURE. 



GENERAL REMARKS 

ON THE MECHANICAL MOULDING OE BRICKS CHOICE OE 

MACHINES SCHEMES OE INSTALLATION. 

When should machine manufacture be preferred to hand 
manufacture ? The question is not always easy to answer. It 
is evident that the first condition is a considerable annual output, 
which we should estimate at two million bricks. In a factory of 
such importance every machine working by hand or animal 
power should be rejected pug-mills, expression machines, etc. 
The work of these is as good as those driven by steam-power, 
but their small output makes their employment a costly one. 
They can only be recommended in small works for making 
hollow articles ; they have also their advantages in new countries 
where animal-power is the only kind available. 

But a large output is not the only condition in favour of 
mechanical manufacture. Factories doubtless exist which pro- 
duce millions of bricks by hand, and such a quantity of 
productions can only find a market in a great centre of 
consumption ; but in such a centre many hollow bricks and 
chimney-pipes are used, that is to say, many hollow articles which 
require machines. As soon as the manufacturer needs power 
for one part of his work, it is certainly advantageous to use it 
for the remainder. It is true that his capital sunk is increased, 
but, on the other hand, he is no longer at the mercy of the 
inclemencies of the weather, which cause serious losses, and he 
no longer needs that vast space which hand-work requires. 

In case the brick-maker is also tile-maker, there can be no 
doubt machinery is necessary. 

Once this question answered, another presents itself: what 
machine is to be chosen ? That is more difficult to answer. 
In a general way it can be said that all machines are good ; 
but to get good results we must choose the one which suits 
the clay to be worked. Many disappointments have occurred 
through a mistaken choice of machines and the use of one 
unsuited to the clay under treatment, We must insist, then, 



BRICKS. 149 

on this important point : It is not every machine iv/tick is 
suited for treating a given clay. Anyone who knows the 
diversity of clays will understand that only a practical examina- 
tion of a clay will teach us the most suitable way to treat it. 
Nevertheless, taking the principal varieties of clay, we shall be 
able to give a few general hints as to the tools to be used in 
the manufacture of bricks by expression machines. 

Vegetable Moulds (tableland clay, lehm, or loess). 
Weathering is always to be recommended but is not indis- 
pensable. Clays which have not weathered need to be passed 
between cylinders to crush the lumps and make sure of a better 
damping. The latter will be done in the mass, or more quickly 
with a moistening machine. Then the clay will be pugged 
and moulded by a machine with propelling cylinders ; we do 
not advise screw machines. We pass over clays containing 
stones ; it is better not to use them. Nevertheless, if the 
stones do not inconvenience the firing, such a clay can be used 
after being passed between crushing cylinders and reduced to 
powder. In the contrary case, and if no other clay can be 
used, stone-removing machines must be employed. To sum- 
marise, the following processes will be carried out, according 
to the circumstances of the case : 



Clays with stones. 

Crushing or stone-removing by cylinders. 
Damping Damping. 



Moulding Moulding. 



Clays without stones. 

Weathering or Rolling. 
Rolling or Damping. 
Damping Pugging. 

Pugging Moulding. 

Moulding. 



Potter's Clays or Clay Marls. The same remarks as to 
weathering apply. Treated in the fresh state, these clays are 
cut into pieces in a mixing mill, then dipped into ditches with or 
without the addition of antiplastics. The mixture is pugged, 
and then moulded by means of cylinder or screw machines. 
When more or less dry clays are used, the mixing is replaced 
by crushing with antiplastics or other clays. Sometimes the 
sand used as an antiplastic contains hard lumps which have 
to be crushed ; then it is passed with the clay between cylinders 



150 POTTERY IN ARCHITECTURE. 

which effect a first blending. Then the treatment will consist 
of the following processes, according to the state of the substances 
employed : 



Green clays. 
Mixing. 
Soaking. 

Pugging and shortening. 
Moulding. 



Dry clays. 
Crushing. 

Rolling with antiplastics. 
Soaking. 
Pugging. 
Moulding. 



Rich Clays. These are not cut up, they are passed between 
cylinders to crush the lumps, then soaked, alone or with anti- 
plastics ; the mixture is then pugged, and afterwards moulded 
by cylinder or screw machines. Let us now examine in a more 
detailed manner each of these operations. 

Crushing and stone-removing require no special remarks ; 
it will be sufficient to refer to what we have previously said on 
the subject. As to rolling with cylinders, it must not be for- 
gotten that the action of the cylinders is more rapid when their 
diameter is greater. If the clays are not held by the smooth 
cylinders, recourse must be had to those with points or flutings. 

Moistening' and soaking should receive special attention from 
the manufacturer. In brick - making we have not to bear in 
mind, as we must in tile-manufacture, certain considerations in 
favour of working on soft clay in preference to firm or hard clay. 
We must choose a convenient degree of dampness, which gives 
products neither too soft nor too firm. Pastes which are too 
soft undoubtedly require less power, but the products are not 
easily handled without loss of shape ; hard pastes have the 
advantage of giving bricks firm enough to bear a pile of five 
or six without loss of shape ; but considerable force is expended, 
machines are quickly worn out, and there is a risk of producing 
exfoliated pieces ; moreover, the output is small. The best 
thing is to choose the happy mean between these two methods, 
that is to say, to mould with a semi-firm paste, the products 
of which can be placed in stacks, three or four bricks high, 
without loss of shape. In this way the production will reach its 
maximum* with^ajnoderate use of motive force. 



BRICKS. 151 

The more plastic a clay is, the better can it be expressed in 
a firm state, subject to the remarks above. 

Pugging is always effected by blade or screw machines : 
this is the best way to get a homogeneous paste, and in this 
respect cylinder-pugging is not to be compared with it. Hori- 
zontal pug-mills are preferable to vertical ones for effecting 
difficult mixtures with substances of different density. 

Moulding is done by machines with cylindrical or screw 
propellers ; the latter are not recommended for the treatment 
of thin clays, which cannot bear the same manipulation as rich 
clays. For the latter both kinds are suitable, but some manu- 
facturers are inclined to prefer cylinder to screw machines. 
In any case, when using the latter, it is advisable to take 
machines in which the screws have a high pitch but not too 
great a length. 

When the same machine is to make, besides bricks, chimney- 
tops and pipes, we may use a cylinder machine of the type 
of the Joly machine (Fig. 101) on account of its arrangement, 
which allows of its producing these articles (Fig. 575). 

Another important question to be decided is, whether it 
is better to put up one single machine capable of producing 
the whole daily number of bricks required (machines can be 
found which produce up to 1 0,000 bricks an hour), or to divide 
the production between several machines of moderate power. 
In our opinion the latter course is better in most cases, for it 
must not be forgotten that a powerful machine is not suit- 
able for the manufacture of hollow bricks, and it is easier to 
regulate production with several machines than with a single 
one. 

It may be useful to point out the precautions which should 
be taken to ensure the regular working of machines, to whatever 
system they may belong. 

When empty, a machine should be easily turned by hand ; 
if there is a difficulty, the cause should be ascertained (tightness 
of bearings, want of oil, etc.). The distributing or propelling 
cylinders should be two to three mm. (about T Vth in.) apart, and 
even less if the product to be expressed is of small section. 



152 POTTERY IN ARCHITECTURE. 

The scrapers are placed near the cylinders, but not touching 
them. Whenever the thickness of the clay sticking to the 
cylinders becomes too great, the scrapers should be brought 
nearer. This is very important, because the output diminishes if 
the cylinders are not properly cleaned. The dies should be 
kept very clean, and care should be taken not to drop oil on the 
leather of those with water-face. Before fixing them to the 
machine, they should be dipped in water for a few minutes. 
It is better not to leave them on the machine during a long 
cessation of work ; they should then be cleaned. 

The cutting-table should be placed quite horizontal in front 
of the die ; the skin-covered rollers should be moistened, and 
should be on the level of the lower edge of the die. The wires 
are placed at the proper distances starting from the pallet 
and tightly stretched. In order not to strain them uselessly, 
they may be loosened during stoppage of work. The rollers 
should always be kept clean, and those made of plaster should 
be renewed as soon as they are perceptibly worn. 

When starting, it is recommended, especially in the case of 
thin clays, that the interior of the compression chamber should 
be filled by means of the hopper with soft clay ; the first pro- 
ducts which issue are rejected ; this precaution facilitates the 
passing of the clay under treatment. It will also be advisable, 
if it is observed that the production diminishes, to take advan- 
tage of a stop to take out the closely compressed clay fitting 
the chamber, and to substitute some soft clay for it. 

In screw machines fitted with cylinders, the production of 
these latter should be equal to that of the screws, otherwise 
there will be an obstruction which will force the clay under 
the scrapers ; this defect can be remedied by bringing the 
cylinders closer together. 

Generally speaking, whenever the output of a machine 
diminishes, we must seek the cause, which is often found to be 
an error in damping, too firm clay, cylinders too far apart, 
scrapers too far away, die out of order, screws worn, etc., all of 
which causes are easily remedied. 

The maintenance of the machines belongs to the domain of 



BRICKS. 153 

the ordinary routine of any mechanical factory ; we will not 
therefore lay stress upon it. 

Types of Installations. The installation of a brick factory 
depends too much upon local circumstances for us to give 
precise details on the subject ; we must be content with a few 
general hints. A very common arrangement consists in the 
construction of a building of two or three storeys, having on the 
ground-floor the kiln or kilns, and on the other floors drying- 
rooms which receive heat from the kilns. At the end of these 
kilns are placed the machines. Communication between the 
machines and the drying-rooms is made either by brick- 
elevators (Fig. 187) or by lifts to carry up the waggons and 
barrows, or by inclined planes. 

When space allows, and work is suspended during the winter, 
open-air drying-grounds are used instead of drying-rooms in 
storeys. We will speak of them in the chapter on drying. 

Economy of labour should be our guide in the arrangement 
of the machines. As far as possible the clay should pass 
automatically from the pit to the machines, and from them to 
the drying-rooms, the workmen's hands being used as little as 
possible. 

Installation comprising Rolling, Damping, Pugging, and 
Moulding Machines. This is for a thin clay easily damped like 
the vegetable moulds (lehm and loess) ; a compact factory 
might be arranged as follows. 

The dividing cylinders are over the moistening machine ; 
they receive the clay direct from the pit and pass it, well 
divided, to the moistening machine. When it issues from the 
latter, the clay falls into a vertical pug-mill, and the blended 
paste is then received into a cylinder expulsion machine, which 
transforms it into bricks (Fig. I 5 3). 

Dividing cylinders and the moistening machine are not 
indispensable, especially for clays which have undergone weather- 
ing, but they facilitate and hasten the treatment. In fact, the 
clay is always extracted in more or less large blocks ; in order 
to get a regular moistening these blocks must be split up with 
the pick or shovel in a slow and irregular manner. The clay 



154 POTTERY IN ARCHITECTURE. 

must be arranged in layers for damping, then damped with a 








Fig. IS3- T }'P e of Installation comprising Separating Cylinders, Damping Machine, 
Pug-mill, and Cylinder Expression Machine. 

watering-can and left for at least twenty -four hours. Then it is 
cut up and thrown into the machine. But it often happens, 



BRICKS. 155 

when there is a large quantity of clay to be moistened, that 
a sufficient volume cannot be prepared in advance, or that 
the distance between the heap of clay and the pug-mill is too 
large for a single stroke of the shovel ; a second workman is 
then required to bring the clay nearer, and the daily cost is 
increased. 

The arrangement shown gives great economy of labour, 
and whenever the clay is suited for this kind of treatment we 
should not hesitate to adopt it. Some makers say that their 
machines treat the clay without previous blending. This is true, 
but the considerable loss caused by the clay being insufficiently 
worked up soon makes up, and more, for the cost of a pug- 
mill. 

Estimate of an installation of this kind, producing from 25,000 to 30,000 bricks 
per day of 10 hours. 

Francs. 
2 moistening machines, each producing about 1500 to 2000 bricks per hour, at 

2500 francs . . . . . . . . . . . = 5,oco 

2 pug-mills, each producing about 1500 to 2000 bricks per hour, at 1800 francs = 3,600 

2 cylinder expression machines, able to make pottery, producing about 1500 

bricks per hour, at 21 oo francs . . . . ... . = 4,200 

Belting, transmission, gearing . . . . . . ... . 1,200 

Motive power necessary : 1 5 to 20 horse-power for damping and cylinder 

machines, 8 to 10 for pug-mills, 6 to 8 for moulding machines in all, 

40 horse-power, costing for engine and boiler and erection about . . 20,000 
Installation of a lift, if the drying-rooms are in storeys, or waggons and tramway 

if the drying is in the open air, about . . . . . . . 5> oo 

Sundries . . . . . 1,000 

40,000 

The building is estimated at . . 

for generally it serves to shelter the kilns, and its price is added to theirs. 

An installation of this kind allows of an annual output of 6 to IO millions, according 
as work is carried on for 7 or 8 months or for the whole year. It requires as staff : 
I engine-driver ; 2 men to empty the waggons as they arrive automatically, and to put 
the clay in the rolling machines ; 2 men for the damping machines ; 2 men for cutting ; 

3 men to carry bricks and place them in the drying-sheds in all, 10 men. 

Net cost of looo bricks : 0.22 x o. 1 1 x 0.065. 

Interest at 4 per cent, on 40,000 fr. = 1600 fr.^ 

Depreciation ,, 10 ,, ,, = 4000 ,, J 5 Francs. 

Per looo, taking minimum output : ^ - = 0.93 fr. .. . . . 0.93 

10 men at 5 fr. per day = 50 fr., or, per looo, 5 = 1.67 fr. . . . . . 1.67 



Carry forward . 2 -6o 



156 POTTERY IN ARCHITECTURE. 

Francs. 
Brought forward .......... 2.60 

Coal, I kilo per horse-power-hour = 400 kilos 

at 25 fr. the ton . . . ' IO fr )i 5 fr., or, per IOOO, L* = o . 5 o 

Oil, repairs, etc.. per clay 5 fr. ) 30 

Total . 3.10 

To this we must add the cost of extraction of the clay, which varies (p. 32) from 
I fr. 30 to 2 fr. 20, according to the gradient (2 cubic metres per 1000 
bricks) the average is . . . . . . . . . . 1.75 



Total cost . 4.85 

We must add the cost of pressing for high-class bricks ; this is estimated at from 2 to 
3 fr. per 1000. 

Installation with Soaking Troughs. When the clays are rich 
and require soaking in troughs, the following arrangement may 
be adopted (Fig. 154). An endless band brings to the pug- 
mill the clay which has been soaked in the troughs, and after 
pugging the clay falls into a machine which transforms it into 
bricks. 

We suppose in this installation that the clays do not need 
to be separated. Rich clays should generally be mixed : Fig. 
1 5 5 shows an installation in which the mixing mill is placed 
above the soaking troughs. These troughs are provided with 
doors in one side, and near these doors is placed a pug-mill. 
The workman cuts the clay out of the troughs vertically and 
throws it into the pug-mill. Thence it goes to the moulding 
machine. 

Estimate oj an installation of this kind, producing from 25,000 to 30,000 bricks 
per day of 10 hours. 

Francs. 

2 mixing mills, at 1 100 francs .........= 2,200 

2 pug-mills, at 1800 francs ..........= 3,600 

2 cylinder machines, at 1600 francs ........ 3,200 

Belting, gearing, etc. ........... 800 

Motive force : 4 horse-power for the mixing mills, 8 to 10 for the pug-mills, 
6 to 8 for the moulding machines in all, 25 horse-power, costing for 

engine, boiler, and erection, about ........ 15,000 

Lift or tramway with waggons, soaking troughs, and sundries . . . 6,200 

31,000 
Building ............. 

The daily output requires a staff of I engine-driver, 2 men for the mixing mills, 2 men 
to spread the clay in the troughs, 2 men to fill the pug-mills, 2 cutters, and 3 men to take 
the bricks to the drying-rooms altogether, 12 men, 



\ 




158 POTTERY IN ARCHITECTURE. 

Net cost of 1000 bricks : o. 22 x o. 1 1 x 0.065. 

Interest at 4 per cent, on 31,000 fr. = 1240^ 

Depreciation ,, 10 ,, ,, = 3ioo/ 4 34 Francs. 



L'er 1000 := = 0.723 .......... 0.723 

6000 

12 men at 5 fr. a day = 60 fr., or, per 1000, = .....== 2.000 

Coal, 1.25 kilos per horse-power-hour = 

310 kilos at 25 fr. the ton . . . = 7.25 fr. j J2 ^ ^ per IQQ ^ 12 = o _ 4oo 
Oil and maintenance, etc. . . . 4. 25 , , J 30 



Extraction of the clay, per I ooo bricks . 



Total cost . 5.000 



Installation for Manufacture with Powdered Clay. We shall 
give as a last example of installations, one for manufacture 
with dry clay. The dry state is obtained by natural means, or 
more frequently by warming in a stove or in the kilns. The 
clay, having been crushed by a mill with perforated pan, falls 
into a receptable below, whence a lift takes it to a sifting 
cylinder. The powder is received into a damping machine, and 
the tailings are returned to the crushing mill. The clay having 
been suitably moistened is once more mixed in a mill and 
finally falls into a receptacle, whence it reaches the press 
through a conduit. These presses (Fig. 157) are placed near 
the kiln, for the bricks manufactured by them are hard enough 
to be at once fired. 

The estimate of such an installation is as follows : 

Francs. 
2 crushing mills, at 5350 francs ......... 10,700 

2 sieves, at 675 francs ........... = 1,350 

2 damping machines, at 835 francs ........= 1,670 

2 mixing mills, at 3000 francs ......... 6.000 

5 moulding machines, at 5300 francs . . . . . . . . = 26,500 

Belting, gearing, lifts, etc. .......... 3,000 

Motive force : IO horse-power for the crushing mills, 6 for the sieves and 
damping machines, 6 for the mixing mills, 20 for the moulding machines 
in all, 42 horse.-power, costing for engine, boilers, and erection, about . 20,000 
Sundries ............. 1,780 

Total for machines . 71,000 
Building, about ............ 9,000 



Total . 80,000 

The staff comprises : I engine-driver, 2 men to put the clay into the crushing mills, 
5 men for the machines altogether, 8 men. 



BRICKS. 



'59 




i6o 



POTTERY IN ARCHITECTURE. 



Net cost per 1000 bricks : o. 22 x o. 1 1 x 0.065. 



, 200 fr. 



Interest at 4 per cent, on 80,000 fr. = 3200 fr. ^ 

Depreciation ,, 10 ,, ,, = 8000 ,, J 

Per 1000 : V' 800 = 1.966 fr 

6,000 

8 men at 5 fr. per day = 40 fr. per 1000 = -- 1.334 

Coal, I kilo per horse-power-hour = 400 kilos 

at2 5 fr Iofr ')i8fr. per 1000 = l8 

Oil, maintenance, etc. 8 ,, J 30 

To this sum we must add the cost of extraction of the clay, and that of drying 

it, which may be estimated at I fr. per 1000 bricks : 
Extraction of clay ............ 

Drying of clay ............ 

Total cost 



Francs. 
1.966 



= O.6OO 



i-75 

I.OOO 

6.650 



This is higher than the preceding estimates ; but it must be observed that, in an 
installation of this kind, drying -rooms, transport of bricks to drying -rooms, and 
pressing are not required. 




Fig. 156. Type of Installation for Manufacture with Dry Clay. 



BRICKS. 



161 



STAMPING. 

The object of this process is to give to the bricks when they 
come from the ordinary machines the sharp edges and regular 
faces lost by them under the manipulations to which they 
have been subjected when in a soft state, however much care 




Fi g- I 57- Installation of Whittaker Machines. 

may have been given to their treatment. In other cases stamp- 
ing is intended to further compress together the molecules of 
the clay ; this is the case when bricks made by hand or by the 
lever press (Fig. 89) are so treated. 

Stamping takes place a certain time after manufacture, 
twelve, twenty-four, and forty-eight hours, in order that the 
bricks may have become firm, and may undergo no further 
change of shape after the operation. We must, however, 



162 



POTTERY IN ARCHITECTURE. 



avoid any drying of the surface, for a too dry clay would not 
take the shape of the mould. The hand-stamping formerly 
practised exists no longer since the introduction of stamping 
machines or " rebatteuses." We know that the invention of these 
ingenious machines is due to Brethon, a Tours manufacturer. 
All the other machines are only copies of that press. It is 
composed (Fig. 158) of two cast-iron standards bolted to a 
solid wooden platform and joined at the top by a cast-iron table 
which carries the mould. These standards carry a cast-iron 




Eig. 158. Brethon Stamping Press (Chavassieux). 

piece called " poitrine," to which the cap of the machine is fixed 
by two rods. The " poitrine " also has a central opening fitted 
with, little steel friction rollers ; those at the top are movable 
about an axis, those below are fixed. Between these slides 
passes a special piece quadrant-shaped and fixed to a curved 
shaft which turns on two bearings in the two uprights. At 
the end of this shaft is fastened a lever with a counter- 
poise. 

The mould is formed of a cast-iron piece (Fig. i 60) placed 
on the table and held by bolts. The inside is often lined with 
copper; the bottom (Fig. 160) is movable. It rests on the 



BRICKS, 163 

table, and the lower rod with which it is furnished passes through 
an opening in the table and rests against the " poitrine " ; it is 
this rod which removes the brick from the mould. 

How does the machine work ? 

When the lever is raised (Fig. 161) the plate at the bottom 
just touches the upper part of the mould ; the distance between 
the cap, which is furnished with an adjusted plate just sliding 
in the mould, and the upper part of the mould is large enough 
for a brick to be introduced. This distance is regulated 
according to the thickness of the brick, by raising or lowering 
the cap, which is fixed by four bolts to threaded rods. 

When the brick is placed on the movable bottom, the 







*'ig- 159- Stamping Press (Jager). Fig. 160. Stamping Press (Laeis et Cie.}. 

lever is sharply brought down with some violence (Fig. 162). 
The shaft to which it is fixed turns through a certain angle, 
and the quadrant-shaped piece, resting on the lower roller of 
the " poitrine," brings the latter down and with it the upper 
cap. 

The bottom of the mould, the rod of which is no longer 
supported by the " poitrine," drops, but soon meets the cast-iron 
table and stops. The brick is then compressed between this 
bottom and the upper cap, and thus takes perfectly the shape 
of the mould, at the same time acting as a spring and throwing 
the lever forward again. This movement is assisted by the 
counterpoise, and it is sufficient to seize the lever to bring it 
back into its first position. But in rising, the shaft has 



164 



POTTERY IN ARCHITECTURE. 



brought back the quadrant-shaped piece which it bears, and 
by this motion has raised the " poitrine " again, consequently 
also the cap and the rod of the movable bottom of the mould : 
the brick reappears in its former position, but stamped or 
" repressce" as it is called. 




Fig- 1 6 1. Stamping Press (Boulet). 



BRICKS. 165 

The ascending movement of the " poitrine " is facilitated by 
the revolution of the friction rollers on which the curved piece 
acts. This revolution, to be as smooth as possible, requires 
lubrication. Moreover, the vertical rods, which run in guides and 
sockets placed on the cast-iron table, also require lubrication. 
These rods bear all the strain of the sliding motion, and are soon 
worn ; this gives play to the machine. To remedy this wearing 
away, the cap is sometimes furnished with two other rods which 
slide in sockets (Fig. I 5 8), or sometimes the ends of the cap are 
guided by fixed slide-bars, as in Figs. 159 and 160. 




Fig. 162. Stamping Press (Lacroix). 



Fig. 163. Stamping Press (Whitehead). 



In these figures the " poitrine " is hidden by a sheet-iron 
plate to protect the frictional parts from dust, and the curved 
piece is surrounded by a sheath to avoid accidents. 

The action of the machine is very simple, as can be seen 
from Fig. 162, which shows the workman bringing the lever 
forward and the boy preparing to put in another brick. 

This machine and the following ones (Figs. 158-165) are 
based on the same principle as the foregoing. They only differ 
as to details, and especially in the way in which the lever moves 
the cap, and so exercises the compression. In the Lacroix and 



I 66 POTTERY IN ARCHITECTURE. 

Boulet machines, the framework is in one single piece instead of 
consisting of two uprights; this makes the machine more rigid. 

In the Joly machine (Fig. 165) the movement is effected by 
means of a cam working on friction rollers ; the whole piece 
bearing the rollers is guided below by a shaft sliding in a ring 
fixed to the base of the machine. 

This press produces considerable effect, but it is less easily 
handled than the preceding ones. 

The same maker has thought oi moving the mould upwards 
by a system of cranks (Fig. 1 64). The cap being fixed, the 
\vorking of this machine causes less violent shocks than in the 





Fig. 164. Stamping Press with Cranks (Joly). Fig. 165. Stamping Press (Joly). 

previous ones ; it can therefore be worked in any storey of the 
drying-rooms. 

Fig. 163 represents an English press in which the parts are 
made extremely simple ; the sketch sufficiently explains the 
machine. 

The machine represented in Fig. 1 66 is typical of the 
German kind of press ; its working is less simple and less rapid 
than that of the French kind, and nearly all German makers 
manufacture the latter (see Figs. 159 and i 60). 

It is easy with stamping presses to stamp the faces of the 
bricks in depression or relief; it is sufficient to provide the plates 



BRICKS. 



i6 7 



of the cap and bottom with the design in relief if we wish to have 
' it depressed, or in depression if we want it in relief. 

Nevertheless, if we want clear-cut reliefs, it will be necessary 
to maintain the pressure longer than a stroke of the lever can 
effect. This result is obtained by using the Whitehead press 
(Fig. 167). 

The operation is performed by means of an endless screw 
driven by a flywheel and handle. 

Steam Stamping Presses. The Jager press (Fig. 168) is 




Fig. 1 66. Stamping Press, German Type 
(Jacobi). 



Fig. 167. Special Press 
(Whitehead). 



composed of a piston with up and down motion which compresses 
the brick in the mould. 

This motion is communicated to the piston by a crank and 
a system of bent shafts and cog-wheels as shown in Fig. 168. 

Like those worked by hand, this press can also stamp any 
kind of ceramic product ; it will be sufficient to change the moulds 
and substitute others suited to the shape and nature of the 
articles to be stamped. Screw and friction-plate presses as used 
for the manufacture of tiles can also be used for bricks. Fig. 
i 69 shows a press of this kind fitted with a brick-mould. 

Steam stamping presses are very little used because it is easy 



i68 



TOTTERY IN ARCHITECTURE. 



to remove hand-presses when the circumstances of manufacture 
require it, and because the latter have as large an output as the 
former. 

General Remarks as to the Stamping of Bricks. It is an 
excellent method for giving bricks finish and a good appearance, 
indispensable qualities for those intended for facades, as they 
must have clean-cut edges and perfectly smooth faces. 

The process is of no use for ordinary bricks, although many 
manufacturers subject them to it. 




Fig. 1 68. Universal Stamping Tress (Jager). 

In choosing a machine, lightness is desirable, but rigidity 
must not be neglected. The double guiding of the cap and 
the easy lubrication of the frictional parts must be taken into 
consideration as well as the distance apart of the rods ; this 
should be great enough for bricks of at least 0.30 metres 
(i foot) to be stamped. 

Cast-iron moulds give more clean-cut shape than those lined 
with bronze, and they do not wear out so quickly. But with the 
former the removal of the brick requires a lubrication of all the 



P.RICKS. 169 

faces of the mould, while with bronze-lined moulds it is sufficient 
to sprinkle the bricks with powdered dry clay, and this is done 
when they are in stacks or on the waggon when brought up to be 
stamped. 

Notwithstanding the necessary lubrication, which increases 
the cost of stamping, owing to the oil used (generally resin oil), 
and the decreased output (due to time lost in greasing), preference 
should be given to cast-iron moulds if we wish to have fine 
products. The same press can stamp several kinds of products ; 




Fig. 169. P" fiction Stamping Press (Jager). 

it is sufficient to change the mould, the bottom plates, and the 
cap. 

We have already stated that bricks cannot be stamped im- 
mediately after they come from the expression machine ; they 
must be left to gain firmness, until they are in a fit state, neither 
too hard nor too soft, to take the shape of the mould. When 
space allows, they are placed on edge on a level tiled floor, or on 
boards, whence they are afterwards removed to the press. This 
can easily be moved, and is placed in a convenient position. It 
is better to carry out the process on the ground-floor on account 
of the shocks produced by the action of the press. 

If space is limited, the bricks are placed on shelves, and when 
they are ready to be stamped, the press is brought near them. 



170 



POTTERY IN ARCHITECTURE. 



A workman takes the bricks from the shelves, and puts them in 
the mould. 

PARTICULARS OK STAMPING PRESSES. 



Name of Maker: ^feUst] Jager ' 


Jacobi. 


Joly. Lacroix. 


Laeis. 


Whitehead. 




Fig. 158 Fig. 159 


Fig. 1 66 


Fig. 165 


Fig. 164 Fig. 162 Fig. 1 60 


Fig. 163 Fig. 167 


Weight of machine 








in kilos . . . 370 500 


850 


600 


400 260 


800 


600 8co 


Price in francs with 












mould complete 550 


IOOO 


500 


570 350 


850 


350 625 










Remarks . . . Four Slide- 


Fly- 


Lever 


Lever Two 


Slide- . . Special 


guides. ; bars. 


wheel. 


and 


and guides. 


bars. 


: press 






cam. 


cranks, j 




without 










mould. 



(2) DRYING. 

The object of this is to take from the bricks coming from 
the machine or mould the uncombined water contained in them. 
The quantity of this is very variable : while it may be neglected 
in products made from dry clay, it reaches a maximum in bricks 
made from soft paste. 

Drying is an important process ; if it is complete, the firing 
will be easily and economically effected ; if incomplete, the firing 
is rendered difficult and more costly. 

In factories which continue work during the winter, drying 
should be carried out in closed drying-rooms warmed by direct 
heat, or, as is more generally the case, by transmitted heat from 
the kilns. In brickworks which are only open during the 
summer, the drying is done in the open air without shelter, or 
under sheds, or in storeyed drying-rooms. 

Open-air Drying. A. WITHOUT SHELTER. This is the 
most economical method ; although excellent in hot countries, 
it often causes disappointment in northern countries, on account 
of the frequent rain ; very often it has to be abandoned, and 
sheds are constructed. 

The arrangements made are as follows ; 



T.RTCKS. 



171 



Near the place where the moulder works, a rectangular piece 
of ground of about a yard or a yard and a quarter in breadth, 
and of a length depending upon the space available, is raised in 
level. On each side of this bed two trenches (R R, Fig. 171) 
are dug in the following manner. A line is stretched in position, 
and along the line lumps of earth are taken up with a spade, and 
laid in a row by the cord. These lumps form the boundary of 
the raised plot ; the trench is about a foot and a half wide. The 
space between the two parallel rows of clods of earth is rilled with 



HACK OF BRICKS. 



Fig. 170. 





Fig. 171. 
Fig. 170. View from Above. 



Fig. 172. 
Fig. 171. End View. 



Fig. 1 72. Side View. 

soil taken from the trenches, and if necessary from elsewhere ; 
when well rammed down and dressed this forms the foot of the 
hack P. 

On this foot the bricks are arranged in open-work hacks, the 
bricks being placed in an oblique direction which changes for 
each layer (Figs. 170, 172). 

The first layer is sometimes composed of fired bricks, in 
order that the dampness of the earth may not soften the unbaked 
bricks supporting the whole hack ; sometimes a layer of straw is 
put down. These precautions, which are useful at the beginning 



172 POTTERY IN ARCHITECTURE, 

and end of the season, are less so in the middle. Two layers at 
a time are stacked along the whole length, and thus four layers 
may be placed in position and then left to recover for a day or 
two so that they may harden and be able to support further 
layers. The vertical rows thus placed one over the other are 
called "feuilles " ; the two middle " feuilles " are first erected, and as 
the air passes quickly between the bricks, drying is fairly rapid. 
For the sake of rigidity, not more than eight or ten rows should 
be placed on each " feuille," but the bricks at the foot are then dry 
enough for a new " feuille " to be begun on each side of them, so 
as to make altogether four " feuilles." When their height is 
sufficient to consolidate the middle " feuilles," more bricks are 
placed on them. Generally a height of 15 to 1 8 layers is 
attained, that is to say, about 5 to 7 feet. The top of the hack 
is so arranged that the straw matting 1 placed on it has the slope 
of a roof. Instead of matting, which soon wears out, tiles are 
often employed. 

It will be easily understood that the total length of the hacks 
depends upon production, since only four layers at a time can be 
placed in position. For works producing 6000 to 7000 bricks a 
day, it will be seen that a length of I 500 to I 800 bricks will be 
required, that is to say that, counting 0.08 m. for the thickness of 
the brick and intervals, we must have one, or, better still, several 
hacks, with a total length of i 20 to 140 metres. In the heat of 
summer this length is not necessary, but it is better to have it 
arranged in advance in order to avoid inconvenience in any case 
of bad weather. The great disadvantage of open hacks is that 
they are exposed to this. Therefore in a large number of 
factories they are sheltered by light wooden sheds like those 
represented in Figs. 173 and 174 and called "hallettes" 

B. DRYING UNDER SHEDS. These sheds or " hallettes" are 
about i 2 feet broad, the posts are 5 feet high, but the length is 

1 The matting consists of strong straw plaited together, and about two yards in length. 
It is attached above and below by two little switches arranged lengthways. Instead of 
straw 7 matting, movable squares of wood of about thirty inches in height are sometimes 
used, and placed vertically against the bricks ; over these, movable wooden roofs are 
placed which take the place of matting. In this case the hack is neither very high nor 
very broad, and the bricks are completely enclosed. 



BRICKS. 173 

variable. To strengthen them against the wind, solid stakes are 
driven into the ground and nailed to the uprights, which, to 
avoid the dampness of the soil, rest upon baked bricks. In con- 
sequence of their lightness, these sheds are easily taken to pieces, 
and are moved as the work advances ; the brick-maker should 
choose a convenient position, so that they may be used as long 
as possible. To obtain satisfactory drying the space between 
two sheds should not be less than 10 metres, so that air and 
light may have free access. 

The same sheds do as well for hand-manufacture, either by 
the Flemish method or by lever presses, as for that by machinery. 
In the latter case, however, special precautions are advisable: we 
must avoid the action of the sun, which dries the bricks too 



SHED OR "HAI.LETTE" FOR THE OPEN-AIR DRYING OF BRICKS. 




Fig. 173. Transverse Section. Fig. 174. Elevation with and without Planks 

(Scale of I centimetre to the metre.) 



quickly and warps them. Certain clays cannot bear drying in 
the open air, but require closed drying-places in which even 
currents of air must be avoided. Under a shed such as we have 
just described, they begin by stacking two " feuilles " in the middle, 
and when the foot is quite dry, a third and a fourth are placed, 
one on each side, which dry in their turn ; then another is placed, 
and so on. Only one row must be placed at a time, for any 
brick enclosed when fresh between other bricks, remains fresh and 
does not dry. 

The thickness of the hack is as much as 1 4 to i 6 " feuilles," 
the height at the centre is from 18 to 22 layers, that is to say, 
about 8 feet ; but the other "feuilles" are not so high on account of 
the slope of the roofing. The bays are 4 yards long, that is to 



74 



POTTERY IN ARCHITECTURE. 



say, about 50 bricks placed side by side with an interval of about 
a finger's thickness between them. 

A shed 60 yards long (15 bays) can therefore shelter 
230,000 bricks. But such a number is rarely allowed to ac- 
cumulate, because for the requirements of manufacture room 
must be made from time to time, and the shed relieved of the 
dry bricks under its shelter. 

In order to guard the bricks from the rain which might be 
driven by the wind under the shed, matting or brushwood is 
used and is laid against the foot of the " feuilles," when the 
weather is uncertain. But this precaution is only necessary when 
the hack is quite close to the side of the shed. 

As deal of the usual trade dimensions is used, it is easy, 
knowing the price of the wood, to make an estimate of the cost 
of a shed (see p. I 82). 

C. DRYING UNDER A COLLECTION OF SHEDS. We have 
said that the preceding arrangement allows of the drying of 




Eig. 175. Section of several Combined "Hallettes." (Scale, 1 6 millimetres 
to the metre.) 

machine-made bricks, but in this case, to avoid the too rapid 
action of the sun, it is advisable to place together a certain 
number of sheds, which thus form one single open surface (Fig. 
175). One side of the covering is formed of Venetian shutters, 
which enable a draught to pass from the lower to the upper part 
of the shed. For this part of the covering a direction least 



BRICKS. 175 

exposed to rain will be chosen. The other part is made of tiles 
or, more cheaply, of planks as in ordinary sheds ; for the use of 
tiles almost triples the cost. A covering of tarred wood lasts 
twenty years or even longer, as we have observed in many cases. 
As economy is required in this class of construction, a simple 
zinc gutter 6 or 7 inches broad is used and fixed by hooks, and, 
to be ready for an always possible accident, the part between the 
uprights is reserved for a tramway or the passing of barrows. 
To avoid waste, the wood used should be of the usual trade 
dimensions, which, as we know, are measured in units of 33 
centimetres (about i foot). For the estimate of such a shed, we 
refer the reader to p. 183. 

Storeyed Drying-rooms. These are used in factories con- 
taining continuous kilns. The kiln or kilns are placed in the 
centre of the building in such a way that the heat from them 
spreads to the different storeys by traps in the flooring. When 
necessary, vertical movable pipes are fixed to the holes in 
compartments which are cooling to conduct the heat to places 
where it is required. The bricks are arranged on the floor 
in hacks as previously described. Shelves are generally useless, 
except for bricks to be stamped, when the space at disposal is 
too limited. 

The floors are strong enough to bear the weight of the bricks. 
Casements are placed in the walls, and are opened to produce 
draughts and hasten the drying of products which are not injured 
by air-currents. Such a drying-place can be constructed in 
various ways; above all things economy is desirable. Therefore 
any building which involves much masonry should not be con- 
sidered ; even iron is not economical enough, and we should 
recommend the erection of a simple one-storeyed or two-storeyed 
shed, according to the daily output. In order to avoid the use 
of pieces of large size which are always costly, we should sub- 
stitute for them joists fastened together with bolts. Fig. 176 
represents a drying - shed constructed in this way. The 
kiln has 20 compartments of 4 metres, and has a total length 
of 44 metres ; the building over it is 48 metres long, and is 
divided into 12 bays of 4 metres. Its width is 20 metres, the 



7 6 



POTTERY IN ARCHITECTURE. 




URICKS. 177 

height of the storeys is 3 metres for the ground-floor and 2 for 
the others. Not including the surface of the kiln, and reserving 
the ground-floor for the management of the kiln and repressing 
of bricks, the surface of the drying-rooms will be : first floor 48 
x 20 44 X 10=520 square metres ; second floor 48x20 = 960 
square metres; third floor 48 x 14 = 672 square metres; making 
a total of 2152 square metres. From this surface we must take 
the passages necessary for circulation of vehicles and for ventila- 
tion. We will suppose that the same system of stacking is used 
as in open-air drying, which is the quickest and most economical. 
Allowing five " feuilles " thickness to the stack, that is about 1.15 
metres, the empty space between each stack will be about one 
metre. 

There will be then altogether : on the first floor 10 -5- 2.1 5 = 
4 stacks; on the second floor 20-1-2.15 =9 stacks; and on the 
third floor 14-7-2.15 = 7 stacks; that is to say, a total of 20 
stacks 48 metres in length, and each row in a stack will contain 
about 585 bricks. As two rows can be placed together, we see 
that by laying one row per day, 20 X 2 = 40 rows of 585 bricks 
each can be accommodated; this makes about 23,000 bricks. It 
is certain then that with a building of the dimensions stated 
above the daily production might be as much as 25,000 to 
30,000, and this even under unfavourable circumstances ; for it is 
rare, as we said on p. 172, that 3 or 4 layers cannot be stacked 
one over the other. But it must not be forgotten that in winter 
and in bad weather drying is a slow process. 

The building shown in Fig. 177 is closed at the sides by a 
brick wall of 8 inches thick, provided with windows which allow 
of air-currents being produced. Some builders make the posts 
supporting the framework rest on the kiln (Fig. 231). This 
arrangement is not advisable, for, however strongly the kiln 
may be built, it undergoes expansion, which after a time would 
have a dangerous effect on the whole construction ; besides, it is 
not worth while to be exposed to annoyances for such a slight 
economy. 

In the flooring openings are made for the hot air to pass 
through ; the communication between the storeys is effected by 

12 



POTTERY IN ARCHITECTURE. 



staircases or inclined planes, but the bricks are raised by 
machinery. 




Storeyed drying-buildings contain open-air or closed drying- 
rooms according to the season ; from the dimensions we have 



BRICKS. 179 

given, it is evident that they occupy a large space, which increases 
with the daily production. In order to economise space, cost of 
installation, and labour, attempts have been made to carry out 
the drying in closed spaces by artificial means. 

Closed Drying-rooms. Numerous systems have been de- 
vised ; attempts have been made to use the heat escaping from 
the kilns by bringing it into the rooms by special arrangements, 
and by using the draught of the chimney, and, later on, of a 
ventilator. But the handling of the bricks was a rather serious 
obstacle, besides the difficulty of bringing the hot air into the 
chambers, and the inconveniences caused to the working of the 
kiln. 

Some have thought of using stoves warmed by a special 
furnace, and actively ventilated ; and, to lessen the labour 
required, the products have been placed upon waggons and run 
into heated galleries, called tunnel drying-rooms. These are much 
used in the United States, where the manufacturing conditions 
are somewhat different from our own. The principle of these 
drying-tunnels is as follows : 

The products to be dried are introduced into a closed 
gallery, and automatically pushed forward, while at the same 
time a current of air is produced in the opposite direction ; in this 
way the bricks meet more and more dry air as they advance, and 
finally arrive at the end of the gallery perfectly dry. In order to 
carry out this principle, the gallery contains a line of rails on 
which waggons with shelves, as in Fig. 1 86, run. 

At the entrance of the gallery is a room with doors ; through 
one door the products coming from the machines enter, the door 
is closed, and another leading into the tunnel is opened (Fig. 
178). This tunnel is provided with a slow ventilation either 
by a ventilator or by draught from the factory chimney ; but 
generally the latter is insufficient, and a ventilator is required. 
At the other end of the tunnel is an opening communicating with 
the outer air. In summer this air suffices for the drying, but in 
winter it is mixed with hot air given out by the cooling of baked 
products, or by any other economical method. The dry air from 
outside only acts upon objects containing very little moisture ; it 



i8o 



POTTERY IN ARCHITECTURE. 



has no bad effects upon them, and completes their desiccation. 
As the air advances through the tunnel it becomes more and more 
loaded with the moisture it receives from the bricks, and when it 
reaches the waggons last introduced, it is almost saturated : it 
therefore only takes from the fresh products the little moisture 
required to completely saturate it before being expelled. The 
quantity of air and its temperature must, for this reason, be 
carefully regulated as it enters. 

When one waggon goes in, another comes out. Thus the 
action is continuous, and a few days are sufficient, at all times 
of the year, to effect drying. Besides, it will be seen from these 




Fig. 178. Tunnel Drying-room (Lacroix). 

arrangements that the bricks, when once placed on the waggon, 
are not handled again until put in the kilns. We have just 
stated the advantages of this system of drying ; we must now 
mention its inconveniences. 

Of these, the most serious is, in our opinion, that it only 
applies to one kind of product. It will be understood, in fact, 
that in the kilns it is necessary to mix products in order to 
utilise space and also to satisfy requirements of consumers. But 
manufacture cannot exactly follow these different phases ; with 
ordinary drying-rooms there is no inconvenience in this, since 
each kind of article has its own drying-place, whence it is taken 



BRICKS. 



181 



as required to the kiln. But with drying galleries, it is no 
longer the same ; in fact, the products must follow one another 
in the order in which they are to be placed in the kiln, otherwise 
they will have to be handled again, and the benefit of economy 
in labour disappears, or else stock will have to be increased and 
a place reserved for loaded waggons which are not at once kilned. 
Another inconvenience, but one more easily remedied, consists 
in the behaviour of clays while drying. There are some which 
cannot bear the draught without splitting ; others resist the 
current of air well, but crack under the influence of hot air. It 




Fig. 179. Closed Galleried Drying-rooms (Chambers). 

is evident that these difficulties may be overcome by great 
precautions and a well-regulated current, but it must not be 
forgotten that, to attain results economically, the drying must 
be done in two days in order to reduce the stock of waggons. 
But all clays cannot bear such rapid desiccation, hence only 
experience can guide us. 

To summarise, galleried drying-places are of great use in 
case of extensive manufacture of one single article with clay 
which bears rapid desiccation. That is why these drying-places 
are much used in the United States, where enormous quantities 
of the same article are made in one factory. Moreover, by the 



1 82 POTTERY IN ARCHITECTURE. 

arrangement adopted (Fig. 179), different products may be 
placed in the different galleries ; but then the cost of installation 
is very high, and such an expense cannot be thought of for an 
output which does not exceed several millions, like the majority 
of French factories whose mean production is two to three 
millions and maximum about fifteen millions of one single 
article. 

Estimate of the Cost of Different Drying-places. Com- 
parison of these Prices. The installation of drying-rooms for 
bricks should be as economical as possible ; so we shall use, 
in the following estimates, only deal of the usual dimensions. It 
is evident that in places where the wood of the country will 
be cheaper than northern firwood, we must not hesitate to 
use it. 

i. ESTIMATE OF A " HALLETTE" (Figs. 173 and 174): 

Joist. 

2 Posts A, 0.22 x 0.08 : 2 of i. 66m. =2x1.66 x= i. 66m. \ 

I King-post A, of i.oo m. = I x i.oo x ^, = 0.50 m. 

1 Tie-beam B, 0.22 x 0.08 : 4 of 3.66 m. = I x 366x } =0.915 m. / 4.408 m. 

2 Supports C, 0.22 x 0.08 : 6 of i.oo in. =2 x i.oo x =0.333 m. 



-19-95 



2 Piles A, of i.ooo = 2 x i.oo x i- = i.ooo m. 

Joists. 

g z + f 3 Purlins .#, of 4.00 m. = 3 x 4.00 x = 3.00 m 

Ol o 5 I 6 Supports C', of i.oo - 6x i.oox ^ = i.oo m 

.^ c I 24 Planks 79, 0.22 x 0.08 : 5 of 2.66 m. =24 x 2.66 x J =12.75 ni - I 

o *" "" V24 Cover-joints 5,0. 22 x 0.08 : 20 of 2.66 m. =24 x 2.66 x J,, = 2.20 m.J 



If we suppose that we have to cover about 2500 square 
metres, which represents 176 bays of 4 m. by 3.66 m., which 
we shall divide into I i sheds of i 6 bays, there will be : 17x11 
= 187 trusses and 176 intertrusses. The total cubic contents 
will be : 

187 x 4. 40 A 

i?6 x I9>95 | =4334 x 0.22x0. 08 = 76. 278 cubic metres. 

Recapitulation.- Valuing the cubic metre at 80 francs, including preparation of the 
ground, various fittings, etc., the cost will be 76.278 x 80 6102.24 fr. 6102.24 fr. 
Tarring of the outside extra : 3745 sq. metres at 0.40 francs. . 1498.00 

Sundries ........... 99' 76 

Total . 7700.00 fr. 



BRICKS. 183 



2. ESTIMATE OF ONE BAY OF COMBINED " HALLETTES " 
(Fig. 175). The woods used are joists 0.22 x 0.08 and basting 
0.15 x 0.06 : 



2 Posts A, Joists of 2 in. = 2 x 2 x i = 2.00 m. -j 

4 Ties C, ,, i m. =4 x i x J=o.66 m. r3-3 2 ni. 

2 ^, ,, i m. and 0.33 m. = 1.33 x \ =0.66 m. 

I Tie-beam F, o. 15 x 0.06, Bastings of 4 m. = I x 4 = 4.00 m. =4.00 m. 

6 Ties B, Joists of i m. and 2 of O.66 in. = 7.33 x = 1.22 m. \ 
12 Planks D, ,, 4111. = i2X4x 1 = 9.60111. [-13.22111, 

1 2 Cover-joints E, ,, 5 m. = 12 x 4 x ^- = 2.40 m. 

4 Purlins F, Bastings of 4 m. =4 x 4= 16.00 m. \ 

4 Plank-supports ^, ,, 1.33 m. =4 x 1.33 = 5.32 in. \Z l -l 2 '- 

13 Planks (7, o. 15 x 0.06 : 5 of 4 m. =4 x 13 x |= 10.40 m. J 



Supposing a surface of 2640 metres to be covered, that is 
to say, about that of the storeyed building in Fig. 177, we should 
have a rectangle of 44.10 m. (9 divisions of 4.90 m.) by 60 
metres (i 5 divisions of 4 metres), including 16x9= J 44 trusses 
and 15 x 9 = 135 intertrusses. 

The total cubic content of such a drying-place would then be : 

I 44 x 3-32= 46o.8oj 2 og 

135 x 13.22 = I798.20/ 
and . 

144 x 4.00= 576.00 j = g gxa ISxao6 = 43.622 cubic metres. 
135 x 31.72=4282.00 J 

Total . 83.380 

Recapitulation. The cubic metre is valued at 80 francs, erection and all fittings 
included, that is : 

83.3800.111. at 80 fr. =6670.40 fr. 

600 metres of gutter at 2.50 fr. = 1500.00 fr. 

Tarring of 3250 metres with Norwegian tar at 0.40 fr. = 1300.00 fr. 
Preparation of the ground, kennel-stones for running 

off the water, and sundries ..... 529.60 fr. 

Total . 10,000.00 frs. 



A drying-place of these dimensions does very well for a 
daily production of 25,000 to 30,000 bricks; it can evidently 
only be used during the summer. Being strongly built, it is 
sure to last at least thirty years, and may certainly last longer. 



184 TOTTERY IN ARCHITECTURE. 

2A. COMBINED " HALLETTES " ROOFED WITH TILES. The 
volume of wood required is as follows : 

Joists. 

Cubic content of a truss. The posts are doubled, the rest is unchanged 5.32 m. 

Basting. 
No change for the basting . . . . . . . . . 4.00 m. 

Joists. 

Cubic content of an interlniss. The planks and cover-joints disappear, 
there remains then . . . . . . . . . . . 1.22 m. 

To the basting, there must be added 5 rafters of 0.06 x 0.07 4 metres 
long ; that is to say, 10 metres extra . . , . . . . 4 1 -? 2 m - 

The total cubic content becomes then : 



. g 

i. 22=164. 7oJ 



135 x i. 22=164 
i 44 x 4.00- 576.oo 
135x41.72=5632.20 



Total 72.25 c.m. 



Recapitulation. 72.25 cubic metres at 80 francs .... 5780 fr. 

2160 square metres, covered with tiles (13 to the metre at 90 fr. 

per 1000) including laying at 2.50 fr. the metre ..... 5400 

600 metres of gutter at 2.50 fr. . ....... 1500 

Preparation of ground and sundries ....... 520 



Total . 13,200 fr. 

The cost is thus increased about 30 per cent, and it must 
not be forgotten that the simple interest on 3200 francs for 
twenty years at 4 per cent, is 2560 fr., that is to say, about 
half of the value of the plank roofing, even admitting that it 
has to be renewed entirely at the end of that time, which is 
not so. 

3. ESTIMATE OF DRYING-ROOMS IN STOREYS (Figs. 176, 
177): 

TIMBER-WORK. Cubic contents of a truss. 



2 <f-f m - [34.666x4= ,38.66,,,. 

2 of 9.66 m. 

Beams H. . . . ist storey 2 of 5.33 m.- 
2nd ,, I of I o. 66 m. 

2 of 4.66 m. ^-50.66 x 4 = 202.66 m. 
3rd ,, i of 10.66 m. 
2 of 4.66 m. 

Beam supports A, 4 doubles of 4 m. 16.00 x 2 = 32.00 m. 
Rafters A. 2 ,, 10.66 m. 10.66x2 = 21.32111. 

Tie-beam A. i double of 10 m. 10.00x2 = 20.00111. 

King-post A, i ,, 3111. 3.00x1= 3.00111. 



BRICKS. 185 

Basting. 
'Small beams 12 doubles of 2m. ^ 

Rafters 2 2. 33 m. I 

^40.66x2 = 81.33 m. 
4 1.66 m. p 

2 ,, 2.66 m.J 

Cubic content of an intertruss. 

Joists. 

Joists : 20 on the 1st, 39 on the 2nd, 29 on the 3rd floor = 88 at 4111. =352.00) 
Purlins : 9 of 4 m. = 36.00) 

Basting. 
Rafters (0.40 m. from axis to axis) : 20 of n.66 m. =233.33 m - 

Total cubic contents of 13 trusses and 12 intertrusses. 



-212.222 c.m. 



MASONRY. 

2 Lateral walls 8 m. high x 48 m. long = 768 sq. m. ~j 
2 Gable-end walls 8 m. ,, x 20 m. ,, =320 ,, Iii68 sq. m. 
2 ,, ,, 2m. ., x 20 m. ,, = 80 J 

/ 72 windows in side-walls^ 
Less j 32 

I 4 doors 3 m. x 2.50 m. = 30 sq. 



in side-walls j ^ of 2 m x fi ^ , 

m end-walls J V 394 sq. m. 

11. X2.50 m. = 70 sq. m.J 



There remain 774 sq. m. 
The thickness of the walls being 0.22 m., the cubic contents 

= 774 x 0.22 = 170. 720 cubic metres. 

Recapitulation : 

212.222 cubic metres of timber at 80 fr. per cubic metre = 16,977.76 fr. 

1 70. 720 masonry at 30 fr. ,, ,, =5,121.60 

2344 sq. metres poplar- wood planking, 0.035 m - thick at 3 fr. = 7,032.00 

1 1 20 sq. metres of tile roofing at 2 fr. 50= 2,800.00 

1 20 metres of gutter, including descent at 2 fr. 50= 300.00 

104 windows, including glass and paint at 50 fr. = 5,200.00 

4 doors, including paint and fittings at 100 fr. = 400.00 

Sundries . . . . . . ... . . 1,168.64 



Total . 39,000.00 fr. 

The gross amount of surface available being about 2500 
metres, this comes to 15.60 francs per metre. 

In the preceding estimates we have taken average French 
prices ; it will be easy, the cubic contents being the same, to 
calculate prices for any other locality. 

4. ESTIMATE OF A GALLERIED DRYING-PLACE. According 
to M. Lacroix, who is interested in this kind of installation, the 
cost of a drying-place sufficient for a daily production of 25,000 



1 86 POTTERY IN ARCHITECTURE. 

bricks is as follows, supposing that they remain not more than 
forty-eight hours (Fig. 178) : 

The galleries will contain 50,000 bricks, and require 100 waggons 
(Fig. 185) holding 500 bricks each ; we must add 25 waggons for 

use outside ; hence altogether 125 waggons at 120 francs . . 15,000 fr. 

The tunnel, 40 metres long, costs about ...... 5,000 

Heating apparatus and accessories . . . . . . . 7, 500 

Rails, turn-table, etc. ......... 2,000 

Sundries ........... 500 

Total . 30,000 fr. 

Besides the cost of installation, the cost of heating must be 
considered ; this varies from I to 3 francs per I ooo bricks. 

To summarise and in conclusion : storeyed or galleried 
drying-places with special heating arrangements are necessary 
for factories which work during the winter. For the latter it is 
especially necessary that the products should be able to bear 
a rapid desiccation by a current of hot air, and that the 
conditions of manufacture allow of regular entrance and exit 
of the bricks. When this is so, we must calculate whether 
economy in labour makes up for the cost of heating. For 
factories which only work during the summer, choice may be 
made between simple " hallettes " and combined " hallettes." 
The cost of installation of the latter is greater, and they have 
less drying power, but they are more easily managed ; the 
expense of tramways is reduced, and there is no danger of 
injury from the heat of the sun. In brick- making by machinery 
they are preferable to the simple sheds. 

Transport of Products front the Machines to the Drying- 
sheds. There are two cases to be considered: (i) when the 
drying-places are on the ground-floor, on the same level as the 
machines ; (2) when they are in storeys. 

(i) When on the Ground-floor. In this case the transport 
is effected by means of barrows and waggons. The barrows, 
which are of a special shape, are made of wood (Fig. 1 80) or 
of iron (Fig. 181); they consist of an inclined platform on 
which the bricks are placed, either flat or on edge, in rows 
separated by spaces of a few centimetres. 



BRICKS. 



I8 7 



When the bricks are made of fairly firm paste, other rows 
may be placed on the first, but the first must be sprinkled 
with sand, otherwise the bricks will stick together. Each 
barrow takes from 30 to 50 bricks, according to their 
dimensions. The barrows may have one wheel or two. 




Fig. 180. Wooden Two-wheeled Barrow for transporting Fresh Bricks (Lacroix). 

Whenever the production is fairly large, it is advisable to 
substitute waggons for barrows. 

Rails of 0.40 or 0.50 metre gauge are laid down in the drying- 
sheds, and at the end of the shed a line of rails is placed, at 




Fig. 181. One-wheeled Iron Barrow for transporting Fresh Bricks (Paupier). 

right angles to the other, and carrying a transfer trolley (Fig. 
182), which is more economical and more quickly worked than 
a turn-table. 

This arrangement is particularly advantageous in combined 



POTTERY IN ARCHITECTURE. 



sheds (Fig. 175); it is at the same time useful for carrying 
away dry products. 

The waggons used consist of a simple framework (Fig. I 84) 
on which is placed a wooden platform. To push the waggon, 




Fig. 182. Transfer Trolley (Lacroix). 

an iron rod is fixed to one end of the frame. The waggons 
used for transport of dry and fired bricks may also be employed 
(Fig. 183). The only difference is that these have two sheet- 
iron ends to the platform. The bricks should be made of 
fairly firm paste, so that several layers may be taken. 




Fig. 183. -Waggon for Transporting Bricks (Decauville). 



If soft paste is used for manufacture, it is better to employ 
waggons with shelves (Figs. 185, 186) which allow of about 
500 bricks being carried on planks. These waggons are also 
useful with cutting - tables with side removal (Figs. 145, 
146). 

All that is required is to carry the board, with the bricks 



1JRICKS. 



189 



on it, from the table to the waggon ; labour is thus much 
simplified. 

The same waggons are also used for drying in galleries ; 
the spaces at the centre of the waggon and between the planks 
allow the hot air to pass and so assist desiccation. 



Fig. 184. 



Fig. 185 



Fig. 1 86 




Fig. 184. Frame of Waggon for carrying Bricks (Lacroix). 

Fig. 185. Waggon with Shelves, empty (Lacroix). 

Fig. 1 86. Waggon with Shelves, full. 

(2) Storey ed Drying-rooms. In this case the products have 
to be transported from the machines to the different storeys 
of the drying-sheds. Therefore the use of lifts is indicated. 
These may be arranged for carrying full barrows and waggons ; 
they are then ordinary lifts of large size. They work satis- 



190 



POTTERY IN ARCHITECTURE. 



factorily but require much power. Hence it is preferable to 
use lifts which raise the bricks direct 
(Fig. 187). On the different storeys boys 
remove the bricks and place them on 
barrows or waggons for transport to the 
various parts of the drying-rooms. 

The trays being hung so that they 
always remain horizontal, a brick may be 
overlooked without its upsetting in passing 
over the top of the lift. 

The wheels of the lower drum are 
adjustable, so that a proper degree of 
tension can always be given to the end- 
less chain. This lift is placed close to the 

Fig. i87.-Vertical Lift cutter of the mac hine, and the bricks are 

for raising and lower- 




ing the Manufactured 
Products ("Bernhardi 
Sohn). 



thus passed direct to the trays. 



Particulars of Vehicles for Ihc TrcDisport of Bricks. 

Wooden barrow, Lacroix (Fig. 180), weighs about 20 kil., carries 
from 30 to 50 bricks, and costs ....... 

Iron barrow, Paupier (Fig. 181), weighs about 33 kil., carries from 
30 to 50 bricks, and costs ........ 

Decauville waggon (Fig. 183), length I metre to 1.40 metres, runs 
on a gauge of 0.40 in., carries from 150 to 200 bricks, and costs 
from . . . . . . . . . . 90 to 130 fr. 

Lacroix waggon with shelves (Figs. 185, 186), carries up to 500 

bricks, and costs . . . . . . . . 1 1 2 fr. 



5 fr- 
50 fr. 



(3) FIRING. 

The firing of pottery is the most delicate and the most 
important process in its manufacture. On the success of the 
operation depends the good quality of the products which have 
already required so much care and time. For a very long 
time firing was effected by burning wood in simple ovens, but 
afterwards coal was substituted for wood in countries possessing 
mines. 

As the means of communication were developed, this sub- 
stitution became more common, but the method of firing bricks 



BRICKS. 

underwent little change. Nevertheless the old Flemish process 
was gradually replaced by the use of various kilns which 
simplified the work, and in 1865 a great step in advance was 
made by the invention of the continuous kilns of Hoffmann 
and Licht of Berlin. Since then the substitution of gas for 
coal heating has been another improvement. We shall divide 
this part of the subject into several paragraphs according to 
the various methods of firing bricks : 

1. Firing in clamps. 

/^. Open. 

2. in intermittent kilns ^.Arched. 

M. With solid fuel. 

3. in continuous kilns ^ With gas . 

Intermittent kilns are those which are allowed to cool after 
firing, to permit of the removal of the bricks. 

Continuous kilns, as the name shows, are always active 
throughout the season or even the whole year. The heating 
and cooling of the products are effected methodically. 

We must not think of describing all the kinds of kiln used ; 
every manufacturer has his own style ; but, generally speaking, 
the differences between the numerous types of kiln are of no 
great importance. We shall content ourselves with describing 
one example of each system, specially mentioning those which 
seem to us most to be recommended on account of their 
economical working and the beauty of the products obtained. 

I. Firing in Clamps. 

Flemish Method. This is undoubtedly the simplest 
method ; but it is neither the most economical, nor the one 
giving the best results. We shall study it in detail because, in 
an improved form, it is still the one most widely used in the 
numerous brickworks of moderate importance. 

This system consists of placing the bricks in regular layers 
intersecting one another, and scattering between them finely 
divided coal, the combustion of which causes the baking of 
the bricks. In order to ignite this coal the foot of the kiln is 
arranged as follows : 



192 



POTTERY IN ARCHITECTURE. 



Upon a smooth piece of ground, slightly elevated so that 
rain-water may not rest on it, rows of fired bricks are laid down 
on edge (Fig. 188). The number and length of these rows 
depend upon the quantity of bricks to be fired, which may be 
from 200,000 to 600,000. The second layer (Fig. 189), placed 
like the first, cuts it at right angles, the third and fourth are 
arranged as in Figs. 190 and 191. At distances of a yard 



iaoi; Ju fonrneau avec 




Eigs. 188 to 200. View of a Furnace, Elevation, Section, and Plans. 

are placed furnaces as shown in Fig. 199; they go from one 
end to the other of the stack, and, before the fifth layer is 
placed, are filled with wood. Then the vaults are closed, and 
above, among the bricks, are placed parallel rows of large lumps 
of coal which will be kindled by the flame from the wood, and 
by their slow combustion will set fire to the fine coal of which 
we shall speak later on. When once the foot of the kiln is 



BRICKS. 193 

finished, the "cuiseur" or stoker proceeds to light the fires. 
When the coal is thoroughly kindled, the " enfourneurs " begin 
their work ; there may be one or two, according to the size of 
the stack, and they are assisted by " entredeux," who receive 
the bricks from the hands of the barrow-men. The " en- 
fourneur," the u entredeux," and the necessary number of 
barrow- men form a gang. The early part of the work is 
unpleasant for the " enfourneur," who has to lean continually 
over burning coal surrounded by the gas and smoke coming 
from it, therefore he cannot remain long over the furnace ; 
another takes his place, and the work continues. When the 
clamp is finished, the stoker sprinkles finely divided coal over 
it. This he does with special baskets which are handed to 
him by the gang ; with a quick motion and without stooping 
he sprinkles the coal in a uniform layer over the bricks. Then 
in the same way he sprinkles a little sand to prevent the bricks 
from sticking together. When the operation is finished, the 
stacking is recommenced, and a new " clamp " is formed at 
right angles to the first. 

When this is finished, it is sprinkled with coal and sand, 
and another is begun ; in this way six or eight clamps are 
built in a day, according to the progress of the fire. 

During the stacking of the bricks, the stoker dilutes some 
clay, and when the paste is sufficiently liquid, he plasters over 
the facing of the four sides of the clamp. After the fire is 
well alight he closes the entrances to the furnaces with bricks, 
which he also coats with clay. The fissures which form in 
the clay plaster permit the entrance of the air necessary for 
combustion. 

Besides, if it is necessary at any time to stimulate the fire 
at a given point, one or several furnaces may be opened again. 
The fire passes from clamp to clamp, and the skill of the 
" cuiseur " consists in guiding it as regularly as possible. 
Experience alone can give the necessary practice, but a few 
general hints as to the course to be adopted may be offered. 
We have stated that a slight layer of finely divided coal as 
uniform as possible is thrown over all the clamps ; it is by 
13 



194 POTTERY IN ARCHITECTURE. 

this that the fire is communicated. Experience teaches the 
amount of coal which should be scattered, but the points at 
which the fire requires to be retarded and stimulated are shown 
by indications that should be carefully observed. Thus, if we 
see the bricks of the last clamp becoming white or yellow, it 
means that the flame is near, and consequently that it is moving 
too fast in that neighbourhood. Although we might not think 
so, this will be the place where more coal must be added. 
When, however, no signs of combustion appear, the fire is 
sleeping, as they say ; therefore no more fuel is added. And 
finally, in order to retard the action of the fire where there is 
too much activity, not only is much coal added, but the spot 
is sanded so as partially to fill up the interstices of the bricks. 
The last clamp built on the previous day should be alight in 
the morning ; this is a sign that all is going well. The " cuiseur " 
quickly scatters coal and sand, then the " enfourneur " who 
follows him hastens to make another clamp ; but, in spite of 
these workmen being accustomed and inured to heat, they 
cannot remain more than a quarter of an hour, sometimes less, 
and others must take their place. 

An equally disagreeable task is the sounding which the 
" cuiseur " must make every morning to test the degree of baking 
of the bricks placed the day before. If he finds them too much 
baked he will consequently diminish the coal ; he will increase it, 
on the contrary, if the firing has not been active enough. 

Sometimes several clamps are made " a blanc," that is to say, 
without coal ; this is done when the fire is too violent, or when a 
change is made from a more to a less strong clay. The number 
of clamps that can be stacked in a day depends upon the conduct 
of the fire. If it is active and uniform, seven or eight or even ten 
may be erected, but if it is not active, we must be careful not to 
build too many, for the fire would slacken and smoulder, which 
exposes the bricks to the danger of being burnt by sudden bursts 
of flame. When, at any point, the fire rises less quickly, its 
progress is assisted by making one or two less clamps and thus 
leaving a vacant space which is filled up on the following day. 

At the beginning of the day's work, no smoke appears, 



BKICKS. 



195 



because poor coal is used ; but at the end, the water from the 
bricks evaporating forms white vapour, which, if the weather is 
damp, become so compact sometimes that all work is rendered 
impossible. 

The skill of the " enfourneur " consists in being able to make 
the facings of the clamp perfectly perpendicular, and especially in 
placing properly the bricks at the edge, for the clamp rises to six 
or even seven metres in height, and not only must it resist the 
pressure of the load, but also that of the fire. This is because 
the centre, being always more baked than the edges, undergoes 
less contraction ; also, towards the edges, the combustion of the 




Fig. 201. Brick Barrow (Whittaker). 

coal is less complete than in the middle, and the effect of all these 
causes is that the subsidence is more marked here than in the 
facing. This inconvenience must then be remedied. 

To raise the bricks on to the clamp, special wooden or iron 
barrows called " brouettes a barque" are used. 

The clamp is ascended by means of inclined planes formed 
of planks resting on trestles, which are raised everyday; a second 
but steeper plane is used for bringing down the empty barrows. 
Planks are also placed on the bricks for the barrows to run on, 
and are taken away in the evening. When the clamp has 
reached the required height, it is covered with a bed of clay 



196 POTTERY IN ARCHITECTURE. 

which will become baked while preventing the heat from leaving 
the upper layers too soon. This clay, when crushed and passed 
through a sieve, will be used by the moulders for powdering their 
moulds. 

Accidents during Firing. When the weather is fine, the brick 
dry, and the stoker skilful, there are no accidents ; but the 
inclemencies of the weather, rain, wind, etc., have to be con- 
sidered. 

To guard against the wind, screens are constructed with 
poles and straw matting, but this does not prevent the gusts of 
wind which pass over the top and drive back the flame. The 
latter concentrates and endeavours to escape, thus causing inflation 
of certain parts of the facing. The furnaces must be at once 
opened, and if that is not enough, the clay coating must be at 
once torn down in order to avoid a breach likely to cause serious 
accidents which would damage the firing and might even ruin the 
whole mass. 

As for rain, it is difficult to avoid its bad effects ; if it 
threatens in the evening, sand and coal are added to protect the 
surface of the bricks. If it falls when the fire is near the surface, 
no great harm is done. But if it comes on towards the end of 
the day, that is to say, when the fire is at some distance, it may 
cause, according to its violence, the loss of one or two clamps, 
which will then have to be removed, sometimes with shovels if the 
bricks are softened. 

Waste and Quality of Bricks fired in Clamps. The waste 
is enormous and the quality of the bricks is poor. The waste is 
explained as follows : 

Let us suppose a mass of 500,000 bricks divided into 60 
clamps of 8600 each. First 50,000 bricks will have to be used 
for building the furnace, which must be rebuilt every time. It is 
true that these bricks can be used again, but some will naturally 
have to be renewed. We will estimate these at . . 5,ooo 

There are always two or three layers at the bottom not properly baked, 

say two of 8000 each .......... 16,000 

At the top the same thing occurs to three or four layers of 8000 each, say 32,000 

Finally, the facing bricks are badly fired, and we may estimate them at . 27,000 

Which makes a total of . 80,000 



BRICKS. 197 

even admitting that the whole interior is well fired, which is not 
always the case ; for we must account for sudden bursts of flame, 
welding together several bricks, and for too quick spread of fire, 
causing the bricks to be too little fired. The quality of the 
bricks is very mediocre, firstly on account of these irregularities 
in firing, and secondly because it is impossible to bake bricks well 
without causing accidents called " loupages," which consist of a 
dilatation of the brick if the fire has had only a violent passing 
effect, and of fusion if the action has been prolonged. The slag of 
the coal and sand become strongly attached to the bricks, and 
cannot be detached, even by energetic washing, and this is called 
" gresage." It prevents bricks fired by this method from being 
used for well-finished facings. 

Expense in Fuel. This is very difficult to estimate, as it 
depends upon variable conditions, such as the quality and price 
of coal, the nature of the clay to be baked, the skill of the stoker, 
state of the weather, etc. 

Generally poor coal is used, giving a steady fire without sudden 
outbursts, and smokeless. Often any kind of coal is used, and 
passed through a sieve ; the remaining slack is used for the firing 
at the foot. Approximately, 130 to 160 kilos of coal are burnt 
for every 1000 bricks kilned of the dimensions 0.22 x o.i I X 0.06. 
We must not forget that the very perceptible waste (at least i 5 
per cent.) increases this quantity, and that the bricks receive a 
poor firing, not nearly as strong as that given by continuous 
kilns. 

II. Firing in Intermittent Kilns. 

A. Open Kilns. In order to obviate certain defects in clamp- 
firing, especially the construction of the foot, and the large waste, 
bricks are baked in kilns which ensure a more regular firing with 
less loss. 

One of the simplest kilns is represented in Figs. 202 and 
203. In order to economise masonry, and also to resist the 
pressure of the fire which is particularly noticeable in the lower 
part of kilns, they are partly made of clay. The foot of the 
kiln or gridiron, which is pierced with a large number of square 



198 



POTTERY IN ARCHITECTURE. 



holes, rests on Gothic arches, called " arches," three in number. 
They are formed of a certain number of vaults, between which are 
openings communicating with the three squares of the gridiron. 
These vaulted galleries serve for the passage of air, and for setting 
fire to the foot of the kiln by means of wood which is burnt on 
the pavement of their floors. One or two holes made in the wall, 
and closed during the firing, give entrance to the kiln. 

OPEN INTERMITTENT KILN. 




Fig. 203. 

Fig. 202. Longitudinal Section. Fig. 203. Plan. 

(Scale of 4 millimetres to the metre.) 

Wood or coal is used as fuel. The part in front of the kiln, 
called " avant-four," is generally below the level of the ground ; 
hence, in order to avoid the collection of rain-water which would 
invade the kiln, a deep well is dug and filled with large stones. 

I. FIRING WITH WOOD. The kiln is filled with bricks, each 
layer being separated from the next by sand. The method of 
filling the kiln is variable, but in kilns holding from 100,000 to 
I 20,000 bricks, about one-half are stacked solid, that is to say, 



BRICKS. 199 

the bricks close against one another in the mass, vertical 
chimneys being reserved corresponding to the holes in the 
gridiron. The rest of the bricks are packed loosely, that is 
to say, the chimneys are omitted, but a certain interval is left 
between the bricks ; the layers cutting one another at right angles, 
the bricks are always placed on edge. It is well to put at the 
bottom of the kiln the bricks which will undergo the least con- 
traction, and which best resist heat ; that is to say, those made of 
strong clays, on account of the weight of the mass which they 
support. 

As filling the kiln takes time, and rain may cause damage, for 
no fire will guard against the moisture caused by it, the kiln is 
covered with a wooden roof which is taken off before firing. 

When the kiln is full, we place on the raw bricks a row of 
baked bricks laid flat and called " platin," then the fire is lighted 
on the floor of the subterranean galleries called " arches " or 
" cloches," and is very gently pushed ; this is the period of the 
" petit feu " during which " enfumage " takes place, that is to say, 
the removal of the hygrometric water still left in the brick. 

The " enfumage " being finished, we pass to the " grand feu," 
which is obtained by actively pushing forward combustion night 
and day. When the mass begins to turn red, the draught is 
lessened by covering the " platin " in places with damped clay, 
especially where the fire is rising too quickly. The progress of 
the firing is followed by measuring the contraction by means of 
fixed marks. The fire is kept up near the orifice of the " cloches," 
and the draught suffices to distribute the heat throughout the 
kiln ; nevertheless, in order to ensure a uniform baking, some 
fagots are from time to time pushed down into the vaulted 
galleries with long pokers ; this is what is called " pousser au 
fond." 

Sometimes soot fills the chimneys and obstructs the draught. 
It will be sufficient to let it burn itself out by diminishing the fire 
in the vault corresponding to the obstructed chimney. From 
day to day the upper part is more plastered to concentrate the 
fire in the mass. When a certain degree of contraction is reached, 
not the total contraction, for the firing mass will continue to 



2OO POTTERY IN ARCHITECTURE. 

diminish in volume, the orifices of the " cloches " are stopped up, 
the top of the kiln is covered with a thick layer of clay, and it 
is allowed to cool. Wood-firing gives excellent products, well 
coloured and ringing well, but it is troublesome and difficult to 
work. For fuel, fagots are used, or, more economically, brush- 
wood. 

Cost of Firing. It is as difficult to estimate, if not more so, 
than in the case of coal. With brushwood at 1 5 francs the 
hundred, however, it may rise to 8 or 10 francs per 1000 bricks. 
The waste is not great if tJie kilning is w } ell done. In the chimneys 
bricks are found which are black and varnished ; this effect is due 
to soot and the fusible products contained in it, which become 
attached to the bricks when heated to a red or white heat. 

2. FIRING WITH COAL. (i) In Clamps. This is carried out 
in exactly the same way and with the same care as by the Flemish 
method. To guard the bricks from rain and wind, a shed is 
built over the walls of the kiln with a tiled roof high enough to 
leave unhindered the progress of the firing and the disengagement 
of gas and vapour. 

When several ovens are close together, a movable roof is 
sometimes constructed which runs on flanged wheels guided by 
rails placed on the walls of the kilns. When the weather is fine, 
this roof is pushed over a kiln not in course of firing ; if rain comes 
on, it is brought over the active kiln. In spite of these pre- 
cautions it is difficult to bake in these kilns during the winter on 
account of the inclemencies of the weather, which cause loss and 
render the work troublesome and sometimes impossible ; this is 
because the bricks have to be transported across the open from 
the sheds to the kiln, and also because much smoke, due to the 
moisture, is produced as soon as one or two clamps are laid. 

Generally two kilns are built one against the other, and this 
is simply done by dividing a single large kiln into two by a 
thick wall. The capacity of these kilns is very variable. There 
are some which can bake as many as 400,000 bricks, but these 
large kilns are less convenient than those holding 150,000, on 
account of the enormous number of raw bricks which must be 
accumulated. The number of kilns in a brick factory depends 



BRICKS. 2O I 

upon its importance, but there must be at least two, for the 
bricks are taken out as they are wanted for sale; and if none 
were being fired while this was being done, the factory would 
find itself without goods, the kiln being empty. 

(2) By Flame. That mode of firing called "a la flamme" is 
carried out in a kiln like the foregoing one, but, instead of burning 
coal placed in thin layers between the bricks, combustion takes 
place on fire-bars placed in front of the kiln. The fireplaces are 
three or four in number, and are fixed, each grating being about 
two yards square. These kilns are not recommended, for, under 
such conditions, it is better to use covered ovens. 

B. Vaulted Kilns. Open kilns lose a considerable part of 
the heat formed by combustion of the coal or wood. Generally 
the upper part is badly fired ; moreover, the wind and rain, in 
spite of a protecting roof, have an injurious effect on the progress 
of the fire. To avoid these disadvantages it has been found 
advisable to close the kilns by an arched roof which shelters the 
fire from the influence of the elements and throws back the heat 
on to the products before it is lost in the air. 

These kilns are divided into 

1. Kilns with direct flame ((i) Rectangular; (2) Round). 

2. Kilns with reversed flame. 

i. Kilns with Direct Flame. (i) RECTANGULAR. In 
these, the furnaces are placed according to the greatest length of 
the kiln ; above is a flooring pierced with a large number of holes 
which communicate with the oven. The upper vault is pierced 
with holes communicating with channels which lead to the 
chimneys, for the escape of the smoke and gas when they have 
produced their effect. A single chimney may serve for several 
kilns, and often the draught is produced without any chimney 
at all. 

The method of filling these kilns depends upon the kind of 
bricks to be fired. For those which bake at a relatively low 
temperature, the bricks are arranged so as to spread the flame 
over as large a surface as possible ; that is to say, they are 
separated about a finger's breadth from one another ; the rows or 
clamps are crossed and inclined to one another, to ensure the 



202 



POTTERY IN ARCHITECTURE. 



solidity of the mass and at the same time divide the flame by 
forming " chicanes." 

The firing begins with the " enfumage " or period of" petit feu," 
then when all trace of moisture has disappeared, the " grand feu " 
begins, which is the period of baking. The fuel used is wood, 
peat, coal or coke, according to locality. The coal should be of 
a kind giving a long flame; its use exposes the products more 
easily to sudden outbursts of heat than wood, the heat of which 
is always uniform ; but cost should decide in these questions, 
unless delicate objects have to be baked, in which case wood 
should be used. 

The longitudinal channels lead into a single transverse 



COVERED RECTANGULAR KILN. 




Fig. 204. Longitudinal Section. Fig. 205. Transverse Section. 

(Scale of I centimetre to the metre.) 



channel opening into the chimney. Registers are placed in each 
channel, so that the fire can be pushed at points where firing is 
progressing less quickly. Openings in the vault permit of the 
degree of contraction, and consequently of firing, being observed. 
In other kilns there is no pierced flooring, and the three 
furnaces are placed in front of the kiln, as in the case of open 
kilns firing " a la flamme." This arrangement is defective ; for 
there is danger of burning the products placed in front of the fire- 
bars, and very often those at the end of the kiln are not baked 
at all. 



BRICKS. 2O3 

(2) ROUND KILNS. The furnaces in these are arranged 
round the products to be fired. Their number depends upon the 
size of the kiln. It is more easy to get a uniform firing with 
these than with the foregoing, for there are no corners into 
which, very often, the flame does not penetrate. Their round 
shape gives them a great resisting power which, in many cases, 
renders unnecessary any iron plating. 

2. Kilns with Reversed Flame. In the preceding kinds, the 
combustion gases and the flames from the furnace reach the 
chimney by the shortest path. The products to be fired must 
then be on the direct route. This condition is not always easy 
to fulfil, and hence it happens that bricks which are not reached 
remain insufficiently baked, and there are inequalities in the firing. 

To obviate this inconvenience and to get a uniform baking of 
the products, kilns with reversed flame, as it is called, have been 
constructed. These may be built square or round ; the latter 
form is the better, and should always 'be preferred. Many 
examples of this type are known, but their principle is always the 
same. The furnaces are arranged round them, and are sufficient 
in number ; the arch of the kiln has no orifice ; the flooring is 
pierced with holes which communicate with a circular channel 
leading to a chimney. 

The flame penetrates into the oven and ascends to the arched 
roof; finding no outlet there, it is forced to descend again towards 
the bottom, whither the draught attracts it. 

In this movement currents are produced which effect the 
mixture of various warm gases in such a way that a uniform 
heat reigns throughout the whole interior of the kiln. Moreover, 
the vault produces an intense radiation which allows of a very 
high temperature being attained. Thus these reverberatory kilns 
are used in the firing of stoneware and similar products requiring 
great heat. 

We have introduced some modifications into these kilns with 
the object of rendering them more easy to fill and more 
economical in fuel. The furnaces are placed in the thickness of 
the wall and arranged as gas-generators, the air necessary for 
combustion being warmed while passing through the " chicanes " 



2O4 POTTERY IN ARCHITECTURE. 

which are on each side of the furnace. Figs. 206 to 2 i I are 
sections and plan of this kiln. 

The dimensions of reverberatory kilns cannot exceed a 
certain limit, on account of the too great height which they 
would reach. We shall take as maximum a cubic content of 
100 cubic metres (40,000 to 50,000 bricks), which corresponds 
to a diameter of 6 or 7 metres and a height of 4 or 5 metres. 
This height has less disadvantages than in the case of continu- 
ous kilns, for the best baked bricks are at the top, while in the 
Hoffmann kilns it is generally those at the base which are most 
fired, and the considerable contraction which they undergo causes 
movements in the mass which often deform the bricks. There- 
fore it is recommended that the height of continuous kilns should 
not exceed a certain limit. It is evident that small kilns are, 
proportionately to their size, dearer and less economical than 
large ones. 

In the foregoing kilns which burn coal on fire-bars, the latter 
are of small or large section. Gratings of large section are 
particularly suitable for rectangular kilns (Figs. 204, 205); it 
is calculated that 0.350 kilos (about 12 ounces) of coal per hour 
are consumed for each square decimetre (about I 5 sq. in.) of the 
fire-bars. For gratings of small section this quantity may be 
estimated as high as a kilogram (2.2 Ibs.) ; it is always better to 
have too large gratings, for it is easy to diminish their section by 
covering them with bricks. 

The section of the chimney ought to be larger than for 
an ordinary grating, for, besides the products of combustion, 
the water - vapour given out by the green bricks has to be 
carried away. Reverberatory kilns require especially a strong 
draught to bring down the flames, which have a tendency to 
remain under the roof. Some manufacturers give a chimney 
to each kiln, others build one only for a combination of four 
or six kilns. In this latter case the kilns are connected by air 
channels provided with trap-doors or registers to give the firing a 
kind of continuity. The burning gases of one kiln at full heat 
help to warm the next one, which is already red when its furnaces 
are lighted, the following one being " en enfumage." If this 



BRICKS, 



205 






I 



r N * 



2O6 POTTERY IN ARCHITECTURE. 

continuity should happen at any given moment to hinder the 
progress of the fire, it would be easy to stop it by altering the 
registers so as to connect the kilns directly with the chimney. 

It is difficult to estimate the consumption in covered kilns, 
with direct or reversed flame ; it depends, in fact, on many 
circumstances : nature of the products, degree of baking, mode of 
stacking, management of the fire, and draught, all of which have 
a more or less important influence on the final result. 

Progress of the Fire in Intermittent Kilns. Whatever the form 
of these kilns may be, the fire is always oxidising in them during 
the filling of the kiln and at the beginning of the " grand feu," for 
during these periods the quantity of fuel is small in comparison 
with the air entering by the open doors, and the latter is in 
excess in the products of combustion. But during the " grand feu " 
the doors of the furnaces are closed, and air is no longer in excess, 
especially at the end of the firing, when all the combustible gases 
are not always completely burnt. The firing then begins in an 
oxidising atmosphere and concludes in a reducing one. 

Covered kilns make better use of the heat than open kilns, 
and they allow of the products being well fired, especially round 
reverberatory kilns. But the loss of heat is still considerable, 
for the gases go to the chimney conduit at the temperature of 
the baked products, that is to say, at a high temperature. 

For a long time attempts had been made to use this waste 
heat for warming cold products by placing two or three communi- 
cating kilns side by side. While one of these was in full swing, 
its neighbour received the hot gases, which produced "enfumage" 
and raised its products to the early red stage, so that, when the 
first kiln completed its firing, the second immediately entered on 
the " grand feu " stage, while the third was " en enfumage." There 
was lacking in this system the principle of continuity, which has 
been introduced into brick-firing by MM. Hoffmann and Licht 
of Berlin. 

On tJie Choice of an Intermittent Kiln Net Cost. Before 
describing continuous kilns we will estimate the cost of the 
different kilns which we have just described. To speak frankly, 
only one of these is to be recommended, the reverberatory round 



BRICKS. 207 

kiln. In France this is reserved for the firing of porcelain, of 
faience, and stoneware, but in the United States of America it is 
extensively used for all kinds of pottery. 

A model built by Mr. Pike (of Chenoa, 111., U.S.A.) is re- 
commended in France by M. Lacroix, grantee of the American 
maker. M. Chambrette-Belon also recommends a kiln of this 
system. As we have said, anyone is free to build a kiln of 
this kind as he wishes, the patent having expired. 

All the types offered by different builders only differ in 
detail. 

In the following estimates, we shall make the same remarks 
as to the prices we take, as we have already done in speaking of 
drying - places (p. 182). For purposes of comparison, and in 
order to show the differences more clearly, we shall suppose a 
baking of five to six millions of bricks per annum. 

ESTIMATE OF AN OPEN INTERMITTENT KILN (Figs. 202, 
203). We shall make this estimate for two kilns placed 
side by side and each containing about 160,000 ordinary 
bricks, which corresponds to a cubic content of about 3 1 2 
square metres with the following dimensions : height 6 metres, 
length 8 metres, breadth 6J metres. 

Earthwork, 850 cubic metres at I fr. 50=1275 fr. 
Masonry, 250 cubic metres at 30 fr. . =750x3 
Sundries . . . . . = 225 

Total . 9000 fr. 
Roofing of kilns ..... extra. 

Note. The kiln being built on the brickworks, it often 
happens that the clay extracted is used for making the bricks, 
which diminishes the cost. 

For filling, cooling, and discharging such a kiln, about three 
weeks will be required : supposing work to continue for seven 
months, that is to say, 2 1 o days, it is seen that I o charges 
can be fired in the same kiln, i.e. 16,000,000 bricks: we must 
have, then, at least four similar kilns to reach the desired six 
millions. 

The cost will then reach twice 9000 francs, which was the 
price of two adjoining kilns, that is to say, I 8,000 francs, not 



2O8 POTTERY IN ARCHITECTURE. 

including the sheds which shelter the kilns and assist the work 
of stacking. 

ESTIMATE OF A REVERBERATORY KILN (Figs. 206 to 211). 
We shall take a kiln 6 metres in diameter and 4 in height, 
giving 84 cubic metres of space and corresponding to 40,000 
or 42,000 bricks. 

Earthwork, 80 cubic metres at I fr. 50= 120 fr. 
Masonry, 200 cubic metres at 30 fr. =6000 
Fire-bars, furnace doors, etc. . . 380 



Total . 6500 fr. 
Roofing of kilns .... extra. 

A fortnight is taken for filling, cooling, and discharging ; 
a single kiln will then fire annually from 800,000 to 1,000,000 
bricks (the kilns being covered and working nearly all the year 
round). 

We shall then want six similar kilns to fire six millions, and 

6 x 6500 39,000 fr. 

A chimney 30 to 35 m. in height 5,000 
Conduits, registers, etc. . . 1,000 



45,000 fr. 

not including the building in which the kilns stand. As we 
shall see, a continuous kiln costs less and has as good a produc- 
tion, and the reverberatory kilns should be reserved for small 
works producing a million to two million bricks. In this case 
the cost of one or two kilns and their chimney will not exceed 
10,000 to 16,000 francs. 

III. Firing in Continuous Kilns. 

The principle of the continuity of firing was stated by 
Peclet, in his Traite de la Chaleur (3rd ed., 1860), and 
various practical applications of this principle had been carried 
out successfully by Muller and Gilardoni, when Hoffmann and 
Licht gave to continuous kilns the definite form which made 
a success of them. 

With these kilns only can be completely acquired what had 



BRICKS. 209 

been already sought for in covered and combined intermittent 
kilns ; that is, the utilisation of the excess of heat necessary for 
firing for the gradual heating of the objects kilned. In continu- 
ous kilns the heating is methodically carried out, that is to say, 
the warm gases after having effected firing are cooled by passing 
over cold products in the kilns and escape into the chimney 
carrying a minimum of heat with them. On the other hand, 
the air necessary to combustion is strongly heated while passing 
over fired products which are cooling. 

Two processes ensure the continuity of the fire while 
fulfilling the above conditions : one is to have a fixed furnace 
to which the products are brought to be fired, and from which 
they are, after firing, removed ; the other is to alter the position 
of the furnace with respect to the bricks which remain stationary. 

The first system does not appear to have reached a practical 
stage in spite of the ingenious attempts of M. Demimuid and 
MM. Boulet frcres, who thought of making waggons, covered 
with refractory clay and filled with bricks, move before a fixed 
furnace. 

The excess of heat was used to warm the waggons in front. 

In M. Barbier's kiln, the reverse took place: the furnace, 
mounted on a waggon, was moved and came to bake in turn the 
different batches of bricks arranged in a fixed kiln. 

The use of these machines, which date from 1855, has been 
prevented by various causes, especially the maintenance of the 
rolling-stock and certain practical difficulties, but more than all 
by the appearance at the Universal Exhibition of 1867 of the 
continuous kiln of Hoffmann and Licht, which was to recommend 
itself to the pottery trade by its logical principle and .the 
excellence of its results, from the point of view of economy as 
well as of the beauty of the products obtained. 

For the last thirty years it has come more and more into use ; 
if its form has been modified in order to simplify its construction, 
and if some details have been altered, its principle and funda- 
mental arrangements have remained the same. But a new 
advance has been made. In the Hoffmann and Licht kiln, the 
firing is effected by a solid fuel which is thrown upon already 
14 



2IO POTTERY IN ARCHITECTURE. 

red-hot bricks and there ignites. It has been thought that the 
system of gas-generators might be applied to continuous kilns, 
and that the firing of the products might be effected by the 
burning of the gas; this presents certain advantages, such as the 
absence of ashes, the great regularity of the baking, and the high 
temperature which can be reached. After many attempts a 
satisfactory result has now been attained, and continuous kilns 
heated by gas will certainly come more and more into use 
when their working is rendered quite easy and some practical 
difficulties are overcome. 

Continuous kilns are divided into two classes 

A. Those with solid fuel. 

B. Those with gas fuel. 

A. CONTINUOUS KILNS WITH SOLID FUEL. Hoffmann and 
Lie/it Kiln. As this kiln is no longer constructed of the primitive 
round shape, and as the rectangular form given to it by M. 
Simon, M. Hamel, and others, has been preferred, we will show 
its working by the diagram in Fig. 212. 

The kiln consists of a circular tunnelled gallery called 
firing-chamber ) which communicates with the exterior by means 
of doors, P P (there are twelve in the diagram). These doors 
are used for charging and discharging, and are hermetically 
sealed during firing ; the distance between them is called a 
compartment. The gallery also communicates by conduits, c c, 
with a circular channel B, which leads direct to the central a 
chimney C. The orifices, o o, by which the conduits open into 
the central channel, are closed by covers or traps which can be 
raised at will by some kind of mechanism : screw, chain, pulley, 
etc. All these traps being lowered, there remains no communi- 
cation between the gallery and the chimney ; if one of them be 
raised, a draught is established through the conduit leading to 
that trap. 

The arched roof of the gallery is pierced with a certain 
number of holes closed above by cast-iron stop-valves which 
fit into a groove filled with sand and hermetically joined. These 
holes are intended for the passage of the coal, which, when cast 
upon the red-hot bricks, will ignite on contact and bake the mass. 



BRICKS. 



21 I 



Let us now consider how the kiln works. We will suppose it 
to be in full swing. At a certain point in the gallery is a sheet- 
iron or paper register, R, fixed against the kilned brick and 
closing the gallery completely. On one side of this register 
the gallery is filled with bricks, on the other side is an empty 
compartment where raw bricks are being placed ; the following 
compartment is quite empty, and the third, still on the same 
side of the register, is being discharged ; thus, of twelve com- 
partments, there is one empty, one being discharged, one being 




212. Horizontal Section of the Hoffmann Kiln, showing how it works. 

charged, and nine full of bricks and with doors closed. Of these 
nine, three are fired and are cooling, one is " en grand feu," 
namely, the one which receives the fuel by chimneys or heating 
wells arranged in the mass of bricks and corresponding to the 
holes pierced in the roof. In these chimneys have been placed 
bricks " en chicane," which, by scattering the coal throughout 
the height of the mass, prevent it from accumulating at the 
bottom of the wells. 

The air necessary for combustion passes over the products 



2 I 2 POTTERY IN ARCHITECTURE. 

which are already baked, hastens their cooling while gaining 
heat itself, and arrives over the coal at a high degree of tempera- 
ture. In this way there is no loss of heat ; the gases of com- 
bustion, mixed with the excess of air, continue their way after 
having baked the products, and heat the bricks in the compart- 
ment next to that "en grand feu" sufficiently to make them 
red-hot : this is the place where it is " petit feu." The gases, 
partially cooled, meet colder and colder products, to which they 
still yield a certain quantity of heat, and this produces " en- 
fumage," that is to say, the removal of the water always contained 
in raw bricks, however dry they may be. Then they reach the 
register R and penetrate into the channel B, which brings them 
to the central chimney C. 

Cooling and heating are therefore progressive, which offers 
great advantages in the firing of pottery, and the heat of the fuel 
is as completely utilised as possible ; the only important loss is 
the heat given out by the cooling products, a small part of which 
only is carried off to warm the air necessary for combustion. 
We have seen that this waste heat has been used for warming 
the drying-rooms, which are often placed over the kiln. 

When the " grand feu " compartment is fired, and this takes 
from twelve to twenty-four hours according to its size, they pass 
on to the next ; at the same time the draught is stopped, for the 
compartment which was being charged has been filled while that 
"en grand feu" was firing. The door of the compartment is closed 
and a new register applied against the brick ; when it is placed 
in position, the first is taken out through the door (formerly it 
used to be removed through the roof, which had an opening for 
the purpose), or is burned when it is made of paper, which is 
most frequently the case. The open trap is then lowered and 
the next one opened. 

The motion continues in this way, the fire being moved one 
or two compartments every day ; on the twelfth day it is in the 
same place again. 

The circular form adopted by the inventors presents certain 
disadvantages : it is costly on account of the considerable volume 
of masonry and sand that it requires, and of its delicate construe- 



BRICKS. 



213 



tion. Therefore the shape was first modified into an oval, and 
finally it was made rectangular. These modifications have been 
praised in turn by Hamel, Simon, etc., who have given their 
names to the kilns thus changed by them. . One of the best 
known is the kiln devised by the last-named, and we shall give 
a description of it with the help of Figs. 213, 214, 215, 216, 
and 217. 

RECTANGULAR KILN. This is composed of two parallel 
galleries in the form of tunnels with slightly elliptical arch, 
joined at the ends by a channel (Fig. 2 1 7). The arrangement 
of the doors for filling and of the heating holes in the roof is 

CONTINUOUS RECTANGULAR KILN. (Scale of 7^ millimetres to the metre.) 
Built by MM. Toisoul and Fradet. 



'~" T ffilp^^ 

^ml^^^^^rn^^^ 

' ^'-i^^^^^s^^-: i^y . / 



.a 








Fig. 213. Transverse Section E F G H I J. 
The Gallery A' is full of Bricks, the Gallery A is empty. 

the same as in the circular kiln, but the escape of the gases 
of combustion and consequently the draught are effected in a 
different way. A central channel (3, Fig. 215) situated between 
the two galleries stretches the whole length of the kiln. It is 
put in communication with the compartments by vertical 
channels, c, closed by cast - iron traps or doors, V, which are 
worked from the outside by means of the flywheels v, which 
turn a threaded rod in a fixed nut. The central channel, C, 
leads to the chimney, either directly, when it is at the end of 
the kiln, or by a subterranean channel when it is at some 
distance from it, as shown in the plan (Figs. 217, 215). 

Shape and Dimensions Number of Compartments. The most 



214 POTTERY IN ARCHITECTURE. 

convenient shape for the galleries is the rectangular covered by 
an arched, or slightly elliptical (Fig. 2 1 3) roof. The dimen- 
sions of these galleries are very variable ; they depend upon 
the daily production, and the extreme limits of section are 
from 3 to 10 square metres, and of cubic space from 8 to 60 
cubic metres ; these are exceptional cases, which it is not always 
advantageous to adopt. We 'may take as a good average 20 to 
40 cubic metres, that is to say, a space containing from 10,000 
to 20,000 ordinary bricks. 

The cubic contents of the compartments in the kiln shown 
in our plans are 28.7 cubic metres, a space capable of accom- 
modating 13,000 bricks. Its dimensions are: 3 metres broad, 
4 metres long, and 2.7 metres high under the arch. This height 
may be reduced without any inconvenience by increasing the 
breadth. 

As to the number of compartments, the minimum for 
satisfactory progress is sixteen. It is better to have twenty or 
even more, for the work is then easier ; the heat is less strong 
during charging and discharging, on account of the distance 
of the fire and the longer period of cooling that the products 
undergo after being fired. Kilns have even been constructed 
with a sufficient number of compartments to have one "en grand 
feu " in each gallery, and this means thirty-two compartments. 
On account of the length of such a kiln, it may be advantageous 
to make two of it, side by side. 

Nature of Materials to be Used. Kilns are generally built of 
brick with or without iron plating. Armoured kilns, like the one 
of which we give the plans, are very solid, very elegant, and do 
not take up much space ; but they are costly. Therefore it is 
more economical to support the inner walls with pillars and 
a thick layer of rammed clay covered with a masonry facing. 
Thus constructed, the kiln resists fire well and costs less than 
with plating. To bake ordinary products it is not necessary 
to make the interior of refractory clay ; it will be enough to 
choose bricks which resist a strong firing well. 

But if a high temperature has to be attained, it is absolutely 
necessary to build an inner covering of refractory bricks. 



BRICKS. 



2I 5 




2l6 POTTERY IN ARCHITECTURE. 

The volume of masonry depends upon the size of the kiln, but 
it is not proportional to this size, because a small kiln requires, 
for its size, a greater volume than a large one, and it is more 
advantageous to build a medium-sized kiln than two small ones. 

Arrangement of the Heating Holes. As these are a cause of 
weakness in the arch, and as it is always they which cause 
deterioration in it, we must avoid multiplying them unduly, and 
content ourselves with the number necessary for good firing. 
We may say that, for a horizontal surface of I 2 square metres 
per compartment, 12 to 14 holes are amply sufficient for firing 
even difficult products. The arrangement of them varies, and 
depends upon the method of firing and of filling the kiln. 

Without being positive, for in these questions special condi- 
tions are of every importance, we may say that the symmetrical 
arrangement is as good as any other recommended by builders. 
Nevertheless it is right to place the holes near the central 
channel a little farther from the side than those along the 
outside walls, because the fire always advances more quickly 
against this channel than against the outside wall, in consequence 
of the cooling which this latter undergoes, and also on account of 
the draught which acts on the slope. 

Chimney. This in some kilns is in the very centre of the 
building, in others it is at one end ; the collecting channel 
opens into it, and this causes some loss in draught owing to the 
height of this channel above the ground. 

As the chimney represents a certain expense which is not 
much increased by making it large enough to serve two kilns, it 
is advisable under these circumstances to place it in the axis of 
separation of the two kilns. It is an advantage to have a strong 
draught which can be moderated, while on the other hand it is 
difficult to remedy a deficiency in draught. Some manufacturers 
prefer a chimney to each kiln, fearing lest the progress of one 
should hinder that of the other, if one chimney only is used. 

As for dimensions, it must not be forgotten that it must 
remove not only the gaseous products of combustion but also 
the water-vapour contained in the products to be fired, which is 
considerable in quantity. 



BRICKS. 



217 



CONTINUOUS KILNS CHIMNEY 




} c 




Elevation. Section. Elevation. Section. 

Fig. 218. Chimney (Scale of 5.4 millimetres to the metre). Fig. 219. Chimney with Pedestal. 



218 



POTTERY IN ARCHITECTURE. 



We give (Fig. 2 1 8) the plans of a chimney which we have 
constructed for the kiln just described. The orifice at the top, 
1.4 metres across, is sufficient for the draught of two kilns. The 
Figs. 2 1 9 represent another chimney which may also serve two 
kilns. 

Working- of the Kiln Stacking Heating We//s.The first 
thing to be considered when a kiln is built is the stacking of the 
bricks. Here once more the nature of the ground has to be 
considered. According to the greater or less difficulty of firing 
of the products, different methods will be employed. First the 
foot of the kiln has to be made. This foot consists of longi- 
tudinal channels arranged along the floor of the kiln to permit 
a draught to pass. The w 7 idth of these channels is small enough 
to allo\v of their being covered by a brick placed lengthways ; 



VARIOUS KILN-FEET. 



HiiKriirinjpi] 
tiTMriWiUippipd 
iramiLnT 




Fig. 220. 




Fig. 221. 



inn Biint 
uiiiiimii 
nmrffntrr 

nnL|nm: 

Fig. 222. 



Nl If 
III N 
lljiJl 

i iii u 



their height varies from 3 layers to 8, that is to say, from a foot 
to 2 1 feet. If the kiln is small, and the goods easy of baking 
with a fairly moderate fire, we can adopt the arrangement in 
Fig. 220, which fails, however, if the products are difficult to 
bake on account of the waste it causes. In fact the foot 
supports the whole weight of the bricks stacked ; if firing takes 
place at a high temperature, the contraction causes movements 
which make the whole mass unsteady, and all the bricks at 
the foot are deformed by crushing, while those of the fourth 
layer are opened in the middle by the weight they support. 
Under these conditions we must reduce the channels to the 
number absolutely necessary, say three, and they are arranged 
below the heating wells, as shown in Fig. 221. 

The foot thus formed is of great resistance and does not give 
deformed products, but the bricks above the channel are always 



BRICKS. 219 

a little curved or opened in the middle. In order to avoid this 
inconvenience, which, we repeat, is only excessive in the case of 
bricks requiring a high temperature for their firing, the width of 
the channel is diminished and its height increased (Fig. 222). 

The foot of the kiln having been formed, the stacking is con- 
tinued, and then arises the question of heating wells. The 
heating wells are hollows left between the bricks, below the 
holes in the arched roof, to receive the burning fuel. Their 
importance will be understood ; with good heating wells a 
regular and economical firing is obtained ; it becomes, on the 
contrary, bad and troublesome with badly arranged wells. 
Every brick - maker is said to have his own system of wells. 
We will mention a few. One (Fig. 220) is to be used with clays 
which fire easily ; another is applicable to clays which bake with 
difficulty. The first requires open stacking, that is to say, the 
bricks are separated from one another by a distance equal to the 
thickness of a finger, the rows crossing at right or acute angles. 
The well is formed of interspaced bricks, placed one upon the 
other, and forming " chicane " (these bricks are distinguished in the 
figure by hatchings). The coal, falling from the hole in the arch, 
is scattered among these " chicanes " ; a little remains on each brick 
and burns there, the bricks being at a sufficiently high tempera- 
ture to cause its ignition. 

A well-made well should retain the coal at different points 
of its height without letting a single piece fall on the floor of 
the kiln. These wells work satisfactorily provided the intervals 
between the bricks be neither too large nor too small. If too 
large, they allow the coal to fall into the channel at the bottom, 
where it accumulates and burns the foot of the kiln without 
baking the top ; if too small, they are liable to be stopped up by 
an accumulation of fuel, and the effect is reversed : the top fires 
too much, while the bottom does not fire at all. 

Finally, this kind of well does not give a sufficiently regular 
baking to products which are difficult of firing. We have found 
the kind of well represented on the right of Fig. 2 1 3 answer 
admirably. 

The stacking is solid, that is to say, the bricks are close together 



22O POTTERY IN ARCHITECTURE. 

and placed in the direction of the length of the kiln. When we 
come below a row of holes, a hollow is left equal to half the 
length of a brick. This interval exists throughout the section of 
the kiln and constitutes the well, which is thus formed of the 
hollow between two "feuilles." It is evident that under these 
conditions the coal, finding nothing to restrain it, would fall on to 
the floor of the kiln. Therefore bricks are placed " en chicane " in 
this hollow in the following way : the first " feuille," which forms 
one of the walls of the well, is stacked perpendicularly without any 
projections ; but in stacking the second, bricks are pushed forward 
here and there which approach the opposite " feuille " and inter- 
rupt the continuity. These projecting bricks will retain the coal. 
Generally they are placed in every other row of the height and 
at every third brick of the breadth, care being taken that the 
bricks so projecting are opposite to those of the lower row. The 
coal, meeting all these obstacles, is uniformly distributed through- 
out the mass of bricks, and produces a regular heat. In this 
solid stacking the draught of the channels at the foot would not 
suffice, and we must make a communication between the different 
wells so that the air may reach all the places where there is fuel, 
and cause it to burn. This is done by leaving in each " feuille," at 
every two or three layers, and at every other brick, small hollows 
in width about half or three-quarters the thickness of a brick. 
This hollow is covered over in the following row. As its width 
is small, the brick or bricks which cover it are not sufficient, 
especially as they are placed lengthwise. These little channels 
stretch in a straight line from one well to another, but of course 
it is not necessary that they should be in a line from one end 
of the kiln to the other ; it is enough if they ensure connection 
between two neighbouring wells. 

For this solid stacking, which gives fine products but which 
has the disadvantage of making the progress of the fire slower, 
open stacking is often substituted ; the bricks are separated by a 
small interval, each layer or clamp crossing at a right or acute 
angle. The wells are made in the same way, and across the whole 
width of the kiln. It is not every clay which will bear this 
method of stacking ; there are some which show the mark of the 



BRICKS. 221 

space separating two bricks. However small this space may be 
it is said that the bricks are cut. 

One important observation must be noted in building heating 
wells ; this is that the fire always draws the bricks forward to 
about half the height, that is to say, that a " feuille " stacked per- 
fectly vertical is found inclined when removed : as the upper 
part overhangs, it will even be necessary to take precautions in 
removing it. This movement always takes place in the direction 
of the draught. This being so, it will be understood that it is 
better to throw the axis of the well a little behind the axis of 
the heating holes, since the wells will come forward during firing. 
It even happens sometimes that, if in stacking, its axis is placed 
too far in front of that of the holes, when one comes to throw in 
the fuel the well is invisible, it has passed the holes. This 
accident is easily avoided : all that need be done is to throw 
through the fuel holes, into the interval between the " feuilles," a 
few pieces of brick, which will act as wedges and hold the " feuilles " 
in their places. 

Transport of the Bricks from the Drying-sheds to the Kiln. 
The most usual method is by wheelbarrows called technically 
" brouette a barque " (Fig. 201). They are made in wood and iron, 
and can carry fifty bricks each. When the drying-places are in 
storeys, lifts are used similar to those which we have described 
in speaking of the transport of bricks from the machine to 
the drying-sheds. The use of waggons necessitates a special 
installation, only possible with kilns of a certain size where space 
allows of some freedom of movement. The following is an 
arrangement which ensures an easy delivery, and avoids the use 
of turn-tables ; the working of the latter is always slow, and has 
the inconvenience of injuring the goods through the shocks and 
jolts produced. 

On each side of the kiln, and in the direction of its length, 
two trenches are dug, and in them is laid a railway to carry a 
transfer trolley (Fig. 182). This trolley carries a single, or 
preferably a double, line of rails of half-a-metre gauge placed 
perpendicular to the first. The half-metre rails correspond to 
other lines which join each door of the kiln to the transfer trolley. 



222 POTTERY IN ARCHITECTURE. 

These lines are fixed and continue into the kiln by means of 
movable branches which are laid in the direction of the place 
of stacking and afterwards removed. 

The working is simple : the waggons, when they arrive from 
the outside drying-sheds, or are lowered by a lift from the upper 
storeys, are placed on the trolley, the rails of which have been put 
in line with those serving the drying-places ; the trolley is pushed 
in front of the line corresponding to the compartment to be filled, 
and fixed by means of a bolt, then the waggon full of bricks is 
passed into the kiln. Near the door there is a curved branch 
leading to a line which ends with a turn-table. When the waggon 
reaches this turn-table it is turned round so that the brick-stacker 
may more conveniently take the bricks from it. Meanwhile the 




Fig. 223. Installation for Charging and Discharging. 

waggon-man has pushed out the empty waggon which was on the 
other turn-table, and which now goes on to the trolley in place of 
the one just sent inside. The trolley is unbolted, and it is taken 
to fetch another waggon which a second workman has loaded. 
A skilful stacker can fill a compartment containing from I 2,000 
to i 5,000 bricks in ten hours. Everything is brought to him, 
the bricks and also the sand which is placed between the layers to 
prevent them from sticking together. While he is working, the 
waggon-men, who have time to spare, close the doors up with a 
wall 2\ inches thick, formed of bricks on edge and coated with 
clay. This wall is placed against the stacked bricks. Then a foot 
away they build another wall of bare bricks and of thickness equal 
to a brick's length ; between they heap up clay (Fig. 212) to 
avoid any entrance of air which would interfere with the draught. 



BRICKS. 223 

The good firing of the neighbouring bricks and the satisfactory 
progress of the fire depend upon the care with which a door is 
closed. From time to time the stoker looks round to see that no 
air is getting in by the doors ; this would be shown by a whistling 
sound, and should it occur it is remedied by heaping clay up at 
the top of the door. 

Registers. We have seen that the closing up of the kiln at 
a particular point is effected by means of a register. These 
registers may be of paper or sheet-iron : they take the exact 
shape of the gallery. They are placed against the stacked bricks, 
and the chinks between the sides of the kiln and the register are 
stopped up with diluted clay in order to close it hermetically. 

When the next compartment is full a second register is 
placed in position. This compartment is thus enclosed between 
two registers. But the first register is then removed and the 
draught is advanced one compartment. 

Sheet-iron registers are in two parts which fit together by 
means of a groove plastered with clay. The lower piece is easily 
moved ; the upper one, which is hemispherical in shape, is fitted 
with hooks ; by means of chains passing through the heating 
holes it is hoisted above the first, and the whole is kept in position 
by a buttress which is taken away when stacking takes place. 
The removal of the registers is somewhat difficult on account of 
the lack of space. The upper part is held by chains, while the 
lower part is drawn out by means of a handle fixed to it ; the 
upper part is then lowered and also taken out. For this removal, 
an opening of the thickness of the register is left in the thin wall 
against the bricks. The register must not be removed without 
first closing the door, for the draught would be stopped and the 
progress of the fire suspended. 

These sheet-iron registers have several disadvantages : they 
are slow and difficult to move, they cause a loss of space, for the 
hooks project, and a space must be left for the descent of the 
upper part. 

There are many advantages to be gained by substituting 
registers made of strong paper for the above. Yellow straw 
paper in rolls 1 .4 metres high are used ; this height, which is the 



224 POTTERY IN ARCHITECTURE. 

width of the paper, should be a little more than half the height 
of the gallery. The kiln is closed by cutting out a first rectangle 
of paper and placing it against the bricks ; care is taken to open 
the trap of the compartment in order to cause draught and draw 
the paper against the brick. The second part of the register is 
made by cutting out a piece of paper in the shape of the arch : 
this is also placed against the brick. The edges of the paper are 
pasted with a little clay diluted very thin, and they are stuck 
against the walls of the kiln. The top is pasted with clay and 
the whole is thus completely attached. 

When the register is to be destroyed, a long iron rod made 
red-hot in the fire is passed in by a heating hole and sets fire to 
it. The expense in paper is trifling and is made up for by the 
time saved in placing and removal of the sheet-iron registers, and 
also by economy in space, for the bricks of the next compartment 
are placed against the paper and help to keep it in position. 

Fuel. Any burning fuel serves for heating continuous kilns : 
such are wood, peat, and especially coal, which is generally used 
in the form of powder, called commercially " fine." This is very 
suitable for firing ; being finely divided it spreads all round, burns 
quickly, and is cheapest. When the Hoffmann kilns were first 
introduced the economy was all the greater because this fine coal, 
which was not otherwise used, encumbered the mine-yards and 
was sold at a price very much less than that of ordinary coal. 
This difference in price, however, has much diminished since the 
installation in various commercial enterprises of furnaces capable 
of burning this slack. 

Rich and poor coals are also very suitable for continuous 
kilns. Some prefer rich coals, on account of their long flame ; 
others prefer poor coal, which heats more uniformly and without 
sudden outbursts. 

Igniting of t/ie Kiln Method of Heating. The ignition of 
the kiln is effected by heating one compartment by means of fire- 
bars placed in front of it ; then when the bricks are red-hot, the 
heating is continued by throwing coal through the holes in the 
vault. In some kilns the igniting furnaces are placed permanently 
at one end of the kiln with their doors outside. When a 



BRICKS. 225 

sufficient quantity of brick has become red-hot, and the fire has 
started properly, the furnaces are extinguished and their openings 
stopped up by a wall. 

In preference to these fixed furnaces we recommend movable 
ones, which are installed in the kiln, and removed as soon as 
the fire is started. The construction of these furnaces is very 
simple. 

Three of them are usually arranged in the width of the kiln ; 
their bars are of cast-iron and the doors are formed of sheet-iron 
plates placed in front. 

The length of the latter is determined by the length of the 
bars. In front of the furnaces a wall of bricks bound together 
with clay is built so as to completely close in the kiln ; in this 
wall three openings are left for passing the gas to the furnaces. 
This wall almost touches the green bricks with which three or 
four compartments are filled. The bricks are thus enclosed 
between the wall of the furnaces, and the register placed against 
the last compartment. The whole forms an ordinary flame kiln, 
the draught passing through the vertical conduits and the central 
channel. We begin by heating with the " petit feu," then we 
pass to the " grand feu." The bricks in the first compartment 
are thus raised to a red-heat at the end of a few days ; from time 
to time we make sure that the heat is sufficient to ignite the coal 
which is thrown in through the holes in the roof. When the coal 
burns well, we begin to heat from above while keeping up the fire 
in the furnaces. At last, when a compartment, or better still a 
compartment and a half, is raised to a red-heat, we let the fire in 
the furnaces go out, and heat only by the holes in the vault. To 
bring coal to the kiln, a small Decauville railway of .4 metre gauge 
is laid on each side ; thus the fuel placed in a waggon is within reach 
of the stoker, who pushes the waggon forward as the fire advances. 
He takes the coal up in a round shovel like those in household 
use, and, raising the lid of the holes with a movable hook or 
with a handle fitted to the lid, he quickly throws the fuel into the 
well, alloiving as little cold air as possible to enter. He goes in 
this way from hole to hole, beginning at one end of the compart- 
ment and finishing at the other ; generally only one compartment 
15 



226 POTTERY IN ARCHITECTURE. 

is heated at a time. When he has finished his round, he waits a 
certain time and then begins again in the same order. In order 
to measure precisely the interval between two heatings, a special 
clock is placed on the kiln which strikes once at the hour, two 
strokes at five minutes past, three strokes at the quarter past for 
beginning again, one stroke at twenty minutes past, and so on. 
In this way it is easy for the stoker to notice the time which has 
passed, especially at night. The heating times are generally ten 
minutes or five minutes apart. 

The progress of the fire depends upon the degree of difficulty 
of baking of the products ; an advance of from 4 to 8 metres a 
day may be expected, that is to say, from one to two compartments. 
If we take the first estimate, the stoker will, at the end of six hours' 
heating, begin to put fuel into another row of holes, and will leave 
one row behind him. As there are four rows of holes to each 
compartment, it follows that this operation will be repeated four 
times in the twenty-four hours. In order to remember at what 
time he began to heat a new row, he writes it down with chalk 
on the lids. When one row is no longer being heated, the well 
is closed with two bricks laid flat, and coal is placed on these two 
bricks for five or six hours. This coal does not fall down, it helps 
to maintain the heat under the vault ; for the fire has always a 
tendency to descend, owing to the draught passing to the floor of 
the kiln. 

A good precaution in firing is to measure the contraction in 
height of the mass of bricks \vith a graduated iron rod, taking the 
distance from the edge of the cast-iron shoulder at the end of the 
heating hole. 

The draught is regulated by raising or lowering the trap-doors, 
the threaded rods of which are worked by a small flywheel (Fig. 
2 I 3). The draught exists throughout the " enfumage," the " petit 
feu," and the " grand feu," but the holes behind the " grand feu " 
should have a return current. Draught and return current are 
easily distinguished from one another. .When a lid is raised, there 
is immediate aspiration through the open hole if there is a draught, 
whereas if there is a return current the hot air is felt issuing from 
the hole. The stoker regulates his trap accordingly ; there are 



BRICKS. 227 

generally one or two traps open, sometimes three, according to the 
number of compartments in front of the " grand feu." 

The draught should come from as great a distance as possible, 
that is to say, there should be the greatest number of full com- 
partments before the one " en grand feu," so that as little heat as 
possible may be sent into the chimney. 

The greater the distance of the draught is, the more regularly 
does the fire progress ; the obliquity of the path of the gases going 
from the outer wall of the kiln to the central channel is less great ; 
it rarely, however, advances more quickly towards the central 
channel than towards the outside wall. It is almost always 
necessary to keep the fire in this part several holes behind. 

Progress of the Fire. Firing and " enfumage " take place in 
an oxidising atmosphere. The air in fact reaches the firing com- 
partment after having been heated but not having lost its oxygen ; 
consequently the products just baked, and those being baked, are 
in a very oxidising atmosphere. As the air is in excess, com- 
bustion does not absorb all the oxygen, and the compartments 
in front of the " grand feu " are also in an oxidising atmosphere, 
but less so than that in the compartment preceding the " grand 
feu." 

In the Hoffmann kiln, then, it is immediately after firing that 
the products are exposed to the most oxidising gases, while in 
intermittent kilns the gases are oxidising before firing and some- 
what reducing during and after. Attempts have been made to 
render the continuous kiln reducing and oxidising at will by 
lowering the draught to its minimum, and stopping it completely 
for half an hour three or four times in the twenty-four hours. The 
results are not very satisfactory, and are costly on account of the 
delay caused in the progress of the fire. 

Enfumage. As we have already stated, the object of this 
process is the removal of the water contained in green products 
before they are subjected to a high temperature. In continuous 
kilns the " enfumage " is effected by the hot gases coming from 
the compartment " en grand feu " ; as these gases progress towards 
the channel leading to the chimney, they cool and at the same 
time take up moisture produced by the combustion of the coal 



228 POTTERY IN ARCHITECTURE. 

and the complete desiccation of the products over which they pass. 
As long as these damp gases pass over bricks which are already 
heated to a high temperature there is no condensation, but we 
must avoid their reaching cold products like those in the compart- 
ment from which the register has just been removed, for the 
moisture will be deposited on them, and produce a damaging 
effect, giving the fired bricks an irregular colour, yellowish or 
whitish in places and disagreeable to the eye. 

These accidents, however, are only persistent in HgJitly fired 
products, they disappear under strong firing. 

Several means of obtaining a good " enfumage " have been 
recommended. In the Simon kiln two large cast-iron stoves are 
placed over the compartment and isolated between two registers ; 
they are joined by a pipe to the heating holes. The trap of the 
compartment is slightly opened to make a moderate draught. 
Two stoves are placed near the outer wall and one in the middle 
of the row of holes farthest from the air trap ; thus the hot gases 
pass over the greater part of the compartment. The progress of 
the " enfumage " is observed by raising the lids ; as long as it is 
not complete damp soot will be observed on the cast-iron, and 
when this disappears the "enfumage" is completed. An average 
of twenty-four hours is required for one compartment. 

Attempts have been made to carry out " enfumage " by means 
of the heat given out by the fired products when cooling, a heat 
which is far from being all absorbed by the air necessary for com- 
bustion. The arrangements consist of a series of air channels 
placed over the central channel and communicating with the heat- 
ing holes. The orifices of these channels are closed by a valve or 
trap to each compartment. This kind of installation is very 
troublesome ; it increases the dimensions of the kiln, and to a 
certain point diminishes its solidity. It is evident that the more 
hollows there are in the masonry of a kiln, the more is the resist- 
ance to the effects of dilatation decreased. 

Moreover, some manufacturers contend that when hot air is 
borrowed from cooling products for the purposes of " enfumage," 
the progress of the fire is slackened, and the heat is greater in the 
discharging compartment. 



BRICKS. 229 

M. Fillard, the well-known pottery expert, resolutely rejects 
" enfumage " by stoves or any other similar method. According 
to him, a separate " enfumage " is in opposition to the continuity 
of the kiln ; he effects it completely by a properly managed 
draught. For instance, directly the register is set fire to, a new 
compartment is put into communication with the others, the trap 
of the compartment is very slightly raised, and the draught passes 
through the two or three preceding ones. 

Thus the water-vapour does not condense on the cold products ; 
the latter are slowly warmed by contact with the hot walls of 
the kiln and the very slight draught going to the last air hole. 
When no more deposit of water is observed in the neighbourhood 
of the burnt register (this is easily verified by passing a cold iron 
rod through a heating hole), the opening of the traps previously 
raised is reduced, and that of the last increased. By these pre- 
cautions all accidents due to the deposit of water-vapour on cold 
products are avoided ; we get rid of the trouble of removal and 
maintenance of the fire in the stoves, and we economise fuel. 

The importance of only firing dry products is known to all 
potters ; not only do they behave better under firing, but the cost 
of fuel is considerably diminished. In fact every kilogramme of 
water to be evaporated means 637 calories, that is to say, about 
IOO grammes of a coal giving 7000 to 8000 calories ; for, besides 
the heat of vaporisation, we must take into account the heat 
necessary to raise water- vapour to 300 or 400 C., the temperature 
at which water of combination is given out. 

If the bricks contain 2 or 3 per cent, of hygrometric water, as 
is generally the case, the expense of fuel on this head will be, for 
every 1000 kilos of green products: 

1000 x 2 X o.i = 2 kilog. of coal. 

If the quantity of water is as much .as 10 per cent, 10 kilos 
of coal will be required, representing 28 kilog. per 1000, if we 
take the weight of 1000 green bricks to be 2800 kilog. It is 
therefore highly advantageous to dry the products well. 

COST OF FIRING IN CONTINUOUS KILNS. In accordance 
with the remarks made on p. 224, the cost of fuel may be 
estimated at from 40 to 60 kilog. per 1000 kilog. of fired 



230 POTTERY IN ARCHITECTURE. 

products, the firing taking place at a temperature of from I 100 
to i 200 C. 

ESTIMATE OF A CONTINUOUS KILN. The price varies accord- 
ing to the form of the kiln. In M. Bourry's opinion round kilns 
are preferable, as regards cost, for a daily production of from 3000 
to 7000 bricks; for an output of 5000 to 10,000 there is very 
little difference between the two shapes ; above that number, 
elongated kilns are more economical, and take up less room. For 
iron-plated kilns with sixteen compartments, like the one repre- 
sented in Figs. 213 to 217, the following are the approximate 
dimensions : 

1. Outside measurement : Length, 34.8 m. ; breadth, 75 m. ; height, 2.75 m. 
Dimensions of one compartment : Length, 4 m. ; breadth, 2 m. ; height, 2 m. ; 

cubic content, 12.6 cubic metres. 

Rough masonry ..... 224 cub. metres^ 
Brick 176 } 400 cub. metres. 

2. Outside measurements (Figs. 213 to 217) : Length, 35.8 m. ; breadth, 9.9 m. ; 

height, 3.4 m. 
Dimensions of one compartment : Length, 4 m. ; breadth, 3 m. ; height, 2.7 ni. ; 

cubic content, 28.7 cubic metres. 
Rough and brick masonry 600 cub. metres. 

It will be seen from these figures that the volume of the 
masonry is far from being proportional to the cubic content. 

We shall now give the detailed estimate of the above kiln, 
adopting, for the sake of uniformity, the same prices as before : 

Masonry ........ 600 cub. m. at 30 fr. 18,000 fr. 

Sand or clay for filling the hollows of the masonry 200 cub. m. at I fr. 5 3 

Iron-ivork : 40 double iron plates bound by 20 

iron tie-rods (.03 m.) with double nut . . . 6700 k. 

224 cast-iron lids and shoulders for the coal holes . 3000 

1 6 traps used as registers with shoulders and 

raising gear ........ 2000 

3 cast-iron openings with double sheet-iron plate 

for the central channel ...... 300 



12,000 k. at 30 fr. = 3,600 
Sundries . ......... 100 



22,000 fr. 
To this sum must be added for the chimney ...... 5,ooo 

The kiln works without being covered, but it is better to shelter it. A 
simple wooden shed covered with tiles, 40 m. long and 20 m. broad, costs about 8,000 

Cost of kiln with chimney and building. ...... 35,000 fr. 



BRICKS. 231 

If storeyed drying-rooms are required, the price is increased. 

A kiln constructed as above is very solid, elegant, and does 
not take up much room. A certain economy is effected by omitting 
the iron plating, and increasing the thickness of the walls. This is 
cheaply done by supporting the inside brick facing with buttresses 
between which clay is heaped up ; the whole is covered with a 
facing of flint or rubble masonry. 

B. CONTINUOUS KILNS WITH GAS FUEL. Historical and 
General Remarks. The advantages gained by firing pottery by 
the combustion of gases were pointed out long ago by Ebelmen 
and Salvetat, who had specially in view porcelain and faience. It 
was only much later, in 1869, that eminent manufacturers like 
Muller, Marie, etc., undertook to apply gas firing to architectural 
pottery, and especially to bricks. If the question seems, theo- 
retically speaking, simple, and is presented in a seductive manner, 
it meets nevertheless in practice many difficulties which have 
much hindered its success. It was in fact necessary to find a 
kiln which would present evident superiority over the Hoffmann 
kiln, and -which would effect firing as economically, even more 
economically if that were possible. 

The few small disadvantages of the Hoffmann kiln are as 
follows : 

The presence of ashes, the residue of combustion, which the 
draught carries into the different parts of the kiln, and which may 
become attached to the products ; 

The direct contact of the fuel with the bricks of the well, 
which always causes loss ; 

The cooling caused by the entrance of cold air when the 
solid fuel is thrown in ; for however short a time the lid may be 
opened, as the action is frequently repeated there is a sensible 
loss of heat ; 

The difficulty of easily transforming the oxidising action of 
the kiln, which is the usual action of the Hoffmann kiln, into 
the reducing action sometimes necessary for certain products ; 

The impossibility of getting a constant heat throughout the 
kiln, and the difficulty of attaining very high temperatures. 

The use of gas kilns does away with all these inconveniences, 



232 POTTERY IN ARCHITECTURE. 

at the price of some difficulties, however, the most serious of 
which has been, until very lately, an increase of the expense of 
firing. That can easily be understood. The problem before us 
as to the firing of bricks is as follows : how to raise to a high 
degree of temperature products which we should be able to intro- 
duce and withdraw in a continuous manner. If it is admitted 
that these products should be fixed with respect to the fire which 
itself moves, we^ come inevitably to this conclusion : collect the 
gases made by the gas generator so as to distribute them after- 
wards to the place of combustion. But, in order that a gas 
generator may give its maximum of effect, the gases must be used 
as hot as possible, at 400 or 500 C., their temperature when 
issuing from the generator. 

In the present case this is impossible ; they have to pass 
through the whole length of the kiln, hence there is a cooling 
which causes a certain loss of heat, and the condensation of the 
soots and tars carried off by the gas. 

This tar at last obstructs the channels ; we get rid of it by 
burning it in the conduit itself by letting in the air, communica- 
tion with the generators being interrupted, and thus a stoppage of 
a few hours being caused in the working of the kiln. Besides, 
this short stop only takes place every five or six months with a 
well-managed generator, and may even be altogether avoided. 

As for the cooling, it is reduced to a minimum by placing the 
gas generators at the end of the kiln. The real cause which has 
so long delayed the application of gas kilns to the firing of bricks 
is that the more a machine is perfected, the more does its 
management become delicate and require care and precautions. 

The Hoffmann kiln was an advance on intermittent kilns ; 
some time was required to achieve its triumph, and even to-day 
it is certain that many manufacturers do not profit by all the 
economy which it may bring, because the possession of a machine 
is not everything, much lies in its proper handling. Gas kilns 
are an important advance on the Hoffmann kiln ; for that very 
reason they require more skill in management, and above all a 
change of habits in the workmen, which is not always easy to 
obtain. When one thinks of the details on which the success of 



BRICKS. 233 

a commercial operation so often depends, one perfectly under- 
stands the difficulties which hinder those who are urging the 
firing of bricks by gas. 

In our opinion, then, the objections made to gas kilns 
such as danger of explosions, greater cost of construction, 
obstruction of conduits by tar, more expensive firing, etc. have 
very little, if any, foundation. But we repeat that to succeed 
in using them carefully, well-trained workmen are required who 
are capable of ensuring a steady and uniform working of the 
generator ; there lies the whole secret of success. 

Gas Generator. We know that when a layer of fuel, not more 
than 6 or 8 inches thick, is burnt on a gridiron, the air passing 
across this incandescent layer burns it completely, turning it into 
carbonic acid by means of the oxygen contained in it, so that the 
products of combustion consist mainly of nitrogen and carbonic 
acid, and, in smaller quantities, of water-vapour, oxygen, etc. All 
these gases are inert. 

If the thickness of the fuel be increased, and the quantity of 
air assisting combustion be reduced, the result is different. The 
carbonic acid formed in the lower strata of the coal is reduced while 
passing through the red-hot upper part, and gives up oxygen ; an 
extremely inflammable gas is thus formed : carbonic oxide. This 
is the reaction which takes place in high furnaces. At the same 
time, small quantities of hydrogen and carburet of hydrogen, also 
inflammable, are produced. The gases given out by this slow 
combustion of the coal consist especially of nitrogen and carbonic 
oxide, and, in smaller quantities, of hydrogen, carburets, water- 
vapour, etc. ; this mixture has received the name of generator gas. 

Another more economical gas called water gas is produced as 
follows. The water is formed by the combination of oxygen and 
hydrogen ; at a very high temperature, about 1 000 C., this 
combination is destroyed, and the two elements separated. This 
reaction takes place more especially when water is thrown on 
an incandescent furnace ; the oxygen burns the coal, and the 
hydrogen is set free. If the operation takes place in presence of 
an excess of coal, the carbonic acid produced will be reduced 
to carbonic oxide ; the gases of combustion will contain 



234 POTTERY IN ARCHITECTURE. 

carbonic oxide and hydrogen, both inflammable gases, and, in 
small quantities, carbonic acid and nitrogen. This result is 
obtained in practice by passing a current of water-vapour over 
the incandescent grate of a generator. The decomposition takes 
place, but as it is endothermic, that is to say, that it absorbs heat, 
the coal gets cooler, and the reaction would cease if the entrance 
of vapour were not stopped to give place to an injection of air. 
During this second period generator gas is produced. When 
combustion has recommenced the air is stopped and vapour 
admitted, and the process continues. The duration of these 
alternate reactions varies according to the conditions of the 
installation ; for instance, water gas will be made for four minutes, 
and then for eleven minutes heat will be raised again and 
generator gas produced. 

Water gas has a much greater calorific power than generator 
gas, as their average compositions show 

Composition Combustion value 

of i cubic metre. in calories. 

Generator Water Generator Water 

gas. gas. gas. gas. 

Carbonic oxide .... 237 440 723 1342 

Carburets of hydrogen ... 19 4 162 34 

Hydrogen 65 486 1 68 1254 

Nitrogen ..... 639 37 o o 

Carbonic acid .... 40 33 o o 



1000 1000 1053 2630 

One kilog. of coal, the heating power of which is about 
8000 calories, gives from 4.5 to 4.9 cubic metres of generator 
gas, which, when cooled to 20 C., has as calorific value : 

4.5 x 1053 + 4-9 X 1053 

= 4949 calories, that is to say only 

62 per cent, of the calorific value of the coal used in its 
preparation. 

In water gas we recover 80 to 85 per cent, of the heating 
power of the fuel, half in the form of generator gas, and half in 
the form of water gas. 

The preceding figures are the result of experiments made 
in the Krupp factories at Essen. 



BRICKS. 235 

It is advantageous, then, to use water gas for the firing of 
bricks, as these cheap products require as low a cost of produc- 
tion as possible. The apparatus for the production of gas 
is the same in both cases, and so is the kiln, as we shall see 
below. 

As in the case of kilns with solid fuel, there are a certain 
number of gas kilns recommended by different makers (Schwan- 
dorf, Marie, Simon, etc.), which only differ from one another in 
details. 

Fillard and Gastelier Kiln. This kiln was invented and 
constructed by M. Fillard (successor of M. Gastelier at Fresnes), 
one of the most ardent defenders of gas firing, who has suc- 
ceeded, after persevering attention, in devising a really practical 
form of kiln. 

This rectangular kiln does not differ in its main features 
from the kiln which we have described in detail, except as to 
its central portion. The smoke channel has above it another, 
stretching the whole length of the kiln and serving for dis- 
tribution of the gas. The arched roofs are pierced, as in 
ordinary continuous kilns, with a series of heating holes closed 
by movable lids. The channel conducting the gas has also 
in its upper part orifices corresponding to each row of holes; 
these orifices are also closed by movable lids. The combustion 
of the gas takes place in hollow pipes, called " chandelles," made 
of refractory clay, and pierced with holes. These pipes, which 
are formed of several parts fitting one within the other, are 
movable and placed below the stoke holes. They are put 
into communication with the gas channel, when necessary, by 
means of a pipe with several branches which are fitted to the 
opening of the channel and the corresponding stoke holes ; 
these branch tubes are fitted with valves which permit of the 
communication between the " chandelles " and the gas conduit 
being shut off. 

As for the gas generator, Figs. 225 to 227 show its con- 
struction : it has two furnaces working simultaneously. The 
gases pass into a chamber which acts as a gasometer, and 
afterwards enter the central conduit of the kiln. 



2 3 6 



POTTERY IN ARCHITECTURE. 



The generators may be placed anywhere ; most generally 
they are at the end of the kiln (Figs. 228, 229), but if space 
does not allow of this, they may be put at the side of the 
kiln. Water is always kept beneath the fire-bars ; this water 
evaporates, and in passing through the incandescent mass gives 



out water gas. 



GAS GENERATOR. (Scale of ii millimetres to the metre.) 





Fig. 225. Transverse Section of a 
Furnace. 



Fin. 226. Elevation of a 



rig 



Furnace. 




L 



Fig. 227. Longitudinal Section of a Furnace. 

Working of the Kiln. The stacking is done as in other 
continuous kilns, but heating wells are not used. When we 
come to a row of holes, we place the " chandelles " under- 
neath, the joints are luted with clay, and the stacking is 
continued, the space between two " chandelles " being left free, 
so that there is throughout the section of the kiln an empty 



BRICKS. 



237 



space of the thickness of the " chandelles " ; it is in this space 
that the combustion of the gas will take place. 

The igniting of the kiln offers no special feature, except 
that the gas generator should work when a sufficient quantity 
of brick is raised to a red-heat capable of setting fire to the 
gas. The distribution of the latter is effected by the sheet-iron 
conduits of which we have spoken, and which are placed over 
the kiln. The number of rows of " chandelles " lighted, depends 
upon the degree of firing and the nature of the products to be 



GAS KILN WITH GENERATOR. (Scale of 5 millimetres to the metre. ) 




Fig. 228. Horizontal Section. 
Fig. 229. Horizontal Section of the Kiln, and View of a Generator from Above. 



baked ; this number generally varies from two to six. The 
supply of gas is regulated by stop-cocks placed in the movable 
conduit above the " chandelles." It is better not to introduce 
the gas into the compartments until the bricks contained in 
them have almost reached the proper degree of firing. In 
this way the gas which is not burnt in the first layer will be 
burnt in the others, and no useful part of the fuel will escape 
into the chimney. The progress and height of the fire- in the 
kiln is observed through little openings in the roof. 

The action of a gas kiln is the same as that of one with 



238 POTTERY IN ARCHITECTURE. 

solid fuel. The air enters through the doors of the cooling 
compartments, passes over the fired products, drawing heat from 
them, and comes in a very hot state into contact with the 
" chandelles " which are emitting gas. The latter burns with 
a brilliant flame behind the fire where the air is in excess, 
but the flames are duller and longer in front where the air 
contains less oxygen. The firing thus takes place in an oxidis- 
ing atmosphere ; moreover, this is the method to be preferred 
in most cases ; but if it is necessary, the atmosphere of the 
kiln may in a few moments be made a reducing one by diminish- 
ing the draught and increasing the volume of gas introduced. 
In order to avoid the loss of the excess of gas, which would 
escape by the chimney, this excess is burnt by introducing a 
little air in front of the fire. There is no disadvantage in the 
fact that the atmosphere at that point is an oxidising one, as 
the " enfumage " of all pottery takes place in the midst of 
excess of air. 

The gas being easily distributed, it may be seen that it 
is possible to stimulate the fire at a given point by opening 
wide the stop-cocks regulating the entrance of gas into the 
" chandelles " ; in the same way it may be moderated by lower- 
ing these valves and even extinguishing one or two " chandelles " 
by closing them entirely. 

The temperature which can be attained in a gas kiln is very 
high, and stoneware pastes fire well in them ; these pastes may 
even be melted by stimulating the fire to its greatest power, 
which, however, can hardly be considered as a normal state. 

Continuous Gas Kiln with Multiple Firing Chambers. 
We shall describe one type of this kiln used by MM. Schneider et 
Cie. in their refractory product works at Perreuil, near Creusot. 
It is shown in Figs. 230, 231, 232. 

The kiln has an outside diameter of 20 metres and possesses 
fourteen compartments, each measuring: depth, 2.9 m. ; mean 
breadth, 2.5 m. ; height, 2.6 m. ; this corresponds to a cubic content 
of about 19 cubic metres. They are separated by walls (Fig. 
232) pierced with three openings making communication between 
them (Fig. 230). The gas arrives below the floor and penetrates 



BRICKS. 



239 



into the firing compartment by three vertical openings placed 
below those connecting the compartments with one another. 

In stacking, an empty space is kept between the separating 

CIRCULAR CONTINUOUS GAS AND HOT-AIR KILN BY SCHNEIDER ET CIE. 

(Scale of 3.1 millimetres to the metre.) 
Fig. 230. 




Fig. 230. Section C D. Fig. 231. Section A B. 

Fig. 232. Horizontal Section of the Kiln and Generators. 

wall and the products (Fig. 230); it is in this chamber that 
combustion is begun, by the mixture of the gas and the air 
which has been heated in passing over the cooling fired products. 



240 



POTTERY IN ARCHITECTURE. 



The combustion when once begun spreads itself through the 
channels left in the stacks, the hot gases continue their way, 
heating the products stacked in the following compartments, 
and finally reach the chimney, 30 metres high, placed in the 
centre. 

The gas generator has 3 gridirons, I metre by 1.3 metres. 
The temperature of this kiln rises to 1500 C. ; hence the 
inside is built of refractory bricks. The firing of a compartment 
requires from 12 to 1 6 hours according to the nature of the 
stacked refractory products, and its cooling requires 3 to 4 
days. 

Water-gas Kiln. In this kiln we have again the parallel 




Fig. 233. Continuous Water-gas Kiln Transverse Section. 
(Scale of 8.3 millimetres to the metre.) 



galleries of the rectangular continuous kilns. The distribution 
of gas is effected by two parallel galleries placed in the centre ; 
the gas passes through vertical conduits under the flooring of 
the kiln and issues by " chandelles " placed below the orifices 
of the conduits. This was the arrangement of the first gas 
kilns ; it had to be abandoned in favour of a distribution of 
gas from the roof on account of obstruction of the conduits 
by tar. This obstruction need not be feared with purified 
water gas. 

Each conduit is closed by a valve which is worked from 
outside; in the kiln shown (Fig. 233), there are three conduits 
placed side by side and corresponding to each row of " chan- 



BRICKS. 241 

delles." The conduits are made simply of earthenware pipes 
encased in masonry. The stacking and the management of 
the fire are precisely the same as in a generator-gas kiln. 

COST OF A GAS KILN. Fillard System. We shall 
make this estimate for a kiln capable of firing from 5 to 
6 million bricks annually and having as dimensions : length, 
49 metres; breadth, 11.35 m - 5 an ^ height, 10.55 m - The 
chimney is 35 metres high and has a diameter at the summit 
of 1.40 m. 

Brick masonry for interior . , . . 270 cub. m. 
Rubble or mill-grit for exterior . . 525 

Total . 795 cub. m. at 30 fr. =23,850 fr. 

Cast-iron for generator and kiln . . . 9000 k. at 30 fr. = 2,700 

Sheet-iron and accessories . . . . . . . 900 

" Chandelles " of refractory clay and sundries . . ... 1,550 

29,000 fr. 
We must add for the chimney . . . ... V. . . 5,ooo 

,, ,, building . . . . - . . . 8,000 



1167 cubic 
metres at an 
average price 



42,000 fr. 

Schneider System. The estimate of a kiln like that in Figs. 
230 to 232 is thus calculated 

Concrete of crushed stones and hydraulic 

mortar 135 cubic metres 

Stoneware and brick masonry . . . 540 ,, ,, 

Brick masonry for chimneys . . . 82 ,, ,, 

Refractory brick masonry ." ". . . . 410 ,, ,, 

cubic metre = 35,010 fr. 

Iron, cast-iron, steel, and sheet-iron ; 26,050 kilog. at an average price of 

30 fr. per 100 kilog. . . . . . . . . . = 7,815 

Building (42 cub. m. of timber and 663 sq. m. of roofing), about . . 7,175 

Total = 50,000 fr. 

These figures are only intended as a rough indication ; 
they may increase or diminish, according to the cost of labour 
and materials in the district where the kiln is built. 

COST OF FIRING IN GAS KILNS. For the same reasons as 

we have already stated, it is difficult to fix this cost exactly for 

want of exact experiments which are capable of comparison. It 

is certain, however, that with a well-managed kiln, the cost is 

16 



242 POTTERY IN ARCHITECTURE. 

no greater than with a solid-fuel continuous kiln ; M. Fillard 
states that, in his factory at Fresnes, he has reached a lower 
cost. He estimates the consumption at 50 kilog. of ordinary coal 
per 1000 kilog. of fired products. 

In the Schneider kiln baking refractory products at 1500 
C., the consumption is as much as 110-115 kilog. of coal per 
1000 kilog. of products. 

But the manifest superiority of gas firing consists in the 
beauty and quality of the results obtained, advantages which are 
much appreciated for delicate articles such as facing bricks, tiles, 
squares, etc. 

Temperature of Firing of Bricks Its Measurement 
Nothing is more variable, naturally, than the temperature at 
which the firing takes place, considering the variety in the 
composition of the clays used. This temperature usually 
oscillates between 1000 and 1200 C., but it may rise to 1300 
or 1400 C. 

In practice there is no advantage in measuring it ; the 
degree of firing is observed by noting the contraction, as 
pointed out on p. 226. 

But if we wish to find out at what temperature the firing is 
taking place, we must have recourse to the pyrometric indicators. 
These are mixtures, in variable proportions, of different oxides 
which soften at different temperatures. They have been 
specially studied by the German pottery expert, Seger. To 
make use of these instruments, which are in the shape of a 
four-sided pyramid, a series of them is placed in the kiln, and 
when the proper degree of firing is reached, their condition is 
examined. The number is noted of the one whose point has 
begun to bend, the next one being still intact. In order to 
regulate later firings, it will be sufficient to place in the kiln 
several indicators near on the list to the one noted, and to observe 
their behaviour. 

Indicators can be obtained in the trade (in Paris, from 
MM. Poulenc freres) fusible at intervals of 30. 

The fusion of metals and even the colour of the fire only will 
show the temperature reigning in a kiln. 



BRICKS. 243 

Here are some hints on the subject 



Aluminium melts at 
Zinc volatises at 
Silver melts at 
Gold melts at 
Copper melts at 
White cast-iron melts at 
Grey melts at 
Nickel melts at 
Palladium melts at 
Platinum melts at 


625 C. 
930 C. 
954 C. 
1045 C. 
1054 C. 
1130 C. 

1220 C. 

1410 C. 
1500 C. 
i775C. 


Dark red. 
Cherry colour. 
Light cherry colour. 
Orange. 
Orange. 
Light orange. 
White. 
Brazing white. 
Dazzling white. 



A large number of types of pyrometer^ based on different 
systems, are in existence, but are seldom used in pottery. The 
simplest one, Wedgwood's, gives very inaccurate indications ; 
the best one, the thermo-electric pyrometer of M. Le Chatelier, 
is too delicate for practical use. 

Production of Kilns Relatively to the Heat Used. The 
production of a kiln, from this point of view, is given by the 
relation between the number c of calories theoretically necessary 
for firing products at a stated temperature, and the number C of 
calories produced by the combustion of the coal employed. 

To determine the ratio ^ we must find e from the composition 
of the paste and the temperature T at which it is fired. 

The factors of this calculation are 

1 . The heat necessary to evaporate the weight e of the 
hygrometric water; 

2. The heat absorbed by the departure of the weight E 
of the water of combination ; 

3. The heat available for raising I k. of clay from the 
ordinary temperature to T, supposing .2 to be the specific heat 
of the clay, between 15 and 1400 C., which is a sufficiently 
near approximation. 

It is supposed that the quantities of heat given out or 
absorbed by the chemical transformation of the silicates balance 
one another, and that the absorption of heat due to the de- 
composition of the carbonates, when there are any, may be 
neglected. 

The number of calories theoretically necessary to fire a 
given weight of clay being thus calculated, we must add to this 



244- POTTERY IN ARCHITECTURE. 

number that due to losses of heat, the principal of which are : 

(1) loss due to the heating of the inner walls of the kiln; 

(2) loss due to the radiation of the outer walls ; (3) loss due 
to the hot gases passing through the channels to the chimney ; 
(4) in gas heating, loss due to gasification. 

All these losses are very difficult to estimate in practice, 
therefore it is much simpler to weigh the quantity of coal 
employed in firing a given weight of the products, and determine 
the calorific power of this coal. Thus we have the number 
of calories practically necessary for the firing. Comparing the 
number so found with the number theoretically necessary, we 
shall have the loss of heat due to the various causes enumer- 
ated above, and consequently the thermic production of the kiln. 

This production is far from being constant ; it depends, 
above all, upon the good management of the fire and the stack- 
ing, two important factors in the firing of pottery. 



2. DIMENSIONS, FORMS, COLOURS, ORNAMENTATIONS, AND 
QUALITIES OF BRICKS HOLLOW BRICKS. 

Bricks have always the shape of parallelepipeds of three 
unequal dimensions bearing a certain relation to one another. 
Ancient bricks were larger than those of the present day and 
their dimensions did not bear the same relation to one another. 
At the present time the width is generally about half the length, 
and the thickness about half the width. 

The latter dimension should not exceed .12 m., so that one 
may take up in the hand a brick laid flat ; the thickness does 
not exceed .07 m. on account of drying, which would be too slow, 
and scarcely ever is less than .05 m., except in special cases. 

The object of the relation between the length and breadth 
of bricks is to facilitate dressing. Brick walls, in fact, are 
divided into partitions, the thickness of which varies from that 
of one brick laid on edge or flat in the direction of the width 
or length, the junction being crossed, and walls of one or several 
bricks' breadth : a brick and a half, two bricks and a half, etc. 



BRICKS. 



245 



These methods of dressing make the work easier and increase 
the solidity of the masonry ; they can only give good results 
with a brick of very regular shape, especially as regards thick- 
ness, for the layers must be of the same height. 

The table below gives the dimensions of the principal 
types employed in different countries. 

The dimensions given are those most generally found, 
but special bricks are manufactured for special uses. For 
example, some have only half the usual length, and are : . 1 1 x 
. i i X .06 ; they are used for making joints without having to cut 
a brick in two; others have only half the usual thickness (.22 x 



Name of Country. 


Dimensions in Centimetres. 


. 






. 


1 




: 


Remarks. 


^ 


*5 


c 


Cubic 


a 




w> 


1 


5 


Content. 


V 
.0 




3 





A 

H 











'Marseilles brick . 
Burgundy , , 
Paris ,, 


21-5 

22 
22 


10.5 
ii 
ii 


5-7 
5-5 
6-7 


I2IO-I694 

1331 
1452-1694 


(I) 


In Paris, the bricks 
of .055 are reserved 
for facades, and the 
thicker ones for in- 


France 


Type Union Cera- 
mique 
,, Northern 
Architects 


22 
22 


10.5 
10.5 


5-5 
6 


I27O 
1386 




teriors. In certain 
buildings, briquettes 
of less than .05 thick- 
ness are used. Clin- 
kers are used for 




^ Clinkers 


16 


6 


4 


384 




paving yards and 


Germany 


Normal 


25 


12 


6-5 


1950 




stables. 


England -j 


Minimum . 
Maximum . 


23.6 
25-4 


12.4 


7.6 
7.6 


2040 
2390 




The cubic content of 
the mortar used in 


Austria 


Normal 
Kleynestern 


25 

3-5 


12 
5 


6.5 
3-5 


1950 

61 




brick masonry varies 
from 10 to 20 per 
cent, of the total 




Derdding . 
Papesteen . 
Klatnpstein . 


19 


7-3 
8.5 

9 


3-8 
4-5 
4-7 


416 
688 
761 




volume, according to 
the care used in 
making the joints. 




Gand . 


22 


ii 


6 


H52 






Holland 





26 


12 


5-4 


1684 






Switzerland, Normal type 


25 


12 


6-5 


1950 






United States 


19-5 


9.8 


5 


980 







(i) Below are some catalogue prices ; they are capable of reduction, and are for goods 
taken at the factory. 

Price. 

60 fr. stamped. 
65 fr. 
Gilardoni freres 



Burgundy 
Champagne 



(Montchanin 
(Perrusson 



Weight. 
2.7 k. 
2.6k. 



Normandy 



Paris 



j Argences . 

^ Rouen (no reduction) 

/Brault 
-JMuller . 
(Radot 



2.5 k. 
1.9 k. 
2.5 k. 

2.6k. 

2.5 k. 

2.6k. 



(35 fr. hand-made. 
(40 fr. die-made. 
(48 fr. ordinary. 
(35 fr. stamped. 
(21 fr. hand-made. 
(28 fr. stamped. 
55 fr. stamped. 
5 fr. , , 
60 fr 



246 POTTERY IN ARCHITECTURE. 

.1-1 X .03), and are used for cellar partitions or to make up a 
difference of level ; and finally, the bricks called " closoirs," 
.22 X .055 x .055, have only half the breadth of ordinary bricks. 
When the bricks are less than .055 m. thick they are called 
" briquettes." Briquettes exist of 2, 3, 4, and 5 centimetres 
in thickness. The brick-maker may of course manufacture any 
brick which lightens labour, and builders often find it advan- 
tageous to use it, even when more expensive, to avoid the 
always burdensome expense of cutting, and to improve the 
workmanship. 

Shapes. Ordinary bricks, as we have stated, are in the form 
of parallelepipeds with the dimensions above shown, but for 
special purposes bricks of special shapes are made, and the 
principal examples of these are shown in Figs. 234 to 257. 

The ordinary shape (Fig. 234) is naturally the one most 
generally used. Conical bricks called "coin" (Fig. 235) are 
used for arches whose surface is solely formed of ends ; for those 
into which only sides enter, bricks called " couteau " are taken 
(Fig. 236). 

For the beginning of arches the bricks have only one inclined 
face. This inclination of the faces bears a relation to the radius 
of the arch. 

The outside embrasures of doors and e,ven of windows are 
made with bricks one edge of which is more or less rounded 
(Figs. 239, 254). 

For entrance pillars, or to decorate the coping of a wall, 
bricks are used having one (Fig. 237) or two corners (Fig. 238) 
cut. 

Bricks with moulded profiles (Figs. 240 to 250) are used in 
coping enclosure walls, in house cornices, garden borders, etc. 

The masonary of wells or fully arched vaults requires to be 
economical and well made, bricks of the arched shape shown in 
Fig. 253. 

For large factory chimneys, bricks are used of the shape of 
that in Fig. 257. Finally, paving bricks have hollows or ribs 
on their surface to prevent slipping in walking on them (Figs. 251, 

252). 



BRICKS. 



247 



The manufacture of these bricks is performed in the same 
way as that of ordinary bricks, the dies having the shape 
required ; the bricks are most frequently stamped with presses 
whose moulds are of the desired size and shape. Each kind of 
brick therefore requires a special die and mould which can only 
be used for that class of brick. If, then, the manufacturer has a 
certain number of types, he must have a considerable stock of 
apparatus which is only used to make annually a limited number 



Fig. 234 



Fie. 237 




Figs. 234 to 257. Bricks of Various Shapes. 

of bricks. The amortisation, interest, and maintenance of this 
stock will raise the cost of these special bricks all the more, 
as the consumption of them is small. 

Colours. The colour, which is very diverse according to the 
nature of the clays, varies from yellowish white through yellow, 
yellowish red, bright red, violet, and grey, to dark brown. For 
bricks intended for facades the colour should be uniform over 
the whole surface. This condition is not necessary for inside 



248 POTTERY IN ARCHITECTURE. 

masonry, but bricks of a good make usually present a single tint ; 
those which are variegated are made of insufficiently prepared 
material or contain many impurities. In fact, the foreign sub- 
stances enter during firing into combination with the clay, and, if 
the paste is not very homogeneous, produce various discolorations. 

The gases of combustion also have an effect on the colour 
of bricks ; this colour will be different according as the gases are 
reducing or oxidising (see p. 227). 

Red is the commonest and the most characteristic colour 
of bricks ; it is the one which, in architecture, gives those fine 
shades so pleasing to the eye. In order to break the monotony 
of one single colour, white bricks are frequently mingled with 
red ones, and designs are executed with bricks whose heads are 
black. We have seen how these bricks are produced in wood 
firing (p. 200). 

A bluish black colouring may also be given to bricks in the 
following manner. They are fired in intermittent kilns ; when 
this is finished, the furnaces are filled with bundles of green 
birchwood having the leaves still on, all openings are closed, and 
a copious smoke is given out which is deposited on the still red- 
hot products, giving them a black colour with a bluish lustre. 

Instead of fagots, oils loaded with petroleum may be burnt. 
The arrangement of the kiln varies, but one of the most con- 
venient consists of placing funnels in the arched roof of a 
tunnelled intermittent kiln, and pouring through them on to the 
incandescent mass tar or oil loaded with petroleum. Care is 
taken to close all openings beforehand. As the colouring is 
effected by a deposit of carbon, it is indispensable that all 
entrance of air should be prevented as long as the temperature 
is above dark red heat, otherwise the carbon deposit would dis- 
appear by combustion. 

To obtain a black colouring with bluish metallic lustre, 
which is the one most esteemed, we must work with strongly 
ferruginous pastes. For 1000 kilog. of fired products, 3 to 8 
kilog. of oil are required, and must be poured in several times at 
intervals of one or two hours. 

At West Bromwich in Staffordshire blue bricks are obtained 



BRICKS. 



249 



by the use of a special purplish clay containing a large proportion 
of oxide of iron. 

The white bricks, which are always slightly yellow, are made 
of clays containing no oxide of iron ; but they are not for that 
reason necessarily refractory. 

Decoration of Bricks. Ornamented Bricks. Besides the 
differently shaped bricks of which we have already spoken, 
bricks with ornaments are also made, which are intended for 
cornices or entablatures. This result is easily obtained by 
stamping with a press like the one represented in Fig. 167. 

Figs. 258 to 265 show some ornamented bricks of different 
shapes and sizes according to the uses for which they are 
intended. Clay by its plasticity lends itself admirably to the 
reproduction of all kinds of designs, and as, by suitable moulds, 
the same type may be repeated in numerous examples, this kind 
of decoration is comparatively cheap. 



Fig. 258. 



Fig. 259. 



Fig. 260. 




Fig. 261. Fig. 262. Fig. 263. Fig. 264. Fig. 265. 




Figs. 258 to 265. Various Ornamental Bricks. 

The brick represented in Fig. 263 is intended for a 
ventilator ; in this way the use of those unsightly iron gratings 
frequently placed at the orifice of ventilating shafts is avoided in 
facades. 

Enamelled Bricks. Another kind of decoration which, besides 
a pleasant appearance, gives valuable qualities to the bricks, is 
varnishing and enamelling ; but the manufacture of such products 
comes under the head of Faiences, and we will postpone further 
details as to enamelled bricks until we come to the chapter 
referring to faiences. 

Qualities of a Good Brick. Besides the colour, the importance 



250 POTTERY IN ARCHITECTURE. 

of which for facing bricks we have already emphasised, a good 
brick should be homogeneous, without fissures or flaws, not frost- 
cracked, easily cut and very resisting. 

Homogeneousness is tested by superficial appearance and also 
by fracture, which should be clean-cut and show a fine close grain 
without sign of crumbling away. 

Regular shape, which depends upon regular dimensions, is, as 
we have said, necessary to ensure satisfactory dressing, especially 
when on the surface : the edges should be very sharp. 

The non-liability to frost-cracking is an important quality, for 
without it a building would suffer from the weather. This 
quality is approximately tested by measuring the quantity of 
water absorbed by the dried bricks ; this should vary from 1 2 
to i 6 per cent, of their weight ; but this measurement is only an 
indication, and so is the method of impregnating the brick with 
a saturated solution of sulphate of soda in order to see if it loses 
small fragments, which would show its liability to crack. 

Direct experiment is the most conclusive ; it consists in 
plunging several bricks into water, and afterwards subjecting 
them to a temperature of several degrees below zero (Essai 
officiel des terres cuites, p. "381). 

Ease of cutting is useful in order that the mason may be 
able to cut the brick without difficulty to fill up gaps or to 
complete a layer, etc. 

The resistance is proportional to the hardness of the bricks. 
It is recognised by the clear sound which should be given when 
they are struck together. This resistance is measured directly 
by making the bricks support greater and greater weights until 
they are crushed or break, according as we attempt their crushing 
or fracture. In buildings bricks tend rather to become crushed. 

According to experiments which have been made since fairly 
remote times, a well-fired brick will be crushed under a weight 
varying from 110 to 150 kilogrammes per square centimetre. 
This weight is reduced to 90 or even to 60 kilogrammes if the 
brick is insufficiently fired. These numbers are mere indications, 
and vary considerably with the manner in which the bricks have 
been made and the degree to which they have been baked. In 



BRICKS. 251 

practice, bricks arc only subjected to the tenth part of the pressure 
which would crush them. 

The effort required to produce rupture is very much less ; 
subject to the remarks made above, the pressure has been found 
to be on an average 30 kilogrammes per square centimetre. 

The density of bricks is also a sign of good quality, because 
well-blended clays give bricks of very close grain, very homo- 
geneous, and consequently of great density. But here again we 
must have recourse to direct experiment, for there are certainly 
bricks which differ in weight and are yet as good in quality. 
The weight of a well-fired and dry brick of dimensions .22 x .1 i 
X .06 to .07 varies from 2\ to 3 kilogrammes. For the official 
tests of bricks see the end of Part I., p. 377. 



HOLLOW BRICKS. 

Hollow bricks, first manufactured mechanically in France by 
M. Borie in 1850, are bricks pierced longitudinally, transversely, 
or perpendicularly with cylindrical or prismatic holes which pass 
from one face to the other parallel to an edge. In France, those 
most used are pierced longitudinally with prismatic holes. 

Manufacture. The preparation of the clay, the soaking or 
moistening, is performed in the same way as for solid bricks ; 
impurities such as roots and stones should be carefully avoided, 
as they would cause a loss in manufacture. 

In some machines, all traces of impurity are removed by 
passing the clay through a sieve. The paste is generally firmer 
than in the case of solid bricks, since more consistency is 
required to prevent the brick from losing shape. 

The moulding is done by expression machines, the compres- 
sion of the clay being effected by means of propelling cylinders, 
screws, or pistons ; all these machines are similar to those we 
have described in speaking of solid bricks, only the dies being 
different. Figs. 266 to 269 give different views of a die which 
gives passage to three hollow bricks having eight holes in each. 
The outer edges of the brick are cut by the die, and to produce 



252 



POTTERY IN ARCHITECTURE. 



the holes bronze pieces are added which carry well-finished parts 
of the dimensions of the holes, and these parts keep back the 
clay. The hollow separating them from the outer edge forms 
the thickness of the brick. Each row of holes requires a special 
piece, as may be seen by the view of the inner side (Fig. 267). 
These pieces are movable, for being of bronze they wear out 
rather fast, and they must be renewed as soon as the holes in 
the bricks become too narrow. 

Sheet-iron combs are frequently placed against the die above 
and below the prism of clay ; the sharp teeth of these bite into 



DIE FOR HOLLOW BRICKS. 



Fig. 266. 

Yue' du cete exterieur 



Fig. 267. 

Vue du c o te mt eri eur . 




Fig. 268. 

Fig. 266. View of Outer Side. 
Fig. 268. Section C D. 



Fig. 269. 

Fig. 267. View of Inner Side. 
Fig. 269. Section A B. 



the fresh clay and dig grooves in it which will increase the hold 
of the plaster or mortar when the bricks are employed for 
partitions, the commonest use for these products. 

The dimensions of the die as well as the distance between 
the wires of the cutting-table vary according to the direction in 
which the holes are to lie, as shown in the following table. We 
suppose a brick which is to be after firing: .22 x .1 i X .055 



Bricks pierced longitudinally 
,, ,, transversely 

,, ,, perpendicularly . 



Dimensions Distance 

of the Hollow of the Die. of Wires. 
.I2X.O6 .24 

.24X.O6 .12 

.24X.I2 .06 



BRICKS. 



253 



As in the case of solid bricks, the same die may pass several 
bricks at the same time, either the issuing orifices being separated, 
as in Fig. 266, or there being one single orifice, and the brick 
being divided, as it issues, by well-stretched wires (Fig. I 30). 

The dimensions are the same as for solid bricks. Hollow 
bricks naturally require less clay for their moulding than solid 



Fig. 270. 



Fig. 27i. 



Fig. 273. 




Figs. 270 to 287. Various Hollow Bricks (Perrusson and Desfontaines). 

ones, therefore large machines of high production are not 
suitable for this work, machines of moderate production being 
better. 

The drying and firing of hollow bricks do not differ from 
those of solid ones, but they require less time and less fuel, hence 
the sale price is lower. 



254 



POTTERY IN ARCHITECTURE. 



In France, hollow bricks are generally parallelepipeds with 
holes in the direction of the length (Figs. 270 to 279, 295 to 
297), but in Germany, where nearly all buildings are of brick, 
hollow bricks of the same shape as the solid bricks are used, 
and we find bricks with cut off corners (Figs. 301 to 303), 

LAPORTE "HOURDIS" (Montchanin Manufacture). 

Fig. 288. For Arched Flooring. Fig. 289. For Straight Floor. 

rounded bricks (Figs. 304, 305), and finally moulded bricks 
(Figs. 306, 307). These products being used in facings, the 
holes must be placed perpendicularly to their large surface ; 
when they are headers, they may be perpendicular (Fig. 299) or 
transverse (Fig. 300). Finally, bricks with cut off or rounded 



Tig 







Figs. 290 to 309. Hollow Bricks of Different Shapes (German Manufacture). 

corners are made having holes in the direction of their length 
(Figs. 290, 291, 292). 

" A couteau " bricks, curved bricks for arches and chimneys, 
are also made with holes (Figs. 296, 308, 309). 

In giving to bricks special shapes like those in Figs. 310, 



BRICKS. 



255 



3 I i, and 314, different pipings of great diameter are produced 
(Figs. 312, 313). 

Hollow bricks are much used for the arches of I -shaped iron 
floorings (Fig. 3 1 6). We see from the figure that the beginning 



Fig. 310. 



Fig. 312 



Fig 313. 



Fig. 314 



Fig. 315. 




Figs. 310 to 315. Hollow Bricks of Special Shapes. 

of the arch does not fit the shape of the iron on account of the 
wing ; therefore, to remedy this inconvenience, bricks of special 
shape are manufactured called " briques a sommier" (Fig. 275). 
Decoration of Hollow Bricks. Hollow bricks are often 




Fig. 316. Arch of Hollow Bricks. 

enamelled for partitions or facings of ordinary walls ; as in the 
case of solid enamelled bricks, we will postpone discussion of 
these until the chapter on Faience. 

Dimensions and Shapes. The dimensions of hollow bricks are 
much more varied than those of solid bricks, as is shown by the 
following table giving current sizes. 



.045 


x 


15 


x 


.22 


.045 


X 


.16 


x 


.22 


055 


x 


.11 


X 


.22 


.065 


x 


.11 


x 


.22 


.065 


x 


.16 


x 


.22 


.07 


X 


15 


X 


.22 


.08 


X 


.16 


X 


.22 


.10 


X 


.12 


x 


.22 


.11 


x 


. II 


X 


.22 



Holes. 












2 or 


3 






045 


X 


.15 


X 


3 


2 or 


3 






045 


X 


.16 


X 


3 


2 or 4 


(Fig. 


272) 


.-7 


X 


.16 


X 


3 


4 or 


6 


(Fig. 


270) 


.07 


X 


.21 


x 


3 


2,4, 


or 6 


.08 


X 


.16 


X 


3 


, , 








.10 


X 


.11 


x 


3 


4 or 


6 






.11 


X 


.11 


X 


3 


6 or 


9 






. ii 


x 


.16 


x 


3 


9 




(Fig. 


277) 


.11 


X 


.22 


X 


3 



Holes. 
2 or 3 

4 or 6 



(Fig. 276) 



,, (Fig. 278) 
6 or 9 

, , 
6, 9, or 12 



256 POTTERY IN ARCHITECTURE. 

Besides the above-mentioned bricks, some are also made of 
special shape (Figs. 285, 286, 287), .22 m. broad, of length 
varying by centimetres from 50 to 80, and of thickness varying 
from 5 to I I centimetres. They are used to fill up intervals 
between the I-shaped irons of floorings (Fig. 286) or to raise 
partitions (Fig. 315). When the I-shaped iron pieces have a 
considerable height, special hollow products called " hourdis " are 
substituted for these bricks. Those most used are the Laporte 
" hourdis," so called from the name of their inventor (Figs. 288, 
289). Their length is .33, and their thickness depends upon the 
height of the I-shaped iron bars. Their upper surface is placed on 
a level with the latter. 

Qualities. These are the same as those required for solid 
bricks, that is to say, that when used in facings they should have 
a uniform colour and sufficient hardness, that they should not be 
liable to crack, and should be of regular shape. The colour and 
resistance of the inside need not be so carefully supervised. 

According to the experiments of Herve Mangon, the resistance 
offered by hollow bricks to crushing presents a curious difference 
according as the pressure is parallel or perpendicular to the 
direction of the holes. Thus, whereas a mean weight of 24 
kilogrammes per square centimetre applied to a brick laid flat 
is sufficient to crush it, a weight of about I oo kilogrammes is 
required to crush the same bricks placed on end. Deducting the 
hollows formed by the holes, the pressure necessary to crush the 
bricks is, per square centimetre of the solid parts, respectively 
from 80 to 150 kilogrammes. That is to say, that a hollow 
brick under a crushing pressure perpendicular to the holes offers 
almost as much resistance as a solid brick. This difference of 
resistance is similar to that noticed in the case of wood, which is 
less resistant with the grain than across the grain. It is also a 
valuable indication to the builder, who should take it into con- 
sideration whenever he uses hollow bricks before exercising strong 
pressure. 

For the official tests, see the end of Part I. 



BRICKS. 257 

3. APPLICATIONS HISTORY AND USES. 

( I ) History. 

The discoveries of scientists have shown that even in the 
geological periods, that is to say, long before historic times, the 
plastic properties of clay were utilised by man for the manufacture 
of various objects. Pieces of pottery have been found contem- 
poraneous with the stone age in the lake dwellings of Switzerland 
and with the bronze age in Denmark. In Europe, Asia, Africa, 
and America similar evidence shows that the use of clay was 
general on the globe and that it dates from the most distant 
antiquity. 

Were the first objects made of clay utensils called potteries 
from the Latin potum, meaning drinking-vase (Brongniart), or those 
parallelepipeds which we call bricks from the Anglo-Saxon brice 
(Littre) ? The question is a difficult one to answer : one thing 
is probable ; that is, that raw bricks, namely those only dried in 
the sun, must have preceded bricks baked by fire. 

As might be expected, those countries whose soil is of a clay 
nature have especially used bricks as building material. Accord- 
ingly the regions near the mouths of large rivers, the alluvions of 
which have formed valleys and attracted man, are remarkably 
rich in interesting vestiges of brick monuments. 

The plains of Asia, the banks of the Tigris and Euphrates, 
the valley of the Nile in Africa, are examples of this. We find, 
on the other hand, no traces of the use of brick in certain parts 
of Norway and Sweden, where wood is almost exclusively used 
for the construction of dwellings. 

It is evident that the first bricks must have been roughly 
fashioned, but clay lends itself so easily to modelling, that this 
primitive manufacture must have rapidly improved. Besides, as 
the taste for ornamentation grew with the advance of civilisation, 
attempts were made from the earliest times to decorate the baked 
clay by enamelling it with brilliant colours. Finally, the plasticity 
of the clay, which takes any shape, led to the modelling of plain 
17 



258 POTTERY IN ARCHITECTURE. 

or enamelled terra-cotta ornaments, which were used to decorate 
buildings, and which are now found among their ruins. We will 
now give a sketch of the principal discoveries which form the 
foundations of the history of the applications of brick in ancient 
times. 

Asia. The valleys of the Tigris and Euphrates offer to 
archaeologists numerous and important ruins of brick edifices. 
Of Babylon, that immense Chaldean city founded by Nimrod 
more than twenty-six centuries before our era, so celebrated for 
its riches and for the remarkable works carried out under the 
orders of Semiramis the Beautiful, there remains nothing to-day 
but a large collection of ruins forming a series of eminences, 
I o kilometres long, on the banks of the Euphrates. 

An examination of some of these ruins has shown the 
important part played by brick in the construction of Babylonian 
buildings. The greater part of these buildings was formed of raw 
bricks, used when fresh and thus rendered adherent in spite of 
the absence of mortar. But there are also many fired bricks to 
be found, most of them bearing inscriptions in cuneiform characters 
which appear to have been made by stamping. They are very 
hard, of a reddish colour, and have the following somewhat large 
dimensions: about .3 m. to .5 m. and .06 m. to .07 m. in thickness. 

The most remarkable ruin built of fired bricks crowns an 
eminence on the right bank of the Euphrates ; it consists of a 
fragment of wall 8 to 10 metres high and 6 metres broad. The 
layers of the bricks, which are almost completely vitrified, and 
the cement joining them, can be distinguished ; the dressing 
is regular and well finished, the bricks are .35X.32X.O72 in 
size. 

Some archaeologists see in these ruins the remains of the 
famous Tower of Babel, others consider that they belong to the 
Temple of Belus. 

According to the Greek historian Herodotus, the bricks used 
to build the high walls of Babylon, which are attributed to 
Semiramis, were made of clay extracted on the site of those 
walls. 

The exploration of the ruins of Nineveh, Babylon's rival and 






BRICKS. 259 

neighbour, has shown that clay was also the principal building 
material in the Assyrian monuments : fired bricks were used for 
facings and decorations, for they were often enamelled ; the bases 
were of limestone. 

Other important ruins of ancient cities of Asia Minor have 
also exemplified the great part played by clay, fired or raw, in 
the construction of their buildings. 

In Persia^ it is probable that the use of brick was introduced 
by the Assyrians, who for a long period held Media (a part of 
Persia) under their rule. 

Many fragments of terra-cotta have been found in the ruins 
marking the site of the famous Ecbatana, capital of Media, and of 
Susa, where the Dieulafoy mission has excavated the palace of 
the ancient Persian kings. 

In all these ruins numerous bricks have been found, some 
whole, some broken, and coated with variously coloured enamels, 
which show the importance of these materials in Assyrian, 
Chaldean, and Persian architecture. We shall return to this 
subject later on. 

The use of brick continued under the dynasty of the Sassanides, 
which was founded by Artaxerxes in the second century before 
our era, and destroyed by the Arabs towards the seventh century. 
But the quality and decoration of the bricks were no longer those 
of ancient times, and, although examples remain to the present 
day, the bricks have neither the dimensions nor the remarkable 
appearance of the ancient products. 

The pagodas of India, while not as ancient as Babylon 
and Nineveh, are also examples of the use of brick in public 
buildings. The ruins which have been discovered do not seem to 
date back beyond the first centuries before our era ; the existing 
buildings, whether well or badly preserved, date from our middle 
ages. 

As far as we can tell, Chinese builders have scarcely ever, from 
the most distant antiquity, used anything but brick and wood, to 
which later on, in the centuries immediately preceding our era, 
they added porcelain, a new application of pottery to architectural 
art. The famous Great Wall, which, according to some historians, 



26O POTTERY IN ARCHITECTURE. 

dates from the 3rd century B.C., is in several parts built of 
brick : the same may be said of certain fortified enclosures of 
Chinese towns, which are made of clay sometimes simply baked 
in the sun, sometimes fired and decorated. 

Africa. The valley of the Nile, in Egypt, like those of the 
Tigris and Euphrates, offered in its slime deposits materials 
suitable for the manufacture of bricks. 

From the raised inscriptions on bricks found in different places, 
it would appear that these products of the industry of the early 
Egyptians date from the i 5th or even the 1 6th century B.C. 
The numerous examples which we possess, both of bricks and 
pottery, prove that not only was the art of firing bricks w r ell 
advanced in Egypt in those early days, but that enamelled pottery 
was also known. 

We read in Exodus (chap, v., verses 7 to 19) that one of the 
numerous labours imposed upon the Hebrews by the Egyptians 
was the making of bricks. A painting found in a tomb at 
Thebes shows the manner in which they worked : two slaves, 
whom we take to be Israelites, are drawing the slime from a 
basin; another works up the clay and probably adds straw to.it; 
and a third slave moulds the brick in a mould similar to those 
which the Egyptians still use at the present day. 

Although the firing of bricks was known to that nation, raw 
bricks were used in large quantities, and monuments built of them, 
such as certain pyramids of Dahschour dating from the 3rd 
dynasty, have remained intact to our day, thanks to their facings 
of stone. These bricks were not used fresh, as in Assyria, but 
were dried in the sun. 

Why is it that in countries like Asia Minor and especially 
Egypt, where stone, porphyry, and granite were abundant, and in 
which economy would scarcely have influenced the Governments, 
we find such a relatively large consumption of raw or fired brick 
in their public monuments ? 

America. Although the ancient history of this part of the 
world is not as well known to us as that of the countries pre- 
viously mentioned, we find in the ruins of ancient monuments 
an index of the civilisation attained by the inhabitants of the 



BRICKS. 26l 

country before its discovery by Christopher Columbus. As an 
example of brick construction we may mention the pyramid of 
Cholula in Mexico, whose horizontal dimensions are greater than 
those of the great pyramid of Egypt, and which is built of raw 
bricks bound together with a clay mortar. 

In Peru, ruins of palaces are found, built of peculiar bricks 
which do not seem to be baked and yet offer great resistance to 
the inclemencies of weather ; they have remained intact, heaped 
up on the ground. We can understand that masonry constructed 
of such materials is of great solidity, and this is confirmed by the 
examination of some of the ruins which, in the parts still standing, 
offer as great a resistance as if they were built of very hard 
stone. This method of hardening bricks seems to be lost, for 
the modern bricks of those countries have no longer that re- 
markable quality. 

The tombs explored in the valley of the Ohio also prove the 
antiquity of the use of baked clay in the New World. 

Europe. Instead of taking the history of each country 
separately, it will be better to follow the different periods of 
architecture from the Greeks and Romans in modern times. 

Greek Architecture. The use of brick in Greek monuments 
has only been proved by the writings of authors and the numerous 
traces found almost everywhere, for no single brick building exists 
which can be affirmed to be of Greek origin. But according to 
the works of the Roman architect Vitruvius (2nd century B.C.), 
the Roman author Pliny (ist century), and the Greek geographer 
Pausanias (2nd century), a certain number of temples, and other 
monuments of a date anterior to the Roman domination, were 
built of raw or baked bricks. Certain parts of the walls of the 
Acropolis at Athens contain these materials. 

According to Vitruvius, there existed three kinds of Greek 
brick: the didoron (-3X.I5); the tetradoron (.3 X .3), used in 
special work ; and the pentadoron (.37 x .37), used in public works. 

Roman Architecture. In contrast to the Greeks, those great 
builders, the Romans, have left as traces, wherever they have 
passed, remarkable and imposing monuments which offer number- 
less examples of the use of bricks. 



262 POTTERY IN ARCHITECTURE. 

The first materials used by the Romans must have been raw 
bricks, although none have been found in the remains of monu- 
ments of that period ; but Vitruvius describes their manufacture 
with details from which our brick-makers may still derive benefit. 
The same author is silent as to the time when fired bricks first 
entered into Roman architecture, but it is certain that their use 
dates from a fairly distant period. The finest specimens of the 
monuments in which brick plays an important part are of the 
early years of Imperial Rome, and imposing ruins remain to prove 
their solidity of construction. 

Roman fired bricks were of various shapes and sizes, for they 
were often made to fit the place they were to occupy in the 
buildings. Generally they were square, the large ones having 
about .6 edge and .055 thickness, the medium .445 and .05, and 
the small .2 I 5 and .04. Large square bricks, .65 and .05 (ancient 
house of Civita Vecchia), and triangular bricks for the facing of 
block masonry have also been found. At the period when brick- 
making reached its apogee (ist century), it was carried out with 
the greatest care under the supervision of the Government, who 
required the maker's mark to be on the products. These marks, 
some of which bear the names of great personages who were 
proprietors of brickworks, were a guarantee of good quality, and 
in consequence have acquired historical and archaeological interest, 
for from the reign of Trajan (ist century) the names of the 
consuls were added to those of the proprietor and maker ; thus 
by examining these marks it is easy to determine the age of a 
Roman monument. 

The Romans, who were skilful builders, used brick in all 
parts of their constructions. In the walls called " medium and 
small dressed," the masonry was formed of rubble enclosed 
between two facings of brick or ashlar-work, and comprising a 
variable number of alternate layers. Among examples of this 
class of construction may be mentioned : the Herculaneum gate 
of Pompeii, the fortified castle of Babylon in Egypt, and finally 
the hot baths of Caracalla, all works dating from the early 
centuries of the Roman Empire. From the 3rd century onwards 
this use of alternate layers of bricks and stones of various 



BRICKS. 263 

dimensions became more frequent; numerous Gallo- Roman 
buildings were constructed in this manner. Bricks alone or 
accompanied by key-stones form the arches of doors and windows. 
The Romans frequently used brick arches hidden in the thick- 
ness of the wall as a means of consolidating and distributing 
the pressure on certain points. They also made a general and 
remarkable use of arches of brick, or more frequently brick and 
rubble, to cover large spaces like the baths and the palaces of 
the Caesars. 

Roman aqueducts also present examples of the use of brick 
in arches and facings. Such are the ruins of Nero's aqueduct 
at Rome, and the aqueducts of Lyons, Aries, Mayence, etc. 

For interiors, brick masonry was generally covered with 
stucco, and such materials were even used for building isolated 
columns as has been shown in the basilica at Pompeii. Finally, 
combinations and arrangements of bricks have been used by the 
Romans for pilasters and cornices to adorn several buildings of 
ancient Rome. 

The history of human arts shows that, whatever may be the 
nation, country, or epoch, they pass through three periods : 
development, apogee, and decadence. This is what happened 
in the case of Roman brick-building. The apogee was reached 
in about the ist century A.D., contemporaneously with the first 
emperors ; then came the decadence, which was marked by the 
little care given to the construction of masonry. While the 
joins were scarcely visible in the fine ancient edifices, now they 
gradually increase until at last masonry came to be composed of 
materials of all shapes and dimensions. The thickness of the 
joins is a means of ascertaining the age of Roman monuments, 
and is found by counting the number of bricks in a given length : 
in the ist century there were 10 bricks in .3 metre (arcades of 
Nero) ; in the 2nd century, 8 bricks (Adrian's villa) ; in the 
3rd, 6 bricks (Aurelian's wall) ; 4th century, 4 bricks (circus at 
Mayence). 

In concluding this historical sketch of the use of bricks by 
the Romans, we need hardly add that remains of pottery are 
found in all parts of their immense empire. 



264 POTTERY IN ARCHITECTURE. 

The architecture of the Christian monuments, built almost 
everywhere between the 4th and i oth centuries, was inspired 
by that of the Romans ; we frequently find the alternate use 
of bricks and stones or rubble, for example, in what remains of 
the walls of Saint-Laurent's Church at Rome (4th century), in 
the churches of the Basse-CEuvre, at Beauvais ; of Vieux-Pont-en- 
Auge (Calvados) ; of Saint-Mesmin (Loiret) ; of Saint-Martin 
d'Angers (9th century), etc. etc. 

Byzantine Architecture. As the name suggests, this originated 
at Byzantium ; its chief characteristic is the almost exclusive use 
of bricks as decorative objects. The materials resemble Roman 
bricks and usually bear inscriptions of various kinds. They were 
used with or without casing for walls and also for arches ; for 
instance at Saint-Sophia in Constantinople, the cupola of which, 
35 metres in diameter, is built of bricks. 

The Greek churches of that period are adorned with very 
varied designs, worked in different dressings of bricks. This 
kind of decoration, which has a quite distinctive character, is also 
found in certain countries whose geographical positions have 
subjected them to the influence of Constantinople ; for example, 
in Roumania and Russia. 

In the latter country, Byzantine architecture has undergone 
transformations due to the influences of Persian and Hindoo art, 
but brick still remains the principal element in both construction 
and ornamentation. 

Turkish Architecture. The Arabs did not impress upon the 
nations whom they conquered such a personal character as did 
the Romans. While the latter gave to vanquished peoples their 
laws and their customs, the Arabs, on the other hand, were rather 
influenced by them themselves. As regards architecture, this 
difference is shown by the diversity of Turkish monuments 
according to the countries in which they were built. The 
architects allowed themselves to be influenced first by Byzantine 
art, and used the materials, stones and bricks, of which existing 
edifices were constructed. 

In Egypt, the Turkish architecture was mainly Arab ; in 
the mosques of the pth and loth centuries, brick, afterwards 



BRICKS. 265 

covered with stucco, plays a great part in the construction of 
the walls. The invasion of the Iberian peninsula by the Arabs 
introduced the Moorish style ; and pottery was used extensively 
for building and adorning those magnificent edifices which still 
stand for the admiration of all. Such are the mosque of Cordova 
(8th and pth centuries) and the Alhambra of Grenada, in which 
brick and faience form a large part of the ornamentation. 

Asia Minor and Persia, in turn dominated by the Arabs, the 
Turks, and the Ottomans, had at first their religious buildings, 
which were afterwards changed into mosques ; then the invaders 
raised other edifices in which we find Byzantine art modified by 
Arab or Persian taste. The most interesting of the monuments 
still remaining, such as the Green Mosque at Nicea (8th century) ; 
the Blue Medrece or religious school at Konieh in Lycaonia 
(i2th century) ; the mosque of Baba-Souctah at Ispahan, etc., all 
exemplify the use of bricks of all shapes and varieties : raw, 
fired, enamelled. But their chief charm lies in the use of faience 
plaques decorated with that taste and skill which have made 
Persian faience one of the finest manifestations of decorative art. 

Romance Architecture. Being derived directly from Roman 
art, this is especially developed in the north of Italy, in Lombardy, 
the region in which there was such an extensive use of brick. 
The chapel called Saint-Aquilirfs and the church of Saint- A mbroise 
(4th and 5th centuries) at Milan have walls and arches made 
of brick. The cupola of the latter building is crowned by a 
very curious terra-cotta cornice ; it stands back a good deal 
from the remainder of the building. Fig. 3 1 9 represents a part 
of it. 

At Pavia, the church of Sainte-Euphcmie (5th century), the 
church of Saint- Michael (i ith century), the church of Saint- 
Theodore and Saint- Lanfranc (i ith and I2th centuries), are 
almost entirely built of bricks ; they offer remarkable examples 
of terra-cotta building and decoration, either alone or combined 
with stone and even marble. 

Brescia, Venice, Padua, Pavia, and Crema with its cathedral 
almost entirely of brick, also possess monuments in which this 
material predominates. The architects of the period, by 



266 



POTTERY IN ARCHITECTURE. 



variety of form, contour, and colour, were able to avoid that 
uniformity and monotony always presented by large surfaces 
built of the same material. Fig. 320 represents a fragment 
of the crown of the frontal of the Crema Cathedral (i3th and 
1 4th centuries). 

The celebrated Carthusian Monastery at Pavia (1396; Fig. 
317) is a brilliant example of the skill of the builders of that 
period. Brick walls, alone or alternated with stone, friezes, 




I'ig- 3 1 7- Interior of the Carthusian Monastery at Pavia. 

cornices, terra-cotta sculptures, all have resisted the march of 
time. 

The state of preservation of these buildings, most of which 
are anterior to the I 3th century, shows that brick and terra-cotta 
bear easily the destructive action of time. 

The north of Italy is very rich in brick-built work, and the 
neighbouring countries certainly do not offer as many examples 
of constructions of that kind. Nevertheless the Roman system 
of building in brick and stone lasted a long time, especially in 
Gaul, during the Gallo-Roman and Merovingian periods. Then, 



BRICKS. 



267 



from about the pth century, brick buildings disappeared from 
those countries in which stone was abundant, but persisted where 
it was lacking, as in Languedoc. The church of Saint-Sernin 
at Toulouse (Fig. 318), which dates from the I ith century and 
was partly restored by Viollet-le-Duc, is almost entirely built 
of bricks, stone being reserved for some special uses ; by its 
beauty and harmonious combination it presents a striking 
example of what can be obtained, without sculpture, with ordinary 
materials arranged in well-calculated proportions. The belfry 
is of brick, with little stone columns at the angles ; it has five 




Fig. 318. Saint-Sernin's Church at Toulouse. 

storeys of double bays, three arched and two terminated by 
triangles at their upper part. It resembles the belfry of the 
Jacobin convent in the same town, one storey of whose bays is 
represented in Fig. 322. 

Gothic Architecture. In Italy, the change from the full to 
the pointed arch has been effected by successive transitions, and 
some churches combine Romance with Gothic style. The north 
of the country is again richest in brick monuments dating from 
that period ; but many towns of other provinces have also brick 
buildings which, without having the importance of the Lombard 
churches, are still none the less interesting. Bologna, Ferrare, 



268 



POTTERY IN ARCHITECTURE. 



Lucques, Pisa, Ravenna, Rome herself, 'possess towers, palaces, 
houses, built of brick sometimes combined with stone. Nearly 
everywhere terra-cotta is skilfully interspersed among the bricks 
to produce very harmonious ornamentations such as those of 



Fig. 319. 





Fig. 321. 



Fig. 320. 



Fig. 322. 




Figs. 319 to 322. Specimens of Brick and Terra-cotta Decoration 
(nth to 1 5th Centuries). 



the church of Santa Maria del Carmine at Pavia (i4th century; 
Fig. 321). The south of France also offers some very interesting 
types of Gothic brick buildings. Toulouse is especially rich in 
monuments of this kind, and we may mention the old Jacobin 



BRICKS. 



269 



convent (end of I 3th century), the Cordeliers church, the Capitol, 
and the Saint- Raymond College (i4th century). The cathedral 
of Albi (i3th and I4th centuries) contains nothing but brick, 




Fig. 323. Windows of the Hotel du Vieux-Raisin at Toulouse. 



except the mullions of the windows and some parts of the choir ; 
it is one of the most imposing of brick buildings. Its tower, 
which is flanked by turrets, has the appearance of a keep, and 
rises 78 metres above the ground. The church of Simorre (Gers) 



270 



POTTERY IN ARCHITECTURE. 



MAISON DE TRISTAN AT TOURS. 




Fig. 324. Exterior. 




Fig. 325. Interior. 

is another example of a church entirely built of brick, and with 
the appearance of a military construction ; it dates from the 
I 6th century. 



BRICKS. 



271 



In private architecture, we find at Toulouse, Alby, Montauban, 
Caussade, numerous houses of which brick is the chief material 




Fig. 326. The Belfry at Bruges. 

(Fig. 323). In the middle and north of France, bricks were not 
at that period used as much as in the south, but they were 
frequently used for filling in the exterior of timber-framed houses, 



272 



POTTERY IN ARCHITECTURE. 



especially in the I5th and i6th centuries. The architects under- 
stood how to utilise bricks with skill, even in works for which 
such material did not seem at all suited. The house of Tristan 
at Tours (Figs. 324, 325), built of bricks and stone, contains 
a winding staircase, which can be seen through the open window 
(Fig. 325), and of which the newel, the arch, the filling of the 
steps, and the risers are brick. Only the hand-rail is of stone 
and the edges of the steps of wood. 

In Germany, at Dantzig, Lubeck, Marienburg, Schwerin, we 




Fig. 327. Church of Santa Maria della Grazie at Milan. 



find some very interesting public and private brick buildings of 
the I 2th and i 3th centuries. 

Belgium and Holland possess some remarkable and important 
brick structures, among which must be mentioned the fine 
belfry at Bruges (Fig. 326), 100 metres high, and dating from 
the i 3th century, and the Antwerp market, an immense construc- 
tion of the i 5th century, made of bricks and stones. England, 
which at the present time uses so many bricks, did not begin to 
do so until the I4th and i 5th centuries ; the oldest brick structure, 
besides Roman remains, is said to be the Little Wenham market- 
hall, which elates from the end of the i 3th century. 



BRICKS. 



273 



The dimensions of the bricks used during the Middle Ages 
are somewhat variable; those of the cathedral of Albi are .35 X 
.27 x .05 ; others, also in the south of France, are .35 x .25 x .06 
and .40 x .28 X .05. In Touraine they are stated to be .25 X .1 I 5 
x .055, very nearly the present size. 

Renaissance Architecture. The use of brick is continued. 
Sometimes architects utilised it for the body itself of the building, 
as in Saint-Peter's at Rome, of which the cupola and its support- 
ing walls are of brick covered on the inside with stucco, on the 




Fig. 328. Farnese Palace at Rome. 

outside with travertin ; Sainte-Marie-des-Fleurs at Florence, etc. 
Sometimes they leave it visible and use it for adorning their work, 
as in the Chancellerie Palace at Rome, built by Bramante at the 
end of the I 5th century, the church of Santa Maria della Grazie 
de Milan (Fig. 327), attributed to the same architect ; the Farnese 
Palace (Fig. 328), restored by Michael Angelo and San Gallo in 
the 1 6th century. 

France was enriched during the Renaissance by magnificent 
edifices in which brick, alone or combined with enamelled terra- 
cotta, formed one of the principal adornments. One of the most 
remarkable of these buildings was the castle of Madrid at the 
18 



274 



POTTERY IN ARCHITECTURE. 



gates of Paris, which was built by Delia Robia during the 1 6th 
century but has now disappeared. 

Fortunately the chateaux of Saint-Germain and Fontainebleau 
still remain to show the effect produced by the combination of 
stone and brick. The charming Louis xil. wing of the chateau 
of Blois (Fig. 329) and the chateau d'Anet also deserve notice. 

Numerous hotels and private houses were also built of stone 
and brick during the Renaissance. 

England, Germany, Belgium, and Holland continued to use 
brick for building under the Renaissance. Many curious houses 
and remarkable edifices might be mentioned which take their 




Eig. 329. Louis xil. Wing of the Chateau de Blois. 

originality from the use of brick. Bruges is particularly rich in 
constructions of this kind ; its houses have a characteristic appear- 
ance (see the right of Fig. 326). 

Architecture of the ijth and i %th Centuries. Under Henry IV. 
and Louis XIII., stone and brick were still used for public 
buildings, and slate was sometimes added to produce such 
picturesque effects as can be seen in the Henry IV. wing of 
Fontainebleau Palace, and in the chateaux of Monceaux and 
Verneuil built for the fair Gabrielle and the charming Henriette 
d'Entragues. The buildings in the Place des Vosges and the 
Place Dauphine in Paris, which date from the same reign, and 



BRICKS. 



275 



the central part of the present castle of Versailles, built under 
Louis XIII., are also interesting examples of the use of stone and 
brick. 

The reign of Louis XIV. offers, if we except the Palais Mazarin, 
few brick and stone structures. The use of brick for the ornament- 
ation of public buildings ceased entirely from the middle of the 1 7th 
to the middle of the ipth century. But the people of the north 
and south of France continued to utilise it for private dwellings. 

The use of brick continued to spread and increase in England 




Fig. 330. School of Architecture at Berlin. 

after the Renaissance, and the I /th and I 8th centuries have left 
some fine structures in which may be noticed bricks ornamented 
by stamping after firing and also by cutting after being laid in 
position. 

Architecture of the \gth Century. Germany. This is one 
of those countries in which bricks are the most important of 
building materials. Many bricks ornamented with designs in 
relief are made there for use in decorating buildings. The 
Schinkel School of Architecture (Fig. 330) and the Werder 



276 



POTTERY IN ARCHITECTURE. 



church in Berlin are remarkable examples of that kind of con- 
struction in which terra-cotta is used side by side with brick. 

England. Baked clay under all forms and colours is here 
used almost exclusively ; London, we may say, is built entirely of 
brick, but it is not embellished thereby, for the modern secret of 
brick architecture does not seem to be yet discovered in England. 
Many Renaissance imitations are built, and still more common- 
place repetitions, but no stamp of originality or beauty is found 
on the modern brick buildings. We must, however, specially 




Fig. 331. Natural History Museum of London. 

mention the new Natural History Museum in London (Fig. 331), 
a vast construction entirely built of stone-coloured brick, which 
is left uncovered both inside and outside. The general effect is 
most imposing. 

Belgium- This is the great brick country, and it is used there 
in all constructions : public buildings, houses, military works, civil 
works, etc. More than a thousand million bricks have been used 
in the extension and management of the port of Antwerp. This 
large consumption is only possible because of their low price. 
Ornamented bricks are also utilised for the decoration of houses. 



BRICKS. 277 

Spain. As in Belgium, the cheapness of architectural pottery, 
and especially of brick, has stimulated the trade both in ordinary 
and decorated products. 

Ho/land. This country being unprovided with building-stone, 
it is only natural that the brick manufacture should be highly 
developed in it. Thus we find on the banks of the large rivers, 
wherever numerous beds of clay are accumulated, huge brickworks 
which supply the bricks necessary for house-building, canals, side- 
walks, roads ; for everything is made of brick, even the mouldings 
which take the place of stone. 

France.- Whole towns in the north and south are built of 
uncovered bricks. Elsewhere they are only used in the interior 
for separating walls and fillings. But of late years a movement 
in favour of pottery has been observed. In Paris, several recent 
buildings offer examples of the combined use of iron and brick 
(Halles centrales, markets, etc.); of iron, brick, and terra-cotta 
(Pavilion de la Ville de Paris) ; or of iron, stone, terra-cotta, and 
brick (College Chaptal, Lycee Sevigne, Museum). The exhibitions 
of 1878 and 1889 have shown the decorative resources offered by 
the use of ordinary brick. Enamelled brick is also more exten- 
sively used (Hotel des Telephones). 

North America. The United States consume an enormous 
quantity of bricks, and all their gigantic many-storeyed edifices are 
built of that material. 

Brick is the principal if not the sole element in their immense 
railway stations, their colossal docks in fact, in all those stupend- 
ous works which, if not showing great artistic merit, are at least 
executed with the greatest care. 

(2) Use of Bricks. 

Walls. The construction is more or less well finished accord- 
ing as the facing is to be visible or not, but the principles on 
which building is based do not change. These principles are: to 
raise the wall perfectly perpendicular, and to interrupt the joins 
as much as possible both in the height and thickness of the wall. 

Bricks are arranged endways and lengthways, that is to 



278 POTTERY IN ARCHITECTURE. 

say, that their length is sometimes perpendicular, sometimes 
parallel to the direction of the walls. This arrangement is 
intended to avoid the continuity of the vertical joins in two con- 
secutive rows ; this interruption should be frequent in the upright 
joins. 

It will be understood that there are many possible ways of 
combining the ends and sides ; and this allows of varied designs 
being made by the use of bricks of different colours. We must, 
however, reject every combination which does not satisfy the 
above-mentioned conditions. It is beyond the province of this 
work to examine in detail every method used, and we will merely 
mention (Figs. 332 to 335) the most common ways of building a 
wall whose thickness is the length of one brick. 

Fig. 332. Fig. 333- 




Fig. 334- Fig. 335. 

Figs. 332 to 335. Various Systems of Wall-building. 

In thicker walls, the possible arrangements of the bricks are 
infinite, and we must choose those which give the best cohesion 
in each direction by interrupting the joins as much as possible. 
If the thickness of the wall allows of it, we begin by erecting two 
facings, and fill the hollow with bricks placed endways ; then, 
every five or six layers, we place two layers of bricks diagonally 
and crossed, thus ensuring great cohesion. 

To build a wall, we begin by erecting the two corners, quite 
vertically to the height of a few layers ; then, between these two 
angles, we stretch a cord horizontally above the first layer. We 
place the bricks on a bed of mortar, and then press upon them 
with the hand while giving them a slight up-and-down motion so 
as to compress the mortar to its least thickness. Bricklayers 
generally effect this by striking the bricks with the edge of their 



BRICKS. 279 

trowel, but this will only do for facings ; for insides the other 
method is more rapid. The upper edge of the bricks should 
follow the cord exactly. If their thickness is not uniform, the 
thickest ones are pushed down on to the mortar so that the upper 
surface of the row may be level and horizontal. The masonry is 
completed throughout the thickness of the wall, and when the 
layer is finished, the cord is raised to the height of the next, and 
the work continues. 

The thickness of the joins naturally depends upon the fine- 
ness of the mortar, the uniformity of the bricks, and the thickness 
of the wall. With cement and well-pressed bricks we may 
succeed in making joins of only .002 to .003 (about T Lth inch), 
with very fine mortar .006 to .007 (J in.), and in ordinary brick- 
masonry from .012 to .015 (about J in.). 

The bricks being always spongy, it is better to water them 
all together before they are used, as otherwise they will absorb 
some of the water of the mortar. 

Finishing the Joins, When the masonry is completed, we 
proceed to finish off the joins. In high-class work, when the 
brick is visible, its fine red colour is brought out by washing 
it with dilute hydrochloric acid ; in this way all the stains of 
mortar or other substances are removed. Then the joins are 
hollowed out to a depth of half an inch or so with a special 
iron hook, cleaned, brushed, and sprinkled with water, after 
which a specially prepared fine mortar is introduced with a 
little pointed trowel. When this has become fixed, it is pressed 
with a polisher to smooth its surface. If fancy joins are required, 
they are cut in hollow or relief with a special iron tool. Hollow 
joins are, as regards durability, to be preferred to the projecting 
so-called " English " joins. More variety may be given to the 
general appearance by colouring the mortar used. 

Arches. The construction of arches of brick may be as 
much varied as that of walls ; the same precautions must be 
observed for the joins, which must be perpendicular to the 
surfaces of intrados. In this way each part of the arch forms 
a corner, and the whole can keep in position without mortar. 
When the thickness of the arch does not exceed the length of 



280 POTTERY IN ARCHITECTURE. 

a brick or a brick and a half, it is built as an ordinary wall, the 
intrados being dressed either with endway or lengthway bricks 
alone, or with endway and lengthway bricks, the choice of arrange- 
ment being subordinated to the solidity of the whole. If the 
thickness is greater, several methods can be used ; for instance, 
several arches each of the thickness of a brick or a brick and 
a half may be arranged, independent and one over the other. 
In England a series of superimposed arches each of one brick 
sideways is preferred, whatever be the thickness. 

When the extrados of the arches remain visible after their 
construction, the dressing must be carefully done ; for that pur- 
pose the position of the joins, according to the thickness of the 
bricks and the system chosen, is marked out on the semicircle, 
bearing in mind that there must be an odd number of layers, 
on account of the one serving as keystone. 

The edges of the bricks being placed normal to the intrados, 
it follows that the join is thicker at the extrados than at the 
intrados. It is to avoid this inconvenience that bricks called 
"corner" and " knife-edge " are made (Figs. 235, 236). 

The dressing of special arches, vaulted, annular, conical, 
spherical, cloister, etc., presents no great difficulty. 

Flooring arches are generally made of hollow bricks, and 
the dressing of them is quite simple. 

Paving. This is clone with special bricks, very hard and 
sometimes vitrified. Their surface is rough or striated when 
they are used flat (Fig. 251), and bevelled when placed on edge 
(clinkers) (Figs. 3 3 6, 337, 338). 

The bricks are laid on a bed of mortar placed where the 
paving is to be done and sloped for the proper draining off of 
water. The adhesion of the bricks to the mortar is increased 
by the use of fluted bricks (Fig. 341). 

For stables and wash-houses where large quantities of water 
are thrown down, special bricks (Fig. 343) are used, which, placed 
end to end, form a trench and so help the water to run off. 

Bricks in the shape of gutters (Fig. 339) are also made to 
collect the moisture on the pavement (Fig. 342), lateral hollows 
(Fig. 340) cut in some of the bricks allowing the water to come 



BRICKS. 



Fig- 336. 




Figs. 336 to 344. Various Paving'^Bricks. 
Fig. 345. Fig. 346. Fig. 347. Fig. 348. 




Fig. 349- 



Fig. 3 5- 




Fig. 35'- 





Fig. 35 2 - 




Figs. 345 to 348. G curlier Bricks for Chimney Conduits. 
Fig. 349. First Layer. Fig. 350. Second Layer. 

Fig- 351. First Layer. Fig. 352. Second Layer. 



282 



POTTERY IN ARCHITECTURE. 



in from other directions. These kennel-stones are either open 
or closed with a flat brick (Fig. 344). 

Chimney Conduits. Besides the hollow pottery conduits, 
called " boisseaux " and " wagons," special bricks are used, called 
Gourlier, after the name of their inventor. They are in four 
shapes (Figs. 345 to 348), which are alternated in every 
layer in order to interrupt the joins. Figs. 351 and 352 
represent two layers for a single conduit, and Figs. 349 and 
350 the two different layers, repeating themselves from top to 
bottom, for two neighbouring conduits. 

Cornices. Dressing 1 with Bricks of Different Colours. 
Balustrades. Ordinary bricks, by means of special dressing, 



Fig. 353- 



Fig. 354- 



Fig- 355- 




-0,12 -4- we *- o.ee < 





i. 0.22 

Fig. 357- Fig. 358. 

Figs. 353 to 358. Hollow Bricks for Cornices. 



may be used to decorate cornices, but, unless the bricks are 
cut, the effects are necessarily limited to straight lines. It 
is better to use solid, or preferably hollow, moulded bricks 
(Figs. 353 to 355), because they are less liable to lose shape in 
drying. 

The section (Fig. 357) and elevation (Fig. 358) represent 
an application of the three types above described, ornamented 
with knobs (Fig. 356). 

The differences in the colours of bricks are made use of 
in the decoration of cornices, openings, and walls, by arranging 
them in the most varied patterns, some examples of which are 



BRICKS. 



283 



shown in Figs. 359 to 364. The resources offered by brick- 
work for decorative purposes were well exemplified at the 



Fig. 359- 



Fig. 360. 



Fig. 361- 




Fig. 362. Fig. 363. Fig. 364. 

Figs. 359 to 364. Various Dressings with White and Red Bricks. 

Exhibition of 1889, m the machine gallery, in the pavilion of 
the Minister of Public Works, and in many other constructions. 




Fig. 365. Fig. 366. Fig. 367. 

Figs. 365 to 367. Open-work Walls for Balustrades. 

If to the natural colours, which are necessarily limited, we 
add the gamut of the artificial tints, the variety of effects 
is increased. 



284 POTTERY IN ARCHITECTURE. 

By combining bricks in different ways, and by using them 
alone or with stone, we can get an infinite number of styles of 
dressing, which may be used for open-work walls in their varied 
applications : window supports, string-courses, balustrades, etc. 
(Figs. 365 to 367). 



CHAPTER IV. 

TILES. 
I. HISTORY. 

THE use of those plates of baked clay which we call tiles > is 
nearly as ancient as that of bricks, but, on account of the state 
of ruin of the ancient buildings belonging to civilisations before 
the Roman period, it is difficult to ascertain what kind of roofing 
covered them. On the other hand, all the necessary materials 
exist for observing the manner in which the Romans used their 
tiles, fragments of them being found wherever Roman dominion 
extended. 

They used two kinds of tile. Some rectangular and flat, and 
furnished with flanges, were 12 to 15 inches long and 8 to I o 
inches broad : these were called tegulce ; the others, called imbrices, 
were semi-cylindrical in shape. The tegulae were fixed on the 
roof by means of notches in the flanges which were placed in 
the direction of the slope of the roof; the imbrices covered these 
flanges and were held at their lower extremity by a larger 
tile (antefix) which was fixed to the cornice and had one end 
generally decorated. 

The Latin buildings were covered with tiles of Roman shape, 
but generally defective, except in Italy, where they were well made. 

Turkish architecture also made use of tiles, which were most 
frequently enamelled in various colours to match the other 
building materials. 

Up to the I I th century the Roman roofing with its flat 
rectangular tiles and curved covers was still preserved in the 
south of France, but after that period the trapezoid shape was 
substituted for the rectangular. 

285 



286 POTTERY IN ARCHITECTURE. 

In the north, Roman tiles had been given up as offering 
too much hold to rain and wind, and had been replaced by 
flat tiles furnished at the top with a flange which attached 
them to the laths. Roman buildings which were roofed with 
tiles generally had their ridge-pieces decorated with terra-cotta 
ornaments. 

The 1 3th century saw the introduction of two kinds of 
tile called "Champagne"; the ordinary ones were .35X.2I5 
metres, were slightly convex in order to give less hold to the 
wind, and were furnished with a hook, instead of a flange, to 
fasten them to the laths, and with a hole by which they could 
be nailed to the rafters, these latter being placed at distances 
apart equal to the width of the tile. The second kind, called 
Comte Henri, were of smaller dimensions than the others, but 
were still better finished and usually enamelled on the uncovered 
part. We may mention, among important roofings executed 
with these tiles, the cathedral at Troyes, the chapel of the 
Abbey of Saint-Denis, the chateau of Beaute-sur-Marne, etc. 

In Nivernais and Poitou, tiles in the shape of shells were 
manufactured at that period, .5 ox. 165 in dimensions, and 
having three flutings to carry away the water. 

The CO - shaped tiles, called FlemisJi tiles, still used at the 
present day, date from the 1 5th century, and were generally 
used at that time. 

In the south, the flat Roman tile had been abandoned, and 
the roofing was done entirely with curved tiles, the channel 
tiles being simply cover-tiles turned upside down-; it was the 
Flemish tile, but in two parts. This system of roofing still 
remains in the whole of the south of France as far as the 
Vendee. 

The ridges were covered with ornamented tiles usually 
varnished ; at the ends were placed spikes which were some- 
times real monuments, especially in the izj-th century. 

From the I5th to the beginning of the iQth century, the 
tile industry in France made no improvement ; on the con- 
trary, the tiles during this period were roughly fashioned and 
poorly baked. In 1851 the invention was made which revolu- 



TILES. 



2 8 7 



tionised tile-making, and raised it to that pitch of perfection 
at which it stands to-day. We refer to the invention of machine- 
made fitting tiles ; this was a French invention due to the 
brothers Gilardoni of Altkirch in Alsace. 

Up to that time tiles had only been made by hand, and 
the introduction of machinery for their manufacture brought with 
it rapid improvements which considerably extended the use of 
these products for the roofing of buildings. If many flat, hollow, 
or Flemish tiles are still made, it is almost entirely for main- 
taining existing roofs. 



2. MANUFACTURE. 

(i) Moulding. 
Hand- moulding. 

The preparation and choice of the clay for the manufacture 
of tiles should be performed with even more care than for that 
of bricks. The clay should have been weathered, should be 
sufficiently rich to prevent the tile from being too porous, and 
should be well separated. 

The moulding has no special features ; it is done with thin 
moulds having a notch on one side, and resting on movable 



Fig. 368. 



Fig. 369. 




Fig. 370. 

Fig. 368." Planchette." Fig. 369. Mould for Flat Tile. 

Fig. 370. Mandrel for making Curved Tiles. 

" planchettes " (Fig. 368). For the demoulding is done on the 
table itself by raising the mould when the excess of clay has 



288 POTTERY IN ARCHITECTURE. 

been removed with the " plane." The boy takes away the 
" planchette," and on his way forms the hook by raising with his 
thumb the small portion of clay moulded by the notch, then 
he deposits the tiles side by side on a well- levelled and some- 
times paved space. When the clay has attained a sufficient 
degree of consistency, it is taken to the drying-rooms, and after 
it has become firm enough it is stamped and curved ; this is 
done with a wooden beater, the workman being seated on a 
bench in front of the tiles. The seams having been cut off 
and the edges dressed, the tiles are placed in the drying-sheds 
to complete their desiccation, which takes from a week to a 
fortnight according to atmospheric conditions. Curved tiles are 
made by bending the fiat slab over a mandrel of suitable shape. 

A large number of special tiles, such as ornamented ridge- 
tiles, end-pieces, finial-pieces, etc., which are used with machine- 
made tiles, are also made by hand in plaster moulds of the 
desired shape. 

Machine- moulding of Tiles. 

The mechanical moulding of tiles comprises three operations : 
(i) the preparation of the clay; (2) the formation of slabs or 
regular plates of clay, the dimensions of which depend upon 
those of the tiles ; and (3) the transformation of these slabs into 
tiles by stamping with plaster or cast-iron moulds of the required 
shape. 

i . Preparation of the Clay. This is carried out in the same 
way as for bricks, but requires more attention. The choice of 
clay is very important, and thin clays no longer being suitable 
alone, there must be added to them a certain quantity of rich 
clay which gives to the paste the degree of cohesiveness and 
tenacity necessary to ensure for the tiles their essential qualities, 
especially imperviousness and resistance. The paste, thus rendered 
as homogeneous and ductile as possible, should be free from all 
impurities. 

Here an important question presents itself: What quantity 
of water should a paste contain to make the best tiles ? 



TILES. 289 

Pastes are placed in three classes according to the quantity 
of water contained in them and evaporated at 100 C. 

Soft pastes containing 20 to 25 per cent. 
Firm ,, ,, 15 to 20 ,, 

Hard ,, ,, 10 to 15 ,, 

that is to say, not much more than the amount naturally contained 
in clays. 

Each kind of paste requires a different method of manufacture, 
possessing advantages and disadvantages of its own. 

Soft Clay. The clay blended in this manner acquires the 
maximum of ductility and homogeneousness which can be 
expected from its plasticity. The separation of the paste into 
thin laminae, which slide over one another, as is always observed 
when it is expressed from the die, will be reduced to a minimum. 
Besides, the passing of the soft slab under the press will perfectly 
weld together the molecules which might become separated, and 
a good firing will give as a final result a product with a good 
ring, a clean fracture, and fine grain, signs of excellent quality. 

The drawbacks of soft paste for manufacturing purposes are : 
difficulty of handling slabs and tiles of no consistency ; the 
adhesiveness of the paste renders the use of cast-iron for moulding 
impracticable, and recourse must be had to plaster moulds, the 
quick wearing out of which necessitates frequent renewal ; as we 
work with soft paste a strong pressure cannot be used, and this 
diminishes the clearness of reproduction of the details of the mould, 
for tiles are not stamped like bricks ; finally, the large quantity 
of water contained in the paste lengthens the time of drying, 
hence an increase in the dimensions of the drying-sheds, and its 
removal causes hollows hence the products are more porous. 

All being considered, the production with soft paste is small, 
and the cost somewhat high. 

Firm or Semi-hard Paste. The quantity of water being 
reduced, the paste is more easily handled than the preceding 
kind ; it can support a greater pressure, and can be moulded in 
cast-iron, which gives the tiles very clean-cut faces, a great 
delicacy of shape, and sharp edges. The drying is quicker and 
the porosity not so great. 
'9 



290 POTTERY IN ARCHITECTURE. 

The inconvenience of this method, which largely counter- 
balances its advantages, is that it requires more powerful 
machinery and in consequence absorbs more motive force. 

Hard Paste. In this process, the clay is taken almost as it 
comes from the pit, or, if it is too dry, a certain amount of water 
is added to it, not exceeding 10 to 15 per cent. Under these 
conditions blending becomes difficult, and requires powerful 
machines absorbing much motive force. Another grave dis- 
advantage is the exfoliation of the paste as it passes through the 
die. With soft clay this is insignificant, but with hard paste it 
becomes very pronounced, and the slabs are formed of laminae 
placed one over the other like the leaves of a book. The slight 
exfoliation of soft or firm paste disappears in the press, thanks to 
the plasticity given to the clay by the water ; with hard clay, 
considerable and repeated pressure is necessary to produce the 
same effect, and the action must also be completed by a strong 
firing, which will weld together all the parts of the tile. 

If the pressure or the firing is insufficient, the laminated 
hollows in the clay will retain the water and the frost will chip 
the tiles, which in a very few years will be useless. 

In this respect, then, manufacture with hard paste is more 
delicate than the previous methods, but by a judicious choice of 
clays, a suitable blending, and a strong firing, it gives good hard 
products, not very porous, and of clean-cut shape. 

In spite of these qualities, however, the products have been 
much decried on account of certain accidents which we must 
explain. When tiles made of hard paste first made their 
appearance, their success, thanks to their beauty of shape and 
bright colour, was very great ; and, as the moulding of them was 
somewhat cheaper than that of those made of soft clay, a large 
number of factories laid down plant for this method of manu- 
facture. But, as often happens, too much advantage was soon 
taken of this economy ; tiles were made without careful choice of 
clays, without proper preparation, and without sufficient firing, 
either to economise fuel, or because the clay used would not bear 
a great heat. The outer appearance did not suffer; on the 
contrary, the slight degree of baking of the products gave them 



TILES. 291 

a fine and uniform red colour, which made them extremely 
fashionable. Architects and engineers and this is how they 
unconsciously helped to create a current of opinion which led to 
numerous disappointments at last only used tiles of uniform 
tint and very red. But this tint is easily obtained by a slight 
firing, and therefore well-fired tiles, which are usually of a less 
agreeable and uniform colour, were partly neglected. 

Time showed how wrong it was to forsake the wholesome 
traditions of good manufacture. When subjected to the weather 
the tiles at first behaved fairly well. But when their surface, 
which was not very pervious and strongly compressed, was 
attacked by the slow action of the water, they were rapidly 
destroyed, for the numerous hollows left by exfoliation filled with 
water, and the cold of successive winters caused these badly made 
tiles to fall into dust. 

The reaction was all the more violent because lawsuits 
followed, and materials which had proved their utility for thirty 
or forty centuries were very nearly abandoned for roofing 
purposes ! But the manufacturers with soft clay, between whom 
and those working with hard clay there was keen competition, 
skilfully took advantage of these circumstances and made hard- 
clay manufacture responsible for them ; and in this they were not 
entirely wrong. In 1879 there appeared a pamphlet (La Tuile 
me'canique, by L. Laubiere, roofing contractor), in which, side by 
side with some excellent observations, other too extreme con- 
clusions were stated. Acccording to the author, only soft-clay 
manufacture could give good tiles. Bad results may be obtained 
from soft clay just as much as from hard clay, and good tiles may 
be made with either. But it is certain that manufacture with 
hard clay is more diffictdt, more delicate, and requires good clays. 
Should we make a method responsible because some people apply 
it badly? Thus hard-clay products require a high degree of 
firing, and it is evident that if we use clays which cannot bear 
that firing, through being too fusible, or contracting unevenly and 
becoming warped, only a bad result can be obtained. 

It is just the same if we work with soft paste made of poor 
clays, although the defects may be less pronounced. Soft paste, 



POTTERY IN ARCHITECTURE. 

firm paste, and hard paste all may give good tiles, but clays 
cannot be used indiscriminately in any one of these processes, 
and it is prudent to diminish the disadvantages of hard paste by 
slightly increasing the quantity of water ; it will then be in a 
better condition for working. 

As for the consumer, his interests may be safeguarded, 
without inquiry as to the method by which the tiles are made, if 
he deals with solvent and well-known firms, and asks them for a 
warranty of ten years against rain and frost : this would never 
be refused by conscientious manufacturers who are sure of the 
quality of their goods. 

The preparation of clays is performed with the same machines 
as for bricks; for firm pastes, however, special pug-mills (Fig. 65) 
or perforated cylinders (Fig. 82) are used. 

2. Preparation of the Slabs. When we work on soft or 
firm pastes, we use the screw or propelling roller machines 
described on pp. 114 and 123, with a modified die. For hard 
pastes we must have recourse to the piston machines called 
" galettieres." Fig. 3 7 1 represents a machine of this kind in 
which two pistons compress the clay alternately in two boxes, 
having the dies in one face. 

M. Dumont, one of the promoters of hard-paste manufacture, 
has invented a double " galettiere " (Figs. 372 to 375), composed 
of a cast-iron frame supporting two compression boxes in which 
move two pistons worked by two cranks fixed to the same 
extremity of a vertical shaft, the lower end of which has a large 
toothed wheel driven by a small pinion. All this gear is hidden 
in such a way that there is no danger in approaching the machine 
a very important advantage. 

The dies are of conical section, and metallic plates, whose 
distance can be regulated by small screws, allow of the section of 
the issuing orifice being altered to suit requirements, or compensate 
for wearing away. 

The clay, having been passed between granulating cylinders, 
or pugged, is thrown on to a sheet-iron plate, which is pierced 
with two openings corresponding to those of the compression 
boxes. When one of the pistons has done its work and returns, 



TILES. 



293 




294 



POTTERY IN ARCHITECTURE. 



it uncovers the orifice of -the box, and the clay at once falls 
into it; the piston continuing its motion compresses the clay 
and drives it out in the form of a continuous slab, which passes 
between two rollers held by flanged springs. The lower roller, 
called the greaser ; dips into a little reservoir of oil, and in its 
rotation lubricates the bottom of the slab. The upper roller, 
called the cutter, carries one or several blades, the distance of 
which, measured on the circumference, is equal to the length of a 
tile. In turning, these blades come in contact with the slab and 
cut it into the required lengths. 




Fig. 374- Fig. 375. 

Figs. 372 to 375. Double-action " Galettiere " (Dumont). 

The slabs thus cut are firm enough to be carried in the hand 
without losing their shape ; a boy takes them, and places them in 
piles on a waggon which carries them to the presses. During 
this handling, the oil on the bottom of each slab is partly 
deposited on the top of the one below, and thus both faces 
become lubricated for stamping. 

The advantages of this " galettiere " are : its small volume, 
its hidden mechanism, the use of one hopper for the two boxes, 
automatic cutting and greasing. 

3. Transformation of the Slabs into Tiles Flat Tiles. The 
manufacture of these tiles by hand is rather slow and con- 



TILES. 295 

sequently troublesome ; therefore, in factories with steam-power 
it is better to use machinery. 

The expression of the clay is performed by a machine of some 
kind furnished with a suitable die. The transformation of the 
slab into tiles is effected in various ways. The Joly cutting-table 
(Figs. 376, 377) is provided with two rollers; the lower one 
has a projection corresponding to a hollow in the upper one, and 
the latter has blades fixed longitudinally upon it. When the 
slab passes between these rollers, it makes them revolve ; the 
projection on the lower roller presses down the paste at regular 

CUTTING-TABLE FOR FLAT TILES (Joly). 




Fig. 376. Front View. Fig. 377. Side View. 

intervals, thus forming the hook, while the blade cuts the tile to 
the required length (Fig. 376). The workman has only to take 
up the tiles and place them on boards (Fig. 377) to be scraped ; 
then they are carried to the drying-sheds. A cutting-table of 
this kind produces from 1200 to 1600 finished tiles per hour. 

Another method, suited to thick tiles, requires a somewhat 
different die : the prism of clay comes out with a projection in the 
middle, of the same section as the required hook. The die is 
arranged either for one tile (Fig. 378), two side by side (Fig. 
379), two, one over the other (Fig. 380), or four tiles (Fig. 381). 



296 



POTTERY IN ARCHITECTURE. 



The special cutting-table (Fig. 382) cuts the prism into slabs 
of the required length, and, at the same time, another horizontal 



Fig. 378- 




Eip-. 380. 









Fig. 379- 




Fig. 381 




Figs. 378 to 381. Dies for Hooked Elat Tiles. 




Fig. 382. Cutting-table for Hooked Elat Tiles. 

wire takes off the projecting rib at the surface, leaving a small 
part which is to form the hook. 



TILES. 297 

When two tiles come out one over the other, the rollers of 
the cutting-table have a notch in the middle which allows the 
lower rib to pass, and there are two horizontal wires to remove 
the ribs. 

Fitting Tiles. These tiles are of different shapes, but are all 
manufactured in the same manner, by stamping between two 
plaster or metal moulds of the desired form. A great number 
of mechanical methods of producing the necessary pressure may 
be devised ; the simplest is the screw press. Cams and levers have 




Fig. 383. Screw Press, worked by Hand (Jager). 

also been used, and for large production the presses called 
" revolver " are utilised. 

There are three classes of machines 

A. SCREW PRESSES: (i) Worked by hand] (2) by steam. 

B. CAM AND JOINTED LEVER PRESSES. 

C. REVOLVER PRESSES. 

A . SCREW PRESSES. ( i ) Worked by Hand. The mechanism 
of these presses is well known. A large flywheel turns a screw, 
which has at its lower end one side of the mould ; the other part of 
the mould slides upon a cylindrical iron rod ; in order to fill it, the 



298 



POTTERY IN ARCHITECTURE. 



workman draws it towards him, and, holding it horizontal by means 
of a handle, places the slab of clay into it, and then pushes it back 
under the screw, where it is held by catches exactly under the 
upper part. The flywheel is set in motion, and the stamping takes 
place ; but two or three compressions should be made in order to 
force the clay into all the cavities of the mould, and to ensure that 
all the bubbles of air, which the shock accumulates in the lower part 





Fig. 384. Swivel Stand for 
trimming Tiles (Boulet). 



Eig. 385. Screw Press, worked by Steam 
(Johnson). 



of the tile, may be driven out. As there are two moulds, while 
one is under pressure the other is being filled, and will be ready 
to take the place of the first as soon as the compression is over. 
The demoulding is done by turning the bottom of the mould 
round its supporting rod, and receiving the tile on a board. How- 
ever well-fitting the moulds may be, the compression always 
leaves seams, and to remove these, the board and its tile is placed 
on a swivel stand (Fig. 384), and they are taken off by means of a 
stretched wire, the tiles being afterwards taken to the drying-sheds. 



TILES. 



299 



For a large output, this stand is replaced by a circular re- 
volving table, in front of which women are seated. 

The tiles come to the presses on an endless band, then pass 




Fig. 386. Screw Press, worked by Steam (Boulet). 

to the trimmers, and afterwards proceed to the drying-sheds by 
another endless band. 

With hand-presses about I 50 tiles an hour can be made, giving 
three compressions to each. 



300 



POTTERY IN ARCHITECTURE 



(2) Worked by Steam. In these presses (Figs. 385, 386) 
the upper part of the screw is furnished with a flywheel which, 
by means of friction discs, can be turned in either direction. A 
lever placed within reach of the workman's hand allows him 
to move the screw in the direction required. Another gearing, 
placed well in sight, acts upon the belting, and is used to stop 
the shaft on which the discs revolve. 

These presses have plaster moulds, and are only suitable for 
working on soft or semi-firm paste; their output is about 250 to 
300 tiles per hour. 

B. CAM PRESSES. These consist of a solid shaft furnished 




Fig. 387. Cam Press with Triple 
Compression (Joly). 



Fig. 388. Press with Crank and 
Handle (Chavassieux). 



with two cams with three hollows and three projections, and set 
in motion by gearing worked by hand or steam. Each hollow 
in the cam corresponds to a pressure of the upper plate upon the 
slab of clay, and is immediately followed by a partial demould- 
ing caused by the projections ; every turn of the shaft then 
produces three compressions, followed by three demouldings ; and 
in consequence of the shape of the cams, the compressing force 
increases from the first to the third, being on an average 60 
kilog. per square metre. 

Demoulding is effected by turning the movable carrier on 
which the mould rests round the bar supporting it, and the tile 



TILES. 301 

is received on a board. The carrier carries two moulds, so that 
one can be filled while the other is being pressed. 

The Chavassieux press (Fig. 388), also worked by hand, has 
only one mould-carrier ; the motion is transmitted to the upper 
mould by means of a crank and winch. 

In the press represented by Fig. 389, the upper mould is 
moved by jointed levers. It is worked by power, and stops 
automatically when the tile is sufficiently compressed. It cannot 




Fi g- 389. Crank Press for Tiles (Joly). 

be started unless the mould is exactly in its place. Its produc- 
tion is about 200 to 300 tiles per hour. 

C. REVOLVER PRESSES. The invention of what are called 
mechanical tiles led to that of machines allowing of a large 
output. 

The problem was also solved by Gilardoni, who, by means 
of some hints given to Jean Schmerber (1824-1895), a partner 
in the firm of Schmerber Brothers of Tagolsheim (Upper Rhine), 
suggested to him the idea of the press which bears his name, and 
of which the present presses are only variations. 



3 02 



POTTERY IN ARCHITECTURE. 



This type of press (Figs. 390, 391, 392) consists of a shaft 
C geared to another shaft A, which carries the driving pulleys 
and two flywheels, B B. On the shaft A is fixed a steel 




eccentric D, which acts on a slide E, also of steel, and placed in 
the mould-carrier F, which holds the upper mould G. 

Below is another mould-carrier with five sides mounted on 
a shaft I, which is furnished at one end with a plate with five 



TILES. 303 

notches L, and at the other with a grooved pulley R. The 
plate L is kept fixed by a bolt K, which slips into the notches. 

While the counter-mould G compresses the clay on the 
mould H, a workman placed behind the machine puts on a 
board the tile just pressed, and a second workman in front of the 
press places on one of the sides of the revolving carrier the slab 
of clay for the next tile. When the compression is finished, the 
mould-carrier F is raised by the arm P of a jointed lever, which is 
fixed to the shaft O, and the second arm N of which is set in 
motion by the eccentric M acting on the slide a, 

When this movement is nearly completed, a little cam b 
comes to unlatch the bolt K, and at this moment the belt 
joining the two pulleys Q and R is stretched by means of a 
projection on the pulley Q, so that the shaft I begins to move, 
and continues until the bolt K, released by the cam b, falls back 
into a notch of the plate L. The lower mould-carrier has then 
described one-fifth of a circle, and another mould is now below 
the counter-mould G. The cam D, by means of the slide E, 
again acts upon the mould-carrier F, the descent of which 
becomes slower as the pressure increases, in order to allow the 
air and the excess of clay to escape from between the two 
moulds. 

The work may be done with soft, firm, or hard clay according 
as the moulds are of plaster or cast-iron. 

The shaft I rests, by means of a regulating screw d (Fig. 
392), on safety plates which protect the supports in case of an 
accidental excessive pressure. A break acting on the felly of 
one of the flywheels allows of the machine being instantaneously 
stopped. 

The tiles are carried to the drying-sheds after being trimmed ; 
the output is from 400 to 450 tiles per hour. 

In the Boulet machine (Fig. 393) the principal parts are the 
same as in the foregoing machine, and its working is similar. 
The moulds are of plaster or cast-iron, according to the method 
of manufacture. 

The Jager machine (Fig. 394) has no belt for moving the 
revolving mould-carrier, but the latter is provided with a wheel 



304 



POTTERY IN ARCHITECTURE. 




Fig. 393- Five-sided Tile Press (Boulet). 



TILES. 



305 



with curved segments which rub against a felly fixed to the 
large gear-wheel. This felly is interrupted for a certain distance, 
and in the hollow is a little rod perpendicular to the wheel, 
which, at a certain moment, enters a notch in the segmented 
wheel and drives it forward one-fifth of a revolution. The rod 




Fig- 394- Five-sided Tile Press (Jager). 

then frees itself, and the felly, rubbing against the segment, keeps 
it in its position. 

A similar arrangement is found in the Groke (Fig. 395) and 
Laeis (Fig. 396) machines. The former is fitted with a break 
for instantaneous stopping as in the Schmerber machine. 

In the Lobin press (Fig. 397), the motion is communicated 
to the counter-mould by means of knee-piece cranks, and the 
intermittent rotation of the revolving mould - carrier is effected 
by a ratchet-work moved by jointed levers of which one end is 
drawn on by a rotatory motion. In this machine, as in the 
20 



306 



POTTERY IN ARCHITECTURE. 





Fig. 396. Five-sided Tile Press 
(Laeis et Cie.). 



Fi S- 395- Five-sided Tile Press (Groke). 




Fig. 397Five-sided Tile Press (L.bin). Fig. 398. -Five-sided Tile Press (Chavassieux). 



TILES. 307 

preceding ones, the movement of the counter-mould is slackened 
at the end of its course, and there is besides a double compression, 
as in the Joly machines. 

The Chavassieux press (Fig. 398) possesses a similar 
mechanism to the last for turning the revolving mould-carrier, 
but the counter-mould is moved by an eccentric. 




Fig. 399- Revolver Press (Chambrette Belon). 

The Chambrette - Belon press (Fig. 399) has this special 
feature, that the upper part is fixed and it is the revolving 
mould - carrier which is movable. The motion is effected by 
cams which cause successive compressions. 

Moulds. 

When the tiles are made of soft clay, the moulds of the 
presses are of plaster. The pressure and damp soon destroy 
them, especially the upper ones which transmit the pressure, 
therefore spare ones should always be at hand. 

The plant necessary for making plaster moulds is as follows : 
(l) two matrices of chased and polished cast-iron, one representing 



3 o8 



POTTERY IN ARCHITECTURE. 



the lower part (Fig. 403), the other the upper part (Fig. 404) of 
the tile; (2) two cast-iron frames (Figs. 400, 402) which are 
to receive the plaster moulds and are fixed by bolts to the mould- 
carriers of the presses; (3) an oak table (Fig. 401) provided with 
iron ribs, and a screw which passes through a bronze nut fixed in 
an iron arch. 

Each matrix, having been well greased with black soap or 
resin oil, receives the plaster (of Paris), which is poured in in a 
fairly liquid condition, without, however, being too soft ; it is 
then covered with one of the cast-iron frames, and carried to 
the table, where it is held tightly pressed down by the screw 

MATRICES, FRAMES, AND TABLE FOR MAKING PLASTER MOULDS. 



Fig. 400. 



Fig. 401. 



Fig. 402. 




Fig. 404. 



Fig. 400. Frame to receive the Upper Mould. Fig. 401. Table on which the Moulds 
are pressed. Fig. 402. Frame to receive the Lower Mould. Fig. 403. Matrix 
of the Bottom of the Tile. Fig. 404. Matrix of the Top of the Tile. 



until the plaster has become hard. The matrix is now removed, 
and the plaster mould remains fixed in the cast - iron frames. 
The frames thus prepared are then attached, those containing 
the upper part of the tile to the upper mould-carrier, and those 
containing the lower part to the press supports (Figs. 383 to 389) 
or the revolving mould-carrier (Figs. 390 to 399). 

To make sure of a continuous supply, there should be a pair 
of matrices (Figs. 403, 404) for every five presses, and for 
each press, seven upper frames (Fig. 400) and four lower frames 
(Fig. 402), which makes five bottoms and one top in use ; two 
bottoms and three tops being used in remaking the plaster 
moulds. For carrier - presses, we must have, besides the two 



TILES. 



309 



matrices, two or three pairs of moulds according as the carrier is 
single or double. 

When we are working on hard clay, the plaster moulds of 
small resistance are replaced by cast - iron moulds, which are 
lubricated for each tile to prevent the clay from adhering to the 
metal. 

In either method each kind of tile requires special matrices 
as well as, in the case of plaster moulds, cast-iron frames. 

Curved Tiles. The Dutch co-shaped face is obtained by a 
die of the required section, and the curved slab, as it comes from 




Fig. 405. Cutting Machine for Curved Tiles (Schlickeysen). 

the machine, slides over a mandrel which is lubricated by a 
current of water (Fig. 405), and is there cut into suitable lengths, 
while a fixed wire divides it into two parts, its breadth being 
double that of the tile. 

By increasing the curvature of the die we obtain the shape 
of the semi - cylindrical Roman tiles. As they are conical, we 
place them, when they come from the mandrel cutter, on another 
conical mandrel shaped like the tile, and with an iron wire we 
take off the parts which project on each side (Fig. 370). The 
tile then is of the required shape (Fig. 405, to the left). 

Another process, less economical, however, consists in express- 



3 io 



POTTERY IN ARCHITECTURE. 



(3 rt 

o MO 



CU 0) . 

II 



^ 5 
* 2 
c/3H W U 



S's 






u.t: 



CO -H 



o 







o o o o 
o o o o 

. VO !O >-O . *O 



; 10000000 



- oo o ^ o 

^^ OO'O O' 

- " 



>-o 

f% 








c/5 

^ '-*-' 

cj >-. 



. 

r I* 

<"w 



TILES. 311 

ing the paste in the shape of a half-cylinder bounded by a flat 
surface, thus having the appearance of a gas retort. An iron 
wire cuts off the flat part A B (Fig. 370), which is thrown under 
the machine, and the curved part is taken to a mandrel and 
shaped conically as above. 

The fitting ridge-tiles of the usual shape are made with screw 
or cam presses. As for those of complicated form or limited 
consumption, it is advisable, as matrices are very expensive, to 
make them by hand with plaster moulds of the desired shape, 
the moulds being constructed with the aid of models, 



(2) Drying. 

As in the case of bricks, open-air drying-places may be either 
on the ground, or in storeys. The former are only possible for 
small installations which make mainly flat tiles. They are mere 
sheds like those used for bricks, but they must, on account of 
the shape of the tiles, be fitted with open shelves of suitable 
dimensions. 

So-called mechanical tiles, which are made of soft or semi- 
firm paste, are received as they come from the press on small 
frames (" planchettes ") (Fig. 406) slightly 
larger than the tiles. In order not to have 
several kinds, their dimensions are fixed 
at: .45 by .25 ; the laths being .04 to .05 
wide and .01 thick; this being so they can 
be used for any products. To avoid waste 
they must be well made. 

After trimming, the frames with the tiles 
on them are placed on the shelves of the Fig. 4 o6.-Planchette" 

for Tiles. 

drying-sheds. In constructing these shelves 

we must take into consideration the space at disposal and the 
dimensions of the tiles ; they are constructed economically and 
so as to take up as little room as possible, leaving the space 
strictly necessary for moving about. 

When the drying-places are on the ground-floor, the frames 



3 I2 



POTTERY IN ARCHITECTURE. 



are placed on special barrows with shelves (Fig. 408) to be taken 
to the drying-shelves ; if the tiles are too high to be put on these 




Fig. 407. Platform Barrow. 



Fig. 408. Shelved Barrow for Tiles. 



barrows, platform barrows are used like those serving for bricks 
(Fig. 407). 




Fig. 409. Shelved Drying Waggons. 

Tiles made of hard clay are firm enough to do without 
frames. They dry very quickly, hence the empty space in the 



TILES. 313 

shelves is much reduced, and more tiles can be placed in less 
compass. M. Dumont, one of the originators of this kind of 
manufacture, only leaves about 2f inches between the shelves. 
Each shelf is formed of three strips for tiles of 28 to the square 
metre, and of four for tiles of 13 to the metre. To move the 
tiles, a two-pronged wooden fork is used, which is slipped under 
them and afterwards withdrawn. 

M. Dumont also used movable drying - places formed of 
shelves mounted on wheels. When the weather is fine, these 
may be left in the open air, and desiccation takes place rapidly ; 
in unsuitable weather, they are placed in a drying gallery, which 




Fig. 410. Tile Barrow. 

may, with the limitations already mentioned, be usefully employed 
for the drying of tiles. 

For transporting the products, M. Dumont used a special 
barrow (Fig. 410), holding twenty large-size tiles on edge, and 
easily handled among the shelves, thanks to its shape. 

Communication between different storeys of the drying-sheds 
is made by lifts adapted for taking barrows, or by special tile- 
raisers with swinging trays like that represented in Fig. 187. 

Cost of Drying- sheds. Only two systems of drying are 
possible for regular manufacture : storeyed drying-places, or closed 
galleries. The cost of their installation has been calculated 
(p. 182) ; but to the first estimate must be added the cost of the 



314 POTTERY IN ARCHITECTURE. 

shelves, and also that of the " planchettes " if soft or semi-firm 
clay is used. 

A building like the one shown in Figs. 176 and 177 is 
sufficient for a daily production of 20,000 to 25,000 tiles from 
soft clay. For such an output we must estimate the cost, in 
addition to that of the building, at 

Shelves, about 10,000 fr. 

Planchettes at 10 centimes each ..... 4,500 

Sundries ......... 5 



Total . 15,000 fr. 

With hard clay, the same building would serve for double the 
daily production mentioned. 



(3) Firing-. 

This is carried out in kilns identical with those used for firing 
bricks, and mainly in continuous kilns, in the case of mechanical 
tiles. As tiles are of a more fragile nature, they must not 
come into direct contact with the fuel. A tile-factory nearly 
always produces bricks also, and in this case they are arranged 
round the tiles, which are thus protected as if by a sagger. 
To do this, however, the production of bricks must be one- 
third or one-half of the products made. When it is less than 
that proportion, we must try to find a kiln which, while ensuring 
the continuity of the fire, keeps the tiles out of contact with the 
fuel. The Virollet continuous kiln, called also " four a tranches," 
is one of those most commonly used. 

Like other continuous kilns, it consists of a certain number 
of compartments which are reached by doors, but which are 
separated from one another by walls pierced below with holes 
(Fig. 412). On the floor of the kiln, a certain number of fire- 
bars 4 to 6 inches broad are arranged transversely. Under these 
bars, which occupy the whole width of the kiln, is an empty space 
into which the outer air is introduced through a conduit in the 
thickness of the wall and issuing at the level of the pavement. 
The orifices of these conduits are closed with sand plugs. 



TILES. 315 

The fuel, being thrown through small openings in the roof, 
falls on the bars and burns there. To preserve the tiles from 
contact with it, several layers of bricks are placed at the bottom 
of the kiln, and receive the heat direct from the coal. These 
highly fired bricks are always of inferior quality and represent a 
certain loss. 

The object of the walls which separate the compartments is 
to isolate them when the firing is completed, and all that need be 

"FOUR X TRANCHES" FOR TILES. 




Fig. 411. Longitudinal Section. 




Fig. 412. Transverse Section. 




Fig. 413. Plan. 

done is to close the openings in the walls with a layer of sand 
or a metallic register. 

As the air necessary for combustion is introduced into each 
compartment, and not behind the fire, the fired and isolated 
compartment may be allowed to cool more or less quickly, and 
is thus similar to an intermittent kiln. 



316 POTTERY IN ARCHITECTURE. 

The kindling and management of the fire differ very little 
from those of the Hoffmann kiln already described. 

From the" point of view of economy, this kiln does not 
present the same advantages as the Hoffmann kiln, for the outer 
air is not heated before it reaches the fuel, nor can we use slack, 
which would burn badly ; but it has the advantage of a more 
rapid cooling when the products can bear it, and so allows of 
a diminution in the number of compartments. Above all, it 
avoids contact between the tiles and the coal. 

This latter advantage is found in gas kilns, which, moreover, 
require no bricks for stacking, as the tiles are placed on the floor 
of the kiln between the refractory clay " chandelles." There is 
no fear of the ash stains which are produced under a high draught 
when solid fuel is used ; and finally, the degree of firing which can 
be reached is much higher than in the Virollet kiln. 

All these advantages should recommend gas firing to tile 
manufacturers, and in new installations it is undoubtedly 
indicated. 

Stacking. The method to be adopted depends upon the 
shape of the tile, and on the kiln at disposal. The important 
thing is to avoid warping during the firing by pressing them 
closely together. Fitting tiles are arranged in pairs and one 
close against the other, so as to take up less space and preserve 
the projecting parts. 

Round tiles stand upright one against the other. But often 
several kinds of tile are fired together, and then the method of 
stacking depends on the special conditions. 

If the firing takes place at a temperature near that of 
softening of the paste, special precautions must be taken to 
avoid loss of shape ; for instance, we may stack in batches, using 
bricks to construct the divisions. 

Installation of Mechanical Tileworks. Details depending 
upon special circumstances excepted, tileworks are composed of 
large buildings in which the ground-floor is occupied by the 
kilns, machines, soaking-ditches, and deposits of prepared clay ; 
the upper storeys are reserved for the drying-rooms. 

The arrangement of the machines depends upon local con- 



TILES. 



317 



ditions. Figs. 414 and 415 are section and plan of an installa- 
tion, and will give some idea of the arrangement. 

At a is the machine for making the slabs, at b and c are 

TYPE OF INSTALLATION OF A MECHANICAL TILE FACTORY. 
Sf choirs. J3 Sections? 



Fig. 414. 




Fig. 415- 



Fig. 414. Vertical Section. 



Fig. 415. Plan. 



two tile presses of different type, one of which can make 
ridge tiles, which require a larger stroke for the upper mould. 
Between these two presses stands a tile-lift, worked by machinery 
and connecting with the upper storeys. 



318 POTTERY IN ARCHITECTURE 

The estimate of such an installation is 

Movable 20 horse-power engine ...... 12,000 fr. 

I pug-mill with crushing cylinders, 8 horse-power . . 2,750 

I expression machine, 7 horse-power . . . . 2,050 

I double-carrier lever press, I horse-power .... 2,000 

i five-sided revolver press, 2 horse-power ... 3>5 

Matrices, moulds, etc. ....... 1,500 

Tile-lift, 2 horse-power ....... 2,500 

Transmission of power ....... 1,000 

Sundries .......... 700 

28,000 fr. 

The staff required comprises an engine-driver, a man to feed 
the pug-mill, a cutter for the slabs, a man to take the slabs to 
the presses, four men at the presses, and three men to put the 
tiles on the shelves : eleven men in all. 

It rarely happens that the manufacture of tiles is not 
accompanied by that of bricks, therefore it is difficult to fix the 
cost of tiles alone, unless we suppose a continuous manufacture 
of them. In that case, the above-described installation will 
produce daily about 8000 tiles, that is, 2,500,000 per annum, and 
tJie cost of 1000 tiles i liberally estimated^ is calculated as follows : 

Interest at 4 per cent, on 28,000 fr. 1120 fr. "j 

Depreciation ,, 10 ,, ,, = 2800 j39 2 r - 

Per i ooo, on an annual production of 2,500,000: ^- . . . . . i fr. 55 

2500 

II men at 5 fr. per day = 55 fr., or. per 1000, 51 . . . . = 6 fr. 87 

8 

Coal, 250 kil. at 25 fr. the ton 6 fr. 25^ 12.60 

Oil, maintenance, etc., per day = 6 fr. 35} " fn 6 ' r ' per IO ' 8~ = ' & 5 

Total . 10 fr. oo 
To this price we must add the cost of extraction of the clay (p. 31) and its 

preparation, which we estimate at an average of . . . . . 2 fr. oo 

Total cost . 12 fr. oo 

Eor a production of 20,000 to 25,000 tiles a day, which corresponds to an annual 
production of 6 to 8 millions, the following plant is required : 
50 horse-power steam engine, about ........ 25,000 fr. 

Rolling cylinders (these are not always necessary), 5 horse-power . . 1,800 
Crushing mill, 5 horse-power ......... 3>5oo 

2 pug-mills, 10 horse-power, at 1800 fr. . . . . . . . 3,600 

2 expression machines, 15 horse-power, at 2250 fr. . . . . . = 4,500 

5 revolver presses (5-sided), 10 horse-power, at 3500 fr. . . . = 17,500 

2 tile-lifts, 4 horse-power, at 2500 fr. . . . . . . . . = 5,ooo 

Matrices, moulds, etc. . . . . . . . . . . 5) 

Transmission of power .......... 35 

Sundries . 1,100 



Total for machines . 70,000 fr. 



TILES. 319 

Net cost per 1000 tiles. 

Interest at 4 per cent, on 70,000 fr. = 2800 fr. 1 Q^QQ f . 9800 r 

Depreciation ,, 10 ,, ,, = 7000 / 7000 

120 
24 men at 5 francs a day =120 fr. per 1000 : . . . . . = 5 fr. 34 

Coal, 500 kil. at 25 fr. =12 fr. 5\ 22 f r 5o per IOOO . 22 - SO _ j f r co 

Oil and maintenance . 10 fr. oo-' 22.5 



Total . 7 fr. 74 
Extraction and preparation of the clay averages . . . . . . I fr. 76 



Total cost of moulding . 9 fr. 50 

In order to obtain the total cost of installation of the-tileworks, 

we must add to the price of the machines T . . . 70,000 fr. 

That of the building, with storeys for the drying-rooms, the 

ground-floor being occupied by the kiln and machines, about 45,ooo 

Continuous kiln, with chimney . . . . . . 35>ooo 

Sundries . - . . . . . . . . . . 5,ooo 



1 55,000 fr. 

We must add to this sum: (i) the cost of the land, 

(2) the cost of vehicles and horses, etc., for delivery of goods, 

(3) the cost of various buildings: stables, coach-houses, offices, 
etc. 

The above figures can only serve as hints, for the plant 
necessary varies with the nature of the clays to be worked. 



3. SHAPES, DIMENSIONS, AND USES OF THE PRINCIPAL 
KINDS OF TILE. 

With respect to their shape, tiles are divided into ancient 
tiles, which possess no sockets and are laid one against the other, 
and modern fitting tiles. 

Ancient Tiles. 

These comprise tiles which are flat, square, or rounded at 
one end, and round or variously shaped tiles. 

Flat Tiles. Square. - These are greater in length than 
breadth, and of variable dimensions (Figs. 416,417); the best 
known ones are .27 x .15 and about .015 thick (about 10 in. x 



3 20 



POTTERY IN ARCHITECTURE. 



6 in. X i in.) ; they weigh about I kilog. (2 Ibs.). They are fixed 
to the laths with a hook, and most of them have one or two 
holes (Fig. 417) by which they can be nailed down. They are 
arranged in horizontal rows which overlap one another from the 

Fig.416 Fig. 417 Fig. 419 Fig. 420 



Fig. 423 Fig.'424 



DI 



T 




Fig 418 



Fig.42i 






Fig 422 



Fig.426 



Fig. 428 



Coup, * 




Figs. 416 to 430. Ancient Tiles of Various Shapes. 

base to the ridge ; only one-third of the tile is left visible, and 
this part is called the "Bureau." Each tile is over three laths 
(Fig. 418), and thus the roofing is three tiles thick, and is of 
considerable weight, averaging 60 kilog. per square metre. The 
slope should be from .75 m. to i m. per metre (30 to 45). 



TILES. 321 

Round or Scaled. These only differ from the foregoing in 
the lower part, which is semicircular (Figs. 419, 420), or pointed, 
which gives the roofing a tasteful appearance resembling the 
scales of fish (Fig. 421), whence the name. 

In order that a roofing may be successfully laid, the tiles 
must be perfectly smooth, which is not often the case. 

The roofing of towers and domes requires the tiles to be 
cone-shaped so as to follow the curvature of the roof (Fig. 
422). They are laid in the same way, being nailed to the laths 
when necessary. 

Roman Tile. This differs very little from the tile of the 
ancient Romans; its shape is trapezoidal (Fig. 423), and the 
joins are covered by round tiles (Fig. 424). Roofings of this kind 
(Fig. 425) are still found in Champagne, in the south of France, 
and in Italy. 

Round Tiles. Canal or Roman Tile. These are used alone 
or in conjunction with the preceding kind. In the former case 
they are laid in different ways according to the locality ; they are 
generally placed upon connecting battens, for which are some- 
times substituted terra-cotta squares (Fig. 428), and the whole is 
sometimes bound together with mortar, making a solid but 
very heavy mass (Fig. 429). In the south of France, the 
tiles are merely placed upon triangular joists (Fig. 430); the 
slope must not be very great, about .4 to .5 metres per metre 
(21 to 26), for the tiles are only kept in position by their 
weight. 

<J)-shaped Flemish Tiles. These tiles are provided with a 
hook which holds them to the laths (Fig. 405), and they can 
therefore be more sloped than the previous kind. To make the 
roof more water-tight, the joins are usually filled in with 
mortar. 

Modern Tiles. 

The invention of fitting tiles by Gilardoni was a great 
advance on earlier tiles, which had many other disadvantages 
besides their weight ; they offered a great hold to the wind, 

21 



322 POTTERY IN ARCHITECTURE. 

they allowed snow and often rain to pass through, and they were 
costly to maintain. 

The first tiles have been improved upon, and we possess types 
to-day which make excellent roofs ; but modifications are always 
being sought after, and every year new shapes of tiles appear, 
which, however, are all based on the same principle, and frequently 
offer no sensible advantage over existing types. 

It may well be asked, with reference to this, whether 
inventors are well advised in trying, under pretext of improvement, 
to complicate the shape of tiles by an infinitude of details. 
What should be the natural shape of a tile that it may be suited 
to its destined position ? This shape should be one which will 
render the roofs absolutely proof against snow and rain in any 
quantity ; it should make the tiles as light as possible consistently 
with their stability under any pressure of wind. A detailed 
examination of the principal types of tile will show how this 
question has been answered. 

Fitting tiles are divided into two classes according as they 
are laid overlapping, that is to say, with vertical interrupted 
join, or in a straight line, that is to say, with vertical continuous 
join. 

Tiles with Interrupted Vertical Join. Gilardoni tile, also 
called diamond '- shaped tile (Fig. 431). This tile has average 
dimensions of .4 x .24, and thirteen are required to the square metre, 
which represents a utilisation of five-sixths of the total surface. 
The joint is at the left, and is formed of a groove with a strong 
inner edge ; at the right is the counter-joint ; at the top is a 
simple flange. 

The lower part is of larmier shape and has a hollow (Fig. 45 i) 
in the middle, in which the counter-joint of the lower row rests. 
In the middle of the tile is a lozenge - shaped strengthening 
rib, hollow inside ; it is below this lozenge that the triangular 
projection caused by the hollow at the bottom of the tile is 
placed, and it has also the effect of directing water to the two 
sides of the lower counter-joint (Fig. 433). The tile is fastened 
to the laths with two hooks, and some types are furnished with 
holes through which they can be nailed to the rafters, others 



TILES. 



323 



(Fig. 448) are furnished below with a projection pierced with a 
hole through which a wire is passed and attached to the laths 
(Fig. 449). 



Fig. 431 fig. 43? Fi K .-134 




Fif.446 



Figs. 431 to 449. Modern Tiles of Various Shapes (Gilardoni Brothers and Muller). 

This type of tile, which was the first to be manufactured, is 
now made by many firms (see table), as the patent has expired. 



324 POTTERY IN ARCHITECTURE. 

It requires half-tiles (Fig. 432). The perfected model No. 4 
(Fig. 440) is double-fitting at the top and at the side. The 
surface of the tile forms two channels (Fig. 441) separated by a 
rib. 

The tile of Martin frcres, called Marseilles tile (Figs. 458, 
460). The dimensions (.42 x .25) of this are almost the same as 
those of the lozenge tile. In the middle is a narrow rib enlarged 
at the base into a triangle, and as it ceases at some distance from 
the horizontal joint, this does not reach under the tile above. 
On the left side the grooves forming the joint are triple, and at 
the top the joint is double. The counter -joint has on it a 
channel which, by means of smaller oblique channels, pours off 
the water which falls upon it. 

This tile, which is manufactured by the United Tileworks of 
Marseilles, makes excellent roofs (Fig. 460). 

The catch and hook tile (Fig. 454) is a lozenge-shaped tile, 
the lower part of which has a fitting arrangement binding all the 
tiles together without its being necessary to fix them to the 
laths. The outer appearance of these tiles is not changed 
(Fig. 453). 

The Boulet tile, called also Artois tile or pantile (Fig. 455). 
The middle rib ends in a rounded portion which sends the water 
to each side of the counter-joint. Its dimensions (.28 X .21) are 
smaller than those of the lozenge tile, and for each square metre 
twenty are required weighing about 40 kilog. This tile is 
principally used in the north of France and abroad. 

The villa or chalet tile only differs from the preceding ones in 
its dimensions, which make it squarer in shape. 

Tiles with Continuous Vertical Join. Gilardoni tile No. 2, 
also called Muller or ribbed tile (Figs. 434, 445, 456). This 
has the same dimensions as the lozenge-shaped tile (.4 x .24), and 
also is i 3 to the square metre. The joint is formed by a broad 
and deep groove bordered through its whole length by two thin 
ribs ; the counter-joint is formed by a broad projection provided, 
below and in the middle, with a rib fitting into the above- 
mentioned groove; the join is thus covered (Figs. 435, 446), 
which is not the case in the lozenge tile (Fig. 444). 



TILES. 



325 



A strong rib, hollow underneath, is placed in the middle of 
the tile and stretches over the whole width. This perfected tile 
has become the : 

Gilardoni tile No. 3, called also Alsace or Altkirch (Figs. 437, 
438, 439). The central rib is omitted, and is transferred to 



Fig. 453 



Fig. 455 



Fig. 450 



Fig. 451 



Fig. 455 





'Fig. 456 



Fig. 454. 
Fig- 451 Fig. 458 




Fie. 460 






Fig. 463 



Fig. 461 Fig. 462 




ps 


Hf 




1 


_ '-..'., 




I^sT 







fSi 


- 


m 



Fig. 464 




Figs. 450 to 464. Modern Tiles of Various Shapes. 

the left, where it forms the edge of the groove. The counter- 
joint, which is double-tongued, is fitted to it and forms with it a 
fairly broad relief from top to bottom of the roof. The horizontal 
joint is also double - fitting ; the flange of the base is larmier- 



326 POTTERY IN ARCHITECTURE. 

grooved ; a second flange, parallel to the first, crosses the tile, 
fits into the groove of the upper flange, and thus forms another 
obstacle to the passage of water. This system is excellent. 

Northern Tile, called Pantile. The inner flange of the groove 
forming the joint turns back towards the top, making an angle ; 
the counter-joint has a shoulder-piece. The tile has a single 
hook at the top, and at the bottom there is an angular groove 
fitting into the upper angular rib so as to form a joint. Such is 
the Legros pantile (Fig. 464). 

In the Royaux de Leforest (Pas-de-Calais) tile, the upper 
grooving is not triangular (Figs. 461, 462). 

Foreign Tiles. 

These differ more or less from French tiles, but are derived 
directly from them. 

Among those of antique shape, there are the German flat tile 
(Figs. 465, 466), which is made by special cutting machines 
(Fig. 382) it has four grooves on the top for drawing off the 
water; the modified Roman flat tile (Fig. 467), carrying its own 
cover-joint; and the Dutch ^-shaped pantile (Fig. 468). Flat 
tiles are also made which are hollow inside. 

The modern French roofing tiles of the lozenge, Boulet, or 
Marseilles type are much used abroad. Tiles with continuous 
(Fig. 469) or interrupted (Fig. 470) vertical joint, and single (Fig. 
471) or double (Fig. 472) overlapping, are made in Germany. 
The figures sufficiently explain the shape of these tiles and the 
way in which they fit together. 

The Italian Ludovici tile is also made either with continuous 
(Fig. 473) or interrupted (Fig. 474) vertical join, and single (Fig. 
475) or double (Fig. 476) fitting. 

The Porz tile (Fig. 477) is triple, overlapping, at the top and 
at the side, and is very similar to the Alsace tile. The Victoria 
tile (Fig. 478) possesses no visible rib; it overlaps doubly both 
at the top and at the side, as the figure shows (Fig. 479). 



TILES. 



327 



Tiles for Special Uses. 

All the preceding tiles are used for covering the flat parts of 
the roofs ; for projecting or re-entrant parts, special tiles are required 



Fig. 468. 



Fig. 467. 



Fig. 466. Fig. 465. 




Fig. 479. 



Figs. 465 to 482. Foreign Tiles of Various Shapes. 



which take their names from the parts they cover : ridge tiles are 
placed upon the ridges, hip tiles on the hips, border tiles on the 
borders of the roof, etc. 



,28 



POTTERY IN ARCHITECTURE. 



Ridge Tiles. The simplest are semi-cylindrical (Fig. 485) and 
of varied dimensions ; they are laid down bare, one against the 
other, and are fixed to the plaster at the bottom and at the joins. 
The fitting ridge tiles (Figs. 483, 535) are provided with a 
hollow hump which is placed on a projection at the end of the 
next ridge tile and so forms a joint (Fig. 484). The over- 
lapping ridge tiles (Fig. 486) are formed of a male end which fits 



Fig. 483. Fig. 484. Fig. 485. 



Fig. 486. Fig. 487. 




P^igs. 483 to 495. Ridge Tiles (Muller). 

to a distance of some centimetres into the female end to form the 
joint (Fig. 487). 

The shape of these ridge tiles is very variable ; some are 
pointed (Fig. 489), some are shelving ridged (Fig. 490), some are 
lozenge shaped (Fig. 534). For fitting tiles hollow ridge tiles are 
made (Fig. 488), which receive the ribs of the tiles like those of 
the Muller type. 



TILES. 



329 



To strengthen ridge tiles, they are sometimes keyed (Fig. 
533); this may be done simply (A and B of Fig. 533), or 
ornamented to give elegance to the roof. Decoration, however, is 



FINIALS FOR RIDGE TILES. 




0.30. { 1 0.23 j 

Fig. 496. Fig. 497. Section. Fig. 498. Application. 

more usually added by means of the ridge tiles themselves, which 
have ornaments on them called finials. Sometimes these finials 



TOP-PIECES AND SUPPORTS. 

Fig. 500. 




Fig. 501. 



Fig. 502. 



Fig. 499. 

Fig. 499. (Perrusson.) Fig. 500. (Muller.) Fig. 501. Support (Muller). 

Fig. 502. Gothic Top-piece (Brault). 

are part of the ridge tile and are of varied and more or less 
complicated patterns (Figs. 492 to 495). The last ridge tile, 
called ridge end, bears a higher ornament which towers up above 



330 



POTTERY IN ARCHITECTURE. 



the crest of the roof. Sometimes the finials are separate, and are 
fitted into a groove in the ridge tiles ; the finial in Fig. 496, 
the section of which is shown in Fig. 497, and application in Fig. 
498, is one of this kind. Like finials, top-pieces are either part 
of the ridge tiles (Figs. 494, 495) or separate (Figs. 499 to 
502). 





Fig. 503. Perrusson Ridge Tile. Fig. 504. Perrusson End Tile. 

The ends of ridges (Fig. 504) are more or less ornamented 
according to the style of the ridge tiles themselves (Fig. 503) ; 
they are divided into closed male ends to the right and closed 
female ends to the left. When they bear top-pieces (poincons), 



. 505- 




COPING TILES. 



Fig. 506. 






Fig. 509. Wall with Coping Tiles. 



they are called poincon-carriers. German ridge tiles are acute- 
angled (Figs. 480 to 482). 

Hip tiles are similar to ridge tiles, and also have end tiles. 

Coping Tiles. These consist of an ordinary tile with a curved 
end forming a ridge (Figs. 505 to 508); their dimensions 



TILES. 



331 



correspond to the thickness of the walls which they are to cover. 
When they are too thick for a single tile, two are placed on them 
(Fig. 509). These tiles are also made double-sloped. 

Border Tiles, Frontons, Pantile Joints. When the ends of a 
roof form a gable, it is very often adorned with a border of terra- 
cotta, which is made up of pieces called border tiles. These fit 



Fig. 510. 

....o 40 



I. 0.66 ^ 




Figs. 510 to 515. Pantile Joints, Frontons, and Borders (Perrusson). 

together (Figs. 514, 522, 527), and are called left border or right 
border according to the side on which the counter-join is ; the 
terminating tiles are called border ends (Figs. 513, 525, 531), 
and at the top of the gable the tiles are joined by a fronton 
(Figs. 511, 524, 529). 

Borders are made plain like tiles (Fig. 5-36) or ornamented 
(Figs. 522, 527); the same may be said of frontons, and the 



332 



POTTERY IN ARCHITECTURE. 

BORDERS, GUTTERS, FRONTONS, ANTEFIXES. 





Fig. 5 J 6. Fig. 517. 

Figs. 516 and 5 J 7- Perrusson Make. 




Fig. 520. Fig. 521. 

Figs. 518 to 521. Muller Make. 




Fig. 522. Fig. 523. Fig. 524. Fig. 525. 



Fig. 526. 




Fig. 527- Fig. 528. Fig. 529. Fig. 530. Fig. 531. 
Figs. 522 to 532. Gilardoni Make. 



Fig. 532. 



general effect is more or less ornate (Fig. 515) according to the 
richness of the pattern. When ornamented, the tiles and frontons 
are called monumental. 



TILES. 



333 



A special border tile (Fig. 539) called membron is used to 
cover the angle in roofs with " comble brise" (Fig. 542). 

Border tiles are substituted for ridge tiles in certain special 
cases, as, for example, in the roofs of factories lighted from above 
(Fig. 540). 

Pantile joints serve the same purpose for pantiles as frontons 



VARIOUS TILES. 



.: o so ^ 4) sa 

Fig. 533- 




Fig. 534- 



Fig. 535- 





Fig. 536. 



Fig- 537- 



Fig. 538. 





Fig. 540. 
Figs. 533 to 541. Montchanin Make. 




Fig- 541- 




Fig. 542. Fig. 543. Fig. 544. Fig. 545. Fig. 546. 

Figs. 542 to 546. Muller Make. 

for gables, but of course they are inverted (Fig. 5 10). They are 
made plain, or more or less richly decorated. In order that they 
may fit all slopes, they are made in two pieces, which are hinged 
together (Fig. 528). Frontons are made in the same way 
(Fig. 529). 

Gutter Covers, Return Angle. Gutter covers are similar in use 



334 



POTTERY IN ARCHITECTURE. 



and appearance to border tiles, and the two kinds are inter- 
changeable. Thus the border (Fig. 527) is used as such and 
also as gutter cover in Fig. 532. The angle of the gutter is 
hidden by a special piece called return angle (Figs. 523, 530). 
The gutter covers may be either plain or decorated, and are 
terminated by end pieces. 

In public buildings they attain monumental proportions and 

"MITRES," "MITRONS," AND CHIMNEYS. 
Fig. 543- Fig. 551. 





Fig. 549- 





Fig. 547- Fig. 550. Fig. 552. Fig. 553. 

Fig. 549. (Brault.) Fig. 552. (Muller.) Fig. 553. (Montchanin, Jacob.) 



contribute much to decoration. Figs. 518 to 5 22 S^ ve the 
general appearance (Fig. 5 1 9), the return angles (Fig. 5 I 8), the 
antefixes (Fig. 521), and the panels (Fig. 520) of the gutters of 
the Law Courts at Havre ; they were executed by Muller. 

The gutter and antefixes of the Hotel des Telephones in 
Paris, executed by Perrusson, are shown in Figs. 516 and 

517. 

Various Tiles. For the passage of pipes, and the lighting 






TILES. 



335 



and ventilation of lofts, special tiles are made. Such are socket 
tiles, which have the width of two tiles (Fig. 541) or of one (Fig. 
546) according to the diameter of the pipe. 

For lighting purposes, tiles are made with an orifice which 
is covered with a pane of glass fitting directly against the clay, 
the dimensions and shape being variable (Figs. 544> 545)- 
If ventilation as well as lighting is required, a skylight sash is 
fitted to the opening (Fig. 538). 

Ventilation alone is effected by means of tiles called "chattieres" 
(Figs. 537, 543), and sometimes the orifice has a clay grating. 





t 24. 



Fig. 554- Fig. 555. 

Figs. 554 and 555. Chimneys (Perrusson). 

Roofing Accessories. These accessories are of various kinds ; 
first the "poingons," of which we have spoken and which are attached 
or not to the ridge tiles. In the latter case they fit into the end 
tiles. When they are placed upon several hip tiles, they are 
fixed to special sockets (Fig. 501). Clay mitres (Fig. 548) 
and mitrons (Fig. 552), lanterns (Figs. 549, 550, 551), and 
chimneys (Figs. 547, 553, 554> 555) may also be considered 
as roofing accessories ; the shape of these varies from the plain 
upright pipe to the most elegant chimney. 

Fig. 556 shows a roof which exemplifies the use of the tiles 



336 



POTTERY IN ARCHITECTURE. 



and accessories above described. The roof, properly so called, 
is of lozenge tiles, and we see two " ckattieres" one open the other 
grated, a window tile, a sash tile, border tiles with fronton and 
decorated ends, gutter covers, ridge tiles with various finials, 
poincons, and lastly, different terra-cotta chimneys fixed to the 
roof either by socket or brick masonry. 

Qualities of a Good Tile, Colour. The ideal tile should be 
as light as possible, while being strong enough to bear walking 
on the roofs without breaking ; it should be smooth, straight in 
all parts, impervious to water ; should have such a surface that 
water will not remain on it, and should closely follow the line 
of greatest slope of the roof. Finally, it should not be liable to 




Fig. 556. Tiled Roof with Accessories (Montchanin). 

crack with frost, but should be of a nature to resist atmospheric 
agencies. 

Which tile most nearly approaches this perfect type? It 
would be rash to decide without careful and comparative experi- 
ments which alone could be the basis of an opinion ; we can say, 
however, that the Gilardoni and Muller tiles (soft clay) enjoy an 
excellent reputation, which is justified by their good quality; 
that the pantile of Leforest (Pas -de - Calais) is made of hard 
paste, and is highly esteemed in the north of France ; that the 
Marseilles tile is said to be a good one. The Norman tiles, 
made at Dieppe and Villequier (Seine- Inferieure), at Argences 
(Calvados), etc., are principally used in that district. 



TILES. 337 

As for the Burgundy tile (hard paste and firm paste), its 
red colour and quality make it much admired. 



Black Tiles. 

The colour of tiles depends upon the kind of clay used in 
their preparation, and varies from yellow ochre to vermilion red. 
It is important to observe that the well-fired and consequently 
the best tiles have a less bright and less uniform colouring than 
those which are less baked. At the present day less importance 
is rightly attached to colour, which formerly was expected to be 
absolutely uniform and of a brilliant red, qualities which are 
incompatible with those of a good tile. 

Slate colour may be given artificially ; this may be useful for 
terra-cotta objects to be placed on slate roofings, or in countries 
where, as in Japan, red is forbidden, but it is generally better to 
preserve the special properties of each building material than to 
hide them for the purposes of imitation. 

The process for making tiles blue is the same as that used 
for bricks (see p. 248). 

Stoneware Tiles. 

To give tiles an absolute power of resistance to weather and 
especially frost, it was suggested that they might be made of 
stoneware paste, which gives impervious and therefore frost-proof 
products. 

The clays used are similar to those employed in making 
stoneware pipes. The tiles are made flat or fitting (Figs. 557, 
558); they are laid like ordinary tiles (Fig. 559), combined 
with ridge tiles (Fig. 560), borders (Fig. 562), end tiles (Fig. 
561), frontons, etc., to give an elegant appearance (Fig. 563). 

Besides their power of resistance to frost, stoneware tiles have 
the advantage of being proof against acid vapours, a quality 
desirable in the case of some chemical factories. Stoneware 
tiles do not seem as yet to be very extensively used, and this 
may probably be attributed to several causes : these tiles, 

22 



338 



POTTERY IN ARCHITECTURE. 



although hard, are very brittle, their shape is less uniform than 
that of ordinary tiles, as they lose shape in firing, and then, 
unless very carefully selected, the fitting sockets are not as water- 




Fig. 563- 
Figs. 557 to 563. Stoneware Tiles. 

proof. But it is probable that by perfecting the methods of 
manufacture and choosing suitable pastes these difficulties will 
be overcome. 



TILES. 339 

PARTICULARS OF THE PRINCIPAL TILES USED IN FRANCE. 



Makers. 


Particulars of Tiles. 


Per Square Metre 
of Roofing. 


Remarks. 


Length in 
Metres. 


Breadth 
in 
Metres. 


|| 

|a 


jj 


Number 
of Tiles. 


Weight 
in 
Kilog. 


i'ej 


Ancient Tiles. 


FLAT TILES WITH HOOKS. 


f 


0.27 


O.2O I.2OO 


35 


55 


66.00 


1.82 




Argences (3) 


0.27 


O.I7 0.950 


34 


65 


61.75 


2.21 




I 


0.24 


0.17 0.750 


32 


75 


56.25 


2.40 




Gilardoni (4) . 


0-35 


0.13 0.750 


25 


60-75 


48.75 


1.75 


Press-moulded, 50 fr. 


Jacob . . 


0.27 


o. 1 5 o. 700 


60 


50-60 


6o.OO 


3.48 




Lartigue (5) 


0.30 


0.18 


1-775 


60 


46 


81.65 2.76 




Legros (6) 


0.20 


0.12 


0.560 


18 


1 10 


61.60 ,1.98 




Marseilles (7) . 
Montchanin (8) 


0.27 
0.27 


0.15 
0.15 


0.750 

I.OOO 


50 
60 


70 
56-60 


52.50 3.50 
60.00 3.48 


Free to 1'Estaque Station. 


Perrusson (9) . 


0.27 


0.15 


0.700 


60 


60-65 


45.50 3.72 




Scale Tile. 


Argences . . 


0.27 


0.15 


1.250 


60 60-70 


65-87 


3.90 




Gilardoni . . . 


O.25 


0.13 


0.750 


25 60-75 




1.62 


Press-made, 50 fr. 


Jacob . . 


O.27 


0.15 


I.OOO 


60 50-60 


50-60 


3.30 




Lartigue . . 


0.27 


0.15 




60 60 


45-56 


3.60 




Marseilles - . 


0.22 

0.27 


0.12 
0.15 


0.600 
0.700 


40 90 
50 75 


54.00 
52.50 


3.60 
3.85 


Gare de 1'Estaque. 

35 


Montchanin 


0.27 


0.15 


I.OOO 


60 50-60 


50-60 


3.30 




Muller (10) . / 






... 


100 70 
175 , no 




7.00 
8.25 




Perrusson 


0.27 


0.15 


0.700 


60 


60-70 


40-45 


3.90 




Royaux (n) . ./ 




0.15 


0.600 


65 


60 


36.00 


3.90 




"GIRONNEE" SCALED TILE. 


Montchanin 


0.27 
0.27 


O.O4-O.O7 
O.I2-O.I5 


0.420 

I.OOO 


70 
70 








Press -made, 80 fr. 


Perrusson (Fig. 422) 




... 




85 


... 


... 


... 


Quantity to the sq. metre 


















variable. 


FLAT ROMAN TILE. 


Gilardoni (Fig. 423) . 0.31 


O.I3-O.I5 


1. 600 


50 


22 




... \\ 22 round tiles are re- 


Marseilles . .0.43 


0.28-0.34 


4.500 


190 


7-8 


... 


... (/ quired in addition. 


ROUND ROMAN TILE. 


1 


0.30 




0.800 


20 








22 of the preceding flat 


Gilardoni (Fig. 424) ! 


to 




I.OOO 


25 


22 






tiles are also required. 


1 


0-35 




1.700 


35 








Moulded type, 55 fr. 


Marseilles . . 


0.44 


0.18 














ROUND TILE CALLED " CANAL." 


Lartigue . 


0.50 




2.600 


70 


25 


57 


1.75 




Marseilles. 


0.49 
0.44 


O.2I 
O.I9 


2.2OO 
1. 600 


60 
50 


22 
25 


% 


... 




(i) Catalogue prices for goods taken at the factory. 


(2) Laying and laths not included. 
(3) Machine tile factory of Argences (Calvados). 
(4) Gilardoni Brothers, Pargny-sur-Saulx (Marne). 


(5) At Auch (Gers). 


(6) At Dieppe (Seine-Infe'rieure). 
(7) Socidte" G6ne"rale des Tuileries de Marseille. 


(8) Grande Tuilerie de Bourgogne at Montchanin (Saone-et-Loire) 


(9) Perrusson and Desfontaines at Ecuisses ( ,, ,, ). 


(10) At Ivry-Port (Seine). 


(n) At Leforest (Pas-de-Calais). 
(12) Jacob freres et fils, at Navilly (Saone-et-Loire). 



340 POTTERY IN ARCHITECTURE. 

PARTICULARS OF THE PRINCIPAL TILES USED IN FRANCE. 



Makers. 


Particulars of Tiles. 


Per Square Metre 
of Roofing. 


Remarks. 


' a 

bO*j 
J S 


Breadth 
in 
Metres. 


e t'c v 
&. : ax 

sE^ .2 

*.s & 


Dumber 
of Tiles. 


Weight 
in 
Kilog. 


J 




Modern Tiles with Interrupted Vertical Join. 


LOZENGE TILE OR GILARDONI NO. I. 


Argences . . . 10.40 


0.24 


2.600 


145 


J 3 


33.800 1.88 


Gilardoni No. 4 (Fig. 
















440) ( - . 






2.700 


150 


15 


40.500 


2.25 


Gilardoni No. I (Fig.) 






2.900 


140 


15 


43-500 


2.10 


430 / 






3-300 


105 


13 


42.900 1.36 


Jacob 


0.40 


0.24 


3-3co 


110 


13 


42.900 1.43 




Lartigue . 


0.41 


0.25 


2.900 


120 


20 


58.000 2.40 


Marseilles. 


-39 
0.42 


0.23 
0.25 


2.600 
2.450 


70 
60 


16 
13-5 


41.600 


1.12 Single covered. 
0.81 (Fig. 438) triple covered. 


Montchanin 


0.40 
0.50 


0.24 
0.24 


3.100 
5.000 


110 
200 


*3 

10 


40.300 1.43 
50.000 2.00 Used specially for cover - 
















ing walls. 


Muller . 






3.000 


200 


13 


39.000 2.601 


Perrusson . 


0.40 


0.24 


3-!5o 


115 


12-13 


39.000 ... Are made fitting, or with 














single or double hook. 


VILLA OR CHALET TILE. 


Argences . 


0-34 


0.21 


2. 2OO 


120 


17-18 


38.500 


2.10 




Lartigue . 


0.30 


O.22 


1.675 


80 


20 


33-500 


1.60 




Legros 






I.9OO 


65 


21 


39.900 


1.36 




Montchanin 


0.28 


0.17 


I.5OO 


90 


27 


40.500 


2.43 




Perrusson . 


-35 


0.22 


2.300 


100 


17 


35-oco 


1.70 




BOULET, ARTOIS, OR PAN TILE. 


Montchanin 


O.28 O.2O 


1.800 


90 


2O 


36.000 


1.80 




Legros 






2.OOO 


65 


20 


40.000 


1.30 




Perrusson . 


O.29 O.22 


2.OOO 


90 


2O 


40.000 


1.80 




Tiles with Continuous Vertical Join. 


GILARDONI NO. 2, ALSO CALLED MULLER OR RIB TILE." 


Argences . . .0.40 


0.24 |2.6oo 145 13 


33.800 1.88 




Gilardoni No. 2 (Fig. ; 














434) : 




3.300 150 


14 


46.200 


2.10 




Montchanin . . o. 39 


0.24 


3.200 


110 


14 


44.800 


1.54 




Muller (Fig. 443) . 






3.000 


200 


14 


42.000 


2.80 




Perrusson (Fig. 456) . 


0.40 


0.24 


3-500 


130 


14-5 


51.000 1.88 




GILARDONI NO. 3, CALLED ALSO ALSACE OR ALTKIRCH TILE. 


Gilardoni (Fig. 437) . 




3.000 


150 | 15 


45.000 


2.25 




Montchanin 




3.200 


110 14.5 


46.400 


1.59 


Perrusson 


0-43 


0.23 3.500 


120 


J 3-5 


47.250 


1.62 


Muller . 






2.800 


200 


i5 


42.000 


3.00 


[NORTHERN TILE, CALLED PANTILE. 


Legros 




i. 600 


52 


22 


35.200 


1.14 


Royaux . 





1.700 


80 


22 


37.400 


1.76 


Tiles of Unglazed Stoneware. 


Bossot(i). 
Jacob et Cie. (2) 


0.30 
0-34 


0.18 


2.300 


90 
130 


25-26 ... 12.351 
17 39.100! 2.21 1 


(i) At Ciry-le-Noble (Saone-et-Loire). (2) French Stoneware Company, Pouilly-sur-Saone (Cote-d'Or). 



CHAPTER V. 

PIPES. 

THE use of hollow conduits made of baked clay in buildings 
dates as far back as that of bricks ; this has been proved by 
excavations made in Asia Minor. 

The Romans frequently used pipes of pottery to distribute 
water, arid pipes of rectangular section to conduct the hot air 
which heated their baths. 

After their time, these products were very little used, and 
it was not until the ipth century that they acquired real 
importance with the manufacture of drain pipes, which began in 
England at the end of the 1 8th century, and that of round 
or square hollow pottery, which dates from the beginning of the 
ipth century. Then came the introduction of glazed stoneware 
pipes, which are so valuable in the distribution of water. For a 
long time the pipes were fashioned by hand, by a series of long 
and difficult operations. The first attempts at machine-manu- 
facture were made in France, about 1858, by Reichenecker, at 
Ottweiler (Upper Rhine). The use of machinery extended 
rapidly, and on all sides appeared different types of machine, 
all based on the principle of the macaroni press. 

Omitting drain pipes, which are not directly concerned with 
architecture, hollow conduits may be divided into 

I. Water distributing pipes. 

II. Pipes for chimneys. 

I. WATER DISTRIBUTING PIPES. 

These are made of ordinary clay or stone-clay. The latter 
are always glazed, and will be considered under the head of 
composite pottery. 



342 TOTTERY IN ARCHITECTURE. 



Manufacture. 

This comprises, as usual, the preparation of the pastes, 
moulding, drying, and firing. The choice of clay depends 
upon the quality of the pipes to be manufactured ; for ordinary 
pipes, such as drain pipes, the clays which are used for hollow 
bricks will be sufficiently good. 

But if a better quality is required, a certain quantity of rich 
clay must be mixed with the poor clays. 

Whatever the composition of the mixture may be, it under- 
goes preparation by rollers and pug-mills, which convert it into 
a homogeneous paste free from all impurity and ready for 
moulding. 

Moulding 1 . This is done by machines, as in the case of 
hollow bricks ; the clay, which has been suitably prepared, is 
pressed into a closed space furnished with a die having an 
annular orifice of the diameter required for the pipe. One or 
several pipes may be produced at once, according to the magni- 
tude of this diameter. If it is not very great, the pipes are 
received upon horizontal cutting-tables similar to those used for 
bricks. Drainage pipes are so treated ; but for pipes of large 
diameter, these cutting-tables must be modified, or, better still, 
machines expressing vertically may be used. 

The machines used for pipe-making are thus 
i. Machines expressing horizontally] 2. Machines expressing' 
vertically. They may be worked by hand or power. 

i. Machines Expressing Horizontally. A. WORKED BY 
HAND. These are used in small factories for making hollow 
bricks and drain pipes. One of the best-known types (Fig. 564) 
consists of two iron boxes in which two pistons, moving in 
opposite directions, work, one compressing the clay while the 
other returns. Advantage is taken of this return to introduce 
the clay, which has been previously blended and prepared. If it 
contains no impurities such as roots, hard lumps, etc., the 
machine is double-actioned, that is to say, each end is furnished 
with a die and cutting-table ; but if the clay contains impurities, 



PIPES. 343 

it is better to sift it by passing it through a metallic sieve 
sufficiently fine to retain the foreign substances. This is fixed 
to one of the boxes of the machine ; the clay is caused by the 
compression to pass through it, and is afterwards placed in the 




Fig. 564. Piston Expression Machine, worked by Hand (Whitehead). 

other box, whence it issues in the form of piping. The machine 
in this case becomes a single-action one. 

B. WORKED BY STEAM. In the Whitehead machine, the 
compression of the clay is always effected by means of a piston 




Fig. 565. Piston Expression Machine, worked by Steam (Whitehead). 

worked by cog-wheels (Fig. 565), which are so arranged that the 
return, that is the waste movement is made at great speed. As 
there is no lid to be raised before introducing the clay, the pro- 
duction is increased. The machine is filled during the return 
motion of the piston. 



344 



TOTTERY IN ARCHITECTURE. 



The diameter of the pipe which can be made with this 
machine does not exceed 6 inches, but by means of what is 
called an expansion mouthpiece (Figs. 566, 5^7), which is 
fitted to the box, we may increase the diameter to a foot. 




Fig. 566. Pipe cut and raised 
(Whitehead). 



Fig. 567. Pipe issuing from the Die 
(Whitehead). 



The cutting-table is provided with a cradle of the same 
curvature as the pipe. The frame E carries the cutting-wires, 
and the swinging shelf B receives the pipe. 

Formation of the Socket of Tiles. The preceding machines 




Fig. 568,- 
Pipe before. 



Fig. 569. Apparatus for forming the 
Socket of Pipes (Whitehead). 



*'ig- 570. 
Pipe after. 



only produce smooth pipes. To form the socket, we use a table 
provided with a metal mould, which consists of two parts turning 
on a hinge and fixed together by a bolt. At one end of this 
mould, a movable mandrel of the same diameter as the socket is 
moved horizontally by a system of levers (Fig. 569). 



PIPES. 



345 



The smooth pipe (Fig. 568), having a mandrel inside it, is 
placed in the mould, which is closed over it ; the lever in front 
of the table is then moved, the movable mandrel is forced into 
the pipe, and the socket is formed (Fig. 570). 

The expression machines used for making bricks, if 
provided with suitable dies, may be used for pipes of small 
diameter. As in the case of hollow bricks, it is better to choose 
machines of small or medium production, in preference to 
large ones which produce more than is necessary for hollow 
articles. 




Fig- 571. Vertical Expression Machine, 
worked by Hand (Joly). 



Fig. 572. Vertical Expression Machine, 
worked by Hand (Boulet). 



2. Machines Expressing Vertically. A. WORKED BY HAND. 
The Joly machine (Fig. 571) is composed of the same parts as 
the one already described (Fig. 101), but, by a change of position, 
the die is now horizontal. The cutting-table is replaced by a 
flat receiver balanced with counterpoises. This receiver is placed 
against the die, the machine is set in motion, the pipe issues 
from the die and presses against the receiver, which descends, 



POTTERY IN ARCHITECTURE. 



since, being balanced, it only requires a slight force to move it. 
When the required length is reached, the machine is stopped, 
and the pipe is cut by means of a horizontal curved frame 
provided with a stretched wire. The pipe is removed, the 
receiving table is raised again, and the operation continues. 
With skill the workmen succeed in making the production 
almost continuous, for the clay is introduced between the 
cylinders without the machine being stopped, as is necessary in 
the piston machine (Fig. 572). In this machine a piston with 

double rack-work compresses the 
clay in a box the bottom of 
which forms the die. One of 
the sides of this box is movable, 
and is used for introducing the 
paste. This must be well com- 
pressed in order to avoid the 
presence of air, which would 
produce hollows in the walls of 
the pipes. 

The Chambrette - Belon 
machine (Fig. 573) is used for 
making fitting pipes ; for that 
purpose the die is provided, at 
the annular orifice through which 
the pipe passes, with a curved 
edge of the external shape of 
the socket. The receiving plate, 
which in this machine is above, 
is provided with a mandrel of 
exactly the same shape as the inner surface of the socket. If, 
then, this mandrel is placed against the die, the annular 
space left between the edge of the die and the mandrel will 
represent the socket. Hence the machine works as follows: 
The workman holds the plate against the die, the top of the 
clay issues, and meeting the mandrel spreads out so as to occupy 
the space between the edge of the die and the plate ; the socket 
is thus made, and rests against the receiver, which is pushed up 




Fi S- 573- Vertical Expression Machine, 
worked by Hand (Chambrette-Belon). 



PIPES. 



347 



by the pressure of trie clay issuing from the normal orifice of 
the die. The pipe is then cut with a stretched wire. 

The loading of the machine with clay is effected by making 
the die turn upon a hinge. 

The Whitehead machine (Fig. 574) is of the same type as 
the preceding one, except that the receiving plate is below 
instead of above the die. 

Hand-worked machines are used in small factories and for 
making fitting pipes of small diameter. 




Fig. 574- Vertical Expression Machine, worked by Hand (Whitehead). 

B. WORKED BY STEAM. These are expression machines 
similar to those described in the chapter on brick-making but 
have a horizontal die. A single machine may even be used 
for both positions; the Joly machine (Figs. 101, 575)> f r 
instance, is turned round on an axis by means of the screw L 
and the nut M, so that the die can be made either vertical 
(Fig. 101) or horizontal (Fig. 575). 

All that need be done, then, to adapt this machine for pipe- 
making is to place it over a pit which will admit the balanced 



348 POTTERY IN ARCHITECTURE. 

receiving plate, and to provide it with a suitable die like the one 
shown in the figure. 

In order to avoid having a pit, vertical machines with pro- 
pelling cylinders are constructed, which rest upon cast-iron 
supports ; between these is the receiving plate, balanced by 
counterpoises inside the supports. The machines are filled 
with clay from the pug-mill by means of a floor built at the 
level of the cylinders. This machine can make pipes 4 feet long. 




r 

l 

fiste 
Fig. 575. Vertical Expression Machine (Joly). 

The Chambrette-Belon machine (Fig. 578) resembles the 
preceding one, but has only one support ; pipes 4 feet in 
length can be made by it. 

Some machines (Fig. 576) are placed upon one floor, while 
the lower storey contains the receiving plate, and the counterpoises 
are in a pit. All the preceding machines are provided with a 
special arrangement for throwing out of gear, usually a check 
pulley with belt and coupler, which allows of instant stoppage 
and starting. Piston machines may also be worked by steam. 
Fig- 579 shows an arrangement of this kind. 



PIPES. 



349 





Fig. 576. Vertical Expression Machine 
(Boulet). 



Fig. 577. Vertical Expression Machine 
with Cast-iron Frame (Joly). 




578. Vertical Expression Machine with Cast-iron Frame 
(Chambrette-Belon). 



350 



POTTERY IN ARCHITECTURE. 



To. make sure of a continuous service, the machine is pro- 
vided with two cylinders turning round one of the uprights of 
the machine. One is being filled while the other is empty. 

The direct action of steam has been used to produce pipes of 
large diameter. The piston-rod of a steam cylinder (Fig. 580) 
works another piston, which compresses the already blended clay ; 
this is placed in a cylinder below the first one, and fitted at the 




Fig. 579. Piston Machine, worked by. Steam (Chambrette-Belon). 

bottom with a special die for large production. The table which 
receives the pipe is balanced. 

When pipes reach a large size, their weight is considerable, 
and the handling of them becomes difficult; in this case the 
plates which are to receive them are placed on a truck running 
on a railway. 

Dies. For drain pipes the dies are made as for hollow 
bricks ; for fitting tiles, water-effect dies are used, entirely of 



PIPES. 



351 



metal and the principal parts of bronze ; or else the orifices are 
provided with a layer of plaster, supported and consolidated by a 




Fig. 580. Vertical Direct-action Expression Machine (Whitehead). 

metallic covering which prevents it from bursting under the 
pressure of the clay. Each die has one or several openings accord- 
ing to the diameter of the pipe to be made. Fig. 5 8 1 represents 







Fig. 581. Die for Pipes. Fig. 582. Fork-shaped Mandrel for handling Pipes. 

a square die with three openings which is suitable for the 
horizontal Whitehead machine. 

The fresh pipes are handled by means of mandrels, which are 
arranged on a fork and are pushed into the inside of the pipes. 



352 



POTTERY IN ARCHITECTURE. 









Q S 




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I* 1 

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PIPES. 353 

Polishing and Finis/ling of Pipes. Ordinary pipes used for 
drains do not undergo any process after their issue from the 
machine, except a rough polishing, which is effected by rolling 
them one by one on a level stone when they have acquired a 
certain degree of dryness. This rolling at the same time gets 
rid of the malformations which sometimes occur during drying. 

High-class pipes undergo a more complete finishing. When 
they have acquired in the drying-shed a sufficient degree of 
consistency, they are placed on a special lathe composed of two 
rollers, which are rotated and make a certain angle with one 
another. 

The clay pipe is placed on these rollers, leaving the socket 
outside ; friction makes them begin to turn ; the length is then 
tested, and the excess is taken off with a sharp instrument. 
Then callipers are introduced into the pipe to make the inner 
surface regular. The socket is polished by turning; and a hollow 
spiral is marked out with a wooden point on the inside to hold 
the mortar and increase adhesiveness. 

When finished, the pipe is taken back to the drying-shed to 
complete its desiccation. 

Pipes of Special Shape. Expression machines only allow of 
the manufacture of straight pipes and, by heading the fresh pipe 
with the hand as it issues from the die, of those having a slight 
curvature. 

When the curvature is too pronounced (Fig. 585), we must 
have recourse to moulding, and this is done in plaster moulds 
which are in two parts, and have a central core equal in breadth 
to the inner diameter of the pipes to be manufactured. As 
for the single (Figs. 584, 588), double (Fig. 586), or per- 
pendicular (Fig. 587) junction pipes, they are made by hand. 
We take two pipes which have been expressed by the 
machine and are sufficiently firm ; by means of templates the 
part where the junction is to be is cut out and removed from 
each pipe, then the join is made in the usual way by thoroughly 
welding together the clay of the two pipes. 

Drying. Drain pipes are dried in the open air under sheds 
in which are arranged horizontal wooden shelves ; the pipes are 
23 



354 



POTTERY IN ARCHITECTURE. 



laid flat upon these, and are turned over from time to time to 
assist desiccation. 

Socket-tiles are dried in storeyed drying-places, and are 
simply placed socket downwards on the floor. The volume of 
these pipes being large (diameters vary from 2 to 20 inches, and 
even more for certain pipes of limited sale), a large space is 
required. 

Firing. All brick-kilns are available for firing pipes ; inter- 
mittent covered kilns are used, but preferably continuous kilns. 
The pipes are placed upright, side by side, small ones being put 
inside larger ones to economise space. The fire is managed as 



Fig. 583- 



Fig. 584- 



Fig. 586. 



Fig. 587- Fig. 588. 




I 

Exeuiple depose de drams ef de'collets 



Fig. 589- 



Collets de drains 

OB 

Fig. 590. 



Dram 




Figs. 583 to 591. Pipes for Water Conduits (Brault) and for Drains (Legros). 

in the case of bricks, but its action is more rapid on account of 
the thinness of the products being baked and the frequent vacant 
spaces. 



II. CHIMNEY CONDUITS. 

These are divided into ventiducts or round " boisseaux " 
(Fig. 592), rectangular "boisseaux" (Fig. 593), and "wagons" 
(Figs. 594, 595), more especially used in Paris. 

They are made like other pipes, with machines expressing 
vertically. The oblique or canted " wagons " are made by inclining 



PIPES. 



355 



the receiving plate. The socket of the " boisseaux " is cut out of 
the thickness of the sides, and this is done by hand when the 
paste is firm enough to keep its shape. At one end paste is 
taken away from the outside, and at the other from the inside. 

To make connection between the " wagons" they are provided 
with projections which fit together. These projections are made 
by the machine when they are continuous, like the dovetails on 
straight (Fig. 600) or oblique (Fig. 60 1) " wagons " ; when they 
are interrupted (Figs. 598, 599), they are made by hand. 

The dimensions of " wagons " and " boisseaux " are extremely 



Fig. 592. 



Fig. 593- 



Fig. 594- 



Fig. 596. 







Fig. 595- 



Fig. 597- 




Fig. 598. Fig. 599. Fig. 600. Fig. 601. 

Figs. 592 to 601. Ordinary (Perrusson), Cross-joint (Gilardoni freres), and Dove-tailed 
(Arthur Metz) " Boisseaux" and " Wagons." 



variable ; the interior dimensions may vary between 5 inches by 
6 inches, and I 2 inches by 20 inches, with a length of from i 3 
to 20 inches. (See table.) 

The drying and firing of these products do not present any 
special difficulty. 

Applications. 

" Wagons" are much used for forming chimney conduits inside 
walls ; this is an interesting and a recent application of pottery 
to the construction of buildings. 



356 



POTTERY IN ARCHITECTURE. 



When several conduits are placed side by side they must be 



bound together, and for that purpose the dove-tailed 
(Figs. 590, 600, 60 1 ) are to be recommended. 

Chimney Tops. (See roofing accessories, p. 335.) 



wagons 



DETAILS AS TO POTTERY EOR BUILDING. 



Internal 
Dimensions in 
Centimetres. 


Height in 
Centimetres. 


"BO 

Weight. 


ISSEAUX." 

Price in 
Francs. 


Remarks. 






Kil. 






I3x 16 
17x19 
16 x 25 
22x25 
25x30 


33 

5) 
5) 

)) 


6 to IO 
8 to 12 

IS 

12 to 16 
16 to 18 


0.50 to 0.70 
O.6o to 0.85 
0.85 to 0.90 
0.85 to i. oo 
i.io to 1.30 


"Boisseaux" are also made 
50 centimetres long. 


VENTIDUCTS. 


.2s H3 

isS i6 

a 1-1 \ *9 

rt c 22 

8<3 Us 


33 

> j 
> ? 
> 
j> 


5 to 6 

5-5to9 
7 to ii 
8 to 13 
9 to 15 


0-35 
0-45 
0-55 
0.65 

0-75 


Catalogue prices subject to 
reduction. 


"WAGONS." 


Straight or Obliqtie Ordinary " Wagons." 


.2 f25 
-*i 

l|| 40 
III [$ 


16.5 

5) 
J> 


8 to 9 
9 to 13 
10 to 19 

20 


0.60 to 0.80 
0.70 to 0.90 
0.80 to i.oo 

I.IO 


The same remark may be 
made as above as to 
prices. 


Straight or Oblique Cross-joint " Wagons" 


35 


25 


17 I 1-35 1 id. 


Straight or Oblique Dove-failed " Wagons " 


35 


I6. 5 


15 


0.90 


id. 



CHAPTER VI. 
QUARRIES. 

THE custom of paving buildings with plates of baked clay of 
greater or less thickness, began with the use of brick ; that is to 
say, it dates from the earliest historic period. The Romans, to 
whom we must always revert when speaking of architecture, used 
squares of baked clay for their pavements ; at Lillebonne squares 
measuring 1 6 inches each side have been found ; and others of 
as much as nearly 2 feet have been discovered at Laudunum. 
These pavements were intended for halls in which many 
people assembled ; special rooms were paved with those 
magnificent marble mosaics of which we still possess such 
fine specimens. 

Under Roman dominion, the Gaul preserved the customs of 
his conquerors ; but with the decadence of the Empire, and the 
great troubles caused by the invasion of the Barbarians, other 
habits prevailed, and the expensive marble was finally 
abandoned in favour of pottery. Elsewhere will be found 
the history of those encaustic tiles from which makers in the 
Middle Ages obtained such beautiful effects. We are only 
concerned now with red clay squares, which were always 
manufactured with more or less care in every country. In 
France, the most admired specimens come from Beauvais, 
Burgundy, and Provence. 

As regards method of manufacture we must distinguish 
between 

1. Ordinary clay quarries, called native. 

2. Choice quarries, of cleaned clay, called Beauvais or 
Marseilles squares. 

i . Ordinary Clay Squares (native quarries], These are made 



357 



358 



POTTERY IN ARCHITECTURE. 



like bricks : by hand or machine ; by hand, the clay after being 
blended, is moulded in square or hexagonal moulds of the required 
dimensions ; then, after having undergone some hardening, the 
quarries are carefully stamped, returned to dry, and fired in 
ordinary brick - kilns. With machinery, the process of manu- 
facture resembles that for bricks, except that the stamping must 
be more carefully carried out, as we shall see in the case of the 
quarries now to be described. 

2. Smooth Quarries of Cleaned Clay. The preparation and 
choice of clays are of great importance in the manufacture of 
these squares. Clays which are too poor cannot be used alone, 




Fig. 602. Expression Machine for 
Quarries. 



Fig. 603. Special Cutting- table for 
Quarries. 



and a certain quantity of rich clay must be added. The cleaning 
is performed under the same conditions as that of the kaolins 
and with the machinery represented in Fig. 24. The clay thus 
purified is transmitted to the pug-mill, and then to the expression 
machine, the die of which has the dimensions of the quarry to be 
manufactured (Fig. 602). 

If the quarries are to be hexagonal, the prism of clay is cut 
with crossed wires (Fig. 603) ; the slabs are then piled together, 
and when sufficiently hardened, are ready for the final work of 
the press. 

The presses used are similar to tile presses; they are worked 



QUARRIES. 



359 






by hand and provided with a special system of demoulding. 
The moulds can be easily changed according to the dimensions 





Fig. 604. Quarry Press (Ja'ger). 



Fig. 605. Quarry Press (Laeis et Cie. ). 



QUARRY PRESSES. 




~ 



Fig. 606. With Jointed Levers Fig. 607. Worked Fig. 608. Worked by Steam 
(Bernhardi Sohn). by Steam (Jager). (Bernhardi Sohn). 



of the quarries to be stamped. Sometimes jointed levers (Fig. 
606) are substituted for the compression screw. The presses 
may also be worked by steam (Figs. 607, 608); they are 



3<5 



POTTERY IN ARCHITECTURE. 



provided with two or three moulds which can be emptied and 
filled during compression. 

When stamped, the quarries are dried again, and afterwards 
undergo polishing by friction between two rollers, one of which 
is of polished bronze, the other of cast - iron and fluted (Fig. 
6 10). 

The upper roller smooths the upper surface of the quarry, 
while the lower one produces on the other side hollows which 
will help to increase its adhesion to the mortar. In order to 
give absolutely uniform dimensions to the quarries, they are cut 
with hand callipers, or more quickly with a cutting machine 




Fig. 609. Cutting Machine for Ouarries. Fig. 610. Polishing Machine for Quarries. 

(Fig. 609), which consists of four or six flexible blades according 
to the shape required. The section is conical and without 
seams. 

Drying and Firing. The quarries are placed in pairs with 
their polished faces against one another, and piles are formed so 
as to prevent the surfaces from warping, which would certainly 
occur with quarries of slight thickness. 

The firing usually takes place in intermittent kilns. Con- 
tinuous kilns do not seem to be suitable for this process, which 
requires a very slow and careful enfumage ; this must be specially 
watched on account of the shape of the quarries, and of the 
contraction which they undergo in baking. 



QUARRIES. 



36 



The colour of these paving bricks is usually red, but white 
ones can be made by a suitable choice of clays, and even black 
ones can be produced by admixture of oxide of manganese, or 
more economically by a deposit of coal on the squares when still 
red (" encastage " in presence of powdered coal). 



Applications, 

The ground to be paved is thoroughly levelled and rammed 
down, and the quarries are laid on a bed of cement or, more 



Fig. 6 1 6. 



Fig. 617. 





Fig. 624. 



Fig. 625. 




Fig. 
. 618. 



Fig. 
, 619. 



620. 



D Jig. 

i&O* 621. 



Fig. 
622. 



623. 




Figs. 611 to 625. Quarries and their Applications. 



economically, on plaster. The quarries may be square (Fig. 
611), hexagonal (Figs. 613, 614), or octagonal (Fig. 622). 
This latter form is combined with little white (Fig. 621) or black 
(Fig. 623) squares to produce various patterns of pavement 
(Figs. 624, 625). In the same way diamond - shaped white 
(Fig. 6 1 8) or black (Fig. 620) are combined with the hexagonal 
shape (Fig. 619) to give the patterns represented in Figs. 616 
and 617. 



362 



POTTERY IN ARCHITECTURE. 






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Hi? 



a* 2 









CT 1 *-. 



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TH TH ' ' T-< -rJ ' T$ oi T c3 T^ ' ' o5 co c4 o5 o5 

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CHAPTER VII. 
TERRA-COTTAS. 

History. Under this name, which is the Italian equivalent 
of " baked clay," we comprise pottery intended for architectural 
ornaments, and especially that which contributes to general 
decoration. The gutter - covers and finials of which we have 
spoken under the head of roofing accessories, might have been 
included among terra-cottas, but their fixed location takes from 
them the special characteristic more particularly attributed to 
ornamental pottery. 

Did this art precede sculpture in stone ? Archaeologists are 
not agreed on this point, but it is certain that it is of very ancient 
date, and we have evidence of this in the numerous cornices, 
friezes, and bas - reliefs found in the ruins of buildings which 
were constructed during the early centuries of historic times. 

A Greek poetical story or legend attributes to the Corinthian 
potter Debutades, the invention of moulding, for reproduction 
in clay, of figures in relief. His daughter loved passionately 
a young and handsome swain, and, being obliged to separate 
from him, manifested such grief that her father, in order if 
possible to mitigate her sorrow, traced the outline of the 
shadow thrown on a wall by her lover's head ; he then filled 
this silhouette in with prepared clay, and fired the medallion 
thus obtained in his kiln. 

Pliny relates that at the period when Corinth was taken by 
the Romans, this first remarkable example of a new art was still 
treasured in the Temple of the Nymphs. 

Fragments discovered among the ruins of several Grecian 
towns show that there was an extensive use of terra - cotta 
ornaments in Greece, and that the art had reached a high 



364 POTTERY IN ARCHITECTURE. 

degree of perfection both in taste and execution. The best 
work of that period dates from the time of Phidias and Polycletes 
(5th century B.C.). 

The Etruscans, who have left us such remarkable specimens 
of pottery, borrowed much from the Greeks, while giving their 
productions an originality of their own. They made friezes and 
frontons of large size for their temples and buildings. 

Rome employed Etruscan sculptors for the decoration of her 
public buildings, and especially for the Capitol, under Tarquin the 
Elder (6th century B.C.). 

Terra-cotta work held such an important place in Roman 
buildings, that there existed at Rome a school, the Collegium 
figulorum y for preparing workmen for that industry. The 
invasion of the Barbarians checked the progress of the arts, 
and for several centuries the use of terra-cotta, without being 
completely abandoned, suffered an eclipse. But in the iith 
century it once more took a prominent position in architectural 
decoration, especially in Germany and Italy. There still remain 
many fine monuments of that period, such as the Carthusian 
monastery at Pisa (Fig. 317), the cathedral at Crema (Fig. 
321), and many others, in which magnificent examples of terra- 
cotta decoration are found. 

The popularity of the plastic art continued until the 1 6th 
century ; great artists like Bramante and Michael Angelo, did not 
disdain to use it in the works which they executed, for example 
the Chancellerie palace (iSth century) and the Farnese palace 
(i6th century, Fig. 328) in Rome, and the apsis of Santa- 
Maria della Gracia at Milan (Fig. 327). After being again 
neglected during the two following centuries, terra - cotta was 
once more successfully utilised 'in Germany and England in 
the i pth century. Among the most remarkable examples of 
buildings constructed of brick and terra-cotta, we may mention 
the School of Architecture of Schmikel, the Werder Church, and 
the Museum of Decorative Art in Berlin. 

In England, where this kind of work is extensively used, the 
palatial Natural History Museum recently built in London is en- 
tirely constructed, both outside and inside, of iron and terra-cotta. 



TERRA-COTTAS. 365 

In France, the claims of terra-cotta have been less readily 
accepted, on account, perhaps, of the abundance of stone in that 
country ; perhaps also through the unreasonable attachment to 
ancient customs which offers such a stubborn resistance to 
novelties. 

In spite of two brilliant displays, the Exhibitions of 1878 
and 1889, which ought to have powerfully recommended the 
advantages of terra-cotta as applied to modern architecture, its 
use is still very limited. Nevertheless there were, in those 
rapidly erected palaces, many happy colouring effects, and 
many truly original combinations, which lead us to think 
that this branch of art, if prosecuted and studied by masters, 
would lead to an architectural renaissance, and that such a 
renaissance would perhaps rid us of those everlasting facades, 
which are always the same, and which make our streets so 
monotonous. May the Exhibition of 1900 settle the question, 
and finally establish the new architecture of which its pre- 
decessors have given us a glimpse ! 

Manufacture. The clays should be as pure as possible, and 
they are selected and mixed in such proportions as will give 
a paste easily worked and behaving well under drying and 
firing. They are then subjected to a preparatory treatment, 
which is more or less thorough according to the quality and 
degree of finish required : crushing, cleaning, drying, blending, 
etc. The machines used are the same as those previously 
described. 

The shaping of terra-cottas is performed, by hand, by stamp- 
ing in plaster moulds. 

The paste is divided into fragments called balls ; sometimes it 
is roughly shaped into slabs called crusts. Balls or crusts are 
placed in the mould and pressed down with the hand until the 
clay takes its shape. Care must be taken to compress it evenly, 
for fear of ruptures in drying and firing. 

When the pieces to be manufactured are of complicated form, 
they are moulded in parts, and the parts are afterwards united. 
Demoulding is facilitated by the use of moulds in several parts 
which are taken off separately. Compact pieces are always 



366 POTTERY IN ARCHITECTURE. 

hollowed inside to lighten them and ensure a uniform drying. 
In pieces which are moulded in parts, we must take care that 
the join does not pass through delicate portions, and for this 
reason we must study the most suitable form to be given to the 
moulds. 

Pieces which are symmetrical about an axis, such as 
balustrades (Figs. 653, 654), are made with the potter's wheel. 
The hollow inside is produced by means of a wooden axis 
surrounded by a string on which the paste is laid, and the outer 
surface is formed by means of a calibre cut according to the 
design of the balustrade. 

Drying is carried out in storeyed drying - sheds, which are 
heated when necessary. Firing is done in various kinds of kilns, 
which are sometimes specially constructed when the pieces are 
of exceptional dimensions, such as the pyramids of the grand 
entrance of the Palais des Arts Liberaux at the Exhibition of 
1889. These fine products, designed by the talented sculptor 
Michel, were executed by the ceramist Muller. One of them, 
Labor, is represented in Plate II. 

Applications of Terra-cotta. 

It would be presumption on our part to point out the best 
way of applying terra-cotta to the decoration of public buildings 
and private houses ; this must be left to the talent of the 
architects and engineers, and talent is not to be advised. It will be 
interesting, however, to recall the excellent remarks of M. Paul 
Sedille, the eminent architect, who, by his pen, by his words, and, 
better still, by his original work, has done so much to extend the 
use in France of terra-cotta for architecture. 

1 " . . . The use of decorative pottery requires close care. 
Very accurate and well-made machinery is required, for decorated 
clays are usually combined with other materials of definite and 
small dimensions, such as building-bricks, and this multiplies 

1 Extract from a letter addressed by M. Sedille to M. Loebnitz, reporter 
to the jury of Class 20 (Pottery) at the Exhibition of 1889, and published in the 
latter's report. 



TERRA-COTTAS. 367 

apparatus indefinitely. We must also calculate the contraction 
of the pieces sufficiently exactly, taking into consideration the 
clays used, to arrange for the necessary space to be left in the 
building. . . . 

" ... If reliable ceramists could guarantee us to-day perfect 
pieces, that would not be enough. We must also know how to 
use them, mingle them skilfully with other materials, and, above all, 
combine in one harmonious gamut the powerful colourings of enamels. 
There lies the difficulty of this modern assemblage of many 
colours, which should, by entrancing his eyes, convince the most 
obstinate of its beauties. I have many times tried to say all 
that I felt on this question, 1 and how enamels should be used. I 
do not propose to revert to this here, I merely urge that the 
poor use sometimes made of enamels should not discourage us 
from benefiting by the infinite resources and marvellous results 
which may be expected from them." 

It would be difficult to speak more pertinently. 

For the sake of clearness, terra-cottas will be divided into 
three classes, according to their special applications. 

1. Terra-cottas intended especially for buildings, including 
(a) Those employed on the exterior : balustrades, lintels, 

pilasters, capitals, friezes, cornices, frontons, pinnacles, and 
inlayings, such as medallions, metopes, panels, polished stones, 
rosework, etc. etc. 

(&) Those used in the interior : ceiling and chimneypiece- 
rosework, etc. 

2. Terra-cottas which have less direct connection with 
architecture, such as garden borders, vases, statues, etc. 

Balustrades. These are composed either of a certain number 
of simple parts connected together, or of a small number of large 
ones, reduced sometimes to one single one. The first case is 
represented by the balustrades A B C D E (Figs. 626 to 630), 
which are formed, the balustrade A (Fig. 626) by the element b 
(Fig, 632), the balustrades B and C (Figs. 627 and 628) by the 
element c (Fig. 633), arranged in two different ways; the 

1 See the pamphlets of M. Sedille on the use of terra-cotta in architecture (Biblio- 
graphy}. 



3 68 



POTTERY IN ARCHITECTURE. 



balustrade E (Fig. 630) by the element d (Fig. 634), and finally 
the balustrade D (Fig. 629) by the two elements d and f com- 
bined (Figs. 634, 636). The hand-rail of these balustrades 
is formed of hollow bricks with two holes of special shape 
(Fig. 631). 

Balustrades are sometimes made up with the classical 




Fig. 629. Fig. 630. 

Figs. 626 to 636. Various Balustrades (Perrusson). 

baluster, the shape and dimensions of which are easily changeable 
(Figs. 653, 654, 658, 659). 

The second type of balustrade is quite different in appearance 
from the first ; it is applied to various styles, and can be much 
diversified according to the inspiration and taste of the artist. 
Sometimes these balustrades are made of a single piece forming 
pedestal and support (Figs. 648, 652), sometimes they are 



TERRA-COTTAS. 



369 



formed of ornaments or panels with stone support and pedestal 
(Figs. 676, 678, 68 1). 

The balustrades of the buildings of the Exhibition of 1889, 
executed by Lcebnitz (Fig. 687), were fixed to the masonry of 
the wall against which they rested, the whole being thus rendered 
very solid. 



Fig. 643. 




Fig. 648. 



TERRA-COTTAS BY MULLER. 





Fig. 644. 



Fig. 645. 



Fig. 646. 



Fig. 647. 





Fig. 649. 



Fig. 650. Fig. 651. 



Fig. 652. 





Fig. 653. Fig. 654. Fig. 655. 



Fig. 656. 



Fig. 657. Fig. 658. Fig. 659. 



Figs. 644, 645, and 646 represent the details of the fronton of the Pavilion of the City 
of Paris at the Exhibition of 1878, afterwards rebuilt on the Champs Elysees, and 
demolished in 1897. 



Openings. Doors and windows may receive most varied 
terra-cotta ornamentation, such as lintels in the form of friezes, 
decorated pieces forming key-stones (Fig. 682), frames surrounding 
the whole opening (Figs. 665, 669), or simply knobs more or 
less richly sculptured (Fig. 680). Besides which, windows often 
receive ornamented panels forming sills, etc. 
24 



POTTERY IN ARCHITECTURE. 




TERRA-COTTAS. 



371 



Columns, Pilasters, and Capitals. The use of terra-cotta 
in these pieces offers great opportunities for copying antique 
patterns (Figs. 649, 651), and also for original work. 

Friezes, Frontons, etc. Friezes and frontons are perhaps 
the most extensively used terra-cotta ornaments, and they are 
made in all styles : simple, original, with human figures or 
allegorical designs (Figs. 660, 66 1, 662, 663, 665, 667), etc. 
The same may be said of frontons ; Figs. 644 to 646 represent 




Fig. 679. 





Fig. 680. Fig. 68 1. Fig. 682. 

Figs. 676 to 682. Terra-cottas by Villeroy and Boch (Mettlach). 

those executed by Muller for the pavilion of the city of Paris at 
the Exhibition of 1878. They are formed of a larger or lesser 
number of pieces according to their magnitude. 

Friezes are either fixed to the masonry, or supported by 
other means, according to circumstances. The " Frise des 
Enfants " at the Exhibition of 1889 (Fig. 684) was held by iron 
rods which were fixed into the terra-cotta and connected by 
rivets to the metallic framework. 



372 



POTTERY IN ARCHITECTURE. 







I 

5 



to S2 

8E 



t/j 

E 






TERRA-COTTAS. 



373 



Friezes, cornices, etc., can also be made of small parts. The 
firm of Gilardoni Brothers has reproduced the principal types of 
decorated bricks in use in the izj-th and I5th centuries in Italy, 
the South of France, and Germany. Figs. 692 to 697 show 
some of these elements, and Figs. 689 to 691 the applications 
which can be made of them. 

It is to be hoped that this reproduction will be followed by 



Fig. 689. 



Fig. 690. 



Fig. 691. 




Fig. 692. 



Fig. 693. 



Fig. 694. 






Fig. 695. 



Fig. 696. 



Fig. 697. 



\AAAA 





L^fe^i 



Figs. 689 to 697. Specimen's of Decorative Pottery (Gilardoni freres). 

the manufacture of new types, harmonising with our modern 
tastes. 

Pinnacles are made of pottery in the most varied styles : 
they may depict animals, bunches of flowers, and all kinds of 
patterns, according to the purpose of the building. 

Medallions, Panels, Rosework, etc. It is from these that 
the architect draws largely for decorating buildings. All forms, 
all types, all styles, may be put under contribution, and, what is 
still more interesting, the artist of talent may easily invent new 



374 



POTTERY IN ARCHITECTURE. 



models which will give his work a personal character, and create 
novelties instead of repeating the commonplace. 

The roses of various forms and sizes (Figs. 655, 657), 
the round medallions (Figs. 643, 647, 685), the panels (Figs. 
656, 667, 670, 673, 674, 675), the scrolls (Fig. 680), and knobs, 
are so many opportunities of decoration placed at the disposal 
of the architect. The porch of the Palais des Arts Liberaux at 
the Exhibition of 1889, was adorned with magnificent panels 
representing figures designed by Michel (Plate II). 

(b) In the interior of buildings we find numerous applications 

TERRA-COTTA CEILING (PerrUSSOn). 

Fig. 698. Fig. 699. 





' 0.62. 




Fig. 698. Panel. 



Fig. 700. 
Fig. 699. Section of Ceiling. 



Fig. 700. Application. 



of terra-cotta, especially in ceilings supported by I-shaped iron 
girders. These ceilings are formed of panels of various shapes 
and dimensions, and more or less decorated. The arrangement 
of the panels depends entirely upon the taste of the architect. 
Figs. 698, 699, and 700 show a simple arrangement; the panel 
is composed of two parts (Fig. 698), with overlapping join and 
resting upon the I-shaped iron bars ; in the middle is a rose. 
When complete, the ceiling is as shown in Fig. 700. 

Unpolished terra-cotta may also be used for making very 
pretty chimneypieces for rooms in plain (Fig. 864) or decorated 
style as desired. 



TERRA-COTTAS. 375 

2. With regard to terra-cottas such as garden borders, vases 
and flower-stands, and statues, they belong, with the exception of 
the first-named, to the domain of artistic and sculptural pottery, 
and have only a distant connection with architecture proper. 



APPENDIX. 

OFFICIAL METHODS OF TESTING TERRA-COTTAS. 1 

SPECIMENS. Tests of terra-cottas should always be made on marketable products. 

If it is desired to know as precisely as possible the value of a manufactured article, it 
is better to work upon specimens at different stages of firing. It is often sufficient to 
examine the most slightly, baked specimens, which will be easily recognised by their 
appearance, and especially by their being less hard and of slightly greater dimensions 
than the average. 

GENERAL RULES. The trade mark of the specimens shall be noted, their shape, 
the state of their edges and surfaces, also their colour. 

In the case of bricks and quarries, their length, breadth, and thickness shall be 
measured. In the case of tiles, their length and breadth shall be measured, and sketches 
or sections shall be drawn which shall indicate, in a sufficiently clear manner, the hollows 
and projections as well as any fitting arrangements that the specimens may possess. 
Finally, for pipes, the internal diameter shall be measured, the effective length not 
counting the socket, the thickness of the walls, as well as the shape and arrangement of 
the socket, if any. 

The dimensions of bricks and tiles should be verified, and should be identical for 
similar pieces ; any differences exceeding I per cent, shall be noted. 

When the laboratory .has at its disposal a sufficient number of specimens from the 
same factory, it will be advisable to measure on the one hand those most baked or the 
smallest, and on the other hand those least baked or the largest. The observed 
differences, if any, shall be noted. 

PHYSICAL TESTS. 

I. Observation of Structure or Homogeneousness. The observation of structure or 
homogeneousness shall consist of the examination of a fracture with the naked eye or a 
magnifying-glass. 

There shall be noted 

(a) The appearance of the fracture, whether full - grained and with more or less 
pronounced toothings, or smooth or of conchoidal surface. 

(b) The coarseness of the grain, stating, according to the classification adopted for 
natural building-stones, 

[Very fine grains (.2 mm. to. 4mm.), fine grains(.3 mm. to .8 mm.), fairly fine grains (.5 mm. to 1.2 
mm.), medium grains (i mm. to 2.5 mm.), rather coarse grains (2 mm. to 4 mm.)j coarse grains (3 mm. to 
7 mm.), very coarse grains (5 mm. and above).] 

whether the grain is fine, medium, or coarse, and if it is uniform or of varied dimensions. 

(c) The homogeneousness, by observing whether the mass is entirely, partly, or 
slightly homogeneous, whether there exist more or less numerous and more or Jess 
accentuated planes of exfoliation or cleavage. 

1 These methods were adopted in 1895 by a Commission nominated by the French Government. 



376 POTTERY IN ARCHITECTURE. 

2. Specific Gravity. The determination of the specific gravity of the substance 
shall be made from the powder of pulverised fragments passed through a sieve of 900 
meshes. 

The powder shall be dried at a temperature of + I IO. 

The specific gravity shall be determined by means of volumetres, by one of the 
methods now used, so as to obtain the first decimal figure with certainty and the second 
with an approximation of two units. 

The liquid used shall be benzine or mineral essence. 

The temperature should remain constant during the whole operation ; it should not 
exceed + 15. 

3. Apparent Density. The determination of apparent'density should be made, as 
much as possible, with specimens which have remained intact, after desiccation at a 
temperature of +30 to +40 C. 

When the specimens have a regular geometric shape which allow of the volume 
being determined by measurement, a sliding-scale approximating to tenths of a milli- 
metre shall be used ; the weight shall be determined by means of a balance sensitive to 
half a centigramme. 

When the specimens are of irregular shape, or present re-entrant angles, the volume, 
and thence the apparent density, shall be determined by finding the difference between 
its weight in air and in water. Care shall be taken beforehand to coat the surface with 
a varnish capable of preventing the entrance of water. A thin layer of melted tallow 
applied with a brush and spread with the finger fulfils this condition very well. 

4. AbsohUe Porosity. The absolute porosity shall be deduced from the difference 
between the specific gravity and the apparent density. 

5. Relative Porosity r , or weight of water absorbed in a given time. The determination 
of the weight of water absorbed, shall be made with a series of at least three specimens 
previously dried either in the open air or in a stove at a temperature of + 30 to + 40 C. 
It is advisable as much as possible to work with whole specimens and not fragments. 

After drying, the specimens shall be immersed in water to the depth of half their 
thickness for twelve hours, then completely submerged either for twelve hours, thirty-six 
hours, seven days, or twenty -eight days. 1 

If the specimens contain an appreciable amount of lime, of magnesium, or of soluble 
salts, it will be advisable to repeat the experiment once or twice on the same specimens. 

The quantity of water absorbed, or the relative porosity, should always be calculated 
by volume, but the percentage of water by weight shall also be noted. 

Special Arrangements for Tiles. As regards tiles, the Committee expresses the wish, 
as in the case of roofing slates, that experiments should be made to find out what quantity 
of water "can be absorbed by a square metre of tiles, fixed just as they really are in 
practice upon a frame inclined at the minimum angle adopted for roofs, by subjecting 
this frame to a regular shower of known intensity for a given time. 

Pervionsness. Tiles. The test shall be made with at least three whole tiles 
which have been previously immersed for forty - eight hours, as described in 5- A 
glass tube of .035 mm. internal diameter and .11 height shall be placed horizontally 
and fixed with pure cement at about the middle of the upper surface of each tile. The 
tube, closed at the top by an indiarubber cork, shall be put into communication with a 
reservoir giving a head of water of . i m. 

By means of a reservoir placed under the lower surface, the water passing through 
each tile shall be collected. 

The perviousness shall be estimated by the volume of water which has passed through 
in an hour, after the experiment has been continued for twenty-four hours. 

1 In the case in which the time of immersion is to exceed forty-eight hours, if it is wished to shorten 
the experiment, use may be made of the process of imbibition by means of the exhausted receiver, as 
described for tests of natural building-stones (Note of the Commission). 



TERRA-COTTAS. 377 

7. Tests of Resistance to Frost. The test of resistance to frost shall, as much as 
possible, be made upon whole products. The trial can, however, be made with fragments. 
In this case, the cut or broken parts of the specimens should be protected by a varnish or 
a thin coating of tallow, in order to leave free for the penetration of water only those 
faces usually seen. 

The correct tests of resistance to frost, carried out as directed in the case of natural 
stones, shall comprise 

In making these trials, note must be taken of the following details : 

1. For the immersion, distilled water at a temperature of +15 to -f-2o C. shall be used, or, in default 
of distilled water, drinking water at the same temperature, which presents no inconvenience when it is 
not required to determine the quantity of soluble salts. 

2. The specimens shall be exposed to a temperature of - 15 to - 20 C. 
3 The duration of exposure to the cold shall be four hours. 

4. Thawing shall be effected by complete immersion of each specimen in distilled or drinking water 
at a temperature of +15 to +20. (In the case of natural stones, a volume of 500 cubic centimetres is 
prescribed for a specimen containing 7 cubic centimetres.) For specimens tested in a state of imbibi- 
tion after an immersion of twenty-four hours, the thawing is effected in damp air and not in water. 
During the interval separating successive freezings and thawings, the specimens are kept inclosed jars to 
prevent a too great loss of the absorbed water; care is moreover taken, before subjecting to cold again, 
to plunge them into water for a few moments so as to keep them, during the whole test, in about the same 
state of imbibition as that in which they were at the beginning of the experiment.] 

(1) The examination of the specimens with a magnifying-glass, with a view to 
ascertaining whether cracks or splits have occurred in those products which have been 
subjected to successive frosts and thaws twenty-five times. 

(2) The determination of the loss of weight of the frozen specimens. 1 

There must be used for these tests at least three specimens soaked in water 
for twenty-four hours ; three specimens saturated with water. 

MECHANICAL TESTS. 

1. Resistance to Rupture by Crushing Bricks and similar Materials. The test of 
resistance to rupture by crushing shall be made on pieces of nearly cubical shape, 
obtained, for example, in the case of ordinary bricks, by placing two half bricks 
one over the other and binding them together by a thin layer of pure Portland 
cement. 

The surfaces of compression shall be rendered exactly parallel by a coating of similar 
aste. 

As in the case of natural building-stones, the tests of resistance to crushing shall be 
made with lever apparatus or hydraulic press. 

The objects should be placed between the compressing plates, covered by a sheet 
of thin pasteboard ; it is advisable that one of the two compression plates should be 
movable in every direction. 

The dimensions of the surfaces exposed to pressure shall be noted in the report of the 
experiment at the same time as the resistance offered per square centimetre. 

The test shall be made upon at least three objects from the same specimen. 

The average of the results given shall be calculated. 

It will be well to make the test with two series of objects, one in the dried state, the 
other in a state of imbibition, the degree of imbibition being noted. 

2. Resistance to Rupture by Flexion Bricks. The test of resistance to rupture by 
flexion shall, in the case of ordinary bricks, be made with whole products placed upon 

1 If the specimens have borne without deterioration the tests of resistance to frost, it will be advisable 
to compare the resistances of those specimens to compression and flexion, after another desiccation, with 
those of specimens of the same origin which have been subjected to the same pressure after drying, but 
without having been submitted to the action of frost (Note of the Commission). 



37$ POTTERY IN ARCHITECTURE. 

two knives .2 metres apart, and loaded at the middle gradually until rupture 
occurs. 

The gross weight which determines the rupture of each specimen shall be noted. 

Products greater in length than ordinary bricks (floor bricks) shall be tested with 
a bearing-space between the two supporting knives equal to that usually given in 
practice. 

Tiles. The tests of resistance to rupture by flexion shall be made upon whole tiles 
placed upon two knives, and loaded at the middle gradually until rupture occurs. 

When the tiles have not a rectilineal section, small transverse horizontal ridges of pure 
Portland cement and I centimetre broad shall be placed in a line with the supports and 
the middle of the knives, with the object of levelling the undulations and dividing the 
pressure uniformly over the whole width. 

One of these ridges shall be placed at the point where, in roofing, the tile is to rest 
upon the laths, and the other at the point where it rests upon the tile below. 

The load which produces rupture shall be noted. 

It will be advisable to make the test with tiles which have been soaked in water, the 
degree of imbibition being noted. 

3. Resistance to Wear by Friction, The determination of the resistance to wear by 
friction shall be made under the same conditions as in the case of natural building-stones, 
both as regards the dimensions of the object tested and the test itself. 

[To determine the resistance to wear by friction, the quantity of the specimens worn away shall be 
measured, when they are subjected, under a given pressure, to the friction of standard sand spread 
uniformly over a circular horizontal cast-iron track which moves with known speed. 

The specimens shall have the dimensions : .06 m. by .04 m. base and a variable height of from .10 m. to 
.12 m. ; they shall be placed in pairs on opposite sides of the axis and on the same diameter of the 
grinding-mill, in such a way that their centres shall be on the circumference of a circle of radius .261 m., 
the lesser dimension being in a direction perpendicular to the radius. 

The total pressure on the friction plane shall be 250 grammes per square centimetre. 

The standard sand used shall be obtained by pounding, and then sifting, medium hard Fontainebleau 
quartz sandstone, passing through a No. 50 sieve (324 meshes) and retained completely on No. 200 sieve 
(4900 meshes). 

The quantity of sand to be spread upon the grindstone shall be one litre per specimen and per 
thousand turns of the mill. 

The machine shall be turned at the rate of 1000 turns per half-hour, and the specimens shall be 
subjected to 4000 turns of the mill. The diminution in the height of the specimen shall be measured, 
and the loss of weight determined. Similar notes shall be made during the course of the test after 1000, 
2000, and 3000 turns. 

The specimen may be turned over after 2000 turns of the mill, in order to compare the results obtained 
on the upper surface and the lower surface.] 

4. Resistance to Rupture by Shock. The experiments now being carried out do not 
yet allow of rules being laid down for this test. 

These experiments should be continued. 

5. Resistance to Rupture by Internal Pressure Special Tests for Pipes. The tests 
of resistance to rupture by internal pressure shall be made either with a force-pump 
or a hydraulic accumulator. 

The unit of pressure to be adopted is a kilogramme per square centimetre, and the 
numbers, unless otherwise stated, refer to effective pressures. 

The pipes to be tested should be exactly filled with water. It is important that the 
pressure should be exerted upon them gradually and without shock. The manometre 
should indicate without risk of error the pressure acting within the pipe. 

The test can be made with a single pipe or several pipes combined. 

The joints closing up the ends of the pipes should be arranged so as not to leak, and 
should be made in such a way that the fixing of them shall not cause a premature rupture 
of the pieces being tested. 

The Committee expresses the wish that the experiments now being carried on with 



TERRA-COTTAS. 379 

a view to finding a convenient closing arrangement for the ends of pipes will be 
continued. 

CHEMICAL TESTS. 

1. Test for Lime and Magnesium. With the object of determining whether, in terra- 
cottas, there exist lime or magnesium caustic, five specimens shall be immersed in boiling 
water for three hours, and it shall be noted whether, under these circumstances, exfolia- 
tions are produced. 

2. Determination of Soluble Salts. To determine the proportion of soluble salts that 
a terra-cotta may contain, five specimens shall be taken, chosen in preference from the 
middle of the terra-cottas, and they shall be pulverised so as to make them pass 
entirely through a sieve of 900 meshes ; 25 grammes of the powder thus obtained shall 
be taken, and boiled for an hour in 250 grammes of distilled water, the evaporated water 
being replaced. After filtering, the liquid shall be entirely evaporated, and the residue 
obtained shall be weighed. 



PART II. 

MADE-UP OR DECORATED POTTERY. 



881 



CHAPTER I. 
GENERAL REMARKS ON THE DECORATION OF POTTERY. 

THE pottery of which we have spoken in Part I. has no decora- 
tion ; Salvetat called it simple pottery. Part II. is devoted to 
what the same author called made-up pottery ; it is distinguished 
from the former kind by its decoration. 

A decorated piece of pottery is one whose surface receives an 
earthy, vitreous, or metallic coating, which modifies its appearance 
and gives it new properties ; the decoration may be reduced to 
a simple engobage, or be composed of brilliant colours, like the 
magnificently painted panels with which walls are covered. 

The different methods of decorating pottery comprise 
decoration with engobes, or dips with glazes, with colours, or 
with metals. 

Decoration with engobes is effected by means of white or 
coloured earthy matters with which pottery is totally or partially 
coated, so as to modify its colour and its appearance, to give it 
sometimes new properties with a view to applying a glaze, or 
finally to produce decorative effects by using variously coloured 
engobes. 

Decoration with glazes is effected by means of vitreous or 
opaque, coloured or colourless substances, which are fixed by fire 
to the pottery to render it impervious, give it a brilliancy which 
will enhance its colouring, or on the other hand hide or mask 
that colour when it is not an agreeable one. 

Decoration with colours is effected by applying to the pottery 
metallic oxides, mixed or not with verifiable substances and 
fixed under or over a glaze. The effect produced is very 
different from that produced by enamelsj and permits of our 
distinguishing them, although they are often confused together. 



384 POTTERY IN ARCHITECTURE. 

Decoration with metals is obtained by applying them accord- 
ing to the effect required, either in the metallic state, when we 
wish to produce the effect called metallic lustre, or in the form 
of salts. 

Having given these definitions, we can now study in detail 
the various styles of decoration. 

Engobes, or Dips. 

Engobes are either white or coloured. When white, they 
serve to modify the colour of the pottery to which they are 
applied. They are made of fine white earths, to which are added 
a thinning substance and different salts. Their composition 
should be such that, when applied to the paste, they shall bear 
the same firing, undergo the same dilatation, behave in the same 
manner under the influence of the atmosphere of the kiln, and 
finally adhere satisfactorily to the paste. The engobe is laid on 
by diluting to a state of paste the mixture of the proper 
ingredients, and dipping the object which has to be coated, in 
this paste, or else, by pouring the liquid engobe over the paste, 
or finally, by applying it with a brush. 

Coloured engobes are used for the same object as white 
ones, or, as is more frequent, for obtaining decorative colouring 
effects. They are produced from earths which have been 
naturally or artificially coloured by the addition of metallic 
oxides to white or only slightly coloured earths. 

In the first case, the coloured engobes are applied like the 
white one ; it is an economical method of giving to a paste a 
colouring, or properties which it would be too costly to communi- 
cate to it in any other way. 

.In the second case, the engobe is used in two different ways : 
diluted with water like a water-colour, it is applied with a brush 
to the piece when unbaked or slightly warmed ; after drying, it 
is fired as it is if the colour is to remain dull, or it is covered 
with a glaze ; this mode of decoration, which is called peinture 
a la barbotine, always gives dull tones and not very varied 
effects. 






GENERAL REMARKS ON THE DECORATION OF POTTERY. 385 

The other method of applying coloured engobes consists of 
making hollows in the object to be covered, which are filled with 
a thick paste of the engobe. Several engobes of different colours 
can be applied to the same piece. It is allowed to dry, and the 
surface is then cleaned in order to bring out the designs ; this is 
the process employed in making paving quarries, in imitation of 
those of the Middle Ages. If the engobe reaches a certain degree 
of thickness, it is called incrustation. 

The Greeks and Romans used extensively engobes made 
with white, red, and yellow clays, to decorate their vases. By 
these simple and primitive methods they have produced master- 
pieces which we now admire in our museums. These coatings 
are dull, except the black one, which shines in consequence of the 
iron contained in it. 

To-day engobes are seldom used alone, and the peinture a la 
barbotine is scarcely used at all except for architectural pottery. 
In most cases they are covered with a glaze ; their composition 
must therefore be allied with that of the glaze. They are 
applied to the pieces when unbaked or slightly warmed. 

Glazes. 

These are complex metallic silicates of variable composition ; 
they are usually divided into : 

Soft glazes, colourless and transparent vitreous substances, 
fusible at a fairly low temperature and generally containing 
lead; 

Hard glazes, also colourless and transparent, but melting at 
a high temperature and containing always an earthy or alkaline- 
earthy substance ; 

Enamels, coloured vitreous substances ; these are divided into 
transparent enamels, which are plumbiferous or alkaline, and 
opaque enamels, which are generally stanniferous and are used 
especially in the manufacture of faiences ; 

Colours, metallic oxides generally mixed with verifiable 
substances ; they are either laid direct upon the pottery and 
afterwards covered with a colourless glaze this is the under-glaze 
2 5 



386 POTTERY IN ARCHITECTURE. 

decoration or upon the glaze itself, which is the over - glaze 
method. 

These subdivisions are . clear enough ; nevertheless more 
precision may be given to the terms employed by adding to the 
name of the glaze those of the principal substances which enter 
into its composition ; we say, for instance, plumbiferous glaze, 
calcareous glaze, stanniferous enamel, etc. 

Composition of Glazes. The foundation of glazes is silica, 
which forms, in combination with other basic substances, fusible 
and transparent multiple silicates which are really glasses. 

Certain bodies which enter into the composition of these 
glasses are called fluxes because they have the property, when 
mixed with other substances, of rendering them fusible if they 
were infusible, .or of increasing their fusibility if they were already 
fusible. Fluxes are not necessarily fusible themselves. Lime and 
alumina are infusible, but the result of their mixture in certain 
proportions with silica, itself infusible, is the formation of fusible 
compounds. It is not always easy to determine which body it 
is which acts the part of flux to the other. Moreover, it has 
been shown that multiple silicates are more fusible than simple 
ones. 

In coloured glazes, the verifiable substances are mixed with 
colouring metallic oxides ; hence we have two series of compounds 
to study. 

i . Vitrifiable Substances Entering into the Composition of 
Glazes. ACID SUBSTANCES. Silica (SiO 2 ) and Silicates. 
These are introduced in the form of white sand, used without 
any preparation, and of quartz and flint, which must be calcined 
and crushed. 

These substances, in spite of their practically similar chemical 
composition, do not produce the same effect. Sand from one 
place would not take the place of sand from another ; for instance, 
Fontainebleau sand is less fusible than that from Nevers, and 
flint is more fusible than Fontainebleau sand. 

Alkaline silicates are only used in special cases. Among the 
silicates of alumina, those most used are the felspar and the 
non-ferruginous pegmatite ; they enter into the composition of 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 387 

porcelain glazes and glazes for the faiences called flint- 
ware. 

Kaolin and wJiite clays enter also into the composition of 
glazes ; they diminish fusibility and give an opaline trans- 
parency. 

Boric acid (BoO 3 H 3 ) and borax (borate of sodium, Bo 4 O 7 Na 2 , 
ioH 2 O). The latter contains much water of crystallisation, 
and it must be calcined before use. The boracic glazes are 
hard and brilliant ; at a high temperature they dissolve the 
metallic oxides and transform them into transparent enamels. 

BASIC BODIES. Alkalies and Alkaline Salts. The alkalies 
are more used in the form of carbonate of soda (CO 3 Na >2 , ioH 2 O) 
or of potassium than in the free state. They dissolve the 
metallic oxides and give enamels a purity and transparency 
which no other fluxes obtain. 

Among other alkaline salts : the chloride of sodium (NaCl) is 
frequently used in the preparation of the stanniferous enamels, 
which it purifies by dissolving all the impurities ; applied to 
stoneware (salting), it gives it a brilliancy which does not make 
them sticky and which cannot be obtained by any other method. 
The nitrate of potash (KNO 3 ) is decomposed at a dull red 
temperature setting free oxygen ; this property is utilised for 
freeing frits from the organic impurities contained in them. It 
enters also into the composition of some enamels. In cryolite 
(double fluoride of sodium and aluminium) we have a means of 
introducing soda and alumina simultaneously into the glaze, for 
this body is decomposed at a red heat into these bases and into 
volatile fluoride of silicon. The glaze must then be silicious. 

ALKALINE-EARTHY DERIVATIVES. The carbonate of lime, 
CaCO 3 (chalk), and the sulphate of lime, CaSO 4 , 2H 2 O (gypsum), 
form with silica, silicates which are not very fusible, but with 
borax they give glazes which are more fusible, and which are 
used for flintware and stoneware. 

1\& fluoride of calcium, Fl 2 Ca (fluor spar), is sometimes used 
as a flux for pottery fired at a high temperature. 

DERIVATIVES OF LEAD. The protoxide of crystallised lead, 
PbO (litharge), and its product of oxidisation, plumbate of lead 



388 POTTERY IN ARCHITECTURE. 

(minium), are used in many glazes, being the more fusible because 
they are rich in lead. 

The carbonate of lead, PbCO 3 (white lead), is also used for 
introducing lead into glazes. 

As for the sulphide of lead, PbS (galena), it is in general use 
for the glazing of common pottery. 

The oxide of bismuth (BL 2 O 3 ) acts like oxide of lead, but 
gives still more fusible silicates. 

DERIVATIVES OF TIN. Stannic oxide, Sn(X (tin putty), is 
the base of the opaque enamels, for it remains in suspension 
and does not dissolve in the vitreous substances ; it is generally 
associated with oxide of lead. This mixture, called calcine, is 
prepared by calcining tin and lead together in a reverberatory 
furnace. 

The oxide of zinc, ZnO, is sometimes used as an opaque 
body in silicious glazes ; the same may be said of phosphate of 
lime, (PO 4 ) 2 Ca ;j . 

2. Colouring Substances Entering into the Composition of 
Glazes. These are generally metallic oxides, sometimes salts, 
and more rarely the metals themselves. 

The table on p. 390 shows the principal colours obtained, under 
different conditions, with the metallic derivatives either single or 
mixed. 

PREPARATION OF GLAZES. This comprises the pulverisation 
of the substances and the mixture of the powders so obtained. 
The crushing is effected dry or wet in various machines, mills, or 
cylinders, care being taken that there is no contact between the 
iron and the substances to be crushed. The grindstones, which 
are generally of hewn flint, are enclosed in an oak trough ; they 
may be worked by hand (Fig. 704) or by steam (Fig. 702) or so 
made as to be worked in either way (Fig. 703). When the 
crushing is believed to be effected, the stopper is removed and 
the liquid mixture allowed to flow out. The crushing of the 
colouring substances which enter into the composition of coloured 
glazes is performed with grinding mills (Fig. 704). 

The insoluble bodies in the water are subjected to direct 
crushing, but the soluble bodies (alkaline carbonates, boric acid, 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 389 

borax, etc.) must first be transformed into silicates or insoluble 
borates by fritting or vitrification. 

Fritting is effected by heating the soluble substances in a 




Fig. 701. Hand-worked Glaze Mill. Fig. 702. Glaze Mill, worked by Steam. 







__.,:.^~^ 

Fig- 703. Glaze Mill (Laeis et Cie.). 



Fig. 704. Grinding Mill. 



crucible or on the floor of a kiln with other insoluble substances 
which enter into the glaze; under the influence of heat these 
different bodies cohere and form a mass, which is then pulverised. 
If the heating is pushed further, the substances melt into a glass, 



390 



TOTTERY IN ARCHITECTURE. 





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S ^ '-3 2 ; 05 <y 






g 


S"g'|| s Is 






N 


|| 1^ p.S 






c 

H 


1 

^3 .t! J15 &n3j| 









N 






2 


Ji "5 








c 

rt 


<u 






M 

C 


<u 






rt 


o 








_r< C ^ 

rt'ot/; 'S .ti *o ol^ 






c 


C/3 *-* ^ C^^r^ i-rf^X 


Q 




o 


^ r^ ^ ^ _^ S O "~O ^ 


>4 






'^ |U 11^'" S ^| 


"o 






.2 c aj 






a 


g G ^ 






G. 
O 


|8 gj^ 






O 


- fc ^ ^ ^ 






3 


Is 






c3 


Si> 






6 


^ 


a^ -s ^ s j I 







|| 


8 -S ^s 2 | -a 




X! 

U 


o' 


g-ll^l'S.ll 




. 




o 




Antimon 




Is 

^3 <u 




Mixed with 


f||| ^Ill^l^llll^fl 

^sSll l||i|^|^l|l^| 

^O.M .5 S t/3 '~ > C '-Sr^^S-S > 
c r5 & \c o-i'SoS- s cj "bjoE" 1 ^ o PI ?j 


with addition of alumina becomes 
,sky-blue. 
Cupric oxide, CuO, with an alka- 
line glaze in an oxidising atmosphere 
gives turquoise blue* which becomes 
greener with boracic glazes and 
less intense with lead glazes. In 
a reducing atmosphere it forms with 
alkaline glazes a purple-red, which 
with other glazes becomes orange- 


tinted or brown. 




U3Ajig -Auomnuv mniiuojq3 -jjuq 


03 uaddo3 





GENERAL REMARKS ON THE DECORATION OF POTTERY. 39 1 



s g.y.t!^ 
f Illll 

= * 



f 

' = *< 



a; 1/5 c 

- 






g -gj 3 'I 



. 




UOJJ 



39 2 POTTERY IN ARCHITECTURE. 

which is poured into water to disaggregate it. As vitrification 
requires more fuel than fritting, it is only used when indispensable 
for making glazes homogeneous ; fritting, on the other hand, is 
preferable when the glazes contain chlorides or sulphides, on 
account of the substances which are formed, and which, in the 
fusion, would remain in the mass and produce explosions on 
contact with the water. 

Frits are crushed either in the dry or the moist state 
according to the mode in which they are to be used. 

As glazes are generally laid on in a state of paste, the 
mixture of their ingredients is generally effected in the presence 
of water. 

The glazes thus obtained are colourless ; but in order to 
colour them, it will be sufficient to incorporate in them a 
metallic oxide, but most frequently it is done by melting the 
whole together, then crushing and bringing it to the state 
required for the application. Coloured glazes are called enamels. 

The opaque enamels are of stanniferous base, and their 
principal constituent is calcine^ a mixture of oxides of tin and 
lead in variable proportions obtained by calcining a mixture of 
lead (100 parts) and tin (15 to 35 parts) in a reverberatory furnace 
to a dull red heat. An average quantity of 120 kilog. of metals 
is treated, and yields 132 kilog. of calcine. This is then mixed 
with its own weight of Nevers sand, 2 per cent, of soda, 8 per 
cent, of salt, and 2 per cent, of minium, and the whole is melted. 
A high degree of heat is necessary to succeed in rendering the 
mass quite liquid, which is an indispensable condition. It is 
cooled, pounded, and crushed in presence of water to a state of 
fine division. Thus we get white enamel. 

In order to obtain the other opaque enamels, oxides in a 
state of fine powder are added to the enamel. These are 
incorporated with it before it is fused, and consequently we get a 
more intimate mixture and can observe the colour better. 

The fusibility of enamels varies with the nature of the pottery 
and the degree of firing to which it is subjected. The lower the 
temperature of firing is, the more varied are the enamels, and as 
it rises this variation diminishes, for it is not all colours which can 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 393 

resist a great heat, and only a small number of them remain 
fixed under the high temperatures of porcelain firing. 

HARMONY OF GLAZES AND PASTES. The preparation of 
glazes and their composition would be relatively easy to carry 
out if it were not necessary to harmonise their physical properties, 
fusibility and dilatation, with those of the pastes which they have 
to cover. In fact, if this harmony does not exist, the glaze crazes 
or peels off. 

The crazing or chipping is due to an excessive contraction 
of the glaze, causing penetration of the liquids which produce 
fissures when cooling takes place. If, on the other hand, it is the 
paste which contracts too much, there is peeling, that is to say, 
that in cooling the glaze becomes detached from the clay. 

The dilatation of glazes and pastes is intimately connected 
with their composition ; hence the first care of the ceramist is to 
become acquainted with the properties of the substances contained 
in the glazes and pastes. As regards the former, he must note that 
alkaline silicates are very fusible and contract much ; that the 
silicates of lead, which are also very fusible, contract less ; and 
that the other metallic silicates, that of copper excepted, undergo 
less contraction than alkaline silicates. The same may be said 
of the borates. The degree of fusibility of the silicates comes 
in the following order : lead, copper, manganese, cobalt, iron, 
uranium, chromium, nickel. If several enamels are applied to 
the same piece, they must melt at the same temperature, and it 
will be therefore necessary to diminish the fusibility of some and 
increase that of others by suitable additions of fluxes on set 
substances. 

As for pastes, it must be observed that silica is very 
expansive, and that this property increases with the fineness of 
the grain, but diminishes when the grain is coarser or clay is 
added. Carbonate of lime and the alkaline sulphates alter the 
dilatation of pastes ; they are therefore used to place them in 
harmony with the glaze. 

The firing of the pieces to which glaze is applied may also 
lead to accidents, especially in the case of those which require a 
high temperature. 



394 



POTTERY IN ARCHITECTURE. 



According to Deck, the following is the course to take in 
order to produce harmony between a paste and its glaze, the 
composition of both being known. 



Composition of 
the Glaze. 

Minium. 

Sand .... 

Potash and soda 

Composition of 
the Paste. 

Rich white clay 
Chalk . . . 

Flint .... 
Frit .... 

Firing. 
Ordinary pottery 

Silicious pottery 



To avoid chipping or peelin| 
we must : 



Increase Diminish 

or or 

Diminish. Increase. 



Remarks. 

It must not be forgotten 
that what prevents 
chipping tends to 
produce peeling, and 



Diminish. 

Increase if the paste is 

to be more calcareous. 

Increase or crush finer. 



Increase. 
Diminish. 



Diminish or do not 

crush so fine. 

Increase if the paste is Diminish, 
to be more alkaline. 

Biscuit not much fired. Biscuit too much Regular firing necessary. 

fired. 

Biscuit not much A too strong firing 
fired. causes fissures. 



The question becomes still more complicated when coloured 
glazes are used, for it may happen that the most convenient 
composition for obtaining the desired colours is easily warped or 
is exposed to peeling. Only numerous experiments can help us 
to overcome these difficulties as they arise, and the scientific 
researches carried out with regard to this question have not 
hitherto been of much help to ceramists. 



Special Processes of Decoration. 

Application of tJie Glazes. They are applied in various ways : 
the pottery may be sprinkled with them, it may be immersed in 
a pulp formed of the glaze, or the latter may be applied by 
volatilisation. 

In the first case, the pottery while still fresh may be coated 
with the glaze in a powdered state, which is generally an 
oxide of lead or of alquifoux. Silica and alumina are provided 
by the piece to be glazed. This process, which is the simplest and 
commonest, is only used for common pottery. 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 395 

Immersion consists of the pottery in a dry state, either warmed 
or baked, being dipped into a pulp of the glaze neither too thick 
nor too clear to be absorbed by the paste. The composition 
should be such that the glaze will not become detached after 
mixture ; hence it must have a certain plasticity. 

Glazing by volatilisation is effected by throwing saline or 
metallic substances into an active kiln ; these will attack the 
surface of the pottery and will form on it a thin layer of a trans- 
parent glass which constitutes the glaze. In other cases, instead 
of throwing the verifiable substances on the pottery when in an 
incandescent state, the interior of the Gazettes containing the 
pieces is coated with the glazing material. When the heat 
becomes fairly strong, these substances (alkaline carbonates or 
borates, oxides of lead) become volatilised and act on the surface 
of the pieces. 

Instead of plunging the piece into the glaze, the latter may 
be poured upon it, and this is to be preferred in the case of 
pastes which are not very porous and which would not, by 
immersion, absorb a sufficient layer of glaze. This process is 
called irrigation. 

Sometimes the pottery is sprinkled with a brush dipped in 
the glaze ; this is the sprinkling process, and used for coating 
pieces on certain parts in order to obtain special effects. 

If we desire to cover a piece entirely by this process, we must 
use insufflation or pulverisation, the principle of which is well 
known. 

A tube with a small orifice is dipped into the glaze pulp ; 
another tube is fixed at right angles to the first, and introduces 
the air under pressure ; the current of air causes an aspiration 
which draws the liquid into the other tube. For small objects 
an india-rubber pear will be enough, but for large surfaces we 
must have bellows which will transmit the air at a pressure of 
\ to J of an atmosphere. 

Decoration with Enamels. Opaque Enamels. These are 
almost always stanniferous, the white enamel being the base of 
them. This enamel is prepared by melting together : 44 parts 
of calcine (oxide of tin and lead), 44 parts of sand, 2 parts of 



396 POTTERY IN ARCHITECTURE. 

Alicante soda (soda partially carbonated), 8 parts sea-salt, and 2 
parts of minium (Deck). The mixture is roughly pounded, then 
finely crushed in presence of water until it has the required 
consistency. The coloured opaque enamels are obtained by 
adding different metallic oxides to the preceding mixture. 

Formula according to Brongniart. White Enamel. Enamel obtained. 

Naples yellow or oxide of antimony 9 p. 91 p. Yellow. 

Oxide of cobalt or azure . . 5 p. 95 P- Blue. 

Battitures of copper . . 5 p. 95 P- Pure green. 

Naples yellow " . ' .' ' 2 p. } 94 P- Yellow green. 

Peroxide of manganese . . . 4 p. 96 p. Violet. 

Several methods are employed for decorating pottery with 
opaque enamels : 

The method of decoration " au grand feu " on unfired enamel 
consists of coating the piece by immersion or irrigation with 
white enamel, which is allowed to dry, and then of placing on 
the friable raw enamel other opaque or coloured enamels by 
means of a brush or by any other quick process, such as 
spraying. The whole is then fixed by baking. 

Instead of working with raw enamel, we may decorate on 
fired enamel. In this case the firing which fixes the decoration 
is done at a somewhat low temperature ; this allows of the use of 
a very rich gamut of colours, which should be easily verifiable. 

When a clay which is naturally white or whitened by dip 
is decorated, the stanniferous enamels may be replaced by 
transparent enamels, whose brighter colourings give different 
effects from those obtained with the opaque enamels. The 
presence in the paste of a sufficient quantity of limestone 
allows of either transparent or opaque enamels being used, the 
latter being especially reserved for light tints and white. 
The effects may be still more varied by giving dull tones 
to the enamels ; for this purpose they are simply hardened, that 
is to say, they are rendered less fusible by the addition, for 
instance, of silica or alumina. 

The alkaline transparent enamels are applied to all faience 
pastes. From the point of view of architectural decoration, 
they conduce to powerful effects and have the very interesting 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 397 



property of remaining as bright in artificial as in solar light, 
while under similar conditions lead enamels become dull. But 
the difficulty and delicacy of the preparation of alkaline enamels 
limit their use. Deck, the first ceramist who used them, gives 
the following fundamental formulae which, by varying the quantity 
of flux, may serve to make an infinite number of intermediate 
tints : 

TRANSPARENT ALKALINE ENAMELS 





V 






























_3 


C 
O 


i 

> t 


o; 


. 


1 


<u 


i 

'o 


B 


6 


n 


is 


a 






N 


"9 * 


i 




Q 








c; 


3 


C 


> 


a; 


Remarks. 




'S. 


.2 
~S 


K 


O 


- 1 


_o 
'a 


1 




3 

H 


O 


1 


* 

5 


l3 

P 


O 






3 


"' 


C/3 








U 






^ 










Flux (I) .";,. 
Antimony (oxide of) . 


95 


44 


52 


82 

2 


52 


45 


47 
4 


93 


35 


45 


89 


92 


3 


(i) Melted together : 
Minium . 30 or 35 parts. 


Cobalt 


n 7 






















o 6 




Sand . 50 or 45 ,, 


Copper . 


A T. 




o 7 










7 




5" 


3^ 






Pot. carb. 1 2 or T 2 , , 


Iron 




8 


1.8 




3- 


JO 


4 






S 


6.1 








Manganese ' . 




n 




6 














2 5 


7 






Nickel 








q 






















Lead (plumbate of) . 




25 




25 


2 5 


25 


25 




55 


25 






5S 


Minium. 


Potash (nitrate) 








c 










c 








10 




,, (carbonate) 






























Sand 




20 




20 


20 


20 


20 






20 










Sodium (borate) 


















S 








T^ 


Melted borax. 


(oxide). 








5 














... 






Soda. 



The different mixtures are melted, then crushed and applied 
to the biscuit or fired faience. Application over engobe is not 
necessary, but this method gives more delicacy to the products. 

In order to deposit a uniform layer of enamel we immerse in 
the coloured paste, which has been thickened by gum or some 
other viscous substance. If we wish to make reserves, we lay 
with a brush on the biscuit, in the places to be reserved, a coating 
composed of chalk and gum or essence, and immerse in the 
glaze. A moderate heat then causes the colour to adhere and 
the portions deposited on the reserves to fall off, thus leaving 
them bare. If coloured reserves are desired, the colour or colours 
which are different from those of the background are diluted with 
oil and applied with a brush to the required parts. Then, when 
immersion takes place, the colour of the background, which is 
diluted with water, does not adhere to the oil decoration. 



398 POTTERY IN ARCHITECTURE. 

Special effects are obtained by giving different thicknesses to 
the enamels, either by running (p. 402), or by filling the hollows 
in the terra-cotta with enamel. In this case hollow impressions 
are made either by moulding or engraving on the pieces when 
fresh. If the design requires several pieces, as in the case of 
decorative panels, it is made up of quarries of this kind. 

The effects obtained differ according as the transparent 
coloured enamels are applied to the paste when unfired, fired, or 
warmed (biscuit). When they are placed close together, they 
have a tendency to run together at the moment of fusion. This 
inconvenience may be avoided by tracing the outline of the 
design with a black and less fusible glaze of sufficient relief. 
The coloured enamels are applied within these outlines. This 
process, wrongly called cloisonne, was used by Deck in 1874, and 
has since spread with astonishing rapidity in France and abroad. 

Decoration with Colours. In the case of enamels, the 
colour is incorporated in the glaze, which if transparent forms a 
coloured glass ; it is otherwise in decoration with colours. Colour 
and glaze are applied separately ; sometimes the latter covers the 
former, and this is under-glaze decoration ; sometimes it is the 
reverse, and we have over-glaze decoration. 

Under-glaze Decoration. The colours, finely ground, are 
mixed with diluted gum or glycerine to render them more 
adhesive. They must resist the temperature of vitrification of 
the glaze, hence their composition depends upon the fusing 
point of the latter. They are often mixed with fluxes. They 
are applied to the warmed pottery by immersion for uniform 
tones, or with the brush when there is a design, or by printing 
when the same decoration has to be reproduced many times. 

The brush-work is done with the colours mixed with gum 
or essence of turpentine; they are applied as in oil painting. 
When once dry, the pieces are heated before putting on the 
glaze in order to remove the essence. 

Printing is done with copper plates having the design 
engraved on them by points ; these are coated by means of a pad 
with the colour which has been prepared with boiled linseed oil 
and a little resin. The plates are heated to 30 or 40 C., to 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 399 

facilitate the removal of the paper, to which the colour remains 
adherent. This paper is then applied to the pottery to be 
decorated and rubbed over with a pad, and is plunged into water 
so that the paper may be detached with a sponge. The pieces 
are dried and afterwards heated to 200 to 300 C, in order to 
remove the oil ; they are allowed to cool, then covered with the 
glaze and fired. 

The design obtained is monochrome, but other colours can be 
added with a brush, or more economically, if a large number of 
pieces are being treated, by printing. 

For this purpose the design is divided among as many plates 
as there are colours, and the different colours are printed off 
separately upon the same paper, great care being taken to fit 
them together correctly. The design is afterwards transferred 
to the piece ; this process is used in the decoration of facing 
quarries. 

Chromolithographic printing^ which is much employed in 
over-glaze decoration, presents certain technical difficulties when 
used under glaze. M. Boulenger, the eminent ceramist of 
Choisy-le-Roi, was the first in France to overcome them. 
Sarreguemines (Alsace) and Mettlach (Prussia), Minton and 
Hollins (England), also use sub-enamel decoration. 

Machine-printing renders great services to the industry, but 
does not give such artistic effects as painting with a brush, which 
alone is capable of satisfying refined tastes. 

Composition of the Colours. This depends upon the nature of 
the paste to be decorated, both with respect to the colouring 
oxides used, and in the choice of the fluxes which are frequently 
added to them. As an example we shall mention the colours 
from which Deck has obtained such beautiful effects in his 
faiences of silicious paste, recalling, in their rich colouring, the 
celebrated Oriental faiences. 

The colours having been finely crushed, are diluted by the 
muller, and applied with the brush. 

Over-glaze Decoration. This is performed with verifiable 
colours, that is to say, mixed with fluxes which generally vitrify 
at a low temperature. It is a very easy process, much used 



400 



POTTERY IN ARCHITECTURE. 



Remarks. 


(/) The flux is prepared with : 
Flint 70 
Carbonate of soda . .10 
,, -of potash . 15 
Minium .... 5 
Mix with care, melt, and grind. 
(2) Grind together : 
Persian white . . .20 
Stanniferous white enamel . 40 
(j) Grind together without melting. 


Alumina. 

Sal ammoniac. 
Chalk. 

(4) To be melted, 
(j) Mix and bake in a crucible under the kiln 
during a firing. 
(6) Grind together, fire, wash, and crush. 

Stannic acid. 
(7) Precipitate with the ammonia a solution in 
water of: 12 k. alum and 9 k. of nitrate of 
cobalt, filter, dry, and calcine " au grand feu." 

Litharge. 
Minium. 
(8) The mixture is heated for some hours at a bright 
red heat, then ground and washed in water 
acidulated with HCI. 


Melted borax. 
Flowers of zinc. 




. 






je>|oi A 


~ :::::: 















U33JQ 


3 :'.:::: 








^ o 


xo 




P 3 a 




' ' ' ' N ' ' 












(^JUIj) 3SO^{ 


!>^. 


CO 00 


^ 


















M3\Nf r 


^fx 










H-t 






^ 




^D 


MO IFA Wt 


^ : : ^ : : : _ 








"^ : : o : : : : 


. . LOOO 10 - . 




AV 113A n ^ ! I 




-rj-O \O'- 






^ o 


10 




uA\o.iq pan 


^D : Si : : : : : 


N 




UA\OJf[ >[Jt!Q 


^ 


::::::::::O:OLO;::: 


^i 













n " n 


o 




,-m 1<f[ asionbanj. 


c^^ : : : : eg : 








"^ o o 




o 


an UI uus.i3j 






. t 




^ ^ 






'Oni*I ^J"G(T 


^-^ >^ 








00 














"ani*! }u2i'[ 




OQ 














"^ 






WHAV uBhWd 


-^ : : : : m : M 












. 


3 'm.\\ ^-> U !HD 




















'' 




Substances used. 


tu ,_ 
. . i- . C . 
rf 

^ "^ 'a; 

?fliiftl 

^-^S'^lS 13 " 5 ^ 
S^-<UHUO^ 


.._. '1 
1 IflL- - -1^1? 

y, J^I-Q O C OJ . - ^ '7? X ""O *- o i 
o >->-P ^ 4 - J oj r ^ "rt ^jO'OS^'^-'^ 


Scda (borate) 
Zinc (oxide) 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 40! 

in pottery, and also by amateurs, but it gives rather dull 
effects, which are far from being equal to the decoration " au 
grand feu." 

The verifiable colours are obtained ready prepared in 
commerce. A large number of French (Poulenc freres, Lavoisier, 
etc.) and foreign firms supply them of excellent quality. It is 
only the great pottery factories which make them themselves. 

The application is made with the brush, the colours being 
diluted with essence and oil. Sometimes the pottery is coated 
with resin dissolved in an essence or in oil, and is then powdered 
over with the dry colour. 

In the trade line- engraving is used for monochrome designs, 
and chromolithographic printing for polychrome decoration. 

The design, having been traced in outline with lithographic 
ink, is printed off in the ordinary way, on to as many stones as 
there are to be colours ; the parts of each stone which are to 
be coloured are coated with a brush with lithographic ink ; 
the remainder of the design is effaced, and the stones are 
placed in acidulated water to fix the ink and give it a slight 
relief. 

The parts of the stone coated with ink are varnished by 
means of a wooden roller covered with leather, and a proof is 
taken off upon paper sized with gum or dextrine. The paper 
when taken off is turned over and sprinkled with a verifiable 
colour which sticks to the varnish ; after drying the excess of 
colour is removed with a soft brush and the second colour is 
printed, great care being taken in fitting the sheet in its place. 
The process is thus continued until all the colours have been 
applied. To remove them to the piece of pottery, the prepared 
sheet of paper is covered with a varnish, and applied to it with 
a pad ; when the varnish has adhered, the whole is plunged into 
water to remove the paper, is then dried, heated in the stove to 
remove the varnish, glazed, and fired. 

This process, which gives good results with flowers and 

ornaments, is not so successful in reproducing animals or figures. 

We must then turn to photolithography, a process in which the 

sketch is replaced by a photograph ; this is transformed into an 

26 



4O2 POTTERY IN ARCHITECTURE. 

engraving, which can be reproduced by printing, for instance, by 
means of the bichromate gelatine. 

The firing is carried out at a rather low temperature in 
special muffled kilns (p. 449). 

Other Processes of Decoration. These are exceedingly 
numerous, for ceramic decoration accommodates itself to every 
fancy, and the unforeseen results sometimes obtained add a 
charm to the decoration. The crackling effect is the utilisation 
of the fault called crazing. The glaze thus formed is covered 
with another, which penetrates into the crack and brings it out. 
Mottlings are produced by firing for a considerable time a fus- 
ible glaze which runs and makes unforeseen marbling effects. 
Flashing effects follow from the alternate use in firing of a 
reducing and oxidising atmosphere. By taking oxides which 
behave differently under the action of these, for instance those of 
copper, we get very diverse colourings, which, being unexpected, 
are very attractive. 

The metallic lustres from which the East has obtained 
such wonderful effects, and which at the present day are 
treated in such a masterly manner by ceramists, are got 
by applying metallic salts crushed with vinegar or rich essence, 
with a brush, to the pieces fired under enamel. 

Firing takes place in a muffled kiln at a low temperature, 
that of early red, in a smoked atmosphere (reducing). The 
pieces are put in open-work saggers, and come out with a layer 
of black on them ; this is removed, and under it appears the 
brilliant decoration. 

Deck gives the following ingredients : 

Gilded lustre. 

Sulphide of copper 10 Sulphide of copper ... 5 



iron ... 5 



Nitrate of silver 2 



,, silver I Colcothar .... I 

Yellow and red ochre . . 12 Armenian bole .... 4 



Red histre. 



Sulphide of copper ... 2 

Protoxide of tin . . . 2 

Smoke black i 

Red and yellow ochre . . 4 



Oxide of copper ... 8 

iron. ... 5 

Colcothar. .... 6 

Armenian bole .... 6 



GENERAL REMARKS ON THE DECORATION OF POTTERY. 403 

Gold and platinum are also used, and on account of their 
inability to be oxidised, they may be fired in an oxidising 
atmosphere. 

Gold has also been applied under glaze. The effect produced 
is very powerful, and much more sparkling than gilding over 
enamel ; the difference is of the same kind as that observed 
between transparent coloured enamels and under-glaze painting. 
This decoration is obtained by lightly enamelling the pieces and 
sprinkling them with grains of sand, then firing ; gold-leaf, cut 
to shape, is applied with a stiff brush to the piece, which has 
been smeared over the required part, with a decoction of 
quince-pips. The glaze is then laid on, and the piece is 
fired at a temperature lower than that of the fusion point of 
gold (1045 C.). This kind of decoration requires great care, 
great taste, and very pure materials. It has been skilfully used 
by Th. Deck, who has been able to obtain remarkable effects 
from it. 



CHAPTER II. 

GLAZED AND ENAMELLED BRICKS AND TILES. 

History. In the ruins of Nineveh and Babylon, there have 
been found, side by side with ordinary fired or unfired bricks, 
others of which one extremity was glazed and even enamelled 
with different colours. The surface of these bricks is not 
smooth, it has designs in relief. It is probable that the bricks 
were collected together when in a fresh state, and that, after 
lines had been grooved on them to mark the outline of the 
design, and a sign to aid in fitting them together, each piece was 
coated with an enamel and carried to the kiln. The pieces 
were afterwards fitted together and fixed with water. 

This Assyrian style of decoration has been observed in 
various forms throughout Asia Minor and even in ancient Persia, 
where, thanks to the remarkable discoveries made at Suse by 
M. and Mme. Dieulafoy, magnificent and irrefutable proofs of 
the use of enamelled bricks have been found. 

These enterprising explorers have removed from the palaces 
of Artaxerxes Mnemon (4th century B.C.) and of the great 
Darius (6th century B.C.), the ruins of which lie one over the 
other, some important examples of enamelled decoration in 
a fine state of preservation, which can be admired to-day in 
the Louvre Museum in Paris. 

One represents lions, another the facing of a staircase, and 
finally there is an admirable frieze on which twelve arches of 
the Royal Guard are represented in bas-relief. This work, 
whose harmonious tints are now mellowed by time, is treated 
with noble simplicity ; there is something imposing in it which 
astonishes and compels admiration. Th. Deck has examined 
this frieze from the point of view of execution. The bricks, 

404 



GLAZED AND ENAMELLED BRICKS AND TILES. 405 

which are 30 to 40 centimetres square and 9 centimetres thick, 
are made of sand mixed with a little clay and alkaline frits. 
The enamels are of tin base, and the colours are formed by the 
metallic oxides at present used by us. These enamels are more 
alkaline than ours, however, because of the large quantity of 
silica contained in the clay. The conclusion of the eminent 
ceramist is that this example of manufacture is an extremely 
remarkable one, and quite worthy of serving as a model for 
architectural ceramic decoration. 

Muller has reproduced these friezes on enamelled stone- 
ware, and we have been able to examine this fine example of 
pottery-work at the Chicago Exhibition and at the annual 
Paris Salons. 

The Greeks and Romans were certainly acquainted with the 
art of enamelling pottery, but for some unknown reason they 
rarely used colours, a strange circumstance with a people 
usually so fond of them. Even under .Hadrian (2nd century), 
when the Egyptian style was very fashionable, the Romans did 
not carry their imitations so far as to use the enamelled facings 
of which they could have found such fine examples in Asia Minor. 

This was evidently the cause which retarded the appearance 
of faience in Europe. It was at Troyes, in 1220, that plumbifer- 
ous glaze first appeared on terra-cotta roof ornaments. It was 
frequently used for varnishing facing bricks and the pureau (part 
uncovered) of tiles intended for roofing public buildings. To 
make those mosaics in colours, which adorn the roofs of many 
cathedrals of that period, especially that of Troyes, the tiles were 
coated with a coloured dip, red, black, yellow, or green, and the 
whole was covered with a lead glaze. 

The popularity of these products lasted till the 1 6th century, 
then declined. Bricks which become varnished black in wood- 
firing were, however, always used in architectural decoration. 

The enamelling of bricks suffered the same fate as their 
glazing, and it was only in the I Qth century that it was revived, 
not only for decoration, but also for the hygiene of dwelling- 
houses. England, which is always at the head of any movement 
in pottery, anticipated us in the use of enamelled brick for the 



406 POTTERY IN ARCHITECTURE. 

inner courts of houses, for servants' staircases, privies, etc. The 
imperviousness of these products gives them precious qualities 
from the point of view of hygiene and cleanliness. 

The movement is much slower in France ; people fear that 
enamelled products will not wear, and their high price is objected 
to. When we look at some of our fagades crowded with costly 
sculptures, we ask ourselves whether a little economy could not 
be realised here, and whether, in less beautiful but equally 
indispensable parts of the houses, materials could not be used 
which present incontestable advantages over painting and are 
less costly to maintain. 

Varnishing 1 . Varnishes are colourless transparent glazes ', 
generally plumbiferous, which are applied to bricks and tiles 
to make them impervious and also to decorate them, either 
simply by bringing out their colour or by modifying it by 
placing the varnish over a dip. 

Simple varnishing is done with alquifoux or minium, 
mixed or not with silica ; in the first case the varnish borrows 
the silica it requires from the paste of the pottery. Here are two 
old formulae : 

Alquifoux .... 80 I Minium 67 

White sand . . . . 12 White sand .... 24 

White clay .... 8 | White clay .... 9 

The varnish is laid on the products when unfired. 

The process, which consists of sprinkling the products when 
still fresh with powdered fluxes, is not to be recommended 
on account of the dust which it causes and which is doubly 
dangerous both as being inert matter and as poison. It is 
advisable to use the immersion process. Generally only one side 
of the brick is glazed (end or side) ; sometimes, for angles in 
building, both. 

The other non-plumbiferous glazes are scarcely ever used on 
account of their higher price ; a saturated solution of sea-salt 
is, however, recommended, in which the products are dipped 
when quite dry ; they are then again dried and fired. 

This silico-alkaline glaze requires pottery rich in silica to 
obtain good adhesion. 



GLAZED AND ENAMELLED BRICKS AND TILES. 407 

The preceding glazes allow the colour of the products to be 
seen. If it is desired to hide this colour, the glaze must be 
placed over a dip ; this renders the manufacture a more delicate 
operation, as has been explained in the general remarks on dips, 
for we must obtain a similar dilatation of the paste, dip, and 
glaze, if we are to get perfect products. 

The glaze, when placed over a dip, is much more brilliant 
than when placed direct upon the paste, but it is more likely to 
crack. In fact, glazed bricks and tiles are rarely free from this 
fault. Manufacturers do not take the trouble, as they ought, to 
accommodate the glaze to the paste of which the pieces are made. 
It is true that, in the case of tiles, the disadvantages which 
would result from the water staying in the cracks of the glaze 
are avoided by giving a great slope to the roofs ; this adds 
to the architectural effect, but necessitates a larger quantity of 
products which are in themselves already dear ; therefore the 
consumption of tiles which are glazed over dips is necessarily 
limited. 

Enamelling". The enamelling of bricks and tiles, like glazing, 
is intended to render them impervious and to produce a decorative 
effect by means of colouring. Enamelled bricks are really 
faiences, and as in the case of these latter, the enamel and the 
paste must be in harmony to avoid cracking; but besides this, 
the adhesion between the two bodies must be such that the 
bricks may be able to resist frost, damp, the different degrees of 
dilatation of summer and winter, etc. in a word, all variations 
of environment. 

It will be understood that these conditions are not satisfied 
in common pottery, and no means have yet been found of 
applying to ordinary bricks an enamel which fulfils the con- 
ditions of solidity mentioned above. 

It was in consequence of accidents which have happened 
to enamelled bricks used in the construction of subterranean 
arched passages, that attention was called to their powers of 
resistance to inclemencies of the weather. 

For instance, under certain conditions of damp this resist- 
ance is not so great as that of ordinary bricks, and in these 



408 POTTERY IN ARCHITECTURE. 

special applications it will be well to make arrangements for 
putting enamelled bricks in the best possible state to resist 
inclemencies. 

In order to avoid such inconveniences, manufacturers have 
still further improved their products ; for instance, Muller applies 
enamel to bricks made of stoneware firing clay. 

Loebnitz uses faience paste moulded by hand. The enamel 
adheres firmly to such paste, becomes a part of the piece, and 
thus satisfies the required conditions of solidity. 

Engineers have gone a step farther, and have had recourse to 
porcelain bricks. An important use of these products was made 
in constructing the tunnels of the extension of the Sceaux line to 
Luxembourg. Time will show the value of these impervious 
products under such conditions ; in any case, they cause a very 
heavy expense. 

Without going as far as this, it is evident that the examples 
left behind them by the ancients prove that enamelled products 
successfully resist the lapse of time when they are well made and 
used with certain precautions. 

The moulding of bricks which are to be enamelled is similar 
to that of ordinary bricks ; nevertheless hand-moulding seems to 
be preferable, perhaps on account of the greater porosity of the 
resulting products. 

The enamel holds less well to machine-expressed bricks, or 
even to those simply stamped stoneware bricks excepted. 

Transparent enamels can only be used directly in certain 
cases, for, bricks being always coloured, a contrast of tints is 
produced. With orange or red pastes, we can obtain brown with 
an enamel containing about 5 per cent, of oxide of manganese, 
and black if oxides of iron and cobalt are also added ; all other 
colours require a dip. 

Yellowish pastes will, with manganese and iron enamels, give 
red or brown colourings, with those of copper green, and with 
those of cobalt blue. But white and light colourings can only 
be obtained with dips or opaque enamels, unless we work upon 
white pastes like those of fine stoneware or felspar faience, which 
form exceptions. 



GLAZED AND ENAMELLED BRICKS AND TILES. 409 

The composition of some enamels is given below 





Blue. 


Brown. 


Yellow. 


Black. 


Green. 


Alquifoux . 
Minium 
White sand . 
White clay . 
Vegetable mould . 
Sulphate of iron 


8l 
12 

6 


66 
24 
9 


78 

3 
10 
6 


60 

33 

5 


78 

3 
ii 
8 


63 

23 
9 

5 


77 

8 
6 

3 

3 
T 


58 

32 
5 
3 

2 


76 
12 

6 
6 


63 

23 
9 

5 


copper 
Oxide of manganese 
, , iron 
,, cobalt . 








... 


,.. 


3 


2 






0.3 


0-3 


... 






... 




0.04 


... 


... 



Applications. 

Ordinary Enamelled Bricks. These are of decorative and 
hygienic interest in the facing of walls. For decorative purposes 
white and coloured enamels are used. As surfaces of a uniform 
white are disagreeable and cold to the eye, the enamel is marbled 
with a greenish tint, which gives a more attractive and softer 
general appearance. Ornamentation of this kind may be seen 
in Paris at the Cafe Riche (executed by Lcebnitz), and on a 
larger scale at the Hotel des Telephones (Perrusson). The 
architect of this latter building does not seem to have obtained 
the best possible artistic effect which might have been expected 
frqm the use of such materials. 

The polychrome style with bricks enamelled in colour offers 
great resources through the variety of designs which may be 
executed in it. The patterns composed of ordinary red and 
white bricks are already very numerous, and the number may be 
increased indefinitely by the use of enamels of varied tints. 

But to arrive at a harmonious effect, without any discordant 
note, a great knowledge of colour and skill in composition are 
required, qualities not found in every architect. 

Figs. 705-710 represent some simple patterns obtained with 
bricks enamelled in colour. 

As regards hygiene, the white enamelled brick presents the 
great advantage of being impervious and easily cleaned. By the 



POTTERY IN ARCHITECTURE. 

reflection of light on its white surface it helps to illuminate dark 
places such as inner yards, arched passages, etc. 

Bricks of Glazed Stoneware. The clay used for these 
bricks is the same as that used for making stoneware pipes. The 
glaze is obtained with sea-salt, as will be explained in speaking 
of stoneware pipes. These bricks are made solid or hollow, and 
are of the usual dimensions and shape. Special bricks for garden 
borders (Figs. 713, 714) are also manufactured. Others are 




Fig. 708. Fig. 709. Fig. 710. 

Figs. 705 to 710. Patterns in Enamelled Bricks (Perrusson). 

hollow and are used for copings (Figs. 711, 712), either single or 
in combination, according to the breadth of the walls to be 
covered. 

They are laid on a bed of mortar with horizontal levelling, 
but without filling. 

Bricks of Enamelled Stoneware. Besides the solid bricks 
of enamelled stoneware, which may advantageously take the place 
of ordinary bricks, special hollow bricks, enamelled on one or 



GLAZED AND ENAMELLED BRICKS AND TILES. 4! I 

both sides, are also made for the economical facing of walls and 
the construction of partitions. 

Bricks enamelled on one face have various dimensions (Figs 

Fig. 7i3- 




Fig. 711. Fig. 712. Fig. 714. 

Figs. 711 to 714. Bricks of Glazed Stoneware (Jacob et Cie.). 



HOLLOW BRICKS AND ENAMELLED "BARDEAUX." 

Fig. 7i5- Fig. 716. Fig. 717. Fig. 718. Fig. 719. Fig. 720. 

- 




Fig. 724. Fig. 725. 

Figs. 715 to 723. (Muller.) 



Fig. 726. Fig. 728. 

Figs. 724 to 728. (Jacob et Cie.) 



716, 718, 719), and Figs. 7 1 5 and 7 1 2 show the manner in 
which they are used. 

For the above-mentioned bricks may be substituted plates 



412 POTTERY IN ARCHITECTURE. 

(Figs. 723, 725), which are obtained by vertically cutting 
" bardeaux," large hollow bricks enamelled on both sides (Figs. 
722, 724). The ribs formed by cutting are used for fixing 
the plates to the coating of the wall (Fig. 721). 

" Bardeaux" enamelled on both faces (Fig. 726) are used for 
constructing partitions having the thickness of a " bardeau " and 
requiring to be faced on both sides. 

For the bottom of the walls, bricks in the shape of plinths 
(Fig. 717) or grooves (Figs. 727, 728) are used in order to avoid 
any angle in which dust may accumulate ; this is of great 
importance in certain cases in hospitals, for instance. 

Enamelled Tiles. These are used in the same way as 
ordinary tiles, but the roofs must be given a great slope, for 
reasons indicated above. We may recall the immense mosaic of 
bright and harmonious tints, due to the architects Formige and 
Bouvard, which covered the domes of the Palaces des Beaux-Art 
and des Arts Decoratifs at the International Exhibition of 1889. 

More than two hundred thousand enamelled tiles of various 
shapes six hundred and twenty different types were necessary- 
were made for this work by Emile Muller, of Ivry. 



CHAPTER III. 
DECORATED QUARRIES. 

ACCORDING to the uses for which they are intended we must 
distinguish between 

I. Paving quarries, either plain or decorated with dips, without glaze. 
II. Facing quarries, plain or decorated, glazed. 
III. Stove quarries, plain or decorated, glazed. 

Each kind requires special qualities, according to its destina- 
tion ; a facing quarry cannot be used for paving, and, even if 
certain stove quarries may under certain circumstances be applied 
to facings, the contrary, as we shall see, is certainly not true. 

I. PAVING QUARRIES. 

With respect to their ingredients, these quarries are divided 



mt( 



1. Quarries of ordinary clay decorated with coloured dips. 

2. Stoneware quarries of various kinds. 



I . Quarries Decorated with Dips. 

These must, without doubt, have been used, like enamelled 
bricks, by the earliest peoples, but their history is not known ; 
we know well, however, that of the incrusted tiles which were 
made with such brilliant success during our Middle Ages. In the 
8th century we find pavements adorned with designs roughly 
executed in relief, unglazed, but laid down with glazed quarries. 
According to Ame, the oldest quarry known dates from 853; 
it bears an inscription under the dark green and very thick glaze. 
From the 9th to the 1 1 th century, a period of ruin and 

413 



414 POTTERY IN ARCHITECTURE. 

struggle, scarcely any progress is to be noted in this branch 
of pottery. In the iith century, monochrome unglazed pave- 
ments are found with incrusted designs ; this simplicity was 
required in the Cisterian churches, and is in contrast with the 
rich decoration of the Clunician churches and abbeys. The 
death of Saint Bernard removed the severe rules which he had 
enacted, and it is actually to the Cisterian abbeys that we owe 
those important improvements in terra-cotta pavements at the 
end of the 1 2th century, due to the use of inlaid clays of 
various colours. 

The pavements at the beginning of the 1 2th century are 
formed of small quarries of a single colour but of various shapes, 
often inlaid with a small piece of terra-cotta of another colour. 
The combination of all these bold-coloured squares, red, yellow, 
green, and black, form a kind of mosaic and give a fine effect, as 
may be seen by the pavements of that period still in existence at 
Saint-Denis (Seine), and Sainte-Colombe-lez-Sens (Yonne). The 
dominant colours of these pavements are black and green. 

At the end of the i 2th century inlaid squares appear, with 
or without glaze, in which black predominates. One of the most 
beautiful pavements of that period is that of Saint-Pierre-sur- 
Dives (Calvados). The 1 3th century made great use of these 
quarries in different colours ; red predominates, yellow-green 
tends to disappear, black and brown are used to enclose divisions, 
but we observe in the manufacture less care and choice than in 
the 1 2th century; nevertheless some of these pavements are of 
great beauty. 

In the 1 4th century the designs of incrusted quarries 
become more confused and more scanty ; a profusion of initials, 
arms, and inscriptions are introduced into them ; green and light 
blue appear among the colours ; black becomes rare. Ornamented 
pavements of the I4th and i 5th centuries abound in Champagne 
and Burgundy. 

In the 1 6th century we see, side by side with incrusted 
squares, faience quarries in which white, yellow, blue, and green 
predominate, and which form the marvellous pavements of 
Ecouen, Blois, Langres, etc. The bright colours of these quarries 



DECORATED QUARRIES. 415 

were soon preferred to the naturally duller tints of clay squares, 
and for more than a century, faience pavements were in fashion. 
Then came the decadence, and in the I7th century, paving 
with incrusted quarries fell into complete oblivion. 

It was the Englishman Wright of Staffordshire who revived 
the old processes, and it was Herbert Minton, assignee of Wright's 
patent, who succeeded in overcoming all difficulties and in manu- 
facturing products superior to those of the Middle Ages in quality 
and decoration. The industry passed from England into France, 
where to-day there are important factories which make exclusively 
that type of quarry. 

Manufacture. After the clays have been crushed, washed, 
decanted, and filtered, they are brought into a state fitting them 
for moulding by the following method. 

The plaster relief of the pattern required is placed at the 
bottom of a plaster mould, and a first layer of clay of the first 
quality is applied with the hand to this relief, then another layer 
of less good clay, then another of inferior quality, and so on, until 
the proper thickness of the quarry is reached. 

The whole is then placed under a quarry-press and strongly 
compressed, the relief at the bottom of the mould being printed 
in hollow on the clay ; the slab is then removed from the mould 
and taken to the drying-room. When the paste is sufficiently 
hardened, the various naturally or artificially coloured dips 
are poured into the hollows in a state of paste, and the slab is 
left again to dry. After a sufficient desiccation, the surface of 
the quarry is freed from irregularities, it is polished, and drying 
is allowed to continue slowly, being completed in twelve to 
fifteen days. Firing may be effected in any suitable kiln. 

One of the difficulties of this method of manufacture is the 
avoidance of the unequal contraction of the different layers of 
clay. The pastes used should therefore be prepared and tested 
with this view. 

As the use of clays of different qualities is only intended to 
reduce the amount of fine clay, there is no reason why a quarry 
should not be made of the same clay throughout its thickness; 
moreover, instead of executing the design by means of dips 



416 POTTERY IN ARCHITECTURE. 

applied to the surface, it may be made to traverse the whole mass 
of the quarry. The earliest pavements were formed in this way. 
The manufacture is more costly, but the products last longer. 
This question is now of secondary importance, for quarries of 
incrusted stoneware have entirely taken the place of those of 
ordinary clay. 

2. Stoneware Quarries. 

Stoneware is pottery made of hard paste, impervious and 
opaque, white or coloured, covered with a glaze or not. This 
definition, which at first sight seems clear, is difficult of applica- 
tion to intermediate products. 

Imperviousness and hardness, distinguish stoneware from 
simple or made-up terra-cottas, but these are relative qualities ; 
opacity distinguishes stoneware from porcelains, which are trans- 
parent, but where does transparency begin and opacity end ? 

Here again practice is better than rigorous classification. A 
man in the trade will not confuse a stoneware with a porcelain, 
and he will know with certainty whether a certain paste should 
be called stoneware or not. 

However that may be, stoneware is obtained by the firing of 
clays, which contain naturally, or have added to them, substances 
called fluxes ; the property of these is to effect in the mass a 
degree of softening sufficient to weld the molecules together and 
thus cause imperviousness, but not pronounced enough to cause 
loss of shape in the pieces. Clays which fire direct into stone- 
ware are called natural stoneware clays. 

Natural Stoneware Clays. These contain a certain quantity 
of alkalies and lime, and sometimes of oxide of iron, which act 
the part of fluxes. The proportion of them should be such that 
the paste is neither too fusible nor too infusible ; the composition 
of these clays must then vary between narrow limits which 
average 

Silica 68 to 75 per cent. 

Alumina 20 to 25 ,, 

Lime and magnesium . . . . . 10 to 20 ,, 

Alkalies . . . . . . . . 3 to 5 ,, 

Oxide of iron variable quantity. 



DECORATED QUARRIES. 417 

Artificial Stoneivare Clays. These clays are prepared either 
by adding a refractory clay to a fusible one, or the reverse, 
i.e. by adding fluxes to a refractory clay. 

In the first case, we must not think that all fusible clays will, 
when mixed with a refractory clay, give good stoneware. The 
properties of these clays must be such, that the softening takes 
place without injury to shape. In this respect, clays containing 
alkalies (2 per cent.) in the form of silicates or felspar, are pre- 
ferable to those which are simply calcareous. As to the com- 
position of the mixture, experience alone can guide us in each 
particular case. 

The addition of fluxes to refractory clays also requires the 
aid of experience in estimating proportions. The substances used 
as fluxes are felspar and pegmatite for stoneware of good quality, 
and marls, or better still, blast-furnace slag (silicate of lime) for 
cheaper stonewares. The clays used are according to the pro- 
ducts required kaolin and white or coloured refractory clays. 

Colour of Stoneivares. This depends upon the composition 
of the paste, and varies from white to a more or less brownish 
yellow. White stonewares require pastes absolutely devoid of 
iron. A small quantity of this metal gives yellow, a larger 
quantity brown ; and these colours pass into a more or less 
bluish grey if firing takes place in a reducing atmosphere. Real 
red tints are more difficult to obtain than with ordinary terra- 
cottas ; a large proportion of oxide of iron is required, very little 
alkali, no lime, and a neutral final atmosphere, neither oxidising 
nor reducing. 

According to the nature of their pastes, stoneware quarries, 
or those so called, are divided into 

ti. Of slag base. 

A. Plain fired stoneware quarries . . . \ ~, c .,. . 

^ 2. Of fusible clay. 

c I. Of special clay firing to stoneware. 

B. Plain or incrusted stoneware quarries . -j t\tt \ i 

A. FIRED STONEWARE QUARRIES. 

These quarries have some of the qualities of stoneware, such 
as hardness, but their paste is not absolutely impervious, and 

27 



POTTERY IN ARCHITECTURE. 



even when entirely melted always remains slightly pervious. 
They are subdivided into 

i. Quarries of Slag Base (also called Pont-Sainte-Maxence, 
principal place of their manufacture). They are made by mixing 
blast-furnace slag with special, and more or less refractory, rich 
clays. This substance, the residue of casting, is a double silicate 
of lime and alumina, with variable quantities of the oxides of iron 
and manganese ; its great fusibility is due to the presence of lime. 
After having been crushed and reduced to powder, this slag is 
blended in a pug-mill with the clay ; the mixture is then machine- 
expressed and cut to the required size. When the slabs thus 
formed have acquired a certain degree of consistency in the 
drying-rooms, they are stamped in the mechanical presses which 
have already been described, are again taken to the drying-sheds, 
and then fired in kilns. 

The principal centres of this manufacture are : in France, 
in the 1'Oise department, at Pont-Sainte-Maxence (Defrance et 
Cie.), at Auneuil (A. Boulenger), at Canteleu-Lille (De Smet et 
Cie.) ; in Belgium, at Jurbine and Tertre ; in Alsace, at Sarre- 
guemines ; in Germany, at Ehrang-lez-Trier, Saint-Johann, etc. 

PARTICULARS OF STONEWARE QUARRIES OR 
PAVING-SQUARES. 













Number 


Price. 




Colour. 


Shape. 


Dimensions. 


Weight. 


to the 
Square 




Per 












Metre. 




Square 
















Metre. 


Boch freres 


Yellow 


Square 


0.147 


0.045 




50 


160 


8 


I 






0.170 


0.030 




33 


240 


8 to 9 


Defrance . 






0.142 

o. 160 






50 
38 






Jacob .... 
Muller .... 
Perrusson fils and Des- | 
fontaines . . ( 
Simons .... 






o. 140 
0.140 
0.170 
0.140 
0.140 


0.045 
0.045 
0.040 
0-035 
0.035 


.700 
.650 
500 
.400 


50 
50 
33 
50 
50 


160 
170 

140 


8 
8 
7 
6.75 
7 


Smet (De) . . j 


Black 




0.140 


0.033 


.400 


5 


120 
150 


6 
7.5 


r 


White 




0.140 


0.030 


I.2OO 


5 




6.75 


Societe des produits ce- ' 
ramiques (Boulogne- { 
sur-Mer) 


Black 
White 
Black 
White 






0-035 
0.040 


j) 
1.400 

1. 600 


5 5 

50 

50 




11.25 
7.00 
11.25 
7.25 


I 


Black 






? > 


" 






12.00 



DECORATED QUARRIES. 419 

2. Quarries of Melting Clay. -These are made in various 
factories which are easily able to procure what are called melting 
clays namely, clays which, used alone, begin to fuse under a 
strong firing, and thus bring the molecules closer together. The 
quarries made of these clays are of the same shapes as those 
of Pont-Sainte-Maxence, and they are called artificial stoneware 
quarries, ceramic quarries, etc. 

Applications. 

Stoneware quarries are used for paving sidewalks, yards, 
passages (Fig. 737), stables, factories, etc. They are generally 
1 4 centimetres square and 4 centimetres thick ; their colour is 
yellow, brown, or black. The surface of them is furrowed so as 
to prevent slipping and give a hold to horses' feet. The principal 
types (Figs. 729 to 736) are: the staircase quarry (Fig. 729), 
quarries striated in arabesques (Fig. 730), diagonally (Fig. 734), 
or in angles (Figs. 731, 732), the granulated quarry (Fig. 733), 
the "grand cross" quarry (Fig. 735). 

The difference of colouring is taken advantage of to execute 
designs which break the monotony of the pavement (Fig. 737). 
The quarries are laid upon concrete or cement. 

The quarries of clay which fire into stoneware are of the 
same shape as the preceding (Figs. 738 to 746), and their 
thickness varies from .035 to .4 5 metres ; they are used for the 
same purposes. 

Thus 739, 741, 742 are used for stables, yards, passages; 
738 and 743 for side- walks ; the plain square 738 is for factory 
hot-air chambers ; and lastly, 744 is used as a kennel-stone. 

According to their shapes, the quarries are cut in two 
medially or diagonally (Fig. 738) or diagonally only (Figs. 742, 
743); the squares 741 can be divided into thirds or two- 
thirds, or into halves and quarters ; and finally, the hexagonal 
quarry (Fig. 746) may be cut along AB or AC. Besides these, 
we have half-squares ready made (Fig. 740). 



4 2 



Fig. 729. 



POTTERY IN ARCHITECTURE. 

Fig. 730. Fig. 731. Fig. 732. 






Fig. 733- 



Fig. 734- 



Fig. 735- 



Fig. 736. 










Fig. 737- 




Figs. 729 to 737. Various Quarries from Pont-Sainte-Maxence (Defrance et Cie.). 
Fig. 738. Fig. 739. Fig. 740. Fig. 741. . Fig. 742. 

i* <v ^i&: 

|- ;|.v. I- || T imp,. ||i' ||... ~* *-* * <T X^M^ktll^l^VV. * m .-^ K > ^- ,- , 

s r M H ? II,' hi i : I ?: winnim _ . -. , 1^1^10^ 



Fig. 743- 









Fig. 744. Fig. 745. Fig. 746. 

"1 



1 





Figs. 738 to 746. Ceramic Paving Squares (Muller et Cie.). 



DECORATED QUARRIES. 



B. STONEWARE PLAIN OR INCRUSTED QUARRIES. 

i. Of Special Clay Firing into Stoneware (Stoke-on-Trent 
manufacture). The Potteries district in Staffordshire is the 
principal and almost the sole centre in England of this manu- 
facture. It was at Stoke-on-Trent, the chief town of the Potteries, 
that Minton began his attempts at the reproduction of mediaeval 
encaustic tiles. Since that time, now many years ago, the 
primitive processes have been perfected, and a certain number of 
large houses successfully produce quarries of this type. 




Fig. 747. Direct-flame Kiln used in England. 

In France, the manufacture of stoneware quarries inlaid with 
clays of different colours was introduced about the year 1855 by 
M. Boulenger the elder, of Auneuil, who remains still almost the 
only regular maker of that style of product. 

Clays of special qualities are required for the manufacture of 
these quarries. The preliminary treatment consists of crushing 
in presence of water, and for that purpose the mills described on 
pp. 57 to 60 are used. Other mills, called block-mills (Fig. 
748) are sometimes 'substitued ; in these, the grindstones are 
replaced by large stones moved by the horizontal arms of a 



422 POTTERY IN ARCHITECTURE. 

vertical shaft. The bottom of the pan is paved with hard stones, 
and a ring prevents the blocks from rubbing against the sides of it. 
The advantage of these mills is that renewal of the grindstones is 
avoided. Alsing cylinders (Fig. 789) may also be used. When 
the clay is properly tempered, it is sent to the filter press, or, 
more simply, is left in the open air until it attains the proper 
degree of desiccation. Plain quarries are made from the clay 
when reduced to powder by some method. This powder is 
placed beside the press, which is generally a screw-press worked 




Fig. 748. Block-mill (Boulton). 

by hand (Fig. 604). With one hand the workman fills the 
mould with the powder, which is moistened to the proper degree, 
and applies pressure with the other. This method of manufac- 
ture is a fairly quick one. After being removed from the mould 
the quarry is trimmed and polished, and then goes to the 
drying-room. 

But when incrusted quarries are to be made, the moulding is 
carried out by the ancient process which we have described in 
the case of ordinary clay quarries decorated with dips. This 



DECORATED QUARRIES. 423 

process requires a considerable amount of labour. The quarry 
is moulded with several layers of different pastes, the composition 
of which is such that their contraction is similar ; the bottom 
layer lies upon a plaster mould, and by pressure the top of this 
mould is reproduced in hollow on the quarry. The latter is then 
taken from the mould and dried. When the paste is dry enough, 
the coloured dip, which is prepared separately in colour -mills 
(Figs. 701 to 704), is poured on to it, and it is again dried ; then 
the second dip is laid on, the quarry is again dried, and so on. 
Finally, when all the dips have settled and are sufficiently hard, 
the excess is taken off and the pattern is disclosed ; the quarry 
is then polished with a steel knife. This manufacture of poly- 
chrome incrusted quarries is less quick than that of the quarries 
of felspar base which we shall describe later. 

After drying, the squares are fired in direct - flame kilns 
(Fig. 747), similar to those used for faience ; they are the kilns 
most generally employed in England. At Stoke, for instance, 
their tops are seen in all directions above the roofs of the 
factories. These kilns are not very economical, but the price of 
coal is not high enough to force manufacturers to improve upon 
their system of kilns. Firing takes place at a temperature high 
enough to transform the clay into stoneware, thanks to its 
natural composition. 

Concurrently with this process we now use moulding with dry 
clay, which is more rapid. It will be described later on under 
the head of Manufacture of quarries of felspar base. 

Applications. 

The variety of designs, their composition, their colour, and 
the manner in which the quarries are combined, present an in- 
exhaustible means of decoration from which everyone can draw 
according to his taste. Let us first give some specimens of 
French manufacture (Figs. 749 to 758). The groundwork of 
the pavement (Fig. 749) is composed of the quarries 755 and 
757, and is framed with the square 756 and the border 754. 
The grouping of four quarries (Fig. 752) round 753 produces the 



424 



POTTERY IN ARCHITECTURE. 



pattern 750. The quarry 752, used alone, gives a different 
effect when arranged as a border. 

The English manufacture is of very varied styles, which 
change less often than in France, and, for that reason, are lower in 
price. This is due to a different method of work. An English 
house issues at great expense magnificent catalogues with which 
it will work for a number of years. All the types mentioned in 
the catalogues are made in large quantities ; the patterns and 
colours are invariable, and therefore the cost is lower. In France, 
public taste demands frequent changes in the types made, and 



Fig. 749. 



Fig. 750. 




Fig. 751. Fig. 752. Fig. 753. Fig. 754. Fig. 755. Fig. 756. Fig. 757. 






Fig. 758- 
Figs. 749 to 758. Incrusted Quarries from Auneuil (Boulenger). 

this causes an increase in prices, as the quantity made of the same 
quarry does not sufficiently repay the always large outlay. 

It would be impossible to mention all the important houses 
making incrusted quarries in England. Among the best known 
are : Messrs Carter & Co., Doulton & Co., Maw & Co., Minton, 
Hollins, & Co., Woolliscroft & Son, etc. ; all of them produce 
pieces which are excellent both in quality and ornamentation. 

Plain quarries are generally red, black, yellow, and grey ; 
their shape is square (Figs. 766, 768), hexagonal (Fig. 759), 
or octagonal (Figs. 770, 771). 



DECORATED QUARRIES. 



425 



The combination of these quarries, together or with others, 
produces patterns of infinite variety (Figs. 763 to 771). Stone- 



Fig. 760. Fig. 761. 



Fig. 762. 




Figs. 759 to 774. Plain and Incrusted Stoneware Quarries (Carter Co.). 

ware quarries are easily broken into small pieces, which are used 
for making coloured mosaics more varied and much more 



426 



POTTERY IN ARCHITECTURE. 



durable than those of marble ; this is of great importance in the 
paving of much - frequented places, such as public halls, cafes, 
hotels, etc. 

These mosaics may be arranged in various ways. For 
instance, the little cubes may be placed in concentric circles 
(Figs. 773, 774); flowers (Fig. 778), geometrical patterns (Fig. 



Fig. 775- 



Fig. 776. 



Fig. 777. 




^^^m 
/ 






Fig. 778. Fig. 779. 

Figs. 775 to 779. Incrusted Quarries (Encaustic and Mosaic Tiles of 
Minton, Rollins, & Co.). 

786), or lastly letters (Figs. 780, 787), may be made with 
them. 

In these mosaics the pieces are always irregular ; regular 
mosaics (Fig. 775) are formed with little uniform cubes made by 
special machines. 

Figs. 776, 777, 779, 781, 782, 783, 785 show the 
numerous combinations which can be effected with incrusted 



DECORATED QUARRIES. 
Fig. 780. 



427 




Fig. 781. 




Fig. 786. 




Fig. 787. 
Figs. 780 to 787. Incrusted Quarries (Encaustic and Mosaic Tiles of^Maw Co.). 



428 POTTERY IN ARCHITECTURE. 

quarries. These illustrations lack the charm of colour which 
makes the pavements so attractive and agreeable to the eye. 
(See Plate I.) 

The firm of Minton, Rollins, & Co. have executed some 
important pavements of incrusted quarries in England, especially 
that in the Palace of Westminster. The patterns of this pave- 
ment are remarkable and most effective in spite of the fact that 
only two colours, yellow and red, are used. Its great wearing 
qualities must also be noted : although laid down more than fifty 
years ago, it has borne the considerable traffic of the corridors 
and central hall without appreciable damage to the incrustations. 
The pavements of the South Kensington Museum, laid down by 
the same firm, are polychrome, and are in the form of mosaics of 
varied tints resembling the patterns shown in Figs. 775 and 
776. 

2. Plain and Incrusted Quarries of Felspar Base. These 
quarries are made in France, Belgium, Germany, and Spain. 
They are made of a mixture of rich clays and felspar, to 
which, for the coloured portions, are added metallic oxides. The 
factories in the North of France obtain their primary materials 
from Luxembourg, the banks of the Rhine, Belgium, and England ; 
those of the centre from a less distance, on account of the cost of 
transport part of their primary materials comes from Diou in 
the Allier (H. Gay), hence there is a difference of appearance 
between their products and those of the North. The ingredients 
of the pastes must be more or less pure according to the type of 
quarry which is to be manufactured, and their quantities are a 
matter of experience only possessed by those who carry on this 
class of manufacture. 

The best pastes are always the result of a mixture of several 
plastic clays thinned with a cement formed of powdered terra- 
cotta. White or only slightly coloured products require fairly 
pure pastes containing little or no oxide of iron. 

The felspar acts as a flux in consequence of the alkalies 
contained in it (p. 5), and the quantity of it necessary in the 
paste depends upon the refractory qualities of the clay and upon 
the temperature at which firing is to take place. 



DECORATED QUARRIES. 429 

We may take as an example of a paste giving a good fine 
white artificial stoneware 

Plastic clay 25 parts 

Clay kaolin . . . . . . . . . 25 ,, 

Felspar . . . . . . . . . 50 ,, 

This stoneware bears a temperature of nearly 1500 C. 
The felspar may be replaced by the sands which are the residue 
of the washing of kaolins. 

Colouring. To produce the coloured patterns which adorn 
artificial stoneware quarries, metallic oxides are added to the 
mixture of pastes. 

Black is obtained by the addition of oxides of iron and 
manganese (5 to 6 per cent, of each) ; 

Blue with .5 to 5 per cent, according to the intensity 
required, of the oxide of cobalt ; 

Green is produced by the oxide of chromium (.5 to i per 
cent), bluish greens by a mixture of oxides of cobalt and 
chromium ; 

Reds and yellows with yellow and red ochres (anhydrous and 
hydrated oxides of iron). 

The intermediate tints are produced by mixing the above 
oxides in various proportions. 

Manufacture. This is performed with powdered dry clays. 
The primary substances are dried in large ovens heated to about 
50 C. by one of the usual methods hot air, steam, waste heat of 
the kilns, etc. 

The clay may also be spread in a layer 6 or 8 inches thick 
upon stone or metal slabs heated underneath by waste heat. 
When large masses of material have to be dried, hot-air kilns 
are used. (See p. 55.) 

Crushing of the Primary Materials. Dry crushing is done 
with the crushing mills described under the head of the 
preparatory treatment of clays. In the case of white pastes, the 
use of iron must be avoided, and flint grindstones substituted. 
It is better to pulverise the felspar in presence of water in 
special machines like those shown in Figs. 748, 788, 789. 

The Villeroy crusher (Fig. 788) consists of a ball of granite 



430 



POTTERY IN ARCHITECTURE. 



weighing from 1000 to 2000 kilog. and rolling on a tray which 
is also of granite. Scrapers keep the sieve clean and bring the 
substances under the ball. This machine has a large output ; 
with five horse-power, and the holes in the sieve being .004 m. 
(about Jth inch), it crushes I 500 kilog. of coarse felspar per hour. 




Fig. 788. Ball Crushing Machine with Sieve. 

The Alsing cylinders (Fig. 789), which may be of cast-iron or 
steel, are coated inside with a casing of millstone grit in which 
fragments of flint are incorporated. Flint pebbles or balls of 
granite or millstone grit are introduced into this casing. The 
cylinder, which moves on an axle, draws the balls along in its 




Fig. 789. Alsing Crushing Cylinder. 

rotation, and the resulting friction wears and pulverises the mass 
to be crushed. The crushing may be effected on the sub- 
stances when either dry or moist. The opening through which 
the substances to be crushed are introduced is closed by a 
stopper (to the right of the figure), and when the operation is 
finished this is replaced by a grating (to the left of the figure) 



DECORATED QUARRIES. 



431 



which allows the crushed substance to pass but retains the 
balls. 

When the clay is crushed in presence of water, it is after- 
wards passed through the filter press, and thence to the oven ; 
when it is sufficiently dried, it is mixed with the other substances 
required to form the paste. 

If the crushing takes place on dry clay, the powder is damped 
in the proper machines (p. 64) and is then mixed with the 
other materials. The required quantity of metallic oxides is 




Fig. 790. Pump for Hydraulic Press. 

afterwards added to the pastes, if they are to be coloured, and 
the mixtures, closely blended together, are placed in pigeon-holes 
within reach of the workwomen who are to perform the moulding. 
Moulding of Plain Quarries. This is effected by compressing 
the powdered mixtures in metallic moulds with powerful hydraulic 
presses worked in different ways. Some have a revolving table 
(Fig. 791), and the water, compressed by a steam pump (Fig. 
790), acts directly, or through accumulators, which is preferable 
for the uniformity of the products. 



432 



POTTERY IN ARCHITECTURE. 



The table bearing the moulds, three or four in number, is 
turned by hand or with a small pump round one of the uprights 
of the press, in such a way that the compression of one empties 
the one just pressed, and a third is meanwhile being prepared. 
The compression is transmitted from the pumps or accumulators 




Fig. 791. Hydraulic Press (Boulet). 



to the press by a distributer provided with a lever. Two 
accumulators are often used, one of which gives the low pressure 
(50 to 80 atmospheres) and the other the high pressure (200 
to 250 atmospheres). One accumulator serves for four or five 
presses, but two will be required if both pressures are used. 

The full mould is placed upon the piston, and the workman, 



DECORATED QUARRIES. 



433 



by moving the lever of the distributers, gives the lower pressure 
in order to expel the air from between the grains of the powder. 
If this precaution were not taken, the bubbles of air disturbed 
by the pressure would accumulate in a horizontal plane ; in the 
firing, they would become heated and would cause accidents, 
especially in insufficiently baked quarries. At the proper moment, 
therefore, this air must be allowed to escape, and then the high 
pressure is applied by means of the distributers. 

When the quarry is finished, a workman withdraws it while 
another full mould is pushed over the piston. The distributer 
is turned to low pressure ; the piston, by means of a series of 





Fig. 792. Hydraulic Press with Distributer and 
Accumulator (Laeis et Cie.). 



Fig. 793. Hydraulic Press with 
Pump Distributer (Laeis et Cie.). 



levers, sets in motion in its ascent the demoulder, which presses 
on the quarry previously pressed and expels it from the mould. 

Working with accumulators and a single block, three work- 
men produce 1 80 quarries per hour ; with double blocks, the 
production reaches 250 quarries. The direct action of the pump 
only allows of 140 quarries per hour. 

Moulding of Incrusted Quarries. This was the first object 
of manufacture with powdered clay. The pattern of the quarry 
is reproduced by means of a network of thin metallic bands 
soldered together, whose height is equal to the thickness of 
uncompressed incrustation (three to four inches). The cells 
thus formed receive the coloured powders. With the chambered 
network, thin metallic plates are prepared, in which are cut out 
28 



434 



POTTERY IN ARCHITECTURE. 



for the punch the parts of the pattern which are to be of a 
different colour ; each colour then requires a plate whose open- 
ings correspond exactly to the hollows in the chambered frame 
(Figs. 794, 799). Each mould must have its own network and 
its different lids. 

All the moulding pieces being previously prepared, the work 
is then divided ; each colour requires a workwoman. In front 
of her is a compartment from which she draws the coloured 
mixture ; the latter she puts into a small sieve, and, a lid (Fig. 
795) having been placed over the network, the workwoman 
shakes the sieve over a funnel with which the mould is provided 



Fig. 794. 



Fig. 796. 




Fig. 797. Fig. 798. Fig. 799. 

Figs. 794 to 799. Networks for the Manufacture of Incrusted Quarries. 

(Fig. 80 1) ; the pulverised clay falls, and fills the disclosed empty 
space. When it is full, the lid is taken off, and the mould 
passes to another workwoman, who puts on it another lid 
having an orifice corresponding to another colour (Fig. 796). 
This process is continued until all the colours are placed. 

The moulds are made in t\vo parts, which are placed one 
over the other ; the lower part has the thickness of the uncom- 
pressed incrustation, and the upper part that of the paste. When 
the first has been filled as above described the caliber is removed, 
a slight pressure is applied with the hand or a mandrel, and 
the second part of the mould, filled with powdered ordinary 
clay, is put on. Chambered effects are produced by giving a 



DECORATED QUARRIES. 



435 



greater thickness to the copper blades composing the caliber. 
When this latter is removed, a hollow is left which is filled with 
a black paste, and then, a slight shaking motion having been 




Fig. 800. Press with Circular Table for Incrusted Quarries. 




Fig. 801. Press for Incrusted Quarries. 

given to settle the powders, the filling is completed with ordinary 
paste, and the quarry is pressed. 

For limited production the preceding presses may be used, 
or the one represented in Fig. 80 1 ; for large output, it is better 
to use presses with circular tables of large diameter (Fig. 800). 



436 POTTERY IN ARCHITECTURE. 

The moulds run on rails and pass in turn before the work- 
women who are to fill them. When the pattern is completed, 
the second part of the mould is placed over and filled ; then the 
whole is pushed under the press. Removal from the mould is 
effected by means of a small hydraulic press. 

Drying. This is done in closed drying-rooms heated by the 
waste heat from the kilns ; by hot-air stoves or steam when 
the first method is insufficient. 

Firing. The kilns used are intermittent and reverberatory, 
in the style of that described on p. 205 and the following 
pages. 

Figs. 802 and 803 are the section and plan of a kiln 
of the same kind which is working in an important factory 
in the North of France. The furnaces are ten in number, the 
draught passes through the centre of the kiln, and the flames 
follow the course indicated by arrows. The quarries are packed 
with sand in large saggers ; the stacking must be judiciously 
done, the quarries whose colouring oxides best resist the heat 
being placed in the hottest parts of the kiln. Care should be 
taken not to put in the same sagger quarries whose colours 
have different properties, etc. The fire, which is pushed gently 
at first, reaches its maximum at the end of the operation ; 
the temperature is then from 1200 to 1400 C., sometimes 
as much as 1500 C., that of dazzling white. The consumption 
of coal depends upon its quality ; as an average, we must allow 
25,000 kilog. for a kiln which contains 40,000 kilog. of quarries, 
which represents I ooo square metres of pavement. 

Continuous kilns with separate chambers, even those using 
gas, do not seem to give satisfactory results. A semi-continuity 
may, however, be established by arranging intermittent reverbera- 
tory kilns in a battery of four or six. 

Applications. 

The manufacture of stoneware quarries with powdered clay 
was introduced into France by Boch brothers in 1861. Their 
factory at Maubeuge was then under the direction of M, Simons, 



DECORATED QUARRIES. 



437 



REVER13ERATORY KILN FOR STONEWARE QUARRIES. 

Fig. 802. 
Vertical Section through C D. 




Horizontal Section~through/A B. 




Fig. 803. 
Fig. 802. Section. Fig. 803. Plan. 



43$ 



POTTERY IN ARCHITECTURE. 



who retired from the firm in 1868 and founded, at Cateau, the 
factory which is at present managed by his sons. Two other 
managers of the Boch firm, MM. Sand and Charnoz, founded 
factories at Feignies and Paray-le-Monial respectively. To 
these four establishments another was added in 1882, that 
of M. van Overstraten de Smet at Canteleu - Lille. The 
firm of Ferrusson fils et Desfontaines also makes incrusted 
quarries. 

The method 
of manufacture in 
the centre of 
France (Charnoz 
and Perrusson) 
differs from that 
of the North both 
as regards mould- 
ing and primary 
substances. 

The principal 
centres of the 
manufacture of 
stoneware in- 
crusted quarries 
> abroad are at 
Saint-Ghislain 
(Cie. generate 
de produits 
ceramiques) and 
at Chimay ; in 
Spain, at Barce- 
lona (Romeu 




Figs. 804 to 807. French Incrusted Quarries (Perrusson 
fils et Desfontaines). 



Fscofet), at Valence (Miguel Nolla) ; in Germany, at Mettlach 
(Villeroy and Boch), at Jingig, etc. 

Generally speaking, the quarries made on the Continent are 
used like English quarries ; only the patterns are different. 
The black and white squares are the simplest, and form geo- 
metrical (Figs. 804 to 806) or fancy patterns (Fig. 807). The 



DECORATED QUARRIES, 



439 



quarries with polychrome patterns are of less severe aspect 
and are arranged in different ways, the commonest being the 

Fig. 808. 






Wb 




Fig. 8 10. 




Figs. 808 to 810. French Incrusted Quarries (De Smet et Cie.). 



combination of four squares to produce roses (Fig. 808) or other 
decorative effects (Figs. 809, 810). 



440 



POTTERY IN ARCHITECTURE. 



But a single qi^arry having a special pattern is sufficient to 
produce a large number of varied designs, as may be seen from 




> ^ s 

;> '.. tf ^ ' ^ r V'V 

-- Jr^t^ "' ;V ^ ^ ' ^" ::>>! 

^^.v^;^; . ^ ^^&^3^aB 

- ^1^^^^^^^^^ 

^^MgSS^g^Bftg^^ ^ 

^ : * r v ,&^Pc!M7*-> * v 1 ^.. ^ . v^idfe^tow 



^hr 



^7 



^: V^ . \>^ 





Figs. 813, 814, 815, which are produced with the quarry 
81 i, 812. 



DECORATED QUARRIES. 



44 I 



As we might expect, we find in the Spanish quarries the 
influence of Arab ornamentations ; the firm of Nolla, one of 
the most important of that country, also produces geometrical 




Fig. 816. Mosaic of Incrusted Quarries (Spanish Manufacture of Miguel Nolla). 

mosaics, with patterns inspired by the Renaissance (Fig. 816) 
and even by Persian art. 

The use of mosaics in stoneware, so extensive in England, 



442 



POTTERY IN ARCHITECTURE. 



is beginning to extend in France, in which country they made 
their first appearance only about ten years ago. Besides their 
variety of colour, they have the advantage of very great dura- 
bility. They may be of geometrical pattern (Fig. 8 1 8) or dis- 
play concentric circles of uniform (Fig. 820) or varied colour 
(Fig. 819), adorned with arabesques or flowers. 



Fig. 817. 




Fig. 819. Fig. 820. 

Figs. 817 to 820. Stoneware Mosaics (De Smet et Cie. ). 

Geometrical mosaics are formed of little cubes of different 
colours, which are made by special machines ; the others are 
executed from fragments of different dimensions and shapes 
obtained by breaking plain stoneware quarries. In laying 
down mosaics we must avoid leaving crevices ; this is 
done by the use of old half-softened cement ; besides, manu- 



DECORATED QUARRIES. 443 

facturers undertake the laying down of their products them- 
selves. 

The price per square metre of pavements of incrusted stone- 
ware (not including laying, which costs from 4 to 6 francs the 
metre) varies from 10 to 20 francs for the best quality and 
from 7 to 14 francs for second quality. 

Stoneware mosaic pavements cost from 25 to 300 francs 
per square metre (laying included) according to the richness of 
the pattern. 

II. FACING QUARRIES. 

Paving quarries are not glazed. It is true that in the 
Middle Ages varnish was used to protect the patterns, and that 
faience pavements were fashionable during the i6th and i/th 
centuries, but these are exceptions which should not be imitated, 
as the slippery surface of these quarries makes them dangerous. 
Their use, however, is distinctly indicated for the facing and 
artistic ornamentation of walls. 

Facing quarries are divided, according to the nature of their 
paste, into 

1. Faience quarries ; 

2. Stoneware quarries ; 

3. Porcelain quarries. 

i. Faience Quarries. 

The word " faience," first applied only to enamelled terra- 
cotta, has been since extended to ceramic products which are not 
enamelled terra-cottas, such as those English flint-wares which 
are made of white paste formed of kaolin, flint, and felspar, and 
have colourless glaze. This same paste is much used in these 
days for making quarries which afterwards receive different kinds 
of decoration, and are called faience quarries from their re- 
semblance to the old quarries of enamelled clay. We must 
then class quarries according to their composition and distinguish 
between 



444 POTTERY IN ARCHITECTURE. 

A. Quarries of limestone paste (stanniferous faience) ; 

B. Quarries of silica paste (Persian faience) ; 

C. Quarries of felspar paste (flint-ware, iron-clay, etc.). 



A. QUARRIES OF LIMESTONE PASTE. 

These receive stanniferous enamels which require the presence 
of lime in the paste in order that there may be harmony between 
the two. We give as examples three formulae for Paris faience 

Bastenaire - Daudenart, White clay or calcareous marl from 

the Combat pit . . . . . . . . 12 

Green clay from the same pit. . . . . . . 12 

Yellow clay (Picpus pit) . . ..... 10 

Arcueil clay (Fontainebleau pit) ...... 6 

Brongniart. Plastic Arcueil clay ...... 8 

Greenish clay-marl ........ 36 

White calcareous marl ....... 28 

Yellowish marly sand ........ 28 

Salvetat. Green Fresnes clay . . . . . -37-5 

White marl 30 

Picpus fireclay ......... 20 

Fontenay sand ......... 8 

Gentilly clay 2.5 

The clays are prepared as usual by blending ; each manu- 
facturer has his own special processes according to the clays he 
has to treat. The quarries are moulded by hand in plaster moulds 
which have the pattern, if there is one, in hollow or relief on 
them. Presses may also be used. 

The glaze for these quarries, which is always stanniferous 
and consequently opaque, has the white enamel as its base. 
The processes described in the general remarks on glazes may 
be used for their decoration, but the method most frequently 
employed is decoration on unfired enamel. In this way are 
made the thousands of common squares used for facing kitchen 
ranges, and, in France, principally manufactured at Ponchon 
(Oise) and Desvres (Pas-de-Calais). 

The white enamel is spread over the quarry by immersion, 
and after drying the pattern is printed by means of a cut-out 



DECORATED QUARRIES. 445 

engraving or a stencil - plate over which a hard brush covered 
with the enamel paste is rapidly passed. 

If the pattern includes beads, they are made by hand. This 
process, called " au pochoir," is carried out with extraordinary 
rapidity by highly- skilled workmen, and they succeed in pro- 
ducing quarries which can be sold finished, at seven francs a 
hundred or even less. 

The decoration is monochrome, but it can be enriched with 
other colours either by the brush, or by the usual processes. 

For outer facings, the quarries have a greater thickness ; the 
unenamelled side, which is placed against the wall, bears hollows 
intended to increase the adhesiveness of the mortar. 

B. QUARRIES OF SILICA PASTE. 

This paste is the base of the Deck faiences, whose brilliancy 
and decorative effects are comparable to the finest ancient Persian 
faiences, and which are now freely manufactured, thanks to the 
generosity of the inventors in publishing their processes. The 
paste is prepared by crushing in a dry state a frit composed of: 
85 parts of Fontainebleau sand, 7 parts of carbonate of potassium, 
3 parts of carbonate of soda, and 5 parts of chalk. To I 5 parts 
of this frit are added 25 parts of refractory white clay and 
60 parts of flint. The addition of 6 to 8 parts of chalk gives 
a harder clay, more easily cut but more liable to lose shape in 
firing. The paste is white, not very plastic, and is difficult of 
treatment, which is not an obstacle since it is intended for small 
smooth surfaces ; its total contraction may be as much as 2 per 
cent. 

The quarries are moulded by hand or in the press ; after 
drying they are fired, and if necessary finished on the grind- 
stone. Although they are white, they are dipped to give more 
delicacy to the colours and to render the biscuit less absorbent, 
thus permitting of greater uniformity of colouring. The manu- 
facture is more troublesome, but the results are much superior. 

The dip is composed of 7 5 parts of frit, I 5 parts of chalk, 
and i o parts of white clay, to give it a little pliability; the whole is 



446 POTTERY IN ARCHITECTURE. 

crushed fine and diluted with water to the required consistency. 
The dip is applied by dipping or sprinkling, and is fixed 
by firing ; it is then decorated with finely ground colours 
diluted in the muller with a little gum arabic. These are 
applied with the brush, each tint in turn, avoiding impastes, 
which the glaze would not be able to dissolve and which would 
give a dull appearance. The piece is then covered with a glaze, 
crushed not too fine in a dry state, and containing 

Deck. Sevres. 

Minium ........ 30 30 38 

Sand ......... 48 50 38 

Carbonate of potassium . . . . . 12 12 15 

Carbonate of sodium . . . . . . 10 8 9 

The temperature of firing is about 1000 to 2000 C. 



C. QUARRIES OF FELSPAR BASE. 

This is the paste of the English flint-wares ; its composition 
varies within certain limits, but usually it contains 

From 20 to 45 per cent, of white plastic clay, which serves as a binding 

substance ; 
From 25 to 45 per cent, of kaolin, to prevent the paste from turning yellow in 

firing ; 
From 20 to 40 per cent, of flint, which shortens and gives whiteness and 

durability ; 
From 5 to 15 per cent, of pegmatite or felspar, which acts as a flux. 

The clays are always washed to separate the coarse parts ; 
the flint is heated in kilns and then crushed, and the felspar is 
also pulverised. The purified substances are diluted in a volume 
of water so measured that they shall have the same degree of 
consistency, and then a calculated quantity of each paste is 
poured into a vat, in which the mixture is effected by stirring. 
After this, the paste is filtered through fine brass wire sieves 
which are shaken by machinery ; the filtered portion is sent to 
the filter press and thence to the cellar to solidify. 

Moulding, in the case of small output, is done by hand ; for 
larger quantities machines working on firm or dry paste are used. 
In this case the paste, when it comes from the filter press, is 



DECORATED QUARRIES. 



447 



carried to hot-air drying-rooms, and is then blended and reduced 
to powder in a centrifugal pulveriser. The two operations are 
performed by the same machine (Fig. 821). 




Fig. 821. Centrifugal Pulveriser. 

The powder is afterwards placed in a metallic mould 
and compressed in a press similar to those described on 

P- 433- 

The quarry may be decorated in various ways. In the case 
of plain glazed quarries, a boracic plumbiferous alkaline glaze is 
used ; some formulae are appended (Pressel). 

Composition of the Glaze. 



Boric acid . 
Borate of soda (borax) 
Carbonate of soda (crystals) 
Carbonate of lime (chalk) . 
Carbonate of lead (while lead) 
Kaolin .... 
Plumbate of lead (minium) . 
Pegmatite .... 

Sand 

Frit . 



Composition of the Frit. 

... 17 ... 18.5 15 ... 18 
35 30 32 ... 

... 22 ... 23.5 1 6 ... 2O 

18 17 ... 15 13 ... 16 



12 15 ii 8 ii 3 13 

19 

3i 25 ... 41 ... 

35 28 17 10 26 24 32 



23 of felspar. 
II-5 

l8 21 12 l8 6 18.5 22 



30 31 8 22 ... ii 18 

6 3 

52 47 74 60 70 59 60 



The glaze is applied by one of the processes mentioned in the 
general remarks on glazing (immersion, insufflation). 



44-8 POTTERY IN ARCHITECTURE. 

When the quarries are to receive a pattern in relief, the out- 
lines are impressed on the clay when still fresh by stamping in 
plaster moulds ; in ordinary patterns the outline is marked out in 
black lines, and in both cases the spaces between the lines are 
fitted in with enamels, generally transparent. This is what is 
wrongly called cloisonne decoration. 

When a large number of quarries are decorated with the same 
monochrome pattern, copper-plate printing is used, and for poly- 
chrome decoration chromolithographic printing. This decoration 
is performed over glaze, and sometimes under glaze. 

Besides, we may use, according to the effects required, one 
or other of the processes mentioned in the general remarks on 
the decoration of pottery. The quarries of which decorative 
panels, intended for the facing of walls, are formed are most 
frequently covered with transparent enamels. 

Firing of the Quarries. This is in two parts : the firing of 
the paste and the firing of the decoration ; sometimes even there 
is an intermediate firing for the glaze or dip, which is placed 
upon the biscuit and fixed before decoration. 

Each manufacturer has his favourite kiln, so to speak, for 
firing the pastes ; many direct-flame kilns are still to be found, 
although reverberatory kilns are increasing in popularity. The 
stacking is done in many ways, and most frequently without 
any precaution, so that the quarries receive the indirect action 
of the flame. Thus in the case of faiences with stanniferous 
enamels, they are arranged in parallel rows and the quarries are 
separated from one another by little pieces of refractory clay 
with angular and pointed surfaces called " spurs." 

The consumption of fuel depends upon the nature of the 
objects fired ; the aim of the manufacturer will be to make the 
best possible use of his kiln by means of a judicous stacking of 
the products. On account of the numerous hollows, the expense 
of fuel varies very little whatever the weight of the stacked 
products may be, and is about 80 to 100 kilog. per cubic 
metre. 

The temperature of firing depends upon the composition of 
the pastes, and rises to about 1000 to 1200 C. 



DECORATED QUARRIES. 



449 



The firing of the decoration depends upon the process and 
the nature of the substances used. The stanniferous enamels 
used for the common quarries of Ponchon or Desvres are 
stacked in loads without special precautions. 

Artistically decorated quarries naturally require more care ; 
we must employ either saggers or stacking " par echappade," 
which consists in dividing the kiln into a series of divisions by 
means of refractory products in the shape of slabs resting on 
supports placed by the quarries and higher than them. 



MUFFLED KILNS. 




Fig. 822. Cross Section. 



Fig. 823. Longitudinal Section. 



The temperature necessary for vitrifying glazes is very 
variable. The enamels for Deck's silicious faience bear up to 
1200 C. ; stanniferous enamels also resist great heat if they do 
not contain too much lead, but over-glaze decoration requires a 
lower temperature: 700 to 800 C. 

Many of these decorations cannot bear contact with the 
gases of combustion, and are fired in muffled kilns. Muffled 
kilns consist of a firing chamber round which the flames and 
gases of combustion circulate without ever penetrating into the 
interior. 
29 



45O POTTERY IN ARCHITECTURE. 

The stacking is done through one side of the chamber, 
which is afterwards built up with a clay mortar. A wall is 
built at a certain distance from the kiln to enclose the 
space in which combustion takes place (Figs. 822, 823). 

The expanded air of the firing chamber escapes through 
an opening which communicates with the upper air-channel and 
in front. Another opening allows of the degree of firing being 
observed. The temperature which can be attained in a muffled 
kiln does not exceed 1000 to I 100 C. at most, and is generally 
much less. 

2. Quarries of Glazed Stoneware. 

Manufacture. They are made in the same way as paving 
quarries, and with the same substances, machines, and kilns. 

Glazing. The glaze with which these quarries are covered 
is always colourless. It is applied in various ways, more 
commonly by salting, as in the case of pipes, by throwing 
sea-salt into the kiln when " en grand feu " ; its nature is then 
silico-alkaline 

Lead glazes are still used, and are applied by volatilisation 
in the following manner. The inside of the saggers is coated 
with a mixture of: sea-salt, 67 parts; carbonate of potash, 28 
parts ; minium, 5 parts. The heat volatilises these substances, 
and they condense on the quarries and attack their surface, 
forming a multiple silicate which forms the glaze. The silica is 
taken from the stoneware, which is always very rich in it. 

Other glazes are also used which contain more lead and 
vitrify at a lower temperature, but which require a second 
firing. Here are two formulae 

Frit for Glaze II. 

Frit 100 

Carbonate of lead . . 35 

Felspar .... 50 





Glaze I. 


Frii 


Melted borax . 


15 




Carbonate of lime . 




15 


,, potash. 


5 




,, soda 




30 


Felspar . 


35 


15 


Kaolin 




10 


Minium , 


. 20 




Quartz sand 


25 


30 



DECORATED QUARRIES. 451 

The glazes are ground and diluted with water ; they are 
applied by sprinkling or immersion. When the paste of the 
stoneware is slightly yellow, the colour is disguised by lightly 
tinting the glaze blue with oxide of cobalt. 



3. Porcelain Quarries. 

The East and especially the far East makes great use of 
porcelain quarries and plates for the ornamentation of walls ; 
this substance does not, however, appear to be used in Europe 
for that purpose. Besides, felspar faience fulfils the same purpose 
in a more economical manner. 

Application of Facing Quarries. 

The applications of these quarries are extremely diverse ; 
we will pass over quarries, for the outside facing of buildings, 
as these belong rather to the category of decorated terra-cottas, 
and we will confine ourselves to quarries which are used on 
interiors. 

Common faience quarries with stanniferous enamels, called 
Ponchon or Desvres (Figs. 824 to 831), are used especially 
for facing the walls above kitchen ranges and for adorning 
these ranges. The most common types of these applications 
are represented in Figs. 827 and 829. 

The quarries of felspar faience compete seriously with the 
foregoing ones ; their patterns are of a higher class (see the 
different styles: Figs 833, 834, 836), and their colours are 
more varied. These quarries are used for mantelpieces, in 
which their appearance is less monotonous than that of white 
panels. 

Bathroom quarries are also made in felspar faience, and 
sometimes of glazed white stoneware. Figs. 848 to 850 repre- 
sent applications of this class of facings. 

The preceding quarries are currently manufactured and have 
not a very decorative appearance, but for higher - class wall 



452 



POTTERY IN ARCHITECTURE. 

Fig. 824. Fig. 825. Fig. 826. 




Fig. 827. 




Fig. 828. 





Fig. 829. 




Fig. 832. 



iiOOP 



^s^m^ 






Figs. 824 to 832. Desvres Faience Quarries (Fourmaintraux-Ccurquin). 



Fig. 833. 




Fig. 834. Fig. 836. 

Figs. 833 to 836. Faience Quarries and Mantelpiece executed with these Quarries 

(D'lluart freres). 



DECORATED QUARRIES. 



453 



ornamentation quarries are made which represent artistic com- 
positions and are sometimes of real value. 

Plate III. represents "Jewellery," a large panel executed by 




Deck from the sketches of Ehrmann, which appeared at the 
Exhibition at Amsterdam in 1883. 

Quite another style is represented by Plate IV.; this is a 
graceful composition executed by the faience factory of Creil and 
Montereau for the Saintes Library. 

Plate V. shows another rustic scene, and is of pleasing effect ; 



454 



POTTERY IN ARCHITECTURE. 



the panel is formed of squares of 1 6 centimetres side, and was 
executed by MM. D'Huart freres of Longwy. 




Fig. 848. Fig. 849. Fig. 850. 

Figs. 848 to 850. Facings of Ceramic Quarries (D'lluart freres). 



III. STOVE QUARRIES CHIMNEY-PIECE FAIENCES. 

The manufacture of these faiences has shown great develop- 
ment, not only in Germany, the country of its origin, but also 
in France, where, according to Deck, a good judge in these 
matters, it has had a great influence on work connected with 
faiences. 

Quarries and Panels for Stoves. These products should, 
without splitting, resist a heat which is uneven, and most fre- 
quently suddenly kindled. For this purpose a paste was used 
whose somewhat loose physical texture is favourable to expan- 
sion. This porous paste, covered with a dip or not, was 
simply glazed. 

When Hirchvogel began the manufacture of enamelled 
faience stoves at Nuremberg, another difficulty presented itself; 
the enamel applied to the paste cracked. It is true that, in 



DECORATED QUARRIES. 455 

Switzerland and Germany, stove quarries which did not crack 
were made with fine calcareous clay containing naturally all 
the elements of an uncrackable paste, but it was impossible 
to manufacture large panels which would bear heat without 
splitting. They fell then from one defect into another ; either 
the faience cracked or it split. As this latter inconvenience is 
more serious than the former, the lesser evil was chosen, and for 
a long time cracked faience was used. At that time only 
stoves in white faience and of small size were manufactured. 

It was in I 840 that Pichenot, a Parisian stovemaker, and his 
son-in-law Lcebnitz succeeded in obtaining a clay suitable for 
making large pieces in which the enamel would not crack ; 
this was the beginning of that faience panel industry which was 
to stimulate so greatly the progress of pottery. 

When Pichenot and Lcebnitz had patented their invention, 
attempts were made to pirate it. Instead of using lime in the form 
of chalk, as the inventors did, marly sands were employed. Pro- 
ceedings were taken which, on appeal, ended in favour of Pichenot 
and Lcebnitz. Having mentioned this as a historical fact, we will 
compare the two formulae which were the subject of contention. 

Pichenot Formula. Barral Formula. 

Vaugirard plastic clay . . -25 Gentilly plastic clay . . . 3 2 

Meudon chalk . . . \ 25) 2vry sandy marl 38 

Belleville sand . . . . 13 i 

Cement made from fragments of Cement made from pottery . . 30 

saggers . . . . .37 

In Germany, where stove quarries are extensively manu- 
factured, Velten clay is used ; this, according to Seger, contains 
on an average 45 per cent, of silica, i I per cent, of alumina, 
5 per cent, of oxide of iron, 16 per cent, of lime, 1.5 per cent, of 
magnesium, 4 per cent, of alkali, and 1 6 per cent, of water and 
carbonic acid. 

Preparation of the Pastes. The clays are carefully chosen 
and the cement is prepared by crushing, but not too finely, 
the fragments of saggers or other pieces (for it is not always 
advisable that the cement should be refractory) in one of the 
mills previously described (p. 57). 



456 



POTTERY IN ARCHITECTURE. 



Fig. 851. 




Eig. 852. 



The whole is blended in pug-mills, and the paste, after 
being made sufficiently homogeneous and plastic, is put into 
parallelepiped or slab shape and carried to the moulding-room 
to be transformed into quarries or panels of different sizes. 

Moulding. Plain panels are made by cutting off a slab of the 
proper thickness from the parallelepiped of clay which must have 
a base equal in size to the largest plate required ; the cake is 
taken up between two rulers in order to avoid tearing it, and is 
placed in a plaster mould (Fig. 851) which has the dimensions 
of the piece to be made ; then it is pressed with the hand as 

evenly as possible, and the excess 
of clay which projects over the sides 
of the mould is removed with an 
iron scraper. In order to support 
the plate and keep it true, " colom- 
bins " made of the same paste are 
welded to it. After being removed 
from the mould, it is carried to dry- 
ing-rooms heated by the waste heat 
of the kilns or by any other means. 

The surface of the slab is either 
plain or has ornamentation in relief 
moulded on it by the hollows of the 
plaster mould. In the case of 
flanged quarries the process is a 
little more complicated. A colom- 
bin made by expression (Fig. 852) 

and having sections represented by C, is welded round the edges 
of the plate, which has been moulded as described above. 

The attachment is strengthened by a small round colombin 
r, which is flattened to the fillet shape c' . In the case of angle 
or corner quarries, the mould is in two pieces to facilitate removal 
of the plate from it (Fig. 853). 

The welding together of the colombin and the previously 
prepared slab may be mechanically effected by a special press 
(Fig- 8 55) The slab and the colombin are placed in a mould; 
a mandrel which has the shape of the inner hollow of the quarry 




Fig- 853. 

Eigs. 851 to 853. Moulding of 
Stove ( )uarries. 



DECORATED QUARRIES. 



457 



is lowered by means of a flywheel, and pressure being exerted 
by two lateral screws, the welding is automatically performed. 
Direct moulding in a press without previous rough fashioning 
does not give good results. 

Drying should take place slowly, and it is often necessary to 
trim the surfaces of the quarries, when the paste has hardened, 
by striking them gently against a flat surface in the case of flat 
quarries, and against two surfaces at right angles in the case of 
angular quarries. 




Fig. 854. Machine for trimming 
Stove Quarries. 



Fig. 855. Press for welding Stove 
Quarries (Schlickeysen). 



Stacking in the Kiln and Firing. Quarries should be stacked 
so as to occupy as little space as possible. The kilns may be 
direct-draught or reverberatory. The quarries when fired are 
trimmed on the grindstone, or with a special machine, which 
consists of a large horizontal cast-iron wheel, covered with 
damped polishing sand. The facing side of the quarries is 
applied to the grindstone. 

Enamelling. Decoration. -- The enamel used is always 
stanniferous, and is of the same composition as the one 
described for faience quarries. The German enamels are more 



458 POTTERY IN ARCHITECTURE. 

alkaline than the French, as will be seen from the subjoined 
analyses 

Alumina . . . . . . . . 4.90 4-24 

Lime 1.36 2.58 

Oxide of tin . . . . . . . 14.00 9.24 

Oxide of lead . . . . . . . 26.75 3 2 - 12 

Potash 1.94 0.67 

Silica 46.70 46.20 

Soda . 4.35 4-95 

The enamelling is effected by immersion or sprinkling, and 
the products undergo their second firing either bare or in 
saggers with the precautions already indicated for enamelled 
pieces. 

For a long time white enamel was the one most used, but 
for the last few years various darker tints such as green, brown, 
blue-grey, or greenish have been applied ; they are obtained by 
means of stanniferous opaque enamels, or transparent coloured 
enamels, laid over dips. The stones have been given an archi- 
tectural style (Figs. 856 to 860), imitated or modernised from 
ancient forms. 

Applications. Figs. 856 to 860 represent some types of 
stoves manufactured by the firm of Loebnitz. The Renaissance 
stove (Fig. 857) is faced with quarries; the angles and cornice 
are formed of moulded pieces. The Gothic stove (Fig. 859) is 
also formed of a collection of quarries ; the other decorative parts 
are moulded and afterwards enamelled. 

The usual stove of Parisian dining-rooms is shown in Fig. 
858 ; it is formed of straight panels curved for angles, supported 
by braces of polished copper. The base of these stoves is 
generally split, and this is due, not to the composition of the 
faience, but to the method of putting together the stoves. A 
certain amount of play should be given to allow for expansion. 
But all the pieces are fitted closely together in order to get a 
fine appearance ; hence ruptures occur. 

Faience Panels for Mantelpieces. These are plates which 
form the frame of fireplaces ; they are made like the preceding 
quarries. They may be white or decorated. The simplest are 
plain, and usually enamelled in white ; other and richer ones have 



DECORATED QUARRIES. 



459 



more or less artistic decorations in colour, executed upon 
unbleached enamel. Figs. 86 1, 862, and 863 show different 



Fig. 856. 



Fig. 857. 



Fig. 858. 




Fig- 8 59- Fig. 860. 

Figs. 856 to 860. Decorative Stoves, Loebnitz Types. 

panels of this kind from the workshops of the well-known 
faience stove-maker, M. Loebnitz. 

Another economical style of decoration has been introduced 



460 



POTTERY IN ARCHITECTURE. 



by the same manufacturer. It is obtained by a special moulded 
embossment ; to this embossment are applied enamels of light 




Fig. 86 1. Fig. 862. Fig. 863. 

Figs. 86 1 to 863. Decorated Panels for Mantelpieces. 



&m 




Fig. 864. Terra-cotta Chimney-piece with Embossed Panels (Loebnitz). 






and dark brown, or other colours, which harmonise with the 
general decoration of the piece (Fig. 864). 



CHAPTER IV. 

ARCHITECTURAL DECORATED POTTERY (FAIENCES, STONE- 
WARES, PORCELAINS). 

UNDER this heading are placed those glazed terra-cotta products 
which are used for architectural ornamentation, and which are 
distinguished by their shape from enamelled bricks. 

The birthplace of this style of decoration, as of many other 
arts, was the East. The Assyrians and the Persians, probably 
also the Chinese, were the first peoples who applied enamelled 
products to the ornamentation of buildings. The Egyptians used 
glazes for their vases, but do not appear to have used them in 
their edifices. 

After having disappeared, under the Greeks and Romans, for 
several hundred years, this style of decoration was again in 
favour during the loth century in the East, and afterwards in 
Europe from the 1 2th century until the i6th, when it once 
more fell into comparative neglect. These ornaments regained 
their popularity in the 1 9th century in certain countries, for 
instance in Switzerland, Germany, England. 

In France, there is also a movement in their favour, but of a 
more tentative nature. 

Speaking generally, all potteries can be enamelled ; all that is 
required is that the paste and glaze should harmonise, so that 
crazing may be avoided. 

The composition of the glazes depends upon the nature of the 
clay. 

The latter may have the composition of faience, of stoneware, 
or of porcelain ; hence the products are of three classes. 

46 1 



462 POTTERY IN ARCHITECTURE. 



I. FAIENCES. 

The paste used is somewhat fusible ; it is coloured pale yellow 
or pink, more rarely white. According to the effects required it 
is covered: (i) with colourless transparent glazes (varnishes), 
which are placed either directly on the paste or over a dip ; 

(2) with coloured transparent glazes (transparent enamels) ; and 

(3) with white or coloured opaque glazes (opaque enamels). The 
three kinds of glaze may be used together, and thus the preced- 
ing effects increased and varied. 

The varnishes, which are generally plumbiferous, contain on 
an average 50 to 60 per cent, of oxide of lead with 40 to 50 per 
cent, of silica, those containing most lead being suitable for the 
most silicious pastes. 

The transparent enamels are prepared with the foregoing 
varnishes to which are added from .5 to 5 per cent., according to 
the intensity of colour desired, of colouring oxides. If several 
varnishes are used together, care must be taken that they melt 
at the same temperature ; this result is obtained by varying the 
quantity of silica, or by introducing alkalies. 

It must be noted that the presence of the metallic oxides 
modifies the fusibility of simple glazes. 

The opaque enamels are most used, because they allow of the 
colour of the clay being masked. The paste must be calcareous 
in order that they may harmonise with it. The fluxes used are 
the oxide of lead, boric acid, and the alkalies ; the oxide of tin 
acts as an opaque substance, and the quantity of it used depends 
upon the colouring of the paste. Above all, the composition 
must be such that there are : ( I ) complete harmony between 
the paste and the glaze, in order to avoid crazing or scaling ; 
(2) penetration of the glaze into the paste, to ensure a solid coher- 
ence between the two substances. 

To satisfy the first condition, we have only to fulfil the laws 
relating to glazes (p. 394). The second is satisfied by noting the 
mutual action of the substances upon one another, for instance : 
to place an alkaline (basic) glaze upon a silicious (acid) paste, 



ARCHITECTURAL DECORATED POTTERY. 



463 



and, conversely, a silicious (acid) glaze upon an aluminous (basic) 
paste, for under these conditions there is a chemical combination 
between the elements of the glaze and those of the paste. As 
regards physical properties, the paste must be porous enough 
without being too much so, and the glaze must be very fusible 
in order that it may penetrate into the pores where the chemical 
reactions will take place. These properties, which are sometimes 
contradictory, oblige us to modify the mixtures, and to choose 







Fig. 865. Sphinx in the Gate of the Palais des Beaux-Arts at the Exhibition of 1878, 
executed by Loebnitz from the Designs of Paul Sedille, the Architect. 



a happy mean. Thus the silicious glazes preferred for aluminous 
pastes are necessarily not very fusible ; the quantity of silica must 
then be reduced or, if possible, an energetic flux added. 

The preparation of the pastes and their moulding is carried 
out as in the case of non-enamelled pastes. 

The glazes are usually applied to the unbaked paste, either 
by immersion, sprinkling, or with the brush, or, for large mono- 
chrome surfaces, by insufflation. Some more delicate pieces are 
glazed when in biscuit or slightly heated. 



464 



POTTERY IN ARCHITECTURE. 



- 



The firing takes place in the usual 
faience kilns, either bare or with appro- 
priate stacking, and most frequently in 
saggers. Certain decorations require the 
muffled kiln. 

The decorative effects obtainable are 
increased by combining opaque enamels 
with transparent enamels, or with dull 
enamels produced by adding a large 
proportion of silica to the glaze, and 
so diminishing its fusibility. Instead of 
applying the enamel to all parts of the 
piece, the natural colour of the clay may 
sometimes be left visible in certain places, 
or it may be covered with gold-leaf, which 
thus adds its brilliancy to that of the 
enamels. 

Lcebnitz was one of the first to make 
ceramic products of this kind, and the 
earliest example was the decoration of 
the monumental gate forming the entrance 
to the French Beaux-Arts at the Inter- 
national Exhibition of 1878; Fig. 865 
shows a part of it. 

The same ceramist executed in a 
similar style the large panels which 
decorated the porch of the Palais des 
Beaux-Arts at the Exhibition of 1889 
(Fig. 866). 

That Exhibition (of 1 889) presented 
a considerable choice of the most diverse 
ceramic products. The Palace of the 
Argentine Republic (Fig. 867) especially 
attracted attention by its remarkable 
ornamentation, consisting only of iron 
and clay, and designed by the architect 
Bellu. 



ARCHITECTURAL DECORATED POTTERY. 



465 



The panels forming the bases of the windows (Fig. 871), the 
metopes (Fig. 870), entrance arcades, knobs and tops of fag ad es 
(Figs. 868, 869), were executed by Loebnitz. Muller had 




Fig. 867. Palace of the Argentine Republic at the Exhibition of 1889 
(M. Ballu, Architect). 



provided bricks and enamelled friezes, such as those on the 
facade pillars, called " Ecus " and " Chats." 

Fig. 873 represents an enamelled frieze with dull ground, 
30 



466 



POTTERY IN ARCHITECTURE. 



"grand feu," executed by Muller, and Fig. 874 is a decorative 
panel with dull ground and reliefs set off by enamels. 

Private buildings, particularly those intended for special 
purposes, such as cafes, restaurants, etc., are also decorated with 
enamelled pottery. It would be easy to mention a great number 



Fig. 868. 



Fig. 869. 



Fig. 870. 








Fig. 871. Fig. 872. 

Figs. 868 to 872. Enamelled Terra-cotta Decorations on the Palace of the 
Argentine Republic (executed by Loebnitz). 

of examples in Paris of this use of decorative pottery, which is 
applied inside in the form of panels of facing quarries, and outside 
in various forms. 

Many of these decorations, however, are not irreproachable 
as regards harmony of colours, and the effects produced are not 
always in the purest taste. As examples we may mention the 



ARCHITECTURAL DECORATED POTTERY. 



467 



design of the entrance gate of the Bal Bullier on the Boulevard 
Saint-Michel, and the fagade of the Cafe Riche on the Boulevard 
des Italiens. Fig. 875 represents the design of one of the 
pillars of this cafe ; the background is formed of enamelled bricks ; 
the figures and bricks, executed by Lcebnitz, are covered with 




Fig. 873. Enamel Frieze, 
"Grand Feu." 



Fig. 874. Decorative Panel 

on Dull Background. 
(Manufactured by Emile Muller.) 



stanniferous opaque enamels in accordance with the traditions of 
the firm, which has remained faithful to this old-fashioned enamel, 
and has, so to speak, made a specialty of it. 

The English naturally make great use of architectural faiences 
in the form of friezes (Figs. 876, 877), decorative panels (Figs. 
878 to 880), etc. 



468 



POTTERY IN ARCHITECTURE. 




Fig. 875. La Danse, executed in Pottery by Lcebnitz. 



2. STONEWARES. 

The use of this material in architectural decoration is, in 
Europe, of recent date; judging from the results obtained, it would 
seem likely that this substance will take an important place in 
the ceramic decoration of future buildings. 

Stoneware will not take the place of terra-cotta ; it will stand 



ARCHITECTURAL DECORATED POTTERY. 



469 



side by side with it, and its presence will introduce a special 
feature into the general ornamentation of buildings. It would 

ENAMELLED POTTERY OF ENGLISH MANUFACTURE (ENAMELLED EMBOSSED TILES). 




Fig. 876. 




<W^\ &g 



tf^l **** 

& *:/K 

^Xi 

"^W 



Fig. 877. 



Fig. 878. 







Fig. 879 




via, Fig. 880. Fig. 88 1. Fig. 882. 

Figs. 877, 879, 88 1. Carter & Co. Figs. 876, 878, 880, 882. Maw & Co. 

therefore be a mistake to try to make one an imitation of 
the other; let us rather leave to each its own qualities and 
characteristics. 



47O POTTERY IN ARCHITECTURE. 

Imperviousness and hardness are the valuable advantages 
which stoneware has over terra-cotta, but these are counter- 
balanced by the difficulties of manufacture, and especially by 
the liability of stonewares to lose their shape at that moment 
in firing when softening takes place. In the case of artistic 
pieces of curved shapes, this deformation is avoided with 
comparative ease. 

The plasticity of stoneware pastes facilitates their moulding 
and even modelling by hand. 

The material is more or less coloured according to the purity 
of the ingredients used ; it may be left dull or be covered with 
a glaze. The latter is generally transparent, as opaque enamels do 
not give good results. 

The silico-alkaline glaze (sea-salt at a high temperature) 
gives satisfactory results in certain cases, but it is often advisable 
to use glazes which are fixed by a second firing at a lower 
temperature, such as soft glazes and even transparent enamels, for 
the colour used in the paste or glaze allows of very pleasing and 
varied effects being obtained. For instance, coloured dips may 
be applied to the stoneware and afterwards developed by a felspar 
glaze ; by firing successively in reducing and oxidising atmos- 
pheres, different tints are obtained, which are the more charming 
as they are unexpected. By taking dips which melt at a lower 
temperature than that of the firing of stoneware, colours of 
pleasing appearance are produced ; the Chinese and Japanese 
have made frequent use of this process. 

The English are past masters in the manufacture of common 
and artistic stoneware ; the firm of Doulton is particularly famous 
for its productions, which are remarkable for their finish, good 
taste, and excellent quality. 

In France, the firm of Emile Muller has for some years 
manufactured decorative stoneware. As long ago as the 
Exhibition of 1889 it produced several enamelled friezes for 
the Palace of the Argentine Republic, one of which, called " des 
Chats" (Fig. 867, to the left on the pillars), was quite a master- 
piece. Since then, at Chicago, and at the different salons in 
Paris, it has shown other specimens (frieze of the Archers 



ARCHITECTURAL DECORATED POTTERY. 471 

and of the Lions of Darius, reproduction of the works of 
Falguiere, etc.) which exemplify the pleasing effects of decorative 
stoneware. We cannot lay too much stress upon these interesting 
attempts, which are evidence of an earnest endeavour to endow 
architecture with a new element of decoration. Experiments of 
this nature are very costly, and the men who initiate them rarely, 
even in case of success, gain great pecuniary benefit from their 
work. 

In a less pretentious manner stoneware has been turned to 
account for the manufacture of decorated balustrades, etc. Its 
durability renders it valuable in certain cases. 



3. PORCELAINS. 

Several attempts have been made to introduce porcelain into 
the facings of walls. MM. Parvillee, the skilful ceramists, had 
exhibited in 1889 some very interesting specimens of decoration 
executed on a special porcelain, the same product which they 
have successfully applied to the manufacture of porcelain articles 
for electrical purposes. The cost of the primary materials and 
certain difficulties in the manufacture have probably prevented 
them from continuing their experiments, and this is much to be 
regretted. 

We know that porcelain is extensively used in the far East 
for the decoration of both the inside and outside of walls. 



CHAPTER V. 

SANITARY POTTERY. 

THIS is a name given to certain ceramic products used for 
household purposes, including more particularly pipes of glazed 
stoneware, sinks, urinals, basins, etc. 

As is always the case with regard to pottery, these articles 
had been manufactured and used in England long before we 
decided to adopt them. All visitors to England are struck 
with the way in which our neighbours have profited by 
these applications of pottery to the hygiene and health of 
dwellings. 

As before, we shall study these different products according 
to their forms and uses. 

Stoneware Pipes. 

For a long time these pipes were made exclusively in 
England, and the products which the firm of Doulton sent all 
over the world from that country were so perfect that it seemed 
impossible to imitate them. The fact is, that besides physical 
appearance, shape, and glaze, another quality is indispensable for 
pipes elasticity ; without it the pipes are brittle, and will crack 
in the ground merely in consequence of the vibrations of traffic 
or other causes. 

It is only in the last ten years that this manufacture has been 
introduced into France. In spite of technical and economic 
difficulties, which it has surmounted, the industry has developed 
to such an extent that the consumption of English products has 
been considerably reduced. 

The principal factories in France are at Pouilly-sur-Saone 

472 



SANITARY POTTERY. 473 

(Jacob et Cie.), at Boulogne (Societe des produits ceramiques), 
at Rambervilliers, at Breteuil-sur-Iton (Rousseau et Cie.), etc. 

Others of less importance are scattered through the North of 
France. Belgium and Germany also make many pipes. 

Manufacture. They are made exactly like pipes of ordinary 
clay, but from special pastes which fire into stoneware. The 
proportions of the different clays used in these pastes depend 
upon the clays available ; it is different in each factory, since the 
materials employed are variable. 

The paste usually consists of a refractory clay mixed with 
felspar or pegmatite, and sometimes, with a view to economy, 
other commoner clays. Verifiable clays are also used mixed 
with antiplastic substances (pulverised fragments of pipes or 
saggers). 

The more refractory the clay is, the less likely is the pipe to 
lose shape in firing ; but then there is no vitrification, and, as in 
the case of English pipes, the pieces retain a certain degree of 
porosity. This slight porosity has no effect on the quality of the 
products. 

The expression of straight or slightly curved pipes is effected 
by machines similar to those already described (p. 343); pipes 
of special shape are made in plaster moulds. 

These special shapes are very numerous (Figs. 883 to 903); 
in addition to single (Fig. 884), double (885, 886), and treble 
(Fig. 887) branched pipes, conical (Fig. 888) pipes are also made 
for connecting two conduits of different diameter, also opercular 
pipes (Fig. 890), the upper parts of which are removable so as to 
allow of cleaning the interior. The drainage pipes (Fig. 893) 
and drains (Fig. 902) for carrying away flood-gate water do not 
present any difficulties. The siphons (Figs. 897 to 901) are 
moulded in two parts which are afterwards welded together. 

Moulding, drying, and polishing are carried out as has been 
described in the case of pipes of ordinary clay. 

Firing. The firing of stoneware pipes takes place at a 
high temperature in round reverberatory kilns (Fig. 206), or 
semi-continuous kilns, or in continuous kilns with several 
firing chambers (Fig. 231). 



474 



POTTERY IN ARCHITECTURE. 



The semi-continuous kilns are of rectangular shape and 
are composed of a series of compartments occupying the whole 
breadth of the kiln and separated by walls. Communication 




Fig. 883. Fig. 884. 



Fig. 888. Fig. 889. 



Fig. 897. 




Fig. 885. Fig. 886. 



Fig. 887. 




Fig. 890. 



Fig. 891. Fig. 892. 




Fig. 893. Fig. 894. MW Fig, 895. Fig. 896. 





Fig. 899. 



Fig. 900. 





Fig. 901. Fig. 902. Fig. 903. 

Figs. 883 to 903. Stoneware Pipes of Different Shapes. 

is made by means of openings in the floors of the chambers. 
The furnaces, four in number, are placed in the angles of 
each compartment ; work is carried on inside the kiln, through 
two doors or gaps situated opposite to one another. 



SANITARY POTTERY. 475 

A " camp " of bricks is laid upon the floor of the kiln, and 
upon this the pipes are placed vertically, some inside others. 
The socket of the large pipes is protected by a cover which 
surrounds it and serves, so to speak, as a sagger. The space 
between the pipes should be large enough to allow the gases 
to circulate freely, thus ensuring a uniform glaze when salting 
takes place. 

The fire is lighted at one end of the kiln, and the gases 
pass through several full compartments before reaching the 
chimney. The firing is effected at a high temperature and 
ends with the salting. This operation, which was used -for the 
first time at the end of the i/th century by the English 
brothers Flers, consists of throwing sea-salt into the kiln when 
the maximum temperature of firing is reached. This tempera- 
ture varies from 1300 to 1500 C. according to the nature of 
the pastes ; upon contact with the silica of the pottery the salt 
(NaCl) splits up into chlorine and sodium, which latter com- 
bines with the silica, forming a complex fusible silicate ; this 
is the glaze. The freed chlorine decomposes the water-vapour 
present in the products of combustion, and escapes into the 
air in the form of hydrochloric acid (HC1). 

This explanation is in accordance with our knowledge of 
chemical reactions, but it is not sufficient to account for the 
facts observed by Salvetat, namely 

i. That dull stonewares, not salt-glazed, contain less silica 
(10 per cent, at least) than the glazed stonewares; 2. that 
sea-salt glazing requires that there should be an excess of 
silica in the paste; 3. that the glazing of the stonewares 
scarcely increases at all the quantity of alkali which they 
naturally contain. 

In order, then, that the salting operation may be successful, 
the pastes must be silicious ; aluminous pastes, that is to say 
pastes of basic nature, cannot receive a glaze in this manner. 

The salt is either introduced direct through the furnaces 
or by orifices in the roof; about a kilogramme and a half of 
salt is required for each cubic metre of stacked products. 

This quantity is introduced gradually, for the volatilisation 



POTTERY IN ARCHITECTURE. 

of the salt, combined with the entrance of the cold air, con- 
siderably lowers the interior temperature of the kiln, and it 
must regain its maximum before salt is again introduced. 

The walls of the kiln also become covered with glaze, and 
repeated operations at last completely disintegrate them ; their 
durability may be increased by constructing them of materials 
of basic nature (alumina, limestone, magnesia). After salting, 
all the orifices of the kiln are closed, it is allowed to cool slowly, 
and then emptied. 

Applications. The use of glazed stoneware pipes has become 
important in modern sanitary installations : canalisation and 
evacuation of flood-gate water, collection and conduction of 
spring-water, etc. 

The advantages of stoneware pipes over other pipes of 
cast-iron, cement, etc., are that they are unaffected by damp, 
completely impervious and smooth in surface, and proof against 
the acids and other corrosive matter contained in the sluice- 
waters. 

Pipes of moderate thickness and with collar-joint will not 
support great pressure, and are therefore only used for drainage 
and evacuation of water. For conduits which have to bear 
considerable pressure, such as those for collection of spring- 
waters, thick pipes with socket-joint are used. 

The first, which are much more extensively used than the 
second, are usually laid in trenches, with a minimum slope of 
one in fifty if there is no flush ; it may be reduced in case of 
there being fairly frequent flushes, but it is always prudent to 
give the greatest slope permitted by the configuration of the 
ground. 

The joints are made with cement which takes with moderate 
rapidity and is mixed with sand ; cements should be avoided 
which swell and would burst the collars. Well-made joints are 
an essential condition of good canalisation. 

On the other hand, it is not sufficient that the joints should 
be water-tight and well made, they must also be easily removed 
when, in consequence of rupture or any other cause, a pipe has 
to be replaced. These contradictory conditions are difficult 



SANITARY POTTERY. 



477 



to fulfil, and the problem of finding a good joint for stoneware 
conduits is always being studied. We give as a suggestion 






R Regard de visile 

R d. C Reservoirs de eliasses auto- 

matiqucs. 
S Siphons oblurateurs 




Fig. 905. Plan of a System of Stoneware Drain-pipes. 

DESCRIPTION. 
R. Inspection opening. 
R d C. Automatic flush reservoirs. 
S. Covering siphons. 

Note. The arrows indicate the direction of flow. 



(Fig. 905) the plan of a system of drains formed of stone- 
ware pipes. 



Sinks. 

These are made of finer stoneware paste than that used for 
pipes, for they receive a glaze. 

The moulding is done by hand, and the shape is usually 



47 8 



POTTERY IN ARCHITECTURE. 



square (Fig. 906) or angular (Fig. 908) for corner sinks. The 
firing takes place in reverberatory kilns, the sinks being protected 
by saggers. Glazing is generally effected by salting, or, when 
the paste allows of it, with alkalino - boracic plumbiferous 
enamels, which are sometimes made opaque ; more often, how- 
ever, the colour of the paste, which is slightly yellowish, is left 
visible. 



STONEWARE SINKS. 



Fig. 906. 



Fig. 907. 




Fig. 908. 





Fig. 909. 



Fig. 910. 



Fig. 906. Rectangular Sink (Soc. des produits ceramiques de Boulogne). Fig. 907. 
Rectangular Sink with Flutings (Jacob et Cie. ). Fig. 908. Angular Sink 

(Rousseau et Cie. ). Fig. 909. Stoneware Bracket (Boulogne). Fig. 910. 
Sink on Bracket with Siphon (Jacob et Cie. ). 



Applications. The advantage of stoneware over stone sinks 
is their complete imperviousness, which renders them easy to 
keep clean. 

The fixing of them depends upon local conditions ; when 
the sink is placed against a wall, it is supported by brackets 
of the same substance (Fig. 909). The evacuation pipe is pro- 
vided with a siphon and discharge plug. 



SANITARY POTTERY. 
PARTICULARS OF STONEWARE SINKS. 



479 



Dimensions in Centimetres. 


Weight in 
Kilogrammes. 


Price in 
Francs. 


Remarks. 


Length. 


Breadth. 


Interior 
Depth. 




45 


35 


6 


12 to 14.5 


12 


The brackets are 0.75 m., 


2 


50 


40 


7 


19 


14.50 


0.78 m., or i in. in height, 


i 


60 


40 


8 


24 to 27 


18 


and cost 30 francs the pair. 


h 


65 


45 


8 


12 


21.50 




1 


75 


45 


9 


34 to 35 


24 






80 


55 


9 


46 to 50 


31.50 




i 


90 


55 


10 


50 to 52 


40 




* 


100 


60 


10 


65 to 67 


46 






IIO 


60 


10 


64 to 73 


58 






40 


63 


5 


n 


9 


Prices taken from the cata- 


i 


45 


70 


6 




15 


logues of Jacob et Cie., 


I 


5 


78 


6 


16 


13 Societe de Boulogne, and 


j 


55 


85 


8 


24 


17 Rousseau et Cie. Reduc- 


3 
bfl 


60 


95 


10 


27 


21 


tion made for large orders. 


| 


70 


55 


10 


2 5 


17 






75 


60 


10 


29 


21 





Urinals, Seats, and Pans. 

These are made either in enamelled stoneware, felspar faience, 
or even in porcelain. In the last two cases, the pastes are 
white and delicate, and receive a glaze similar to those applied 
to faiences and porcelains. 



Fig. 911. 



Fig. 913. 



Fig. 914. 




Fig. 917. 




Fig. 916. 



Fig. 918. 



Fig. 919. 



Fig?. 911 to 919. Enamelled Stoneware Kennel-stones for Urinals 

Figs. 911, 912, and 913 represent block kennel-stones 
of white enamelled stoneware, serving to carry off the urine 
from the floor. The end-piece (Fig. 913) has a cover. The 
stoneware kennel-stones (Figs. 914, 915, 916) are of different 



480 



POTTERY IN ARCHITECTURE. 



shape but are used for the same purpose. Figs. 917, 918, 
and 919 represent trough urinals and are also of enamelled 
stoneware; the entrance piece (Fig. 919) has a tube for admis- 




Fig. 920. Fig. 921. Fig. 922. 

Figs. 920 to 922. Bracket Urinals (Jacob et Cie., Soc. ceram. de Boulogne). 

sion of water, and the issue piece (Fig. 917) has another for 
carrying off the liquids. 

"A LA TURQUE" SEATS OF ENAMELLED STONEWARE. 



Fig. 923. 



Fig. 926. 




Fig. 924- Fig. 925. Fig. 928. 

Figs. 923 to 925. Societe des produits ceramiques de Boulogne. 
Figs. 926 to 928. Rousseau et Cie. 

The bracket urinals (Figs. 920 to 922) are of white enamelled 
stoneware or of faience, and cost from 20 to 30 francs each. 

The seats called " a la turque" (Figs. 923 to 928) are of various 



SANITARY POTTERY. 



48l 



shapes. The one in Fig. 923 is of enamelled stoneware, and 
its accessories comprise a galvanised grating, a bronze water- 
spout, and a siphon of enamelled stoneware (Fig. 925). The 
complete apparatus (Fig. 923) is quoted at 137 francs. 

The canted seats (Fig. 928), circular (Fig. 927), or school 
seats (Fig. 926) are fitted up in different ways. Figs. 929 
and 930 represent a good arrangement which ensures a thorough 
washing of all the sides of the closet. The partitions are built 

INSTALLATION OF AN "A LA TURQUE " SEAT (Soc. ceramique de Boulogne). 



;, H 




Fig. 929. Seat before Cleaning. Fig. 930. Seat during Cleaning. 

of enamelled " bardeaux," and the sloping surface washed is 
itself of enamelled stoneware. This arrangement gives good 
results but requires a great deal of water ; each compartment, 
including the reservoir but not fixing, costs 300 francs. 

Figs. 931 and 934 represent other types of installations 

of common closets with " a la turque " seats fitted up by 

the engineers in several military establishments, notably at the 

Iicole poly technique. The seats in installation 932 are laid 

3 1 



482 



POTTERY IN ARCHITECTURE. 
Fig. 931. Fig. 937. 




5= 




























1 

- 




j; 


i 














































































| ji j 




















































j 
































.3 


\N 

V 

I 


r 

\_ 


/- 

~ 


? 


i 


~ 


7 
7 


/ 


v 
T - 


t 

r 


i 

r-* 


1 


























5= 
P 


J 





1 S 

nr 

if 






A "" tp^'iJ/0^:' 
_] 



^'g- 933- Fig. 934. 

Figs. 931 to 934. Typ^s of Installation of Common Closets with " a la Turque " Seat 

(Jacob et Cie. ). 



PANS OF VARIOUS KINDS. 

!'\ r - 935- Fig. 936. 

;.* I- - 




i! 

Fig. 942. Fig. 943. 



Fig. 944. Fig. 945. 



Figs. 935, 936. Soc. ceram. de Boulogne. Figs. 937 to 941. Jacob et Cie. 





SANITARY POTTERY. 



483 



over a collector which is formed of the several detached pieces 
represented in Figs. 894, 895, 896. The flush water enters 
at one end and issues at the other, while a siphon prevents 
communication between the air and the drain. 

The pans are made of fine enamelled stoneware or of porce- 
lain, and are moulded by hand. They may consist of pan 



T W/M, 




Fig. 946. Installation of a Closet with Flush-pan (Soc. ceramique de Boulogne). 

and siphon in a single piece (Figs. 935, 938, 941, 945), or of 
pans with separate siphons (Figs. 939, 940). Some have direct 
flush (Figs. 939, 941, 945), others have interrupted flush (Figs. 
936, 943). The price of a pan with siphon varies from 40 to 
60 francs according to the decoration. 

The installation of a closet with pan and flush to the drain 
is represented in Fig. 946 ; it comprises : a descent pip e A, 



4 8 4 



TOTTERY IN ARCHITECTURE. 



a pan 13, a flush reservoir containing 10 litres of water, a flush- 
pipe C, a feed-pipe D with pull E, a ventilation-pipe F, and 
a hinged seat G of varnished wood. 

The apparatus for an installation of this kind, namely : pan, 
mahogany hinged seat, flush reservoir with chain and pipes, 
costs from 50 to 170 francs, according to the style of the pan. 
We must acid to this price the cost of fitting up, and the facing 
of the walls when they are faced with quarries. 

Drinking-fountains Washstands. 

These are made of white enamelled stoneware or of porce- 
lain. Some (Figs. 948, 949) have a siphon below ; in others 
the siphon is of metal and is fitted to the evacuation pipe. 

DRINKING-FOUNTAINS WASH-STANDS. 




Fig. 947. Fig. 

Figs. 947 and 950. Jacob et Cie. 



Figs. 948, 949. Soc. ceram. de Boulogne. 



The price of porcelain basins (Figs. 947, 950) varies from 
30 to 45 francs for a diameter of 0.26 m. or 0.30 m. ; that of 
drinking-fountains varies from 35 to 80 francs according to size 
and ornamentation. They are also made in felspar faience. 



THE END 



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JAUNEZ, 



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Brussels, 1865, I vol. in-8. 



486 



BIBLIOGRAPHY. 



GRUNER (LEWIS) 
HITTORFF 

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LANGLES . 

LAYARD (HENRY) 

LEJEUNE . 
NICOLI.E . 

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PLANAT . 

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SEDILLE (PAUL) 

5 J 

VERDIER et CATTOIS . 

VlOLLET-LE-DUC 

'5 

VOGT 



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1 86 1, 2 vol. gr. in-4. 
Discoveries in the ruins of Nineveh and Babylon. 

London, 1853. 

Guide du briqnetier. Paris, 3 e ed. 
De 1'emploi des briques ordinaires, I vol. gr. in-4 avec 

planches en couleurs. 

Architecture et decoration /wr^wj au xv e sieck, 1874. 
Ninive et T Assyrie. Paris, 1867-70. 
Encyclopedic de 1'architecture et de la construction, 12 

vol. gr. in-8. 
Etude sur les carrelages histories du xn au xvn siecle. 

Paris, 1855. 

Manuel du briquetier. Paris, 1864. 
Lecons de ceramique. Paris, 1857, 2 vol. 
Histoire de 1'architecture en Belgique. 
La terre cuite et la terre emaillee dans la construction et 

la decoration, 1877. 

Conference sur la ceramique monumentale, 1879. 
Architecture civile et domestique au moyen age et a la 

Renaissance. Paris, 1857, 2 vol. in-4. 
L'Artritsse. Paris, 1877, I vol. gr. in-8. 
Dictionnaire raisonne de f architecture fran^aise du xi e an 

xvi e siecle. Paris, 10 vol. in-8. 
La porcelaine. Paris, 1893. 




PLATE I. CERAMIC PAVEMENT. 



487 







y* 




PLATE II. LABOR. 

Terra-cotta executed by Emile Muller, from the Design of Michel, for the Porch of the 
Palais des Arts Liberaux at the Paris Exhibition of 1880. 



488 




PLATE III. JEWELLERY. 

Panel of Ceramic Quarries, executed by Deck from the Designs of Ehrmann, 

for the Amsterdam Exhibition of 1883. 
489 




PLATE IV. PANEL OF CERAMIC QUARRIES. 

Executed by the PVience Factories of Creil and Montereau for the Saintes Library. 

490 




PLATE V. PANEL OF CERAMIC QUARRIES. 

Executed from the Designs of Schuller by the Faience Factory at Longwy 
(D'lluartfreres). 



491 



INDEX. 



Alkalies, 387. 

(Carbonates), 387. 

(Silicates), 393. 
Alkaline glazes, 396. 
Alkaline-earthy compounds, 387. 
Alquifoux, 406. 
Alsing cylinders, 430. 
Alumina, 386. 
Antefixes, 332. 
Antimony, 390. 
Antiplastics, 68. 
Application of glazes, 394. 
" Arches," 198. 
Arches of bricks, 279. 
Armenian bole, 402. 



B 



Ball crushing mill, 430. 
Balustrades (of bricks), 283. 

(of terra-cotta), 367. 
Barbotine, peinture a la, 384. 
Bardeaux, 253. 

enamelled, 412. 
Barrows, for bricks, 187, 195. 

for tiles, 312. 
Baryte, 253. 
Bismuth, oxide of, 388. 
Block-mill, 422. 
Boisseaux (pipes), 355. 
Borax, 387. 
Border tiles, 331. 
Boric acid, 387. 
Bricks, 94. 

black, 248. 

blue, 248. 

clinker, 280. 

corner, 246. 

couteau, 246. 

decoration of, 249. 

dimensions of, 245. 

drying of, 170. 

enamelled, 404. 

firing of, 190. 

glazed, 406. 

Gourlier, 282. 



492 



Bricks, history of, 257. 

hollow, 251. 

manufacture of, 94. 

moulding of (by hand), 95. 
(machine), 102. 

ornamented, 249. 

paving, 246. 

prices of, 245. 

qualities of, 249. 

shapes of, 246. 

stamping of, 161. 

stoneware, 410. 

transport of, 1 86. 

uses of, 277. 

white, 249. 

Brickworks, 101, 154, 182. 
Briquettes, 246. 
Building of walls, 278, 283. 



Calcine, 388, 392. 
Calcium, Carbonate, 387. 

Fluoride, 387. 

Oxide, 21. 

Phosphate, 390. 

Sulphate, 387. 

Carbonates (see name of metal). 
Chalk, 387. 
Chimneys, for kilns, 217. 

of terra-cotta, 334. 

bricks for, 282. 

pipes for, 354. 
Chipping of glazes, 393. 
Chloride of sodium, 387, 406. 
Chromium, 390, 393. 
Chromolithography, 401. 
Clay pits, open, 24. 

underground, 36. 

laws as to, 38. 
Clays, analysis of, 17. 

classification of, 2. 

cleaning of, 46. 

definition of, I. 

drying of, 55. 

effervescent and figuline, 2, 3. 

extraction of, 24. 

fusibility of, 1 6. 



INDEX. 



493 



Clays, grinding of, 51. 

kaolin, 2, 3. 

mixing of, 43. 

moulding of, 94. 

ochreous, 2, 4. 

origin of, 4. 

plastic, 2, 14. 

preparation of, 41. 

properties of, 14. 

pugging of, 70. 

pulverisation of, 56. 

purifying of, 46. 

refractory, 3, 18. 

shrinkage of, 15. 

tests of, 17. 

thinning of, 68. 

transport of, 26. 
Clinkers (bricks), 280. 
Cloches, 199. 

Cloisonne decoration, 398. 
Cobalt, 390, 393. 
Colcothar, 402. 
Colouring matters, 388. 
Colours, 385. 

application of, 398. 

composition of, 400. 

firing of, 402. 

verifiable, 401. 
Conduits, chimney, 282. 
Contraction of clays, 15. 
Copper, 390, 393. 

Sulphate, 409. 

Sulphide, 402. 
Cornices, 282. 
Crackling effects, 402. 
Crazing, 393. 
Cryolite, 387. 
Cutting-tables, for bricks, 135. 

for tiles, 295, 296. 
Cylinders, Alsing, 430. 

grinding, 53. 

rolling, 81. 



I) 



Damping of clays, 66. 
Decomposition of clays, 42. 
Decoration, a la barbotine, 384. 

chromolithographic, 401. 

with colours, 384, 398. 

with dips, 384. 

with enamels, 398. 

under-glaze, 384, 398. 

over-glaze, 384, 399. 

by incrustation, 429. 

lustre, 384. 

by metals, 384, 409. 

by printing, 399. 
Dies, for bricks, 132. 

for tiles, 295. 

for pipes, 351. 
Dips, 384. 
Disintegration, mechanical, 51. 

natural, 42. 

by heat, 55. 



Drinking-fountains, 484. 
Drying, of clays, 55. 

of bricks, 170. 

of tiles, 311. 
Drying-rooms, 172. 

storeyed, 175. 

enclosed, 179. 

galleried, 181. 

cost of, 182. 

tunnel, 180. 



Enamels, 385, 396. 

cloisonne, 398. 

opaque, 395. 

transparent alkaline, 396. 
Encaustic tiles, 426. 
Enfumage, 199, 213, 228. 
Engobes, 384. 
Expansion of pastes and glazes, 393. 



Facing quarries, 443. 
Faiences, architectural, 460. 

felspar, 446. 

for mantelpieces, 454. 

quarries, 443. 

silicious, 445. 
Felspar, 4. 
Filter press, 48. 

Finishing joins of masonry, 279. 
Firing, of bricks, 190. 

in clamps, 191. 

with wood, 198. 

with coal, 200. 

with gas, 231. 

in continuous kilns, 208. 

in intermittent kilns, 197. 

cost of, 200, 206, 229, 241. 

temperature of, 242. 

of colours, 402. 

of glazes, 402, 448. 

of pipes, 354, 473. 

of quarries, 448. 

of terra-cotta, 366. 

of tiles, 314. 
Flashing effects, 402. 
Flatting cylinders, 80. 
Flint, 7, 386. 
Fluor spar, 387. 
Fluxes, 386. 
Foot of kiln, 192, 218. 
Friezes, 374. 
Frittage, 389. 
Frontons, 332, 371. 
Frost-cracking, of bricks, 250. 

of enamelled bricks, 407. 
Fuel, 198, 200, 224. 
Furnaces, 201, 204. 
Fusibility, of clays, 16. 

of glazes, 396. 



494 



INDEX. 



G 



Galettieres, 293. 
Gas kilns, 231. 
Gilding, 403. 
Glazes, 385. 

composition of, 386. 

classification of, 390, 

preparation of, 388. 

application of, 394. 

harmony of pastes and, 393. 

for quarries, 444. 
Gneiss, 4. 
Gold, 390. 
Granite, 4. 

Grinding of clays, 51. 
Grinding mills, 56. 
Gutters, tiles for, 333. 
Gypsum, 387. 



IJ 



Hack of bricks, 171. 
Ilallettes, 172. 

cost of, 182. 
Halloysite, 3, II. 
Heat indicators, 242. 
Hip tiles, 330. 
Hourdis, 256. 



Imbrices, 283. 

Immersion, application of glaze by, 395. 
Imperviousness of stoneware, 407. 
Incrustation, decoration by, 422. 
Insufflation, application of glaze by, 395. 
Iron, 390, 393. 

Oxides of, 22. 

Sulphate of, 409. 

Sulphide or Pyrites, 23, 402. 
Irrigation, application of glaze by, 395. 



K 

Kaolin, 2, 3. 

chemical composition. 18. 

origin of, 5. 
Kilns, 197. 

continuous, 208. 

cost of, 230. 

direct-flame, 201. 

Fillard, 235. 

gas, 231. 

Hoffmann and Licht, 209. 

intermittent, 197- 

muffle, 449. 

open, 197. 

production of, 243. 

for quarries, 421. 

rectangular, 213. 

reverberatory, 203. 

Schneider, 238. 



Kilns, for stoneware pipes, 472. 
"a tranches," 315. 
vaulted, 201. 
water gas, 240. 



Lamp-black, 402. 
Lead, Carbonate, 388. 

Plumbate, 387. 

Protoxide, 387. 

Silicate, 393. 

Sulphide, 388. 
Lehm or loess, 4. 

origin of, 7. 
Lift for bricks, 190. 
Limestone, 387. 
Litharge, 387, 400. 
Lubrication of moulds, 169, 308. 
Lustres, metallic, 402. 



M 



Machines, compression, 104, 297, 359. 

cutting, 135, 295, 309, 358. 

expression, 113, 292, 343, 358. 

grinding, 51. 

mixing, 43. 

moistening, 64. 

pugging, 73- 

rolling, 80. 

stamping, 161. 

stone-removing, 50. 
Magnesium, Oxide of, 22. 
Manganese, 390, 393. 

Oxide of, 397, 409. 
Marls, 2, 3, 149. 
Matrices for tiles, 308. 
Medallions, 374. 
Metallic lustres, 402. 
Metals, colouring, 388. 
Minium, 388, 397, 400, 4o6 / 409. 
Mixing of clays, 43. 
Moistening of clays, 62. 
Mosaics in stoneware, 425, 442. 
Mottling, 402. 
Moulding, by hand, 94, 473, 477. 

by machinery, 102, 292, 298, 342, 358. 

of hollow bricks, 251. 
Moulds, for incrusted quarries, 434. 

for tiles, 307. 
Muffle kilns, 449. 



N 

Nickel, 390. 

Nitrate of Potassium, 387. 







Ochres, 2, 4, 402. 

Organic substances, influence on clay of, 23. 

Oxides (see name of metal). 



INDEX. 



495 



Panels, 373, 453, 467. 
Pans, 482. 
Pantiles, 324. 
Paving, bricks for, 280. 

quarries for, 413. 
Pegmatite, 4. 
Pink, 390. 

Pinnacles in terra-cotta, 373. 
Pipes, 341. 

chimney, 354. 

dies for, 351. 

distributing, 341. 

firing of, 354. 

machines for making, 342. 

polishing of, 353. 

stoneware, 472. 
Planchettes, for flat tiles, 287. 

for fitting tiles, 311. 
Plane, 97. 

Plaster, moulds of, 307. 
Plasticity of clays, 14. 
Platin, 199. 
Platinum, 403. 
Plumbiferous glazes, 406. 
Porcelain, in architecture, 471. 

quarries, 451. 
Potassium, 387. 

Carbonate of, 387. 

Nitrate of, 387. 

Oxide of, 21. 
Potter's clays, 149. 
Pottery, decorated, 383. 

sanitary, 472. 
Pounding mill, 60. 
Presses, 104, 162, 297. 

for dry clay, 1 10. 

hydraulic, 432. 

lever, 105. 

for quarries, 359, 432. 

stamping, 161. 

for tiles, 297. 

Printing, decoration by, 401. 
Production of kilns, 243. 
Pugging, 70. 
Pug-mills, 73. 

with cylinders, 81. 
Pulp, 47. 

Pulverisation of glazes, 395. 
Pulveriser, centrifugal, 447. 
Purifying of clays, 46, 251. 
Purple, Cassian, 390. 
Pyrometers, 242. 



Quarries, 357. 

applications of, 361. 
of cleaned clay, 358. 
decorated, 413. 
facing, 443. 
incrusted, 421, 428. 
kilns for, 421. 



Quarries, machines for making, 358. 

of ordinary clay, 357. 

particulars of, 362. 

stoneware, 416. 

for stoves, 454. 
Quartz, 386. 



Registers, paper, 223. 

sheet-iron, 223. 
Reserves, decoration by, 397. 
Resistance, of bricks, 250, 256. 

of enamelled terra-cotta, 407. 
Ridge end tiles, 330. 
Ridge tiles, 328. 

Roof accessories in terra-cotta, 335. 
Roses in terra-cotta, 373. 



Saltpetre, 386. 

Salts (see name of metal). 

Sand, 386, 406, 409. 

Sand-box, 96. 

Sanitary pottery, 472. 

Scraper, 96. 

Sea-salt, 475. 

Seats (" a la turque") in stoneware, 481, 

Shelves, 175, 312. 

Shortening of clays, 68. 

Shrinkage, 15. 

Sifting of clays, 56, 251. 

Silex, 7, 386. 

Silicates (see name of metal). 

Silver, 390. 

Nitrate of, 402. 
Slabs for tiles, 292, 294. 
Slag, 418. 

Soaking of clays, 66. 
Sodium Carbonate, 387. 
Sprinkling, application of glaze by, 395. 
Stacking, of bricks, 199, 218. 

" en charge," 219. 

"en echappade," 449. 

of pipes, 354. 

of quarries, 436, 448. 

with saggers, 436, 449. 

of tiles, 316. 
Stamping, 162. 
Stone, Thivier, 400. 
Stones in clay, 49. 
Stoneware, 416, 468. 

bricks, 410. 

mosaics, 425, 442. 

pipes, 472. 

quarries, 416. 

sanitary pottery, 479. 

sinks, 477. 
Stoves, 459. 

Sulphates (see name of metal). 
Swivel stand for trimming tiles, 298. 



496 



INDEX. 



Tailings, 47. 
Tegula, 283. 

Temperature of firing. 242. 
Terra-cottas, 363. 

applications of, 366. 

history of, 363. 

manufacture of, 365. 

official tests of, 375. 
Thinning substances, 68. 
Tiles, 285. 

ancient, 319. 

d'Artois, 324. 

barrows for, 312. 

black, 337. 

Itoulet, 324. 

Comte Henri, 286. 

coping, 330. 

curved, 309. 

cutting-table for, 309. 

diamond-shaped, 322. 

drying of, 311. 

drying- waggons for, 312. 

Dutch CO-shaped, 326. 

enamelled, 405. 

firing of, 314. 

fitting, 297. 

flat, 319. 

Flemish, 286. 

foreign, 326. 

Gilardoni, 322, 324. 

glazed, 405. 

hip, 330. 

history of, 285. 

hollow, 326. 

Italian Ludovici, 326. 

kilns for, 315. 

manufacture of, 287. 

Marseilles, 324. 

matrices for, 308. 

membron, 333. 

modern, 321. 

moulding of, 287. 

moulds for, 307. 

Muller, 324. 

pan-, 324. 

particulars of, 339. 

Porz, 326. 

press for, 297. 

qualities of, 336. 

ridge, 328. 

Roman, 321. 

round, 321. 



Tiles, scaled, 321. 

socket, 335. 

stoneware, 338. 

various, 333. 

Victoria, 326. 

villa, 324. 

Tileworks, installation of, 316. 
Tin, 388, 390. 
Transport of clays, 26. 

of bricks, to kiln, 221. 

to drying-rooms, 186. 
Trimming of tiles, 298. 
Trolleys," 188. 
Troughs, damping, 66. 



U 

Uranium, 391. 
Urinals, of stoneware, 480. 
kennel stones for, 479. 



Ventiducts, 356. 
Verifiable colours, 399. 
Vitrification, of glazes, 392. 

of stoneware, 473- 
Vitrified bricks, 200. 
Volatilisation, application of glaze by, 395. 



W 



Waggons, for transport of bricks, 1 88. 
clay, 27. 

for drying of bricks, 189. 

for tiles, 312. 
"Wagons" (pipes), 355. 
Walls, building of, 278, 283. 
Water, added, 62. 

in combination, I, 14. 

hygroscopic, 14. 
Water-gas, 233. 
Weathering of clays, 42. 
| Wells, heating, 218. 



Zinc, 390. 

Oxide of, 390. 



PRINTED BY MORRISON AND GIUB LIMITED, EDINBURGH. 



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A CATALOGUE 

OF 

Special Technical Works 

FOR 

Manufacturers, Professional Men, Students, 
Colleges and Technical Schools 

BY HXPHKT WRITERS 

FOR THE 

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Scientific Professions. 



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Books on Oils, Soaps, Colours, 
Glue, Varnishes, etc. 



THE PRACTICAL COMPOUNDING OF OILS, TALLOW 
AND GREASE FOR LUBRICATION, ETC. By AN EXPERT OIL 
REFINER. 100 pp. 1898. Price 7s. 6d. ; Abroad, 8s. ; strictly net, 
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Contents. 

Chapters 1., Introductory Remarks on the General Nomenclature of Oils, Tallow and 
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Solidified Oils and Petroleum Jelly. VIII., Machinery Greases: Loco and Anti- 
friction. IX., Clarifying and Utilisation of Waste Fats, Oils, Tank Bottoms, 
Drainings of Barrels and Drums, Pickings Up, Dregs, etc. X., The Fixing and 
Cleaning of Oil Tanks, etc. Appendix of General Information. 

Press Opinions. 

" This work is written from the standpoint of the oil trade, but its perusal will be found very 
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Guardian. 

" The properties of the different grades of mineral oil and of the animal and vegetable non- 
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thing else. . . . The chapters on grease and solidified oils, etc., are excellent." The Ironmonger. 

" In its ninety-six pages this little work contains a wealth of information ; it is written without 
waste of words on theoretical matters, and contains numerous formulas for a great variety of 
compounds for the most varied lubricants. In addition there are many practical hints of use in 
the factory in general, such as of tanks, etc., and altogether the book is worth several times its 
price in any factory ot these compounds." American Soap Journal. 



SOAPS. A Practical Manual of the Manufacture of Domestic, 
Toilet and other Soaps. By GEORGE H. HURST, F.C.S. Illustrated 
with 66 Engravings. 390 pp. 1898. Price 12s. 6d. ; Abroad 13s. ; 
strictly net, post free. 

Contents. 

Chapters I., Introductory. II., Soap=maker's Alkalies. III., Soap Fats and Oils.- 
IV., Perfumes. V., Water as a Soap Material. VI., Soap Machinery. VII , Tech 
nology of Soap = making. VIII., Glycerine in Soap Lyes. IX., Laying out a Soap 
Factory. X., Soap Analysis. Appendices. 

Press Opinions. 

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" This is a better book on soap-manufacture than any of the same size which have been 
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even the arrangement of soap factories. . . . The book is produced well, and s splendidly illus- 
trated." Chemist and Druggist. 



ANIMAL FATS AND OILS : Their Practical Production, Puri- 
fication and Uses for a Great Variety of Purposes. Their Properties, 
Falsification and Examination. A Handbook for Manufacturers of Oil 
and Fat Products, Soap and Candle Makers, Agriculturists, Tanners, 
Margarine Manufacturers, etc., etc. By Louis EDGAR ANDES. With 
Sixty-two Illustrations. 2^0 pp. 1898. Price 10s. 6d. ; Abroad, 11s.; 
strictly net, post free. 

Contents. 

Introduction. Occurrence, Origin, Properties and Chemical Constitution of Animal Fats. 
Preparation of Animal Fats and Oils. Machinery. Tallow-melting Plant. Extraction Plant. 
Presses. Filtering Apparatus. Butter : Raw Material and Preparation, Properties, Adul- 
terations, Beef Lard or Remelted Butter, Testing. Candle-fish Oil. Mutton Tallow. Hare 



Fat. Goose Fat. Neatsfoot Oil. Bone Fat: Bone Boiling, Steaming Bones, Extraction, 
Refining. Bone Oil. Artificial Butter : Oleomargarine, Margarine Manufacture in France, 
Grasso's Process. " Kaiser's Butter," Jahr & Milnzberg's Method, Filbert's Process, Winter's 
Method. Human Fat. Horse Fat. Beef Marrow. Turtle Oil. Hog's Lard : Raw Material, 
Preparation, Properties, Adulterations, Examination. Lard Oil. Fish Oils. Liver Oils. 
Artificial Train Oil. Wool Fat : Properties, Purified Wool Fat. Spermaceti: Examination 
of Fats and Oils in General. 

Press Opinions. 

" The descriptions of technical processes are clear, and the book is well illustrated and 
should prove useful." Manchester Guardian. 

" It is a valuable work, not only for the student, but also for the practical manufacturer of 
oil and fat products." Journal of the American Chemical Society. 

"The work is very fully illustrated, and the style throughout is in strong contrast to that 
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"An important handbook for the 'fat industry,' now a large one. The explanation of the 
most scientific processes of production lose nothing of their clearness in the translation. "- 
Newcastle Chronicle. 

" The latest and most improved forms of machinery are in all cases indicated, and the many 
advances which have been made during the past years in the methods of producing the more 
common animal fats lard, tallow and butter receive due attention." Glasgow Herald. 



VEGETABLE FATS AND OILS : Their Practical Preparation, 
Purification and Employment for Various Purposes, their Properties, 
Adulteration and Examination. A Handbook for Oil Manufacturers 
and Refiners, Candle, Soap and Lubricating Oil Makers, and the Oil 
and Fat Industry in General. Translated from the German of Louis 
EDGAR ANDES. With Ninety-four Illustrations. 320 pp. 1897. Price 
10s. 6d. ; Abroad, 11s. ; strictly net, post free. 

Contents. 

Statistical Data. General Properties of the Vegetable Fats and Oils. Estimation of the 
Amount of Oil in Seeds. Table of Vegetable Fats and Oils, with French and German 
Nomenclature, Source and Origin and Percentage of Fat in the Plants from which they are 
Derived. The Preparation of Vegetable Fats and Oils : Storing Oil Seeds ; Cleaning the Seed. 
Apparatus for Grinding Oil Seeds and Fruits. Installation of Oil and Fat Works. Ex- 
traction Method of Obtaining Oils and Fats. Oil Extraction Installations. Press Moulds. 
Non-drying Vegetable Oils. Vegetable Drying Oils. Solid Vegetable Fats. Fruits Yielding 
Oils and Fats. Wool-softening Oils. Soluble Oils. Treatment of the Oil after Leaving 
the Press. Improved Methods of Refining with Sulphuric Acid and Zinc Oxide or Lead Oxide. 
Refining with Caustic Alkalies, Ammonia, Carbonates of the Alkalies, Lime. Bleaching Fats 
and Oils. Practical Experiments on the Treatment of Oils with regard to Refining and 
Bleaching. Testing Oils and Fats. 

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of." Commerce, 

" The proprietors of the Oil and Colourman's Journal have not only placed a valuable and 
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have rendered no slight service to experimental and manufacturing chemists." Ma mi fa during 
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6 

IRON-CORROSION, ANTI = FOULINQ AND ANTI- 
CORROSIVE PAINTS. By Louis EDGAR ANDES. Sixty-two 
Illustrations. 275 pp. Translated from the German. 1900. Price 
10s. 6d. ; Abroad, lls. ; strictly net, post free. 

Contents. 

Ironrust and its Formation Protection from Rusting by Paint Grounding the Iron with 
Linseed Oil, etc. Testing Paints Use of Tar for Painting on Iron Anti-corrosive Paints 
Linseed Varnish Chinese Wood Oil Lead Pigments Iron Pigments Artificial Iron Oxides 
Carbon Preparation of Anti-corrosive Paints Results of Examination of Several Anti- 
corrosive Paints Paints for Ship's Bottoms Anti-fouling Compositions Various Anti-cor- 
rosive and Ship's Paints Official Standard Specifications for Ironwork Paints Index. 

Press Opinions. 

" This is a very valuable book, translated from the German, discussing in detail anti-fouling 
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" Will be of great service to paint manufacturers, engineering contractors, ironfounders 
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" The author goes fully into his subject, and the translator has been successful in reproducing 
in another language what he has to say. There are given in the text numerous illustrations of 
the rusting of iron, prepared in the course of a series of personal experiments on the formation 
of rust." Journal of Gas Lighting. 

" This work is a very elaborate and useful record of the various phenomena in connection 
with the corrosion of iron and its protection against corrosion. . . . The book is an exceed- 
ingly useful record of what has been done in connection with iron preservation, and will 
undoubtedly prove to be of much value to railway engineers, ship-owners, etc." Fairplay. 

" This knowledge is conveyed with characteristic German thoroughness in this useful work 
of Herr Andes, which loses nothing of clearness in Mr. Salter's excellent translation. The 
causes of rust formation are examined, the proper methods of cleansing the ironwork detailed, 
and the constitution and application of suitable preventative coverings explained. . , . The 
book is a welcome contribution to technological literature, and will be found worthy of the 
careful study of all who are professionally engaged in the arrangement or superintendence of 
the class of work dealt with." Western Daily Mercury. 

" The author explains the nature of rust and its formation, and the text is illustrated from 
about fifty photographs. An immense amount of carefully arranged information follows as to the 
best methods of applying anti-corrosive substances and the various pigments most efficacious 
for use under all circumstances. The author has evidently thoroughly investigated and mas- 
tered the subject of iron corrosion, its cause and its prevention ; and we regard his book as of 
the greatest importance to bridge-builders, and makers and users of structural iron and steel. 
The book is illustrated throughout and is admirably indexed and arranged." Iron and Steel 
Trades Journal. 

" It is of the utmost importance to have reliable information on the various so-called infal- 
lible anti-corrosive paints which flood the market, and the large experience which evidently had 
been gained by the author in relation to the subject enables him to present in the work under 
notice an important contribution towards the solution of the problem involved, which is bound 
to prove extremely serviceable not only to paint manufacturers, but to engineers, contractors, 
iron-founders, ship-builders and others. The subject is thoroughly dealt with in all its various 
phases, and the vast fund ot information afforded not only regarding rust formation and its 
prevention, but in reference to paints, varnishes, oils and pigments generally, should prove very 
valuable to the large class interested, while additional importance is given to the book by the 
numerous illustrations which were prepared by the author in the course of a series of personal 
experiments on the formation of rust* ' Builders' Reporter 



LUBRICATING OILS, FATS AND GREASES : Their Origin, 
Preparation, Properties, Uses and Analyses. A Handbook for Oil 
Manufacturers, Refiners and Merchants, and the Oil and Fat Industry 
in General. By GEORGE H. HURST, F.C. S. Sixty-five Illustrations. 
313 pp. 1896. Price 10s. 6d. ; Abroad, 11s. ; strictly net, post free. 

Contents. 

Chapters I., introductory Oils and Fats, Fatty Oils and Fats, Hydrocarbon Oils, Uses 
of Oils. II., Hydrocarbon Oils. Distillation, Simple Distillation, Destructive Distillation, 
Products of Distillation, Hydr^ca-bons, Paraffins, Olefins, Naphthenes. III., Scotch Shale 
Oils. Scotch Shales, Distillation of Scotch Oils, Shale Retorts, Products of Distilling Shales, 
Separating Products, Treating Crude Shale Oil, Refining Shale Oil, Shale Oil Stills, Shale 
Naphtha Burning Oils, Lubricating Oils, Wax. IV., Petroleum. Occurrence, Geology, Origin 
Composition, Extraction, Refining, Petroleum Stills, Petroleum Products, Cylinder Oils, Russian 
Petroleum, Deblooming Mineral Oils. V., Vegetable and Animal Oils. Introduction, 
Chemical Composition of Oils and Fats, Fa'.ty Acids, Glycerine, Extraction of Animal and 
Vegetable Fats and Oils, Animal Oils, Vegetable Oils, Rendering, Pressing, Refining, Bleaching, 
Tallow, Tallow Oil, Lard Oil, Neatsfoot Oil, Palm Oil, Palm Nut Oil, Cocoanut Oil, Castor 
Oil, Olive Oil, Rape and Colza Oils, Arachis Oil, Niger Seed Oil, Sperm Oils, Whale Oil, Seal 
Oil, Brown Oils, Lardine, Thickened Rape Oil. VI., Testing and Adulteration of Oils. 
Specific Gravity, Alkali Tests, Sulphuric Acid Tests, Free Acids in Oils, Viscosity Tests, Flash 
and Fire Tests, Evaporation Tests, Iodine and Bromide Tests, Elaidin Test, Melting Point of 
Fat, Testing Machines. VII., Lubricating Greases. Rosin Oil, Anthracene Oil, Making 
Greases, Testing and Analysis of Greases. VIII., Lubrication. Friction and Lubrication, 
Lubricant, Lubrication of Ordinary Machinery, Spontaneous Combustion of Oils, Stainless 
Oils, Lubrication of Engine Cylinders, Cylinder Oils. Appendices. A. Table of Baume's 
Hydrometer B. Table of Thermometric Degrees C. Table of Specific Gravities of Oils. 
Index. 



Press Opinions. 

" The book is well printed, and is a credit alike to author, printer and publisher." Textile 
Mercury. 

" It will be a valuable addition to the technical library of every steam user's establishment." 
Machinery Market. 

" Mr. Hurst has in this work supplied a practical treatise which should prove of especial 
value to oil dealers and also, though in a less degree, to oil users." Textile Manufacturer. 

"This is a clear and concise treatment of the method of manufacturing and refining lubri- 
cating oils. . . . The book is one which is well worthy the attention of readers who are users 
of oil." Textile Recorder. 

"We have no hesitation in saying that in our opinion this book ought to be very useful to 
all those who are interested in oils, whether as manufacturers or users of lubricants, or to those 
chemists or engineers whose duty it may be to report upon the suitability of the same for any 
particular class of work." Engineer. 

" The author is widely known and highly respected as an authority on the chemistry of oi4s 
and the tecl -ics of lubrication, and it is safe to say that no work of similar interest or equal 
value to the neral oil-selling and consuming public has heretofore appeared in the English 
language." Drugs, Oils and Paints, U.S.A. 



8 

" This valuable and useful work, which is both scientific and practical, has been written with 
a view of supplying those who deal in and use oils, etc., for the purpose of lubrication with some 
information respecting the special properties of the various products which cause these various 
oils to be of value as lubricants." Industries and Iron. 

"A mere glance at the table of contents is sufficient to show how various are the conditions 
to which these materials have to be applied, how much knowledge is required for the selection 
of the right kind for each particular purpose, and how by processes of mixture or manufactuie 
the requisite qualities are obtained in each case." Manchester Guardian. . 



THE MANUFACTURE OF VARNISHES, OIL REFINING 
AND BOILING, AND KINDRED INDUSTRIES. Describing 
the Manufacture of Spirit Varnishes and Oil Varnishes ; Raw Materials : 
Resins, Solvents and Colouring Principles ; Drying Oils : their Pro- 
perties, Applications and Preparation by both Hot and Cold Processes; 
Manufacture, Employment and Testing of Different Varnishes. Trans- 
lated from the French of ACH. LIVACHE, Ingenieur Civil des Mines. 
Greatly Extended and Adapted to English Practice, with numerous 
Original Recipes. By JOHN GEDDES MC!NTOSH, Lecturer on Oils, 
Colours and Varnishes, Regent Street Polytechnic. Twenty-seven 
Illustrations. 400 pp. 1899. Price 12s. 6d. ; Abroad, 13s. ; strictly 
net, post free. 

Contents. 

I. Resins : Gum Resins, Oleo Resins and Balsams, Commercial Varieties, Source, Collection, 
Characteristics, Chemical Properties, Physical Properties, Hardness, Adulterations, Appro- 
priate Solvents, Special Treatment, Special Use. II. Solvents: Natural, Artificial, Manufac- 
ture, Storage, Special Use. III. Colouring : Principles, (i) Vegetable, (2) Coal Tar, (3) Coloured 
Resinates, (4) Coloured Oleates and Linoleates. Gum Running : Furnaces, Bridges, Flues, 
Chimney Shafts, Melting Pots, Condensers, Boiling or Mixing Pans, Copper Vessels, Iron 
Vessels (Cast), Iron Vessels (Wrought), Iron Vessels (Silvered), Iron Vessels (Enamelled), 
Steam Superheated Plant, Hot-air Plant. Spirit Varnish Manufacture : Cold Solution Plant, 
Mechanical Agitators, Hot Solution Plant, Jacketted Pans, Mechanical Agitators, Clarification 
and Filtration, Bleaching Plant, Storage Plant. Manufacture, Characteristics and Uses of the 
Spirit Varnishes yielded by : Amber, Copal, Dammar, Shellac, Mastic, Sandarac, Rosin, Asphalt, 
India Rubber, Gutta Percha, Collodion, Celluloid, Resinates, Oleates. Manufacture of Varnish 
Stains. Manufacture of Lacquers. Manufacture of Spirit Enamels. Analysis of Spirit Var- 
nishes. Physical and Chemical Constants of Resins. Table of Solubility of Resins in different 
Menstrua. Systematic qualitative Analysis of Resins.Hirschop's tables. Drying Oils : Oil Crush- 
ing Plant, Oil Extraction Plant, Individual Oils, Special Treatment of Linseed Oil, Poppyseed 
Oil, Walnut Oil, Hempseed Oil, Llamantia Oil, Japanese Wood Oil, Gurjun Balsam, Climatic 
Influence on Seed and Oil. Oil Refining : Processes, Thenard's, Liebig's, Filtration, Storage, 
Old Tanked Oil. Oil Boiling: Fire Boiling Plant, Steam Boiling Plant, Hot-air Plant, Air 
Pumps, Mechanical Agitators, Vincent's Process, Hadfield's Patent, Storer's Patent, Walton's 
Processes, Continental Processes, Pale Boiled Oil, Double Boiled Oil, Hartley and Blenkinsop's 
Process. Driers: Manufacture, Special Individual Use of (i) Litharge, (2) Sugar of Lead, (3) 
Red Lead, (4) Lead Borate, (5) Lead Linoleate, (6) Lead Resinate, (7) Black Oxide of Man- 
ganese, (8) Manganese Acetate, (9) Manganese Borate, (10) Manganese Resinate, (n) Manganese 



Linoleate, Mixed Resinates and Linoleates, Manganese and Lead, Zinc Sulphate, Terebine, 
Liquid Driers. Solidified Boiled Oil. Manufacture of Linoleum. Manufacture of India 
Rubber Substitutes. Printing Ink Manufacture. Lithographic Ink Manufacture. Manufacture 
of Oil Varnishes. Running and Special Treatment of Amber, Copal, Kauri, Manilla. Addition 
of Oil to Resin. Addition of Resin to Oil. Mixed Processes. Solution in Cold of previously 
Fused Resin. Dissolving Resins in Oil, etc., under pressure. Filtration. Clarification. 
Storage. Ageing. Coachmakers' Varnishes and Japans. Oak Varnishes. Japanners' Stoving 
Varnishes. Japanners' Gold Size. Brunswick Black. Various Oil Varnishes. Oil-Varnish 
Stains. Varnishes for " Enamels ". India Rubber Varnishes. Varnishes Analysis : Pro- 
cesses, Matching. Faults in Varnishes : Cause, Prevention. Experiments and Exercises. 



Press Opinions. 

" There is no question that this is a useful book." Chemist and Druggist. 

" The different formulae which are quoted appear to be far more ' practical ' than such as are 
usually to be found in text-books ; and assuming that the original was published two or three 
years ago, and was only slightly behindhand in its information, the present volume gives a fair 
insight into the position of the varnish industry." The Ironmonger. 

Letter front the Teacher of a Technical Class. 

" As a teacher I have often been consulted as to the best work on Varnish Manufacture and 
kindred industries, and have been at a loss in recommending a really practical one. It is 
therefore with pleasure that I can now testify as to the merits of the book on these subjects by 
A. Livache and J. G. Mclntosh recently published by Messrs. Scott, Greenwood & Co. In my 
opinion no varnish maker ought to be without it ; moreover, it is the best text-book that could 
be put into the hands of trade studdents or beginners. It has also the merits of being 
thoroughly up-to-date and of possessing a remarkably comprehensive index. I can con- 
scientiously recommend it to my students and trade friends. CHARLES HARRISON, Lecturer on 
the Manufacture of Painters' Oils, Colours and Varnishes Borough Polytechnic, Borough 
Road, S.E. 

"lyd May, 1899." 



THE MANUFACTURE OF LAKE PIGMENTS FROM 
ARTIFICIAL COLOURS. By FRANCIS H. JENNISON, F.I.C., F.C.S. 
15 Plates. 135 pp. 1900. Price 7s. 6d. ; Abroad, 8s. ; strictly net, 
post free. 

Contents. 

Chapters I., Introduction. II., The Groups of the Artificial Colouring Matters. III., The 
Nature and Manipulation of Artificial Colours. IV., Lake-forming Bodies for Acid Colours. 
V., Lake-forming Bodies' Basic Colours. VI., Lake Bases. VII., The Principles of Lake 
Formation. VIII., Red Lakes. IX., Orange, Yellow, Green, Blue, Violet and Black Lakes. 
X., The Production of Insoluble Azo Colours in the Form of Pigments. XL, The General 
Properties of Lakes Produced from Artificial Colours. XII., Washing, Filtering and Finishing. 
XIII., Matching and Testing Lake Pigments. Index. 



10 

THE TESTING AND VALUATION OF RAW MATERIALS 
USED IN PAINT AND COLOUR MANUFACTURE. By M. W. 

JONES, F.C.S. A book for the laboratories of colour works. 88 pp. 1900. 
Price 5s. ; Abroad, 5s. 6d. ; strictly net, post free. 

Contents. 

Aluminium Compounds. China Clay. Iron Compounds. Potassium Compounds. Sodium 
Compounds. Ammonium Hydrate. Acids. Chromium Compounds. Tin Compounds. Copper 
Compounds. Lead Compounds. Zinc Compounds. Manganese Compounds. Arsenic Com- 
pounds. Antimony Compounds. Calcium Compounds. Barium Compounds. Cadmium 
Compounds. Mercury Compounds. Ultramarine. Cobalt and Carbon Compounds. Oils. 
Index. 

Press Opinions. 

" Though this excellent little work can appeal only to a limited class, the chemists in colour 
works, yet it will appeal to them very strongly indeed, for it will put them on the track of short, 
rapid, and yet approximately, accurate methods of testing the comparative value of competing 
samples of raw material used in paint and colour manufacture." \orth British Daily Mail. 

" This little text-book is intended to supplement the larger and more comprehensive works 
on the subject, and it embodies the result of Mr. Jones' experiments and experiences, extending 
over a long period. It gives, under separaie headings, the principal ingredients and impurities 
found in the raw materials and is a handy work of reference for ascertaining what is valuable or 
detrimental in the sample under examination." Blackburn Times. 



THE CHEMISTRY OF ESSENTIAL OILS AND ARTIFI- 
CIAL PERFUMES. By ERNEST J. PARRY, B.Sc. (Lond.), F.I.C., 
F.C.S. Illustrated with twenty Engravings. 400 pp. 1899. Price 
12s. 6d. ; Abroad, 14s. ; strictly net, post free. 

Contents. 

Chapters I., The General Properties of Bssential Oils. II., Compounds occurring 
in Bssential Oils. III., The Preparation of Bssential Oils. IV., The Analysis of 
Bssential Oils. V , Systematic Study of the Bssential Oils. VI , Terpeneless Oils. 
VII., The Chemistry of Artificial Perfumes. Appendix : Table of Constants. 

Press Opinions. 

" There can be no doubt that the publication will take a hi.^h place in the list of scientific 
text-books." London A rgits. 

"We can heartily recommend this volume to all interested in the subject of essential oils 
from the scientific or the commercial standpoint." British ami Colonial Druggist. 

" Mr. Parry has done good service in carefully collecting and marshalling the results of the 
numerous researches published in various parts of the world." Pharmaceutical Journal. 

" A most useful appendix is inserted, giving a table of constants for the more important 
essential oils. . . . This, in itself, is of sufficient importance and use to warrant the publication 
of the book, and, added to the very complete classification and consideration of the essential 
oils which precedes it, the volume becomes of great value to all interested." Glasgow Herald. 



11 

" At various times monographs have been printed by individual workers, but it may safely 
be said that Mr. Parry is the first in these latter days to deal with the subject in an adequate 
manner. His book is well conceived and well written. ... He is known to have sound practical 
experience in analytical methods, and he has apparently taken pains to make himself au fait 
with the commercial aspects of the subject." Chemist and Druggist. 

" Mr. Parry's reputation as a scientist is fully established, and we can therefore accept any 
work emanating from his pen as being of the greatest practical value. We have perused the 
work before us with much care, and are convinced that the contents will be found most service- 
able and its publication most opportune. ... He avoids unnecessary details, but includes 
everything that is essential to systematic treatment, while he attempts no more ' than to give 
an outline of the principles involved'. . . . We congratulate Mr. Parry on the scientific value 
of his work, and hope that if the progress of the colonies in the manufacture of essential oils 
and perfumes equals what we are justified in expecting, it will become an Australian hand-book, 
everywhere appreciated." The Australian Brewers' Journal. 



THE LEATHER WORKER'S MANUAL. Being a Com- 
pendium of Practical Recipes and Working Formulae for Curriers, 
Bootmakers, Leather Dressers, Blacking Manufacturers, Saddlers, 
Fancy Leather Workers, and all Persons engaged in the Manipulation 
of Leather. By H. C. STANDAGE. 165 pp. 1900. Price 7s. 6d. ; 
Abroad, 8s. ; strictly net, post free. 

Contents. 

Chapters I., Blackings, Polishes, Glosses, Dressings, Renovators, etc., for Boot and Shoe 
Leather. II., Harness Blackings, Dressings, Greases, Compositions, Soaps, and Boot-top 
Powders and Liquids, etc., etc. III., Leather Grinders' Sundries. IV., Currier's Seasonings, 
Blacking Compounds, Dressings, Finishes, Glosses, etc. V., Dyes and Stains for Leather. 
VI., Miscellaneous Information. VII., Chrome Tannage. Index. 

Press Opinions. 

"The book being absolutely unique, is likely to be of exceptional value to all whom it con- 
cerns, as it meets a long-felt want." Birmingham Gazette. 

" This is a valuable collection of practical receipts and working formulae for the use of those 
engaged in the manipulation of leather. We have no hesitation in recommending it as one of 
the best books of its kind, an opinion which will be endorsed by those to whom it appeals." 
Liverpool Mercury. 

" We think we may venture to state, so far as the opinion of the leather trade under the 
Southern Cross is concerned, that it will be one of approval. As practical men, having a long 
and wide experience of the leather trade in Australia, we are certain that there are many tanners 
and curriers carrying on business in remote townships f the colonies to whom such a manual 
of practical recipes will be invaluable. . . . This manual is not a mere collection of recipes for 
the various purposes to which they may be applied, but it is also replete with instructions con- 
cerning the nature of the materials recommended to be used in making up the recipes. . . . We 
think every intelligent leather man should avail himself of the manual. It is undoubtedly a 
valuable contribution to the technology of the leather trade." Australian Leather Journal and 
Boot and Shoe Recorder, 



12 

GLUE AND GLUE TESTING. By SAMUEL RIDEAL, D.Sc. 
Lond., F.I.C. Fourteen Engravings. 144 pp. 1900. Price 10s. 6d. ; 
Abroad, 11s. ; strictly net, post free. 

Contents. 

Chapters I., Constitution and Properties: Definitions, Sources, Gelatine, Chondrin and 
Allied Bodies, Physical and Chemical Properties, Classification, Grades and Commercial 
Varieties. II., Raw Materials and Manufacture : Glue Stock, Lining, Extraction, 
Washing and Clarifying, Filt- r Presses, Water Supply, Use of Alkalies, Action of Bacteria and 
of Antiseptics, Various Processes, Cleansing, Forming, Drying, Crushing, etc., Secondary 
Products. III., Uses of Glue : Selection and Preparation for Use, Carpentry, Veneering, 
Paper Making, Book-binding, Printing Rollers, Hectographs, Match Manufacture, Sandpaper, 
etc., Substitutes for other Materials, Artificial Leather and Caoutchouc. IV., Gelatine : 
General Characters, Liquid Gelatine, Photographic Uses, Size, Tanno- Chrome, and Formo- 
Gelatine, Artificial Silk, Cements, Pneumatic Tyres, Culinary, Meat Extracts, Isinglass, 
Medicinal and other Uses, Bacteriology. V., Glue Testing : Review of Processes, Chemical 
Examination, Adulteration, Physical Tests, Valuation of Raw Materials. VI., Commercial 
Aspects. 

Press Opinions. 

" This work is of the highest technical character, and gives not only a full and practical 
account of the raw materials and manufacture of glues, gelatines and similar substances, but 
gives many hints and information on the use of such substances in veneering,, carpentry and 
many other purposes. Many tests are given for glue in different stages of the progress of its 
manufacture, and the commercial value of a commodity so much in general use is exemplified 
by statistics and figures. It is certainly a valuable treatise upon an article for which very little 
literature in any form has previously been obtainable." Carpenter ami Builder. 

" Books on the art of glue making are more than usually scarce, and users of that article, as 
well as those who may be tempted to embark in the industry, should therefore welcome this 
book by Dr. Samuel Rideal, a Fellow of the Institute of Chemistry, and a leading authority. 
In this book he has collected the more important facts connected with the manufacture of glue 
and allied products, and stated the experience he has gained in examining various commercial 
samples during the past ten years. . . . Dr. Rideal's book must be regarded as a valuable con- 
tribution to our technical literature, which manufacturers, merchants and users may study with 
profit." British Trade Journal. 

" This volume is the latest addition to the excellent series of special technical works for 
manufacturers and professional and commercial men issued by the well-known publishers of 
The Oil and Coloitnnan's Jo-inuil. The volume in every way fully maintains the high standard 
of excellence of the whole series, and deals with the subject of glue making and glue testing in 
a thoroughly exhaustive manner. Chapters are given on the constitution and properties, and 
raw material and manufacture, and of the uses of glue, and in this latter respect it will doubtless 
be information to many readers to learn to what extent glue enters into the manufacture of 
many commercial products not apparently associated with glue. Exhaustive chapters on the 
processes and methods of glue testing, and on its commercial aspects, complete this useful and 
most carefully prepared volume." Carriage Builders' Journal. 



13 

PURE AIR, OZONE AND WATER. A Practical Treatise 
of their Utilisation and Value in Oil, Grease, Soap, Paint, Glue and 
other Industries. By W. B. COWELL. Twelve Illustrations. 1900. 
Price 5s. ; Abroad, 5s. 6d. ; strictly net, post free. 



Contents. 

Chapters I., Atmospheric Air; Lifting of Liquids; Suction Process; Preparing Blown Oils; 
Preparing Siccative Drying Oils. II., Compressed Air; Whitewash. III., Liquid Air; Retro- 
cession. IV., Purification of Water ; Water Hardness. V., Fleshings and Bones. VI., Ozon- 
ised Air in the Bleaching and Deodorising of Fats, Glues, etc. ; Bleaching Textile Fibres. 
Appendix: Air and Gases; Pressure of Air at Various Temperatures; Fuel; Table of Com- 
bustibles ; Saving of Fuel by Heating Feed Water ; Table of Solubilities of Scale Making 
Minerals ; British Thermal Units Tables ; Volume of the Flow of Steam into the Atmosphere ; 
Temperature of Steam. Index. 



Press Opinions. 

" This is a valuable work in little space. ... In arrangement it is a commendable work, and 
its value is increased by the index which brings the little volume to a close." Newcastle Daily 
Journal. 

" The book is written solely for manufacturers, who, without doubt, will find it exceedingly 
practical and useful. The volume contains an appendix wherein is given a great many tables, 
etc., which manufacturers in the trades referred to will find of inestimable value." Blackburn 
Times. 



THE MANUFACTURE OF MINERAL AND LAKE PIG- 
MENTS. Containing Directions for the Manufacture of all Artificial, 
Artists and Painters' Colours, Enamel, Soot and Metallic Pigments. 
A Text-book for Manufacturers, Merchants, Artists and Painters. By 
Dr. JOSEF BERSCH. Translated from the Second Revised Edition by 
ARTHUR C. WRIGHT, M.A. (Oxon.), B.Sc. (Lond.), formerly Assistant 
Lecturer and Demonstrator in Chemistry at the Yorkshire College, 
Leeds. Forty-three Illustrations. Price 12s. 6d. ; Abroad, 13s. ; 
strictly net, post free. [In the press. 



14 

THE RISKS AND DANGERS OF VARIOUS OCCUPA- 
TIONS AND THEIR PREVENTION. By LEONARD A. PARRY, 
M.D., B.S. (Lond.). 1900. Price 7s. 6d. ; Abroad, 8s.; strictly net, 
post free. 

Contents. 

Chapters I., Occupations which are Accompanied by the Generation and Scattering of 
Abnormal Quantities of Dust. II., Trades in which there is Danger of Metallic Poisoning. 
III., Certain Chemical Trades. IV., Some Miscellaneous Occupations. V., Trades in which 
Various Poisonous Vapours are Inhaled. VI., General Hygienic Considerations. Index. 

This book contains valuable information for the following trades Aerated Water Manu- 
facture, Alkali Manufacture, Aniline Manufacture, Barometer Making, Brass Founders, Bromine 
Manufacture, Bronze Moulders, Brush Making, Builders, Cabinet Makers, C?lico Printing, 
Chloride of Lime Manufacture. Coal Miners, Cocoa-nut Fibre Making, Colour Grinders, 
Copper Miners, Cotton Goods Manufacture, Cotton Yarn Dyeing, Cutlery Trades, Dry Clean- 
ing, Electricity Generating, Electroplaters, Explosives Manufacture, File Making, Flint 
Milling, Floor Cloth Makers, Furriers, Fustian Clothing Making, Galvanised Iron Manufacture, 
Gassing Process, Gilders, Glass Making, Glass Paper Making, Glass Polishing and Cutting, 
Grinding Processes, Gunpowder Manufacturing, Gutta-percha Manufacture, Hat Makers, 
Hemp Manufacture, Horn Goods Making, Horse-hair Making, Hydrochloric Acid Manufacture. 
India-rubber Manufacture, Iodine Manufacture, Ivory Goods Making, Jewellers, Jute Manu- 
facture, Knife Grinders, Knife Handle Makers, Lace Makers, Lacquering, Lead Melters, Lead 
Miners, Leather Making, Linen Manufacture, Linoleum Making, Lithographic Printing and 
Bronzing, Lithographing, Masons, Match Manufacture, Melanite Making, Mirror Making, 
Needle Grinders, Needle Making, Nitro-benzole Making, Nitro-glycerine Making, Paint 
Makers, Paper Making, Philosophical Instrument Makers, Photographers, Picric Acid Making, 
Portland Cement Making, Pottery Manufacture, Printers, Quicksilver Mining, Rag Pickers, 
Razor Grinders, Red Lead Making, Rope Making, Sand Paper Making, Saw Grinders, Scissors 
Grinders, Shoddy Manufacture, Shot Making, Silk Making, Silver Mining, Skinners, Slag Wood 
Manufacture, Steel Makers, Steel Pen Making, Stereotypers, Stone Masons, Straw Hat Makers. 
Sulphuric Acid Manufacture, Sweeps, Table-knife Grinders, Tanners, Telegraphists, Textile 
Industries, Tin Miners, Turners, Type Founders, Umbrella Makers, Wall Paper Making, 
White Lead Making, Wood Working, Woollen Manufacture, Wool Sorters, Zinc Oxide 
Manufacture, Zinc Working, etc., etc. 

Press Opinions. 

" The language used is quite simple, and can be understood by any intelligent person en- 
gaged in the trades dealt with." The Clarion. 

" This is an appalling book. It shows that there is scarcelv a trade or occupation that has 
not a risk or a danger attached to it." Local Government Journal. 

" Dr. Parry has not only pointed out the ' risks and dangers of various occupations ' ; he has 
suggested means for rheir prevention. The work is primarily a practical one." Colliery 
Manager. 

" This is a most useful book which should be in the hands of all employers of labour, 
foremen, and intelligent workmen, and is one of great utility to sanitary inspectors, and even 
on occasion to medical men." Heal.h. 

"The writer has succeeded in collecting a large amount of information, and though one 
could wish he had presented it in a rather more attractive style, he has certainly condensed it 
into a very small space." Physician and Surgeon. 

" The little book before us is one which will be found exceedingly useful to manufacturers 
and even factory inspectors. . . . No attempt is made to show how diseases when originated 
are to be c ired, but, acting on the sound principle that prevention is better than cure, means 
are stated how to avoid the harm.' liristol Mcrcurv. 

" The author has endeavoured to treat the question in simple rather than in technical lan- 
guage, and he has lucidly catalogued the most dangerous trades and their symptoms, and in 
each case specified the best methods of dealing with them. ... To those for whom the volume 
is specially designed, Dr. Parry's treatis should be a useful handbook." She/field Independent. 

" A very useful manual for employers of labour, foremen, intelligent workmen, and, in spite 
of the author's modesty, for medical men. We have the peculiar risks and dangers of all the 
dangerous trades carefully described; the mode of action of various chemicals, etc., used in 
different industries given, with full directions how to minimise unavoidable risks." Leeds 
Mercury. 

" The work is well written and printed, and its verbiage such as to be comprehensible to the 
workman no less than to the master. The careful and general perusal of a work of this nature 
cannot but be attended by beneficial results of a far-reaching nature, and we therefore heartily 
recommend the book to our readers. Medical Officers of Health and Sanitary Inspectors 
especially should lind the work of great interest." Sanitarv Record. 

" It is written in simple language, and its instructions can be easily followed. . . . There 
are some employers, at any rate, who are more ignorant of, than indifferent to, the slow 
murder of their workpeople, and if the facts so succinctly set forth in this book were brought to 
their notice, and if the Trade Unions made it their business to insist on the observance of the 
better conditions Dr. Parry described, much might be done to lessen the workman's peril." 
Weekly Times and Echo. 



15 



Books on Pottery, Glass, etc. 



THE MANUAL OF PRACTICAL POTTING. Second Edition, 

Revised and Enlarged. 200 pp. 1897. Price 17s. 6d. ; Abroad, 18s. ; 
strictly net, post fr^e. 

Contents. 

Introduction. The Rise and Progress of the Potter's Art. Chapters I., Bodies. China 
and Porcelain Bodies, Parian Bodies, Semi-porcelain and Vitreous Bodies, Mortar Bodies, 
Earthenwares Granite and C.C. Bodies, Miscellaneous Bodies, Sagger and Crucible Clays, 
Coloured Bodies, Jasper Bodies, Coloured Bodies for Mosaic Painting, Encaustic Tile Bodies, 
Body Stains, Coloured Dips. II., Glazes. China Glazes, Ironstone Glazes, Earthenware 
Glazes, Glazes without Lead, Miscellaneous Glazes, Coloured Glazes, Majolica Colours. III., 
Gold and Cold Colours. Gold, Purple of Cassius, Marone and Ruby, Enamel Colour Bases, 
Enamel Colour Fluxes, Enamel Colours, Mixed Enamel Colours, Antique and Vellum Enamel 
Colours, Underglaze Colours, Underglaze Colour Fluxes, Mixed Underglaze Colours, Flow 
Powders, Oils and Varnishes. IV., Means and Methods. Reclamation of Waste Gold, The 
Use of Cobalt, Notes on Enamel Colours, Liquid or Bright Gold. V., Classification and 
Analysis. Classification of Clay Ware, Lord Playfair's Analysis of Clays, The Markets of the 
World, Time and Scale of Firing, Weights of Potter's Material, Decorated Goods Count. 
VI., Comparative Loss of Weight of Clays. VII., Ground Felspar Calculations. VIII., The 
Conversion of Slop Body Recipes into Dry Weight. IX., The Cost of Prepared Earthenware 
Clay. X., Forms and Tables. Articles of Apprenticeship, Manufacturer's Guide to Stock- 
taking, Table of Relative Values of Potter's Materials, Hourly Wages Table, Workman's 
Settling Table, Comparative Guide for Earthenware and China Manufacturers in the Use of 
Slop Flint and Slop Stone, Foreign Terms applied to Earthenware and China Goods, Table 
for the Conversion of Metrical Weights and Measures on the Continent of South America. 



CERAMIC TECHNOLOGY : Being some Aspects of Technical 
Science as Applied to Pottery Manufacture. Edited by CHARLES F. 
BINNS. 100 pp. 1897. Price 12s. 6d. ; Abroad, 13s. ; strictly net, 
post free. 

Contents. 

Preface. Introduction. Chapters I., The Chemistry of Pottery II., Analysis and Syn- 
thesis. III., Clays and their Components. IV., The Biscuit Oven. V., Pyrometry. VI., 
Glazes and their Composition. VII., Colours and Colour-makingindex. 



16 
RECIPES FOR FLINT GLASS MAKING. By a British Gla?s 

Master and Mixer. Sixty recipes. Being Leaves from the Mixing Bock of 
several experts in the Flint Glass Trade, containing up-to-date recipes 
and valuable information as to Crystal, Demi-crystal and Coloured Glass 
in its many varieties. It contains the recipes for cheap metal suited to 
pressing, blowing, etc., as well as the most costly crystal and ruby. 
British manufacturers have kept up the quality of this glass from the 
arrivals of the Venetians to Hungry Hill, Stourbridge, up to the 
present time. The book also contains remarks as to the result of the 
metal as it left the pots by the respective metal mixers, taken from 
their own memoranda upon the originals. Price for United Kingdom, 
10s. 6d. ; Abroad, 15s. ; United States, $4 ; strictly net, post free. 

Contents. 

Ruby Ruby from Copper Flint for using with the Ruby for Coating A German Metal- 
Cornelian, or Alabaster Saphire Blue Crysophis Opal Turquoise Blue Gold Colour 
Da-k Green Green (common) Green for Malachite Blue for Malachite Black for Mela 
chite Black Common Canary Batch Canary White Opaque Glass Sealing-wax Red- 
Flint Flint Glass (Crystal and Demi) Achromatic Glass Paste Glass White Enamel - 
Firestone Dead White (for moons) White Agate Canary Canary Enamel 



COLOURING AND DECORATION OF CERAMIC WARE. 

By ALEX. BRONGNIART. With Notes and Additions by ALPHONSH 
SALVETAT. Translated from the French. 200 pages. 1898 Price 
7s. 6d. ; Abroad, 8s. ; strictly net, post free. 



Contents. 

The Pastes, Bodies or Ceramic Articles Capable of being Decorated by Vitrifiable Colours 
The Chemical Preparation of Vitrifiable Colours Composition and Preparation of Vitrifiable 
Co'ours- The Oxides Preparation of Oxides Preparation of Chromates Preparation of 
other Colours Composition and Preparation of Fluxes Muffle Colours Recipes for Colours 
Use of Me'tals Lustres Preparation and Application of Colours Composition of Coloured 
Pastes Underglaze Colours Colours in the Glaze Overglaze Colours Painting in Vitri- 
fiable Colours Gildirg Burnishing Printing Enlarging and Reducing Gelatine Prints- 
Muffle Kilns for Vitrifiable Colours Influence of the Material on the Colour Changes Re- 
sulting from the Actions of the Fire Alterations Resulting from the Colours Alterations in 
Firing. 



17 

HOW TO ANALYSE CLAY. Practical Methods for Practical 
Men. By HOLDEN M. ASHBY, Professor of Organic Chemistry, Harvey 
Medical College, U.S.A. Twenty Illustrations. 1898. Price 2s. 6d. ; 
strictly net, post free, home or abroad. 

Contents. 

List of Apparatus List of Atomic Weights Use of Balance, and Burette, Sand Bath, and 
Water Bath Dessicator Drying Oven Filtering Fusion Determination of Water, Organic 
Matter, Iron, Calcium, Alkalies, Limestone, Silica, Alumina, Magnesium, etc. Mechanical 
Analysis Rational Analysis Standard Solutions Volumetric Analysis Standards for Clay- 
Analysis Sampling. 



THE ART OF RIVETING GLASS, CHINA AND EARTHEN- 
WARE. By J. HOWARTH. Secc.nd Edition. 1900. Price Is. net ; by 
post, home or abroad, is. 2d. 

Contents. 

Tools and Materials Required Wire Used for Rivets Soldering Solution Preparation for 
Drilling Commencement of Drilling Cementing Preliminaries to Riveting Rivets to Make 
To Fix the Rivets Through-and-through Rivets Soldering Tinning a Soldering-iron 
Perforate-! Plates, Handles, etc. Handles of Ewers, etc. Vases and Comports Marble and 
Alabaster Ware Decorating How to Loosen Fast Decanter Stoppers China Cements. 



PAINTING ON GLASS AND PORCELAIN AND ENAMEL 

PAINTING. A Complete Introduction to the Preparation of all the 
Colours and Fluxes used for Painting on Porcelain, Enamel, Faience 
and Stoneware, the Coloured Pastes and Coloured Glasses, together 
with a Minute Description of the Firing of Colours and Enamels. On 
the Basis of Personal Practical Experience of the Condition of the Art 
up to Date. By FELIX HERMANN, Technical Chemist. With eighteen 
Illustrations. 300 pp. Translated from the German second and En- 
larged Edition. 1897. Price 10s. 6d. ; Abroad, 11s.; strictly net, post 
free. 



18 

Contents. 

History of Glass Painting. Chapters I., The Articles to be Painted : Glass, Porcelain, 
Enamel, Stoneware, Faience. II., Pigments : i, Metallic Pigments: Antimony Oxide, Naples 
Yellow, Barium Chromate, Lead Chromate, Silver Chloride, Chromic Oxide. III., Fluxes: 
Fluxes, Felspar, Quartz, Purifying Quartz, Sedimentation, Quenching, Borax, Boracic Acid, 
Potassium and Sodium Carbonates, Rocaille Flux. IV., Preparation of the Colours for Glass 
Painting. V., The Colour Pastes. VI., The Coloured Glasses. VII., Composition of the 
Porcelain Colours. VIII., The Enamel Colours: Enamels for Artistic Work. IX., Metallic 
Ornamentation: Porcelain Gilding, Glass Gilding. X., Firing the Colours: i, Remarks on 
Firing: Firing Colours on Glass, Firing Colours on Porcelain; 2, The Muffle XL, Accidents 
occasionally Supervening during the Process of Firing. XII., Remarks on the Different 
Methods of Painting on Glass, Porcelain, etc. Appendix : Cleaning Old Glass Paintings. 



Press Opinions. 

" Mr. Hermann, by a careful division of his subject, avoids much repetition, yet makes 
sufficiently clear what is necessary to be known in each art. He gives very many formulae ; 
and his hints on the various applications of metals and metallic lustres to glass and porcelains 
will be found of much interest to the amateur." Art A tnateur, New York. 

" For the unskilled and amateurs the name of the publishers will be sufficient guarantee for 
the utility and excellence of M. Hermann's work, even if they are already unacquainted with 
the author. . . . The whole cannot fail to be both of service and interest to glass workers and 
to potters generally, especially those employed upon high-class work." Staffordshire Sentinel 

"In Painting on Glass and Porcelain, the author .has dealt very exhaustively with the 
technical as distinguished from the artistic side of his subject, the work being entirely devoted 
to the preparation of the colours, their application and firing. For manufacturers and students 
it will be a valuable work, and the recipes which appear on almost every page form a very 
valuable feature. The author has gained much of his experience in the celebrated Sevres 
manufactory, a fact which adds a good deal of authority to the work." Builders Journal. 

" The compiler displays that painstaking research characteristic of his nation, and goes at 
length into the question of the chemical constitution of the pigments and fluxes to be used in 
glass-painting, proceeding afterwards to a description of the methods of producing coloured 
glass of all tints and shades. . . . Very careful instructions are given for the chemical and 
mechanical preparation of the colours used in glass-staining and porcelain-painting ; indeed, 
to the china painter such a book as this should be ot permanent value, as the author claims to 
have tested and verified every recipe he includes, and the volume also comprises a section de- 
voted to enamels both opaque and translucent, and another treating of the firing of porcelain, 
and the accidents that occasionally supervene in the furnace." Daily Chronicle. 

" In Dr. Hermann's hand-book if such a term is fitting for so erudite and masterly a treatise 
the student is first delighted by an interesting historical introduction, after which an ex- 
haustive description follows of the metallic oxides and salts, the earths and earthy bodies and 
the free metals used in the composition of the pigments. All who take an interest in the 
colouring properties of matter will not fail to be instructed in this section of the work. . . . 
Exhaustive recipes are given in separate chapters for the composition of the colours and 
fluxes for every shade and tint in the painting of glass, porcelain, enamel, faience, and stone- 
ware, for the- preparation of coloured pastes, for the application of metallic ornamentation, for 
the colouring of the foundation in the " frit " or " charge " stage, and for the encaustic opera- 
tions in the kiln. ... In every district of England where art porcelain and glass is manufac- 
tured, this treatise should be widely circulated, and its contents made familiar to all engaged, 
in whatever .capacity, in the trade." Leeds Mercury. 



19 

A Reissue of THE HISTORY OF THE STAFFORDSHIRE 
POTTERIES; AND THE RISE AND PROGRESS OF THE 
MANUFACTURE OF POTTERY AND PORCELAIN. With 
References to Genuine Specimens, and Notices of Eminent Potters. 
By SIMEON SHAW. (Originally Published in 1829.) 265 pp. 1900. 
Price 7s. 6d. ; Abroad, 8s. ; strictly net, post free. 

Contents. 

Introductory Chapter showing the position of the Pottery Trade at the present time 
(1899). Chapters I., Preliminary Remarks. II., The Potteries, comprising Tunstall, 
Brownhills, Greenfield and New Field, Golden Hill, Latebrook, Green Lane, Burslem, 
Longport and Dale Hall, Hot Lane and Cobridge, Hanley and Shelton, Etruria, Stoke, Penk- 
hull, Fenton, Lane Deiph, Foley, Lane End. III., On the Origin of the Art, and its 
Practice among the early Nations. IV., Manufacture of Pottery, prior to 1700. V., The 
Introduction of Red Porcelain by Messrs. Elers, of Bradwell, 1690. VI., Progress of 
the Manufacture from 1700 to Mr. Wedgwood's commencement in 1760. VII., Introduc- 
tion of Fluid Glaze. Extension of the Manufacture of Cream Colour. Mr. Wedgwood's 
Queen's Ware. Jasper, and Appointment of Potter to her Majesty. Black Printing. VIII., 
Introduction of Porcelain. Mr. W. Littler's Porcelain. Mr. Cookworthy's Discovery of 
Kaolin and Petuntse, and Patent. Sold to Mr. Champion resold to the New Hall Com. 
Extension of Term. IX., Blue Printed Pottery. Mr. Turnef, Mr. Spode (i), Mr. Baddeley, 
Mr. Spode (2), Messrs. Turner, Mr. Wood, Mr. Wilson, Mr. Minton. Great Change in 
Patterns of Blue Printed. X., Introduction of Lustre Pottery. Improvements in Pottery 
and Porcelain subsequent to 1800. 

Press Opinions. 

" There is much curious and useful information in the work, and the publishers have rendered 
the public a service in reissuing it." Burton Mail. 

" Copies of the original work are now of considerable valu :, and the facsimile reprint now issued 
cannot but prove of considerable interest to all interested in the great industry." Derby Mercury. 

" The book will be especially welcomed at a time when interest in the art of pottery manu- 
facture commands a more widespread and general interest than at any previous time." Wolver- 
hampton Chronicle. 

" This work is all the more valuable because it gives one an idea of the condition of affairs 
existing in the north of Staffordshire before the great increase in work and population due to 
modern developments." Western Morning News. 

"... The History gives a graphic picture of North Staffordshire at the end of the last and 
the beginning of the present century, and states that in 1829 there was ' a busy and enterprising 
community ' in the Potteries of fifty thousand persons. . . . We commend it to our readers as a 
most entertaining and instructive publication." Staffordshire Sentinel. 

A Reissue of THE CHEMISTRY OF THE SEVERAL 
NATURAL AND ARTIFICIAL HETEROGENEOUS COM- 
POUNDS USED IN MANUFACTURING PORCELAIN, 
GLASS, AND POTTERY. By SIMEON SHAW. (Originally 
Published in 1837.) 750 pp. 1900. Price 14s. ; Abroad, 14s. 6d. ; 
strictly net, post free. 

Contents. 

PART I., ANALYSIS AND MATERIALS. Chapters I., Introduction: Laboratory and 
Apparatus; Elements: Combinative Potencies, Manipulative Processes for Analysis and 
Reagents, Pulverisation, Blow-pipe Analysis, Humid Analysis, Preparatory Manipulations, 
General Analytic Processes, Compounds Soluble in Water, Compounds Soluble only in 
Acids, Compounds (Mixed) Soluble in Water, Compounds (Mixed) Soluble in Acids, Compounds 
(Mixed) Insoluble, Particular Analytic Processes. II., Temperature : Coal, Steam Heat for 
Printers' Stoves. III., Acids and Alkalies: Boracic Acid, Muriatic Acid, Nitric Acid, Sul- 
phuric Acid, Potash, Soda, Lithia, Calculation of Chemical Separations. IV., The 



20 

Alumine, Clays, Silica, Flint, Lime, Plaster of Paris, Magnesia, Barytes, Felspar, Grauen (or 
China Stone) China Clay, Chert. V., Metals : Reciprocal Combinative Potencies of the Metals, 
Antimony, Arsenic, Chromium, Green Oxide, Cobalt, Chromic Acid, Humid Separation of 
Nickel from Cobalt, Arsenite of Cobalt, Copper, Gold, Iron, Lead, Manganese, Platinum, Silver, 
Tin, Zinc. 

PART II., SYNTHESIS AND COMPOUNDS. Chapters I., Sketch of the Origin and 
Progress of the Art. II., Science of Mixing : Scientific Principles of the Manufacture, Com- 
binative Potencies of the Earths. III., Bodies: Porcelain Hard, Porcelain Fritted Bodies, 
Porcelain Raw Bodies, Porcelain Soft, Fritted Bodies, Raw Bodies, Stone Bodies, Ironstone, 
Dry Bodies, Chemical Utensils, Fritted Jasper, Fritted Pearl, Fritted Drab, Raw Chemical 
Utensils, Raw Stone, Raw Jasper, Raw Pearl, Raw Mortar, Raw Drab, Raw Brown, Raw Fawn, 
Raw Cane, Raw Red Porous, Raw Egyptian, Earthenware, Queen's Ware, Cream Colour, Blue 
and Fancy Printed, Dipped and Mocha, Chalky, Rings, Stilts, etc. IV., Glazes: Porcelain 
Hard Fritted, Porcelain Soft Fritted, Porcelain Soft Raw, Cream Colour Porcelain, Blue 
Printed Porcelain, Fritted Glazes, Analysis of Fritt, Analysis of Glaze, Coloured Glazes, Dips, 
Smears, and Washes; Glasses: Flint Glass, Coloured Glasses, Artificial Garnet, Artificial 
Emerald, Artificial Amethyst, Artificial Sapphire, Artificial Opal, Plate Glass, Crown Glass, 
Broad Glass, Bott'e Glass, Phosphoric Glass, British Steel Glass, Glass-Staining and Painting, 
Engraving on Glass, Dr. Faraday's Experiments. V., Colours: Colour Making, Fluxes or 
Solvents, Components of the Colours; Reds, etc., from Gold, Carmine or Rose Colour, 
Purple, Reds, etc., from Iron, Blues, Yellows, Greens, Blacks, White, Silver for Burnishing, 
Gold for Burnishing, Printer's Oil, Lustres. 

PART III , TABLES OF THE CHARACTERISTICS OF CHEMICAL SUB- 
STANCES. Preliminary Remarks, Oxygen (Tables), Sulphur and its Compounds, Nitrogen 
ditto, Chlorine ditto, Bromine ditto, Iodine ditto, Fluorine ditto, Phosphorus ditto, Boron ditto, 
Carbon ditto, Hydrogen ditto, Observations, Ammonium and its Compounds (Tables), Thorium 
ditto, Zirconium ditto, Aluminium ditto, Yttrium ditto, Glucinum ditto, Magnesium ditto, 
Calcium ditto, Strontium ditto, Barium ditto, Lithium ditto, Sodium and its Compounds, 
Potassium ditto, Observations, Selenium and its Compounds (Tables), Arsenic ditto, Chromium 
ditto, Vanadium ditto, Molybdenum ditto, Tungsten ditto, Antimony ditto, Tellurium ditto, 
Tantalum ditto, Titanium ditto, Silicium ditto, Osmium ditto, Gold ditto, Iridium ditto, Rhodium 
ditto, Platinum ditto, Palladium ditto, Mercury ditto, Silver ditto, Copper ditto, Uranium ditto, 
Bismuth and its Compounds, Tin ditto, Lead ditto, Cerium ditto, Cobalt ditto, Nickel ditto, 
Iron ditto, Cadmium ditto, Zinc ditto, Manganese ditto, Observations, Isomorphous Groups , 
Isomeric ditto, Metameric ditto, Polymeric ditto, Index. 

Press Opinions. 

" The atomic weights have been more accurately determined, and experiments in synthetic 
chemistry have given us readier methods of producing certain materials requisite, but the 
fundamental principles were always discovered, and for all practical purposes the book is as 
valuable now as when first published." Lungton Times and Echo. 

"This interesting volume has been kept from the pencil of the modern editor and reprinted 
in its entirety by the enterprising publishers of The Pottery Gazette and other trade journals. 
. . . There is an excellent historical sketch of the origin and progress of the art of pottery 
which shows the intimate knowledge of classical as well as (the then) modern scientific litera- 
ture possessed by the late Dr. Shaw; even the etymology of many of the .Staffordshire place- 
names is given." Glasgow Herald. 

" The historical sketch of the origin and progress of pottery is very interesting and instruc- 
tive. The science of mixing is a problem of great importance, and the query how the natural 
products, alumina and silica can be compounded to form the best wares may be solved by the 
aid of chemistry instead of by guesses, as was formerly the case. This portion of the book may 
be most suggestive to the manufacturer, as also the chapters devoted to the subject of glazes, 
glasses and colours." ttirminglmm Post. 

" Messrs. Scott, Greenwood and Co., are doing their best to place before the pottery trades 
some really good books, likely to aid the Staffordshire manufacturers, and their spirited enter- 
prise is worthy of encouragement, for the utility of technical literature bearing upon the 
practical side of potting goes without saying. . . . They are to be congratulated on their 
enterprise in republishing it, and we can only hope that 'they will meet with the support they 
deserve. It seems to be a volume that is worth looking through by both manufacturers and 
operatives alike, and all local institutions, at any rate, should secure copies." Staffordshire 
Sentinel. 



21 

Enamelling on Metal. 

ENAMELS AND ENAMELLING. An Introduction to the 
Preparation and Application of all Kinds of Enamels for Technical 
and Artistic Purposes. For Enamel Makers, Workers in Gold and 
Silver, and Manufacturers of Objects of Art. By PAUL RANDAU. 
Translated from the German. With sixteen Illustrations. 180 pp. 
1900. Price 10s. 6d. ; Abroad, lls. ; strictly net, post free. 

Contents. 

I., Introduction. II., Composition and Properties of Glass. III., Raw Materials for the 
Manufacture of Enamels. IV., Substances Added to Produce Opacity. V., Fluxes. VI., Pig- 
ments. VII., Decolorising Agents. VIII., Testing the Raw Materials with the Blow-pipe 
Flame. IX., Subsidiary Materials. X., Preparing the Materials for Enamel Making. XL, 
Mixing the Materials. XII., The Preparation of Technical Enamels : The Enamel Mass. 
XIII., Appliances for Smelting the Enamel Mass. XIV., Smelting the Charge. XV., Com- 
position of Enamel Masses. XVI., Composition of Masses for Ground Enamels. XVII., 
Composition of Cover Enamels. XVIII., Preparing the Articles for Enamelling. XIX., 
Applying the Enamel. XX., Firing the Ground Enamel. XXL, Applying and Firing the 
Cover Enamel or Glaze. XXIL, Repairing Defects in Enamelled Ware. XXIIL, Enamelling 
Articles of Sheet Metal. XXIV., Decorating Enamelled Ware. XXV., Specialities in 
Enamelling. XXVI. , Dial-plate Enamelling. XXVII. , Enamels for Artistic Purposes: Re- 
cipes for Enamels of Various Colours. Index. 

Press Opinions. 

" Should prove of great service to all who are either engaged in or interested in the art of 
enamelling." Jewellers and Watchmakers' Trade Advertiser. 

" I must inform you that this is the best book ever I have come across on enamels, and it is 
worth double its cost." J. MINCHIN, Jr., Porto, Portugal, zzndjuly, 1900. 

" This is a very useful and thoroughly practical treatise, and deals with every branch of the 
enameller's art. The manufacture of enamels of various colours and the methods of their 
application are described in detail. Besides the commoner enamelling processes, some of the 
more important special branches of the business, such as cloisonne work are dealt with. The 
work is well got up, and the illustrations of apparatus are well executed. The translator is 
evidently a man well acquainted both with the German language and the subject-matter of the 
book." Invention. 



THE ART OF ENAMELLING ON METAL. By W. NORMAN 
BROWN. Twenty-eight Illustrations. 60 pp. 1900. Price 2s. 6d. ; 
strictly net, post free. 

Contents. 

Chapters I., History Cloisonne Champs Leve Translucent Enamel Surface Painted 
Enamels. II., Cloisonne Champs Leves Translucent Painted. III., Painted Enamel 
Apparatus Furnaces and Muffles for Firing. IV., The Copper Base or Plate Planishing 
Cloisons Champ Lev6 Plates.- V., Enamels Trituratipn Washing Coating a Plate with 
Enamel Firing Ordinary Plaques for Painting Designing Squaring off. VI., Designs for 
Cloisonne Designs for Painted Enamels Technical Processes Brushes, etc., Colours 
Grisaille Full-coloured Designs. 

Press Opinion. 

" The information conveyed in The A rt of Enamelling on Metal is as complete as can be ex- 
pected in a manual of ordinary length, and is quite ample in all respects to start students in a 
most interesting branch of decorative art. All necessary requisites are fully described and 
illustrated, and the work is one, indeed, which any one may peruse with interest, for those who 
are interested artistically in enamels are a numerous body." Hardware Metals and Machinery, 



22 



Books on Textile and Dyeing 
Subjects. 



THE TECHNICAL TESTING OF YARNS AND TEXTILE 

FABRICS, with Reference to Official Specifications. Translated 
from the German of Dr. J. HERZFELD. Sixty-nine Illustrations. 200 
pp. 1898. Price 10s. 6d. ; Abroad, 11s. ; strictly net, post free. 



Contents. 

Yarn Testing. III., Determining the Yarn Number. IV., Testing the Length 
of Yarns. V., Examination of the External Appearance of Yarn. VI., Determining 
the Twist of Yarn and Twist. VII., Determination of Tensile Strength and 
Elasticity. VIII., Estimating the Percentage of Fat in Yarn. IX., Determination 
of Moisture (Conditioning). Appendix. 



Press Opinions. 

"It would be well if our English manufacturers would avail themselves of this important 
addition to the extensive list of German publications which, by the spread of technical infor- 
mation, contribute in no small degree to the success, and sometimes to the supremacy, of 
Germany in almost every branch of textile manufacture." Manchester Courier. 

" This is probably the most exhaustive book published in English on the subject dealt with. 
. . . We have great confidence in recommending the purchase of this book by all manufacturers 
of textile goods of whatever kind, and are convinced that the concise and direct way in which it 
is written, which has been admirably conserved by the translator, renders it peculiarly adapted 
for the use of English readers." Textile Recorder. 

" A careful study of this book enables one to say with certainty that it is a standard work on 
the subject. Its importance is enhanced greatly by the probability that we have here, for the 
first time in our own language, in one volume, a full, accurate, and detailed account, by a prac- 
tical expert, of the best technical methods for the testing of textile materials, whether in the 
raw state or in the more or less finished product." Glasgow Herald, 

" The author has endeavoured to collect and arrange in systematic form for the first timt all 
the data relating to both physical and chemical tests as used throughout the whole of the 
textile industry, so that not only the commercial and textile chemist who has frequently to 
reply to questions on these matters, but also the practical manufacturer of textiles and his 
subordinates, whether in spinning, weaving, dyeing, and finishing, are catered for. . . . The 
book is profusely illustrated, and the subjects of these illustrations are clearly described," 
Textile Manufacturer, 



23 
DECORATIVE AND FANCY TEXTILE FABRICS. With 

Designs and Illustrations. By R. T. LORD. A Valuable Book for 
Manufacturers and Designers of Carpets, Damask, Dress and all 
Textile Fabrics. 200 pp. 1898. Price 7s. 6d. ; Abroad, 8s. ; strictly 
net, post free. 

, Contents. 

Chapters I., A Few Hints on Designing Ornamental Textile Fabrics. II., A Few Hints on 
Designing Ornamental Textile Fabrics (continued). III., A Few Hints on Designing Orna- 
mental Textile Fabrics (continued). IV., A Few Hints on Designing Ornamental Textile 
Fabrics (continued). V., Hints for Ruled-paper Draughtsmen. VI., The Jacquard Machine. 
VII., Brussels and Wilton Carpets. VIII., Tapestry Carpets. IX., Ingrain Carpets. X. 
Axminster Carpets. XL, Damask and Tapestry Fabrics. XII., Scarf Silks and Ribbons. 
XIII., Silk Handkerchiefs. XIV., Dress Fabrics. XV., Mantle Cloths. XVI., Figured Plush- 
XVII., Bed Quilts. XVIII., Calico Printing. 



Press Opinions. 

" The book can be strongly recommended to students and practical men." Textile Colourist. 

" Those engaged in the designing of dress, mantle tapestry, carpet and other ornamental 
textiles will find this volume a useful work of reference." Leeds Mercury. 

" The book is to be commended as a model manual, appearing at an opportune time, since 
every day is making known a growing desire for development in British industrial art." 
Dundee Advertiser. 

" Designers especially, who desire to make progress in their calling, will do well to take the 
hints thrown out in the first four chapu rs on 'Designing Ornamental Textile Fabrics'. 1 
Nottingham Duily Guardian. 

" The writer's avocation is that of a designer for the trade, and he therefore knows what he 
is writing about. . . . The work is well printed and abundantly illustrated, and for the author's 
share of the work we have nothing but commendation. It is a work which the student designer 
will find thoroughly useful." Textile Mercury. 



POWER-LOOM WEAVING AND YARN NUMBERING, 

according to various Systems, with Conversion Tables. ' An Auxiliary 
and Text-book for Pupils of Weaving Schools, as well as for self- 
instruction and for general use, by those engaged in the Weaving 
Industry. Translated from the German of ANTHON GRUNER. With 
twenty-two Diagrams in Colours. 150 pp. 1900. Price 7s. 6d. ; 
Abroad, 8s. ; strictly net, post free. 



24 

Contents. 

I., Power=Loom Weaving in General. Various Systems of Looms. II., Mounting 
and Starting the Power=Loom. English Looms. Tappet or Treadle Looms. Dobbies. 
III., General Remarks on the Numbering, Reeling and Packing of Yarn. Appendix. 
Useful Hints. Calculating Warps. Weft Calculations. Calculations of Cost Price in Hanks. 



Press Opinions. 

" A long felt want in the weaving industry has been supplied by the issue of a cheap volume 
dealing with the subject." Belfast Evening Telegraph. 

" The work has been clearly translated from the German and published with suitable 
illustrations. . . . The author has dealt very practically with the subject." Bradford Daily 
Telegraph. 

" The book, which contains a number of useful coloured diagrams, should prove invaluable 
to the student, and its handy form will enable it to become a companion more than some cum- 
brous work." Cotton Factory Times. 

" The book has been prepared with great care, and is most usefully illustrated. It is a capital 
text-book for use in the weaving schools or for self-instruction, while all engaged in the weaving 
industry will find its suggestions helpful." Northern Daily Telegraph. 

" The various systems are treated in a careful manner ; also the different looms and their 
manufacture, as well as the whole processes of the work. Yarn numbering according to various 
systems, with conversion tables and numerous coloured diagrams, materially assist tp a clear 
comprehension of the subject." Northern Whig. 

" It will be found most useful by those who have not time to go through the large standard 
work, and the volume may be aptly. described as a nutshell of power-loom weaving. Yarn 
numbering according to various systems is dealt with, and conversion tables included, and we 
have no hesitation in commending the book to our readers." Oldham Standard. 

" The ' inside' managers of our textile mills in which the work is complex or greatly varied, 
and where yarns of different materials are in use, will find this work convenient .for reference in 
case of novelty or difficulty. We may also say the same in relation to the textile student. Its 
description of the parts of the loom and their functions will be of use to the latter, being of the 
most elementary kind." Textile Mercury. 

" The author attempts to fill a gap in weaving literature caused by the neglect of many 
obscure points connected with the industry. A short review is given of the power-loom as a 
whole, followed by a description of the different parts of the machinery with their advantages 
and defects. . . . The book is severely technical, but must on that account be very valuable to 
the pupil who is determined to master this industrial art." Cheshire County News. 

" It is clear and concise, and gives just that knowledge in quality and amount which any 
student of the weaving industry ought to consider as the minimum necessary for his thorough 
comprehension of his future profession. The handiness and variety of the information com- 
prised in Section III., dealing with the numbering and reeling of yarns employed in the various 
systems in different countries, struck us as particularly useful." North British Daily Mail. 

" This work brings before weavers who are actually engaged in the various branches ot 
fabrics, as well as the technical student, the different parts of the general run of power-looms in 
such a manner that the parts of the loom and their bearing to each other can be readily under- 
stood. . . . The work should prove of much value, as it is in every sense practical, and is put 
before the reader in such a clear manner that it can be easily understood." Textile Industries. 

" The book under notice is intended as an instructor to those engaged in power-loom weaving, 
and, judging by its compilation, the author is a thorough master of the craft. It is not over- 
loaded with details, and he manages to compress in a book of some 150 pages all that one can 
possibly wish to know about the different parts of the machinery, whether of English or foreign 



25 

make, and for whatever kind of cloth required. A comprehensive summary is also included o 
the various yarns and methods of numbering them, as well as a few useful hints and a number 
of coloured diagrams for mandarin weavings. The book is printed in bold, legible type, on 
good paper, has a copious index, and is well and strongly bound." Ashton-under-Lyne Herald. 

" In dealing with the complicated parts of various classes of power-looms, the writer, who is 
one of the professors at the Royal Weaving School of Asch, brings to the work a thorough 
knowledge of the subject, and, what is of great value, he has the gift of communicating his 
knowledge in a way which is jeasily understood. The smallest details of loom-setting are 
entered into, and a full explanation of problems, which are a source of anxiety to many en- 
gaged in overlooking, is given. Students will find the work an admirable text-book, and all who 
are interested in weaving will see in it a valuable addition to the literature on this subject. . . . 
The book is in small compass, and is crowded with valuable information." Bradford Observer. 

" A short and valuable review is given of the power-loom as a whole, and this is followed by 
a description of the mounting of the different parts of the machinery, with their advantages 
and defects. In preference to illustrations the readers being presumed to already possess a 
suitable acquaintance with the subject the various systems of numbering yarn are explained, 
together with certain calculations useful in weaving. . . . How power-loom weaving has 
advanced in recent years is explained at some length in this book, which will prove invaluable 
to intending students of practical weaving^ and will also be found very useful to those whose 
knowledge of the subject is more advanced, to whom the calculations, which give evidence of 
careful study, will frequently come in handy." Stockport Advertiser. 



COLOUR: A HANDBOOK OF THE THEORY OF COLOUR. 

By GEORGE H. HURST, F.C.S. With ten coloured Plates and seventy- 
two Illustrations. 160 pp. 1900. Price 7s. 6d. ; Abroad, 8s. ; strictly 
net, post free. 

Contents. 

Chapters I., Colour and Its Production. Light, Colour, Dispersion of White Light, 
Methods of Producing the Spectrum, Glass Prism and Diffraction Grating Spectroscopes, The 
Spectrum, Wave Motion of Light, Recomposition of White Light, Hue, Luminosity, Purity 
of Colours, The Polariscope, Phosphorescence, Fluorescence, Interference. II., Cause of 
Colour in Coloured Bodies. Transmitted Colours, Absorption Spectra of Colouring 
Matters. III., Colour Phenomena and Theories. Mixing Colours, White Light from 
Coloured Lights, Effect of Coloured Light on Colours, Complementary Colours, Young- 
Helmholtz Theory, Brewster Theory, Supplementary Colours, Maxwell's Theory, Colour 
Photography. IV., The Physiology of Light. Structure of the Eye, Persistence of Vision, 
Subjective Colour Phenomena, Colour Blindness. V., Contrast. Contrast, Simultaneous 
Contrast, Successive Contrast, Contrast of Tone, Contrast of Colours, Modification of Colours 
by Contrast, Colour Contrast in Decorative Design. VI., Colour in Decoration and 
Design. Colour Harmonies, Colour Equivalents, Illumination and Colour, Colour and 
Textile Fabrics, Surface Structure and Colour. VII., Measurement of Colour. Colour 
Patch Method, The Tintometer, Chromometer. 

Press Opinions. 

" This useful little book possesses considerable merit, and will be of great utility to those for 
whom it is primarily intended." Birmingham Post. 

" It will be found to be of direct service to the majority of dyers, calico printers and colour 
mixers, to whom we confidently recommend it.'' Chemical Trade Journal. 

" It is thoroughly practical, and gives in simple language the why and wherefore of the many 
colour phenomena which perplex the dyer and the colourist." Dyer and Calico Printer. 

" We have found the book very interesting, and can recommend it to all who wish to master 
the different aspects of colour theory, with a view to a practical application of the knowledge so 
gained." Chemist and Druggist. 

" Mr. Hurst's Handbook on the Theory of Colour will be found extremely useful, not only to 
the art student, but also to the craftsman, whose business it is to manipulate pigments and 
dyes." Nottingham Daily Guardian. 

" This is a workmanlike technical manual, which explains the scientific theory of colour in 
terms intelligible to everybody. ... It cannot but prove both interesting and instructive to all 
classes of workers in colour." Scotsman. 



26 

THE COLOUR PRINTING OF CARPET YARNS. A Useful 
Manual for Colour Chemists and Textile Printers. By DAVID PATER- 
SON, F.C.S. Seventeen Illustrations. 132 pp. 1900. Price 7s. 6d. ; 
Abroad, 8s. ; strictly net, post free. 

Contents. 

Chapters I., Structure and Constitution of Wool Fibre. II., Yarn Scouring. III., Scouring 
Materials. IV., Water for Scouring. V., Bleaching Carpet Yarns. VI., Colour Making for 
Yarn Printing. VII., Colour Printing Pastes. VIII., Colour Recipes for Yarn Printing. 
IX., Science of Colour Mixing. X., Matching of Colours. XI., "Hank" Printing. XII., 
Printing Tapestry Carpet Yarns. XIII., Yarn Printing. XIV., Steaming Printed Yarns. 
XV., Washing of Steamed Yarns. XVI., Aniline Colours Suitable for Yarn Printing. 
XVII., Glossary of Dyes and Dye-wares used in Wood Yarn Printing. Appendix. 

Press Opinions. 

" The book is worthy the attention of the trade." Worcester Hi raid. 

" The treatise is arranged with great care, and follows the processes described in a manner 
at once clear and convincing." Glasgow Record. 

" An eminent expert himself, the author has evidently strained every effort in order to make 
his work the standard guide of its class." Leicester Post. 

" The subject is very exhaustively treated in all its branches. . . . The work, which is very 
well illustrated with designs, machines, and wool fibres, will be a useful addition to our textile 
literature." Northern Whig. 

" It gives an account of its subject which is both valuable and instructive in itself, and likely 
to be all the more welcome because books dealing with textile fabrics usually have little or 
nothing to say about this way of decorating them." Scotsman. 

" The work shows a thorough grasp of the leading characteristics as well as the minutiae of 
the industry, and gives a lucid description of its chief departments. ... As a text-book in 
technical schools where this branch of industrial education is taught the book is valuable, 
or it may be perused with pleasure as well as profit by any one having an interest in textile 
industries." Dundee Courier. 

" The book bears every mark of an extensive practical knowledge of the subject in all its 
bearings, and supplies a real want in technical literature. Chapters IX. and X., on the science 
of colour mixing and colour matching respectively, are especially good, and we do not remember 
to have seen the bearing of various kinds of light, and of the changes from one kind of light to 
another on the work of the colourist, so well treated elsewhere." Dyer and Calico Printer. 

" It is thoroughly practical, and contains much information which has not hitherto appeared 
in book form. It is pleasing to note that the practical part is not crowded out with purely 
' practical recipes '. A few typical examples are given, and the rest is left to the common sense 
and judgment of the printer or works' chemist. Another pleasing feature is the accounts given 
here and there of the author's own researches on the subject. The work will be of interest to 
printers of wool generally, and to those engaged in the dyeing of this fibre." Journal of the 
Society of Dyers and Colourists. 



PRACTICAL TREATISE ON THE BLEACHING OF LINEN 
AND COTTON YARN AND FABRICS. By L. TAILFER, Chemical 
and Mechanical Engineer. Translated from the French by JOHN 
GEDDES M'!NTOSH, Lecturer on Chemical Technology, London. 

[In the Press. 



27 

THE SCIENCE OF COLOUR MIXING. A Manual in- 
tended for the use of Dyers, Calico Printers and Colour Chemists. 
By DAVID PATERSON, F.C.S. Forty-one Illustrations, five Coloured 
Plates, and four Plates showing eleven Dyed Specimens of Fabrics. 
1900. Price 7s. 6d. ; Abroad, 8s. ; strictly net, post free. 

Contents. 

Chapters I., Colour a Sensation; Colours of Illuminated Bodies; Colours of Opaque and 
Transparent Bodies ; Surface Colour. II., Analysis of Light ; Spectrum ; Homogeneous 
Colours; Ready Method of Obtaining a Spectrum. III., Examination of Solar Spectrum; 
The Spectroscope and Its Construction; Colourists' Use of the Spectroscope. IV., Colour by 
Absorption; Solutions and Dyed Fabrics; Dichroic Coloured Fabrics in Gaslight. V., Colour 
Primaries of the Scientist versus the Dyer and Artist ; Colour Mixing by Rotation and Lye 
Dyeing; Hue, Purity, Brightness; Tints; Shades, Scales, Tones, Sad and Sombre Colours. 
VI., Colour Mixing; Pure and Impure Greens, Orange and Violets; Large Variety of Shades 
from Few Colours; Consideration ol the Practical Primaries: Red, Yellow and Blue. VII., 
Secondary Colours ; Nomenclature of Violet and Purple Group : Tints and Shades of Violet ; 
Changes in Artificial Light. VIII., Tertiary Shades; Broken Hues; Absorption Spectra of 
Tertiary Shades. Appendix : Four Plates with Dyed Specimens Illustrating Text. Index. 

Press Opinions. 

" The work has evidently been prepared with great care, and, as far as we can judge, should 
be very useful to the dyer and colourist." Halifax Courier. 

" Mr. Paterson's work not only clearly deals with the theory of colour, but supplies lucid 
directions for the practical application of the theory. His work will be found exceedingly 
helpful, not only to the practical colourist, but also to students in 0ur textile colleges, by 
forming a useful complement to their class lectures. There are several exquisitely coloured 
plates and a large number of other illustrations of theory and practice in colour blending, and 
also a series of plates with specimens of dyed fabrics attached, in explication of the author's 
views." Wakejield Express. 

" For some time the proprietors of The Oil and Colourman's Journal have been engaged in 
the publication of a series of practical handbooks intended for the use of those interested in 
certain branches of technology, and the present volume is the latest addition to their list. 
The feature which the works have in common and it is an all-important one in treatises 
of this sort is their eminently practical character. The primary aim of the publishers is to 
provide scientific text-books which will be helpful to those who are either actively engaged 
in the practice of the arts in question, or who are studying with that immediate end in 
view. . . . Mr. Paterson speaks with that assured knowledge of an expert, and in the present 
volume, as in that which he has already contributed to the same series, he sets forth the 
true foundation of the art of colouring in a manner at once comprehensive and judicious. 
. . . For dyers, calico printers and colourists in general, whose desire it is to work with 
accuracy in their respective branches, the treatise will prove an invaluable guide-book, 
provided the principles and methods it describes are studied with intelligence and care. To 
this end, every encouragement has been given that well chosen examples, carefully executed 
plates and diagrams, and an exhaustive index can supply. Glasgow Herald. 



Books on Plumbing, Decorating, 
Metal Work, etc., etc. 

EXTERNAL PLUMBING WORK. A Treatise on Lead Work 
for Roofs. By JOHN W. HART, R.P.C. One hundred and eighty Illus- 
trations. 270 pp. 1896. Price 7s. 6d. ; Abroad, 8s. ; strictly net, post 

free. 

List of Chapters. 

Chapters I., Cast Sheet Lead. II., Milled Sheet Lead. III., Roof Cesspools. IV., Socket 
Pipes. V., Drips. VI., Gutters. VII., Gutters (continued). VIII., Breaks. IX., Circular 
Breaks. X., Flats. XL, Flats (continued). XII., Rolls on Flats XIII., Roll Ends. XIV.. 



28 

Roll Intersections. XV., Seam Rolls. XVI., Seam Rolls (continued). XVII., Tack Fixings. 
XVIII., Step Flashings. XIX., Step Flashings (continued). XX., Secret Gutters. XXI., 
Soakers. XXII., Hip and Valley Soakers. XXIII., Dormei Windows. XXIV., Dormer 
Windows (continued). XXV., Dormer Tops. XXVI. , Internal Dormers. XXVII., Skylights. 
XXVIII., Hips and Ridging. XXIX., Hips and Ridging (continued). XXX.. Fixings for 
Hips and Ridging. XXXI. , Ornamental Ridging. XXXII., Ornamental Curb Rolls. XXXIII., 
Curb Rolls. XXXIV., Cornices. XXXV., Towers and Finials. XXXVI., Towers and Finials 
(continued). XXXVII., Towers and Finials (continued). XXXVIII., Domes. XXXIX. .Domes 
(continued). XL., Ornamental Lead Work. XLL, Rain Water Heads. XLII., Rain Water 
Heads (continued). XLIIL, Rain Water Heads (continued). 

Press Opinions. 

" This is an eminently practical and well-illustrated volume on the management of external 
lead work." Birmingham Daily Post. 

" It is thoroughly practical, containing many valuable hints, and cannot fail to be of great 
benefit to those who have not had large experience." Sanitary Journal. 

" Works on sanitary plumbing are by no means rare, but treatises dealing with external 
plumbing work are sufficiently scarce to ensure for Mr. Hart's new publication a hearty recep- 
tion." 1 he Ironmonger. 

" With Mr. Hart's treatise in his hands the young plumber need not be afraid of tackling 
outside work. He would do well to study its pages at leisure, so that he may be ready for it 
when called upon." Ironmongery. 

" The publication of this book will do much to stimulate attention and study to external 
plumbing work, for it is a book which we can heartily recommend to every plumber, both old 
and young, who desires to make himself proficient in the several branches of his trade. We 
can heartily recommend the book to plumbers and architects." Sanitary Record. 



HINTS TO PLUMBERS ON JOINT WIPING, PIPE 
BENDING AND LEAD BURNING. Second Edition, Revised 
and Corrected. By JOHN W. HART, R.P.C. One hundred and eighty- 
four Illustrations. 300 pp. 1896. Price 7s. (Sd. ; Abroad, 8s. ; strictly 

net, post free. 

List of Chapters. 

Introduction. Chapters I., Pipe Bending. II., Pipe Bending (continued). III., Pipe 
Bending (continued). IV., Square Pipe Bendings. V., Half-circular Elbows. VI., Curved 
Bends on Square Pipe. VII., Bossed Bends. VIII., Curved Plinth Bends. IX., Rain-water 
Shoes on Square Pipe. X., Curved and Angle Bends. XL, Square Pipe Fixings. XII., Joint- 
wiping. XIII., Substitutes for Wiped Joints. XIV., Preparing Wiped Joints. XV., Joint 
Fixings. XVI., Plumbing Irons. XVII., Joint Fixings. XVIII., Use of " Touch" in Solder- 
ing. XIX., Underhand Joints. XX., Blown and Copper Bit Joints. XXL, Branch Joints. 
XXII. , Branch Joints (continued). XXIII. , Block Joints. XXIV., Block Joints (continued). 
XXV., Block Fixings. XXVI., Astragal Joints Pipe Fixings. XXV II., Large Branch 
Joints. XXVIII., Large Underhand Joints. XXIX., Solders. XXX., Autogenous Soldering 
or Lead Burning. 

Press Opinions. 

" Rich in useful diagrams as well as in hints." Liverpool Mcrciny. 

" The papers are eminently practical, and go much farther into the mysteries they describe 
than the title ' Hints' properly suggests." Scotsman. 

" The articles are apparently written by a thoroughly practical man. As a practical guide 
the book will doubtless be ot much service." Glasgow Herald. 

" A well got-up and well-done practical book. It is freely illustrated and is a reliable help in 
respect of some of the most awkward work the young plumber has to perform." The Ironmonger. 

" So far as the practical hints in this work are concerned, it will be useful to apprentices and 
students in technical schools, as it deals mainly with the most important or difficult branches of 
the plumber's craft, viz., joint wiping, pipe bending and lead burning. . . . ' Hints ' are the 
most useful things to an apprentice, and there are many in this work which are not to be found 
in some of the text-books." English Mechanic. 

"It is a book for the intelligent operative first of all, not a mere manual of instruction 
for the beginner, nor yet a scientific treatise on the whole art of sanitary plumbing. The 
special subject with which it deals is joint-making, the most important branch of the operative's 
work, and into this topic the author goes with a thoroughness that is full of suggestion to even 
the most experienced workman. There is no one who has to do with plumbing but could read 
the book with profit." Ironmongery. 

"22 PKVME STKKET, HULL, 2i\th Xoreiniicr, 1894. 

" Gentlemen, Your books to hand for which accept my best thanks, also for circulars. I 
myself got one of J. W. Hart's books on Plumbing from your traveller, and having looked 
through the same I can safely recommend it as being the best book I have seen. Mr. J. W. 
Hart treats exhaustively upon soldering and pipe bending which are two of the most ess'ential 
branches in the plumbing trade." 



29 

THE PRINCIPLES AND PRACTICE OF DIPPING, BURN- 
ISHING, LACQUERING AND BRONZING BRASS WARE. 

By W. NORMAN BROWN. 35 pp. 1900. Price 2s. ; strictly net, post 
free, home and abroad. 

Contents. 

Chapters I., Cleansing and Dipping; Boiling up and Cleansing; Dipping. II., Scratch- 
brushing and Burnishing; Polishing ; Burnishing. III., Lacquering; Tools; Lacquers. 
IV., Bronzing ; Black Bronzing ; Florentine Red Bronzing ; Green Bronzing. Index. 

Press Opinion. 

" A successful endeavour has been made to show in the course of four chapters of compara- 
tively few words the most scientific and economical methods of treating brass ware. . . . The 
book is prefaced with a contents list, and concludes with a complete index. It is substantially 
bound, and should prove invaluable to gasfitters, decorators and ironmongers in country 
towns, who at spring time and during the re-decorating of a house undertake the work of 
renovating the brass fittings." Hardwareman. 



HOUSE DECORATING AND PAINTING. By W. NORMAN 
BROWN. Eighty-eight Illustrations. 150 pp. 1900. Price 3s. 6d. ; 
strictly net, post free, home and abroad. 

Contents. 

Chapters I., Tools and Appliances. II., Colours and Their Harmony. III., Pigments and 
Media. IV., Pigments and Media. V., Pigments and Media. VI., Pigments and Media. 
VII., Preparation of Work, etc. VIII., Application of Ordinary Colour. IX., Graining 
X., Graining. XI., Graining. XII., Gilding. XIII., Writing and Lettering. XIV., Sign 
Painting. XV., Internal Decoration. Index. 



A HISTORY OF DECORATIVE ART. By W. NORMAN 

BROWN. Thirty-nine Illustrations. 96 pp. 1900. Price 2s. 6d. ; 
strictly net, post free, home and abroad. 

Contents. 

Chapters I., Primitive and Prehistoric Art. II., Egyptian Art. III., Assyrian Art. IV., 
The Art of Asia Minor. V., Etruscan Art. VI., Greek Art. VII., Roman Art. VIII., 
Byzantine Art. IX., Lombard or Romanesque Art. X., Gothic Art. XL, Renaissance Art 
XII., The Victorian Period. Index. 

Press Opinion. 

" In the course of a hundred pages, with some forty illustrations, Mr. Brown gives a very 
interesting and comprehensive survey of the progress and development of decorative art. It 
cannot, of course, be pretended that in the limited space named the subject is treated ex- 
haustively and in full detail, but it is sufficiently complete to satisfy any ordinary reader ; 
indeed, for general purposes, it is, perhaps, more acceptable than a more elaborate treatise." 
Midland Counties Herald. 



THE PRINCIPLES OF HOT WATER SUPPLY. By JOHN 

W. HART, R.P.C. With 129 Illustrations. Price 7s. 6d. ; Abroad, 8s. ; 
strictly net, post free. 

Contents. 

Chapters I., Water Circulation. II., The Tank System. III., Pipes and Joints. IV., The 
Cylinder System. V., Boilers for the Cylinder System. VI., The Cylinder System. VII., The 

Combined Tank and Cylinder System. VIII., Combined Independent and Kitchen Boiler. 

IX., Combined Cylinder and Tank System with Duplicate Boilers. X., Indirect Heating and 
Boiler Explosions. XL, Pipe Boilers. XII., Safety Valves. XIII., Safety Valves. XIV., The 
American System. XV., Heating Water by Steam. XVI., Steam Kettles and Jets.-^XVIL, 
Heating Power of Steam. XVIII., Covering for Hot Water Pipes. Index. 



30 

Brewing and Botanical. 

HOPS IN THEIR BOTANICAL, AGRICULTURAL AND 
TECHNICAL ASPECT, AND AS AN ARTICLE OF COM= 

MERCE. By EMMANUEL GROSS, Professor at the Higher Agricul- 
tural College, Tetschen-Liebwerd. Translated from the German. 
Seventy-eight Illustrations. 1900. Price 12s. 6d. ; Abroad, 13s. ; 
strictly net, post free. 

Contents. 

PART I., HISTORY OF THE HOP. 

PART II., THE HOP PLANT. Introductory. The Roots. The Stem and Leaves. 
Inflorescence and Flower: Inflorescence and Flower of the Male Hop; Inflorescence and 
Flower of the Female Hop. The Fruit and its Glandular Structure: The Fruit and Seed. 
Propagation and Selection of the Hop. Varieties of the Hop: (a) Red Hops; (b) Green Hops; 
(c) Pale-green Hops. Classification according to the Period of Ripening: i. Early August 
Hops; 2. Medium F^arly Hops; 3. Late Hops. Injuries to Growth: Malformations; Diseases 

Eroduced by Conditions of Soil and Climate: i. Leaves Turning Yellow, 2. Summer or Sun- 
rand, 3. Cones Dropping oft, 4. Honey Dew, 5. Damage from Wind, Hail and Rain ; Vegetable 
Enemies of the Hop ; Animal Enemies of the Hop. Beneficial Insects on Hops. 

PART ill., CULTIVATION. The requirements of the Hop in respect of Climate, Soil 
and Situation : Climate; Soil; Situation. Selection oi Variety and Cuttings. Planting a Hop 
Garden: Drainage; Preparing the Ground; Marking-out for Planting; Planting; Cultivation 
and Cropping of the Hop Garden in the First Y'ear. Work to be Performed Annually in the 
Hop Garden: Working the Ground; Cutting; The Non-cutting System; The Proper Per- 
formance of the Operation of Cutting : I. Method of Cutting : Close Cutting, Ordinary Cutting, 
The Long Cut, The Topping Cut; II. Proper Season for Cutting: Autumn Cutting, Spring 
Cutting; Manuring; Training the Hop Plant: Poled Gardens, Frame Training; Principal 
Types of Frames ; Pruning, Cropping, Topping and Leaf Stripping the Hop Plant; Picking; 
Drying and Bagging. Principal and Subsidiary Utilisation of Hops and Hop Gardens. Life 
of a Hop Garden ; Subsequent Cropping. Cost of Production, Yield and Selling Prices. 

PART IV. Preservation and Storage. Physical and Chemical Structure of the Hop Cone. 
Judging the Value of Hops. 

PART V. Statistics of Production. The Hop Trade. Index. 

Press Opinions. 

" Farmers are but little given to reading ; but nowadays brewers have to study their trade 
and keep abreast of its every aspect, and as far as regards our trade, to them this book 
especially appeals, and will be especially useful." Licensed Victuallers' Gazette. 

" Like an oasis in the desert comes a volume upon the above subject, by the Professor at 
the Higher Agricultural College, Tetschen-Liebwerd, Germany, who has been fortunate 
enough to obtain an excellent translator from the German in the person of Mr. Charles 
Salter. The paucity of works upon the history and cultivation of hops is surprising, con- 
sidering the scope it gives for an interesting and useful work." Hereford Times. 

" We can safely say that this book deals more comprehensively and thoroughly with the 
subject of hops than any work previously published in this country. . . . No one interested in 
the hop industry can fail to extract a large amount of information from Professor Gross's 
pages, which, although primarily intended for Continental readers, yet bear very closely on 
what may be termed the cosmopolitan aspects of the science of hop production." South Eastern 
Gazette 

" This is, in our opinion, the most scholarly and exhaustive treatise on the subject of hops, 
their culture and preservation, etc., that has been published, and to the hop grower especially 
will its information and recommendations prove valuable. Brewers, too, will find the chapter 
devoted to ' Judging the value of hops ' full of useful hints, while the whole scope and tenor 
of the book bear testimony to the studious and careful manner in which its contents have been 
elaborated." Brewers' Journal. 

" Considering the extent to which this country draws its hop supplies from abroad, this 
translation of Professor Gross's volume will prove an interesting and instructive addition to 
the library of any brewer or brewers' chemist, the more so as the work of translation has been 
admirably carried out in simple and vigorous English. . . . The volume is one of a valuable 
series of special technical works tor trades and professions the publishers are issuing, and is 
the first so far dealing with the brewing industry." Burton Mail. 

" A work upon the above subject must be welcomed if for no other reason than the dearth 
of books dealing with so interesting a theme, but fortunately apart from this the book will 
afford excellent reading to all interested in hops and their culture. Professor Gross takes one 
over the whole field, by commencing with the earliest history of the plant so far back as the 
days of Ancient Greece and from both practical, theoretical and scientific standpoints, deals 



31 

with the cultivation, classification and formation of the hop. ... In speaking of the produc- 
tion of new varieties sound information is given, and should be of value to those who are 
always in search of improvements." Hereford Journal. 

" This work is, without doubt, the most thorough and extensive compilation on Hops ever 
yet offered to the public, and for this reason should be warmly welcomed and appreciated by 
men interested in the subject. Although primarily written for those engaged in the industry 
abroad, and mainly Continental in theory and practice, it nevertheless appeals to those con- 
nected with the hop growing and brewing business in England, not only by way of a com- 
parison, but also as an instruction. The volume is at once practical and scientific, is well 
got up, and teems with illustrations and statistics. In a word, it is a book .that should find 
its way into the hands of all who are occupied in hop production and distribution at home ; 
and it also contains valuable information and suggestions for the brewers themselves." 
Brewers' Guardian. 

" The value of a comprehensible and reliable text-book must be clearly apparent to every 
scientific hop grower, and in this county of Kent the chief hop-producing district of England, 
for over 400,000 cwts. were grown here last season alone its advice regardihg the cultivation, 
preservation and storage of the cones will be found extremely useful. Year by year scientific 
education is becoming more and more essential to the training in common with the re- 
mainder of agriculturists of the hop planter. Continental and American competition, the 
higher price and scarcity of hand labour, and many other causes make it necessary that 
the utmost should be extracted from a limited area of land. To accomplish this end all sorts 
of devices must be resorted to in the matter of cultivation. The lesson imparted in this treatise 
deals exhaustively with these ' devices '. And therein lies the basis of its value : whereas one 
man's life is ' made up of fails and successes,' here is to be found the collective successes, 
tabulated results, and logical inferences drawn from sources extending over the whole hop- 
growing area of the world." Kentish Gazette. 

Public Libraries. 

BRITISH LIBRARY YEAR BOOK, 1900=1901. A Record of 

Library Progress and Work. 54 Illustrations. Edited by THOMAS 
GREENWOOD. Price 3s. net, post free. 

Contents. 

Notes for Library Committees. Contributed Articles : The Library Rate. Some points in 
Library Planning Mr. Burgoyne. Library Classification Mr. Jast. Developments in Lib- 
rary Cataloguing Mr. Quinn. Children and Public Libraries Mr. Ballinger. Fire Prevention 
and Insurance Mr. Davis. The Educational Work of the Library Association Mr. Roberts. 
The Library Assistants' Association Mr. Chambers. British Municipal Libraries established 
under the various Public Libraries or Special Acts, and those supported out of Municipal Funds, 
giving particulars of Establishment, Organisation, Staff, Methods and Librarians. Table 
showing the Rate, Income, Work and Hours of the Rate-supported Libraries. Statistical 
Abstracts. British Non-municipal Libraries, Endowed, Collegiate, Proprietary and others, 
showing date of Establishment, number of Volumes, Particulars of Administration, and Lib- 
rarians. Library Associations and Kindred Societies. 



WORKS IN PREPARATION. 
WAXES. 
AGRICULTURAL CHEMISTRY. 

THE MANUFACTURE OF LEATHER. Translated from the 
French of M. VILLON. [In the Press. 

A TREATISE ON THE CERAMIC INDUSTRY. By 

EMILLE BOURRY. 

MINING SAFETY APPLIANCES. [In the Press. 

COLOUR MATCHING ON TEXTILES. A Manual intended 
for the use of Students of Colour Chemistry, Dyeing and Textile 
Printing. By DAVID PATERSON, F.C.S. 



32 

ARCHITECTURAL POTTERY BRICKS, TILES, PIPES, 
ENAMELLED TERRA=COTTAS AND ARCHITECTURAL 
STONEWARE. By LEON LEFEVRE. Nine hundred and fifty Illus- 
trations. [In the Press. 

DICTIONARY OF CHEMICALS USED IN THE OIL, 

PAINT AND CHEMICAL TRADES. [In the Press. 

THE DYEING OF PAPER PULP. By ERFURT and HUBNER. 
With one hundred and forty-five Specimens of Dyed Papers. 

TECHNOLOGY OF PETROLEUM. By NEUBURGER and 
NOALHAT. [In the Press. 

TEXTILE RAW MATERIALS AND THEIR PREPARA- 
TION FOR SPINNING. 

THE RONTJEN RAYS IN MEDICAL PRACTICE. 

SULPHATES OF IRON AND ALUMINIUM AND ALUM 
INDUSTRY. By L. GESCHWIND. 

RESINS AND BALSAMS. 

DRYING OILS, OIL BOILING, AND LIQUID AND COM= 
POUND DRYERS. By L. E. ANDES. Forty-two Illustrations. 
Expressly written for this series of special technical books, and the 
publishers hold the copyright for English and foreign editions. 

GAS AND COAL DUST FIRING. [In the Press. 



SCOTT, GREENWOOD & CO. 

are Publishers of the following old-established and well-known 
Trade Journals : 

THE OIL AND COLOURMAN'S JOURNAL. The Organ 
of the Oil, Paint, Drysaltery and Chemical Trades. Home Subscrip- 
tion, 7s. 6d. per year; United States, $2; Other Countries, 10s. per 
year. 

THE POTTERY GAZETTE. For the China and Glass Trades. 
Home Subscription, 7s. 6d. per year; United States, $2; Other Coun- 
tries, 10s. per year. 

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year; Foreign Subscription, 9s. per year. 

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REYIEW. Home Subscription, 6s. 6d. per year; Foreign Sub- 
scription, 9s. per year. 

19 Ludgate Hill, London, E.G. 

15/10/1900. 



33 



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