INTEENATIONAL EXHIBITION, LONDON, 
 18 7 1. 
 
 POTTEKY. 
 
 OBSERVATIONS ON THE MATERIALS AND MANUFACTURE 
 
 OF 
 
 TERRA-COTTA, STONE-WARE, FmE-BRICK, 
 
 MAJOLICA, AND ENCAUSTIC TILES, 
 
 "vnTH 
 
 EEMAEKS ON THE PRODUCTS EXHIBITED. 
 By ARTHUR BECKWITH, 
 
 CIVIL ENGINEER. 
 
 NEW YORK: 
 D. VAN NOSTRAND, PUBLISHER, 
 
 23 Murray St. and 27 Warren Sr. 
 
 1872. 
 
CjOMS 
 
 IP 
 
 7S7 
 IS7I 
 
 Entered according to act of Congress, in the year 1872, by 
 D. VAN NOSTEAND, 
 in the Office of the Librarian of Congress at Washington. 
 
PREFACE. 
 
 In making a brief report upon the Pottery displayed in 
 the Exhibition, relating to objects of use and ornament in 
 every house and family, the opportunity presented itself to 
 examine the processes of manufacture employed in the prin- 
 cipal branches of the ceramic art. 
 
 In describing these, I have endeavored to add to the 
 enumeration and treatment of the materials employed, a 
 summary of their different qualities for their respective uses, 
 together with analysis drawn from reliable sources, and a 
 slight sketch of the origin and progress of these great in- 
 dustries. 
 
 To render the subject more intelligible, I found it impos- 
 sible not to enter somewhat into technical details, which I 
 hope will not prove wholly without interest. 
 
 Aethue Becewith. 
 
 9071 
 
INTRODUCTION. 
 
 The International Exhibition, held this year in London, 
 contains a very complete collection of Pottery in all its 
 branches. The machinery employed in its manufacture is 
 also exhibited, but only to the extent of a small portion of 
 the various machines employed. 
 
 The following pages contain a notice of the principal 
 objects of interest in each department, and a summary of 
 the various processes of manufacture, with the differences 
 between them. 
 
 The composition of almost every kind of Pottery is fre- 
 quently guarded as a trade secret, but of late years, with 
 indifferent success. The materials available in each locality, 
 which form the basis of local manufactures, differ in their 
 chemical element, and especially in the mode of their aggre- 
 gation. In Pottery, the mode of aggregation or grouping of 
 the chemical elements, exerts an all-important influence (see 
 Fire-brick), and even when the exact composition of a ware 
 is known, it cannot be reproduced by merely bringing together 
 in correct proportion, the right chemical elements. To use 
 the different available materials, direct experiment with them 
 must be made from the start ; and as the substances ex- 
 tracted from the earth vary from year to year, these experi- 
 ments must be repeated subsequently, in order to maintain 
 the quality of the products. 
 
 In the presence of modern chemical analysis and micros- 
 copical research, it avails little to keep secret the composition 
 of wares. Analysis reveals the proportion of the primary 
 elements ; the microscope goes far to determine their mode 
 of grouping ; and as to the choice of natural materials, this is 
 inevitably, even when the composition is known, the subject 
 of direct experiment. 
 
6 
 
 POTTERY WARES. 
 
 Before proceeding further it may be well to recall that 
 the term Pottery is comprehensive, including all things 
 fashioned of earth and hardened by heat, from the rough 
 baked clay in the shape of bricks and massive articles, to the 
 fine china clay worked up to the lightest and most transparent 
 porcelain. 
 
 The term Pottery, as distinguished from Porcelain, is some- 
 times used to indicate only opaque earthen-ware, but the 
 variation in the degree of transparency of semi-vitreous 
 substances is so gradual that the boundary hne determining 
 where the one ends and the other begins cannot be well 
 traced. 
 
 All pottery wares may be divided into unglazed and unvit- 
 rified ware, which is absorbent and permeable to water, and 
 glazed and partly vitrified ware, which is non-absorbent and 
 impervious. At an early period, glazes consisted of a coating 
 of wax or oil and ochreous earth, or an alkaline solution to 
 vitrify the surface, until the discovery of an adherent vitreous 
 glaze, which could be fused upon the surface of the porous 
 clay. Later, in Southern Europe, a glaze composed of siHca 
 and lead was used, and the Moors, by adding oxides of lead 
 and tin to glass, formed an opaque white enamel, which was 
 imitated in Italy, and various metallic colored enamels were 
 discovered. 
 
 Pottery wares may also be divided into hard and soft 
 ware, according to the materials used and the temperature 
 at which they are solidified in the furnace, which results in a 
 marked difference of texture. Thus common brick and earth- 
 enware are soft, while fire-crockery and stone-ware are hard. 
 And porcelain, likewise, is either like the hard Oriental china- 
 ware, or the soft English porcelain, which receives its greatest 
 fire in the biscuit or unglazed condition. Hard porcelain 
 was known to the Chinese many years B. C, and imported 
 into Europe by the Portuguese about the year 1500, but its 
 composition remained unknown there until, in 1709, Bottcher, 
 in Saxony, accidentally discovered it, and Cookworthy, in 
 England, discovered the china clay. 
 
7 
 
 PORCELAIN, 
 
 Excellent qualities of china claj are found in Cornwall, 
 West Devon, Central France, Northern Germany and 
 America ; they all seem without exception to be formed by a 
 process of natural or artificial washing from the decomposed 
 felspar of certain kinds of granite. Felspar contains 62 silica, 
 20 alumina, 15 potash, and 3 of water, lime, magnesia and iron. 
 The materials from Cornwall are artificially prepared, and 
 the uniformity of quality thus obtained makes them more 
 valuable than the natural china clay which varies more in 
 quality. One hundred parts of the finest china clay, or 
 kaolin, contain : Silica 46, alumina 40, oxide of iron, lime, 
 magnesia together 1, water 13. When more silica is present, 
 especially in a free state, as fine or coarse sand, 10 or 12 per 
 cent, of which is sometimes found mixed in the clay, as in 
 Cornish stone, the china is rendered coarser. 
 
 The process of natural washing of porcelain clays has 
 been performed on a large scale in Cornwall and Devonshire. 
 The decomposed granite has been washed through an ex- 
 tended valley, leaving the coarser particles of quartz behind, 
 and conveying only the particles of fine clay to the lower 
 parts of the valley, where they are found covered by a bed 
 of local gravel. These deposits are cut with a spade into 
 cubical blocks called " china stone," and partially dried and 
 removed, leaving large pits. 
 
 When the kaolin is artificially prepared, the decomposed 
 rock is washed in a series of tanks, in the first of which the 
 heavier particles of quartz, mica, and impurities are collected, 
 while the fine particles, consisting of the decomposed felspar, 
 are allowed to settle in the succeeding tanks. The water is 
 run off, the sediment is dried in sheds and cut into cubical 
 blocks of about one foot, and sent to market. 
 
 The soda granites, in which the felspar contains soda 
 instead of potash, decompose most readily and are most 
 used for porcelain. 
 
 There are differences in texture and appearance between 
 the English porcelain called " china " and the " hard por- 
 
•8 
 
 celain " manufactured in China, France, and Germany. The 
 body and glazes of hard porcelain are composed of the same 
 purely granitic materials, used only in different proportions, 
 and under the very high temperature employed they vitrify 
 together. As this high temperature would be destructive to 
 coloring, the colors are laid on over the glaze subsequently 
 to it, and fixed by again firing at a lower temperature. The 
 result is a certain dead opacity in the appearance of the 
 coloring. 
 
 The composition of Enghsh or soft porcelain is more 
 complex ; a large proportion of calcined bone is mixed with 
 the china clay and Cornish stone to produce an effect of 
 white transparency, and small proportions of gypsum, sand, 
 chalk, alum, soap, soda, lime, nitre, and salt are added. This 
 body receives its strongest firing first, and the glaze and 
 colors are then applied and fired at a lower heat. The glaze 
 is formed of oxide of lead or tin, with borax and silica, 
 potash or soda, resembling that of old Sevres. This glaze 
 vitrifies separately from the body, and forms over it a coating 
 similar to glass ; it sometimes incorporates the colors in such 
 a way that the subjects painted over it appear through the 
 glaze as under a glass, presenting a briUiant and finished 
 appearance, Hke the soft Sevres porcelain of the last century. 
 
 The hard porcelain differs from the soft in being closer 
 grained, denser, more translucid, capable of supporting 
 greater heat, presenting many crystalUne specks in the frac- 
 ture, and its glaze is harder, not so easily scratched by the 
 knife, and incorrodible by acid. Hard porcelain is not man- 
 factured in England ; twenty years ago Messrs. Minton tried 
 to manufacture it, but abandoned the attempt. 
 
 The nature of the fuel used in England, which is coal, 
 together with the softer nature of the clays, are attended 
 with greater difficulties than the use of wood, as in France. 
 There are some advantages in the matter of colors in making 
 soft porcelain, for turquoise, Bleu de Koi, and transparent 
 green can be freely employed on English china, and they 
 have more brilliancy, especially by candle-light, than the 
 colors of the hard porcelain. The fusibility of the softer 
 
9 
 
 lead glaze, by incorporating the colors, produces this trans- 
 parency. The plasticity of the body also allows of greater 
 perfection of form, and it is of a purer white. 
 
 Analysis of English porcelain, by Couper, show a compo- 
 sition of : 
 
 Sihca 40 per cent. 
 
 Alumina , 21 to 25 per cent. 
 
 Lime 10 " 14.22 
 
 Magnesia 0 " 0.43 
 
 Phosphate of lime and some iron. 26.44 " 15.3 " 
 Alkalies and loss 2 " 6 
 
 The bones used are chiefly imported from South America. 
 Those of oxen are best, those of horses and hogs contain too 
 much iron. They are deprived of grease by boiling in hot 
 water, then calcined openly or first distilled in closed vessels 
 and then burnt in contact with the air. The white ashes are 
 ground and tempered before use. This phosphate of lime 
 has a strong whitening power, and is considered to act me- 
 chanically to form the skeleton of the ware. As much as 
 fifty per cent, is sometimes introduced. 
 
 The biscuit fire lasts twenty-five to fifty hours, and is con- 
 ducted in kilns, similar to those for earthen-ware. The fire 
 for the glaze lasts fifteen to twenty hours. 
 
 The glaze contains : 
 
 Oxide of lead 20 to 23 per cent. 
 
 Oxide of tin 0 " 3 
 
 Cormsh stone 20 " 33 
 
 Flint 7 " 17 
 
 Flint glass 0 " 20 
 
 Crystallized borax 19 " 25 
 
 Soda and potash 0 " 8 
 
 and instead of Cornish stone sometimes thirty-eight to forty- 
 two per cent, of felspar. A fraction of smalt is occasionally 
 introduced. 
 
 The elements of hard porcelain are kaolin fluxed with 
 felspar. Examined under the microscope this porcelain 
 
10 
 
 shows a framework of minute opaque particles of burnt 
 kaolin, cemented by the fluxing elements, which are fused to 
 a transparent glass (Ehrenberg). Occasionally, to diminish 
 the shrmkage, quartz sand or ground porcelain are added, 
 and to increase plasticity, the alumina is increased. 
 
 When felspar is wanting, there are substitutes, such as 
 pegmatite (a granite), dust from granitic roads, kaolin melted 
 up with carbonate of potash, gypsum and chalk. The ma- 
 terials are ground particularly fine and well washed. All the 
 devices of kneading, balling, beating, etc., which produce an 
 intimate and homogeneous mixture, are applied. Warm 
 water, which dissolves earths and alkalies, is recommended 
 to remove those causes of softening. 
 
 The analysis of porcelains from China, Sevres, Berlin, 
 Dresden, etc., show a composition between : 
 
 Silica 63 to 75 per cent. 
 
 Alumina • 18 " 35 " 
 
 Potash 0 " 5 
 
 Soda 0 " 3 " 
 
 Lime 0 " 5 " 
 
 Magnesia 0 " 1.5 " 
 
 Iron, as little as possible. 
 
 Laurent analyzed the best chinas, and the composition he 
 found has since served as a model at Sevres, viz. : 
 
 Silica 58, 
 
 Alumina 34.4 
 
 Lime 4.5 
 
 Potash 3, 
 
 In Vienna, 72 per cent, of kaolin was fluxed with 12 felspar, 
 12 quartz, 4 gypsum. The Dresden china contains even 26 
 per cent, felspar. 
 
 The glazes of Dresden and Munich are formed of : 
 
 Burnt quartz 35 to 37. 
 
 Kaolin and ground porcelain 46 " 48. 
 
 Limestone and gypsum 16 " 18. 
 
11 
 
 The glaze of Sevres is simply pegmatite, wLicli contains 
 silica, 76, alumina, 16, potash, 8. The glaze used being of the 
 same composition as the mixture which fluxes the kaolin, it 
 readily unites with the latter in the fire, and porcelain can 
 be made in one firing, as in china, the object being moulded, 
 painted and glazed in the clay state, and completed in one 
 firing. 
 
 It is usual, however, to heat the body first to 30° or 60° 
 Wedgwood, so that it may rapidly absorb the water of the 
 glaze when subsequently dipped in it. The degree of this 
 first heat requires attention, for if too high the ware will no 
 longer absorb the glaze. By greasing any part, it will not 
 take the glaze. The second firing requires the strongest 
 heat used for any pottery (130" to 160° W.), to obtain a 
 sufficiently hard glaze, and great care in modulating the heat. 
 The total shrinkage reaches up to 17 per cent., the quarter of 
 which occurs in the first fire. The ware must be separated 
 from the products of combustion. 
 
 The ovens are various. The Qinori or Sevres Oven, is in 
 three stories, the two lower directly heated by fires at the 
 sides, the upper one by waste heat. The Berlin Oven has 
 4 stories, the lower one is used exclusively as a combustion 
 chamber from which the gases ascend to the three others suc- 
 cessively. It is said to give higher heat than the Sevres. 
 Among the best are those fired with gas ; the preceding one, 
 and that of Thomas, are somewhat of this kind, the flame 
 being direct, but those of Venier and Gustavsberg are more 
 perfect. They resemble somewhat Bosch's oven (see Stone- 
 ware.) The gas generator is separate and under perfect 
 control ; the gases are introduced in the centre of the floor 
 of the oven, ascend, are reverberated, and drawn through 18 
 apertures in the floor into flues in the outer walls, which 
 lead to a second story chamber, and thence to a third, where 
 a central chimney exhausts them. Preliminary heating of 
 the air produces a higher temperature. An analogous oven 
 is being tried at Berlin, in which the successive chambers 
 are placed side by side, instead of being superposed. This 
 
12 
 
 disposition allows of the continuous principle being applied, 
 as by Hoffmann. 
 
 There is still room for improvement in porcelain ovens, 
 since 1 lb. of porcelain requires the heating of 15 lbs. of other 
 material, irrespective of the masonry of the ovens, for all of 
 which, 8 lbs. of coal are necessary. 
 
 Porcelain Exhibited. — In examples of common En- 
 glish pottery, the mere manufacture is of the highest and 
 soundest quality, though the design and harmony of colors 
 are not unfrequently deficient in comparison. 
 
 The high technical excellence of modern ceramic art is well 
 represented at the Exhibition. 
 
 Dr. Wall, the founder of the Royal Worcester Porcelain 
 Works, first turned to account the discovery of Cornish 
 stone, and these works exhibit very fine porcelain ; espe- 
 cially of a dark blue color. In decoration they have avoided 
 the use of too great diversity of color in the same work ; 
 the brilliant positive hues they use, in connection with the 
 human figure, have been objected to as less effective than 
 half tints. The transparency of their porcelain is noted. 
 Their Parian is admired, and they also exhibit Majolica. 
 
 Copeland & Sons make a fine show of porcelains. Their 
 most successful colors are a purple and a rich gi'een. A 
 novelty in their decoration consists in small subjects and 
 figures in black, traced out with a fine gold line on a white 
 ground, having the effect of a Silhouette. 
 
 In coming to the name of Minton it is proper to recall 
 that there are three firms, Minton & Co., Minton, Hollins & 
 Co., of Stoke-on-Trent, and Eobert Minton Taylor, of Een- 
 ton, in the same vicinity. The specialty of the two latter is 
 flooring tiles, though they exhibit other goods. 
 
 Messrs. Minton & Co.'s specialty is not flooring tiles, 
 which they do not manufacture, but they exhibit largely in 
 all other descriptions of earthen-ware and porcelain. Mr. 
 Thomas Minton founded the firm in 1791, and to the labors 
 of his son, Mr. Herbert Minton, are due in great part the 
 medals which the firm acquired at all the exhibitions. The 
 present proprietor is Mr. Colin Minton Campbell. Mr. Ar- 
 
13 
 
 noTix directs the staff of artists who assist the firm. The 
 excellence of their colors, and the variety in the kinds of 
 ware they exhibit, place them among the first manufacturers. 
 
 They obtain a new process of gilding by corroding the 
 glaze with an acid and applying gold leaf upon the body. 
 
 The revived and modified Orientalism of ceramic decora- 
 tion first in Paris and now in London, is a notable feature. 
 Oriental surface decoration seems to have due regard to the 
 right principles, as it is always pleasing. The Persian ware 
 of Minton's is one of the novelties of the Exhibition. Its 
 brilliant blue rivals the turquoise in richness and texture. 
 The brothers Deck, in Paris, first revived this art. A pair 
 of celadon vases by Minton, on pate changeante or chame- 
 leon ware, which from gray green by day changes to a deep 
 pink or crimson hue under artificial Ught, and enriched by 
 some delicately executed Cupids, are admired. 
 
 John Mortlock's turquoise blue is as fine as Minton's, 
 but the glaze applied is defective from being crackled by 
 unequal expansion. 
 
 The names of Wedgwood, Pellatt, Goode, Adams, Kerr, 
 Phillips & Pearce, Powell & Bishop, Eose, Battam, Boucher 
 Guy, Hancock, Garrard, Elkington are also prominent 
 among English manufacturers. 
 
 Italian, Spanish & Portuguese pottery are exhibited by 
 the Science and Art Department. The Italian and Spanish 
 wares exhibited are defective in coloring and glaze. The 
 Portuguese Palissy ware shown is highly glazed, but pre- 
 sents a striking example of utility made subservient to deco- 
 ration. 
 
 A collection of Moorish ware, lent by Mr. G. Maw, 
 shows good forms and tasteful ornamentation. It is said 
 that the history of the potter's art is the history of civiliza- 
 tion, and in this sense the Egyptian pottery, lent by the 
 Khedive, is interesting. It shows a coarse body and inferior 
 coloring, but the forms are quaint and graceful. The yellow 
 glaze used at Old Cairo consists of oxide of lead and pounded 
 pebbles of silex. The green glaze contains copper in addi- 
 tion. The body is formed of clay mixed with ashes, sand. 
 
and sometimes hemp, and slime of the Nile. Likewise 
 Indian pottery is curious and instructive in form and 
 color. In some specimens gray or brown mica mixed with 
 the clay, or rubbed on it, produces a metallic effect on the 
 surface. 
 
 Canada contributes some pottery of a common description. 
 
 Danish pottery is well represented. The Eoyal Copen- 
 hagen Manufactory has a high reputation, and Bing & 
 Grondahl exhibit good work. A plate pattern, of tendrils 
 and flowers lightly sketched on a ribbed surface, is admired. 
 This decoration is of a simple and pleasing kind, and in 
 better taste than more elaborate and expensively painted 
 dishes, in which the idea of actual use seems out of place. 
 
 Hungarian porcelain, exhibited by M. F. de Farkashaza, 
 ornamented with a light red design on a light-colored 
 ground, is admired in the same way for its pleasing effect and 
 good taste. The porcelain is of a fine quality, and very hard, 
 produced at Herend. The ornamentation has a pecuhar and 
 somewhat Japanese character. 
 
 The body of the Swedish porcelain is good and haid; 
 the correctness and grace of the decorative wares are char- 
 acteristic. 
 
 Prussian pottery is represented by some very fine white 
 biscuit or unglazed ware from the Royal Berlin Porcelain 
 Works, and an Urbino vase, price $260, of great beauty and 
 richness of coloring. The porcelain is hard, and noted for 
 the precision of manufacture. 
 
 Some Belgian dishes are shown, profusely covered with 
 paintings of merit as works of art, but which may be re- 
 proached with the common error of making the use subser- 
 vient to the decoration. Several Danish, Swedish, Hunga- 
 rian, English, and other exhibitors have happily avoided this 
 extreme. 
 
 As novelties, the smoke-painted porcelain from Berne, 
 executed by Mme. A. Leuzinge, and a set of photographs of 
 landscapes on porcelain plates by Leth, of Vienna, are 
 pleasing specialties. 
 
 Also W. J. Goode, of South Audley street, London, exhib- 
 
15 
 
 its etchings on the glaze, of special merit. The designs 
 are eaten into the glaze with fluoric acid, so that they could 
 be printed from ; and the hnes thus produced are colored. 
 
 PATE-SUR-PATE, 
 
 Or " clay-upon-clay." In this method of decorating porce- 
 lain, the actual ornament is produced by the application, 
 with the brush, of white liquid porcelain, or " engobe," used 
 as a pigment, in successive layers upon the colored body of 
 the ware — i. e., a given thickness is added to it, with a brush 
 or by immersion, presenting a rough surface in rehef, which 
 is trimmed to the required design by cutting implements 
 and sharp scrapers. By successive applications, the painter, 
 who requires to be also a modeller in the treatment of his 
 subject, gains his effect of relief. When the bas-relief is 
 completed, the object is subjected to several bakings or 
 firings, and at the last firing it is covered with a coating of 
 glaze. The strong oven fire vitrifies the porcelain and the 
 pigment, embodying them together, and rendering the salient 
 objects translucent. These portions, in vitrifying, retain a 
 relief which forms the actual outline and the high lights, 
 while its thinner parts enable the colored groundwork to be 
 seen through them, and these form the transparency of float- 
 ing draperies', clouds, or flesh, according to the design. 
 
 The principle of pate-sur-pate thus differs from that of 
 ordinary white porcelain transparencies used for lamp and 
 window decoration, by transmitting color through the design 
 instead of light. 
 
 The clay ground generally used is a soft yellowish gray or 
 sage green, known as celadon. The tint is tender and un- 
 obtrusive, and its effect, seen through the thin parts of the 
 superimposed design, is pleasing. Like most European 
 novelties, however, it is an old acquaintance of the Chinese, 
 from whom the idea has been derived. Pate-sur-pate was 
 first attempted in Europe in 1847, at Sevres, under Ebelmen, 
 and until the late war many articles in this style were pro- 
 duced of great beauty. During the siege of Paris, Messrs. 
 
16 
 
 Minton secured the services of Mr. Solon from Sevres, and 
 at once began experimenting to obtain the colored clays re- 
 quired. They met with complete success, obtaining the 
 Sevres colors and several others in addition, and now pro- 
 duce celadon cups and vases, graceful in form and delicate in 
 execution. 
 
 Mr. Solon's work possesses a cameo-like softness, which 
 yet harmonizes well with the somewhat coarser grain of the 
 body of the ware. Mr. Burty, in. his " Chefs d'oeuvres of 
 the Industrial Arts," says of this artist : " Mr. Solon, who 
 also signs his delicate bas-reliefs with the word " Miles," is 
 gifted with a perfectly modern sentiment for decoration. 
 These nymphs who push aside the reeds of the brook; these 
 Psyches who are lighting a Diogenes lantern ; these water- 
 nymphs reclining on the brink of the waters which flow from 
 their bended urns ; these chimeric figures which stand erect 
 with bulging throats ; these Medusas whose hair is composed 
 more of strings of pearls than of snakes, — these are the 
 dreams of an artist born in our day, and who only claims of 
 Antiquity or the Renaissance the more exquisite details of 
 their fancy." 
 
 The prices set upon Mr. Solon's work, are $90, $70, $110, 
 for three vases respectively 7, 10 and 18 inches high. 
 
 The very high temperature employed in firing this ware, is 
 destructive to most colors, and only those obtained from the 
 oxides of cobalt, nickel, chrome, uranium, etc., are used. 
 Specimens are shown with a ground of a warm chocolate 
 color and other dark colors. The effect of these is apt to be 
 flaky and less delicate. One of the difficulties, when figures 
 are delineated, seems to be that the glaze has a tendency to 
 mar the effect by destroymg the sharpness of outUne. Oxide 
 of chrome, fired in a neutral atmosphere, produces Celadon 
 green. 
 
 In the Limoges ware, the difference is that a regular enamel 
 or vitrified pigment is used, while in pate-sur-pate, porce- 
 lain clay merely is used. 
 
17 
 
 "PATE CHANGEANTE." 
 
 Another peculiarity of the Sevres work is their "pate 
 changeante " invented by the director, Mr. Eegnault, and so 
 named from the color changing from grayish celadon by day- 
 light, to a decided pink by candlelight. Messrs. Minton have 
 succeeded in producing a similar dove color, which changes 
 to a light crimson by artificial light. Oxide of chrome, fired 
 in an oxidizing atmosphere, produces a similar color. 
 
 GRAFFITO WARE. 
 
 This ware recalls by its decoration, that of the walls of 
 Pompeii ; from the objects exhibited, and the simplicity and 
 beauty of their ornamentation, it promises to develop well. 
 
 Graffito, which means scratched ware, is of ItaUan origin, 
 and is supposed to have been first invented in the province 
 of Perugia in the 15th century. At the period of the Renais- 
 sance in Italy, the potters, ignoring the decorative processes 
 with colors and enamels, then familiar to the Moors in Spain, 
 and which Delia Robbia subsequently imitated, made 
 use of two clays of different color. The body of their vessels 
 they formed of the darker clay, and after drying them only 
 sufficiently to be able to handle them, they dipped them into 
 a liquid " slip " formed of the lighter colored clay. As soon 
 as this coating was dry, the artist, with a sharp wooden or 
 steel point, traced his ornament on the surface, removing the 
 upper light-colored surface and showing everywhere on the 
 lines of the design, the dark body beneath. The vessel was 
 then covered with a natural sulphuret of lead ore previously 
 triturated, which, when fired, melted on the ware and pro- 
 duced a rich yellow glaze. This process of decoration allows 
 the artist to express his feeling on the ware without the 
 intervention of any assistants. After firing, some parts of 
 the work were touched up by the application of slips of cop- 
 per or manganese ore, which produced the green or violet 
 patches which give additional richness to the ware. The 
 natural colors of the clays, which form the decoration of this 
 
18 
 
 ware, generally harmonize perfectly together and consequent- 
 ly produce a good effect. Messrs. Minton & Maw have lately 
 revived this process, and show fine specimens. Minton's de- 
 signs are by W. A. Stevens. 
 
 HENRI DEUX WARE ; OR, FAIENCE D'OIRON. 
 
 Henri Deux ware is the only description of pottery in 
 which clays of different colors are inlaid together. The artist 
 having made his design, each distinct part of the ornament 
 is stamped on separate " bats " of clay. The design is thus 
 indented in the soft body of the ware and this indentation 
 filled up with another colored clay, and when dry the super- 
 fluous clay is removed from the surface. The separate bats 
 are then placed into their proper forms side by side, in a 
 complete mould, and a backing formed of a general coating 
 of clay was appHed to unite them together. The plastic 
 state of the clay required great care not to distort the 
 design. 
 
 Though this process is very similar to the 12th century 
 art of tile making, yet the application of the encaustic pro- 
 cess to vessels of delicate size and complicated forms was not 
 attempted till about 1540. It is held in high esteem, and 
 valued above its intrinsic merit on account of the scarcity of 
 the original examples ; its revival by Minton is all the more 
 interesting. 
 
 The ornaments of Henri II. ware are in the Renaissance 
 style, and the forms have a metallic rather than fictile char- 
 acter. 
 
 A toilette suite ordered by Henri II. for Diana of Poitiers 
 is all that is said to have been originally manufactured ; Mr. 
 Chaffers gives a list of the pieces known, of which there are 
 only 63, namely 26 in England, 26 in France, and 1 in Rus- 
 sia. The bowl that Sauvageot left to the Louvre was bought 
 by him for 200 francs. In 1835, the ewer possessed by De 
 Monville brought 2,500 francs. A salt-cellar at the Rattier sale, 
 in 1859, brought 12,500 francs. A restored candlestick, plainly 
 ornamented, went for 16,000 francs at the Lafayette sale, in 
 
19 
 
 1862, and tlie Science and Art Department of the Kensing- 
 ton Museum gave 18,000 francs for it. Finally, at the Pour- 
 tales sale, a biberon was bought by Mr. J. Malcolm, of 
 London, for 27,500 francs. Such were the values set on the 
 original Henri II. ware, and now for a comparatively moderate 
 outlay possession may be had of reproductions by Mintcn, 
 quite equal to the originals. Although Minton & Co. have 
 not attempted to copy the exact tint of the clays, their speci- 
 mens prove that they are fully acquainted with the process. 
 Mr. Charles Toft is the name of the maker. 
 
 POTTERY MOUNTED IN DAMASCENED 
 METALS. 
 
 Senor Suloaga, of Madrid, is the only producer at the 
 present day of the Damascene work of the Saracens, and in 
 1855, he exhibited a fine display of damascened fire-arms 
 
 He now exhibits, in connection with Minton & Co. a com- 
 bination of pottery with this metal work which is very effec- 
 tive. 
 
 CLOISONNE ENAMEL. 
 
 A specialty undertaken of late years in Paris is the repro- 
 duction of Chinese and Japanese cloisonne enamel. In this 
 Oriental work, a vessel of metal, usually copper, is first made 
 and the lines of a pattern traced on its surface. A fine wire 
 beaten into a flat supple riband is then taken and soldered 
 by one edge to the lines traced on the surface of the copper 
 vessel. The wire stands on its edge, forming a number of 
 cells or cloisons which are filled with a paste composed 
 mainly of oxide of lead and silica, with some lime and soda, 
 and colored as required, either with the oxide of copper, iron 
 or cobalt. The vessel is then fired at a heat sufficient to 
 vitrify the paste, and finally the whole surface is polished by 
 friction. 
 
 The character of the Chinese cloisonne work is coarser 
 and bolder than that of the Japanese, and in both the con- 
 
20 
 
 trasts of colors are successfully harmonized. Barbedienne 
 and other Paris makers have made very gra ceful work of this 
 description. 
 
 A novelty undertaken by Messrs. Minton,is their imitation 
 of the above cloisonne work, using only porcelain instead of 
 metal, and painting on it with colors which have been mixed 
 with opaque enamels, as practised also in China. This 
 method of decoration is very effective, except when the 
 attempt is made to imitate metallic cloisonn6 work, which is 
 more subdued and sober in tone and glaze. The soft nature 
 of Enghsh porcelain lends itself to the production of great 
 richness and depth in turquoise color, when the body is 
 covered with turquoise enamel ; when appropriately decor- 
 ated with colored enamels, the effect is admirable. 
 
 UNDER-THE-GLAZE PAINTING IN OPAQUE 
 ENAMEL COLORS. 
 
 Messrs. Minton have introduced a new set of materials for 
 painting on a densely colored body, in the same manner as 
 body colors are used in ordinary painting ; the whole can be 
 subsequently glazed over without affecting the most delicate 
 touches. Mr. Mussill, their artist in this department, was 
 acquired by them since the late French war. The colors are 
 perfectly opaque, have the appearance of colors for canvas, 
 and have much more body than the ordinary colors for paint- 
 ing on porcelain. By firing they do not change or sink, and 
 retain the spirit of the brush. They withstand perfectly the 
 action of the glaze in the glost oven. 
 
 This method of painting (see Chinese Porcelain), practised 
 in the East, has since been imitated at Dresden, and lately 
 been revived at Sevres and Stoke-on-Trent. 
 
 The advantage it presents, of depth of tone in colors, dura- 
 bility owing to hard firing, and economy of manufacture, 
 since the decoration can be apphed and made fast at one 
 firing (unlike the paintings on porcelain, that frequently re- 
 quire several firings), make it desirable that this method 
 should come into more general use. 
 
21 
 
 To produce these colors, the following considerations may 
 assist. They are obtained by mixing opaque enamels in the 
 colors. The different colors must act alike in withstanding 
 a hard fire, and fusing at the same high point ; in adhering 
 to porcelain or stone-ware, and in taking the glaze uni- 
 formly. 
 
 To obtain the requisite opacity, oxide of tin, oxide of anti- 
 ^0^7, phosphate of lime, oxide of lead with some salt, 
 alkalies and sihca, and in general the enamels applied to 
 majolica, fayence, and stone-ware, are available. The me- 
 talHc oxides which supply the color, act as a flux upon the 
 enamel, and tend to increase its fusibility. Only those 
 oxides should be used which will stand a strong heat, and, 
 like the oxides of iron, cobalt, chrome, titanium, uranium, 
 manganese, and chromate of iron, possess strong coloring 
 powers, and in consequence do not require to be used in 
 quantity large enough to fuse the enamel too soon. 
 
 To diminish the fusibihty, the steps taken in the manufac- 
 ture of fire-bricks and of majolica enamels (which see), apply. 
 The fritting of the glaze {i.e., preparatory melting up to a 
 glass), and sudden immersion while hot in cold water, in- 
 creases its refractory power, and heightens its crystalline 
 lustre. In BerHn, white glass ground is used as an ingredient 
 for stanniferous enamels. If the colors used are fat, the ob- 
 ject should be heated to volatilize the fat substance before 
 applying the glaze. 
 
 PERSIAN WARE. 
 
 The old, not the modem, Persian ware is distinguished by 
 a special brilliancy and effectiveness of colors. Messrs, Min- 
 ton. Maw, and Minton Hollins have attempted to attain the 
 richness of vitrified colors characteristic of this ware, and in 
 adopting Persian patterns on turquoise and plum-colored 
 enamel grounds, they have met with considerable success in 
 their reproductions. Messrs. Deck, of Paris, were first pro- 
 minent in this line. 
 
 According to Scheill, the Persian body contains silex, oxide 
 
22 
 
 of lead, and kaliab ; and the Persian glaze consists of 50 
 white silex and 40 kaliab (ashes of a plant growing on salt 
 soil) ; it is fritted, powdered, and mixed with gum and syrup. 
 
 CAMPBELL'S PATENT MOSAIC WALL 
 DECORATION. 
 
 '' In this process, also called Permanent Fresco or Fictile 
 Vitrification, the material for painting on consists of a num- 
 ber of small hexagon pieces in stone-ware, highly vitrified, 
 and joined together in placques of convenient size by a vitre- 
 ous cement. 
 
 This ground is painted on in the new opaque enamel colors, 
 prepared to stand a very high heat, to secure the permanency 
 of painting in any climate. Curved surfaces can be easily 
 managed. The inventor, Mr. C. M. Campbell, is now casing 
 the ceiling of the staircase of the South Kensington Museum 
 after designs of Mr. Moody. Two specimens of this novel 
 work are shown, executed by Mr. Thomas Allen. A perma- 
 nent surface hitherto used for fresco work has consisted of wide 
 placques of pottery ware, but the warping of these in the fur- 
 nace has presented obstacles which this invention is adapted 
 to overcome ; the shrinkage of each pellet being small, the 
 general proportions are preserved. The process still remains 
 to be tried, applied to a large surface. 
 
 BELLEEK WARE. 
 
 The Belleek ware from Ireland is a new appearance. Sets 
 of tea-cups and saucers of an original character are exhibited 
 by Mr. Mortlock. 
 
 The Belleek ware is distinguished by the high lustrous 
 silvery quality of the glaze, which attracts the eye, and recalls 
 the nacreous coating of a sea shell. Table ornaments of this 
 ware are shown imitating shells in form and translucency. 
 The material used is a group of different colored clays, found 
 recently at Belleek, in Ireland, some of which possess the 
 
23 
 
 property of yielding upon firing, a natural enamel or " skin" 
 like the finest egg-shell porcelain. The glaze is iridescent, 
 like mother of pearl, and requires to be used with discrimi- 
 nation for decorative purposes. 
 
 Messrs. Kerr, Phillips & Pearce, and the Eoyal Worcester 
 Works, produce similar ware, in which the glaze is probably 
 one of the artificial glazes invented by Brianchon, in which 
 the lustre is obtained by the reduction at a low heat of me- 
 tallic substances such as nitrate of bismuth, iron, uranium, 
 nickel, and cobalt, or chloride of gold, by an excess of carbon, 
 introduced in the glaze in the shape of resin and essential 
 oils of lavender or turpentine, and formerly by a reducing 
 atmosphere of smoke. The thin metallic deposit, like all 
 films of great tenuity, decomposes the light falling upon it 
 into prismatic colors. The lustre is applied with a brush, 
 thinly, and should not be absorbed by the ware. After firing 
 at a low heat, it adheres to the surface, and does not incor- 
 porate itself with the body like ordinary glazes. At an early 
 period, wax and mastic were used to procure the adhesion of 
 the lustre. 
 
 JASPER WARE, 
 
 More popularly known as Wedgwood ware, differs from 
 pate-sur-pate in the method of applying the clay, which is 
 usually white clay squeezed into moulds and then withdrawn 
 to be attached to the surface of the body of the vases ; the 
 ware is not glazed ; it has no more vitreous appearance than 
 is produced by the hard fire on the mixed clay body, and pre- 
 sents a dead texture. The ground may be of any color. 
 Josiah Wedgwood invented jasper ware, and the firm of 
 Wedgwood & Co. is constituted by his descendants. 
 
 Although Wedgwood ware presents less varied and subtle 
 effects than pate-sur-pate, yet the outline of the relief is 
 generally more perfect. Most of the designs used by Wedg- 
 wood & Co., are Flaxman's; and the beauty of their ware 
 with blue, dove, or oHve colored ground is well known. Jasper 
 ware may be defined as a superior quaHty of vitrified stone- 
 
24 
 
 ware. It requires more careful preparation, and is formed of 
 a plastic clay to which vitrifying ingredients such as Cornish 
 stone, flint, ground glass, felspar, sulphates and carbonates 
 of lime and of barytes (L. Arnoux) have been added. 
 
 According to Salvetat fine yellow Wedgwood ware .consists 
 of: 
 
 White jasper ware contains variously 15 to 30 per cent, of 
 plastic blue clay, 0 to 16 kaolin, 0 to 15 Cornish stone, or, 
 summing up, 40 to 50 per cent, of these clay materials ; to 
 which is added 25 to 45 per cent, heavy spar, 0 to 10 flint, 
 and 0 to 2 gypsum. Sometimes 20 per cent, calcined bone 
 is introduced. This white body may be differently colored 
 by metallic oxides, ^ per cent, cobalt giving blue, with 1 per 
 cent, chrome dark green, nickel light green, copper bluish 
 green. 
 
 From natural ochreous clays and quartz a reddish por- 
 phyritic jasper ware is made. 
 
 Basalt ware, susceptible of high polish, and Egyptian 
 ware are made by introducing in the body some 40 per cent, 
 of burnt ochre, or 16 per cent, ochre and 45 of red clay, and 
 sometimes 10 per cent of mill cinder (iron). 
 
 The researches of Ebelmen and Salvetat hfive revealed 
 the distinct characteristics of Chinese Porcelain. 
 
 The body is felspathic and hard ; the glaze is softer than 
 that of European hard porcelain ; the colors are properly 
 enamels, transparent or opaque ; the coloring oxides are very 
 few. The whole is made in one firing, at a somewhat low 
 heat. 
 
 Silica 
 
 Alumina 
 
 Oxide of iron 
 Lime , 
 
 66.49. 
 26. 
 
 Magnesia 
 Alkalies . . 
 
 6.12. 
 1.04. 
 0.15. 
 0.20. 
 
 CHINESE PORCELAIN. 
 
25 
 
 Tlie ware of M. Lesme, of Paris, is similar. 
 
 The enamel colors are crystals (composed of 6 miniam, 
 2 sand, 1 borax melted, and some soda and potash) holding 
 in solution a few hundredths of coloring oxides. The fun- 
 damental colors are very few, viz., cobalt for blue, copper 
 for blue and green, gold for carmine, antimony for yellow. 
 All other tones, with one or two exceptions, are obtained by 
 mixing these. 
 
 The harmony of Chinese decoration results from the re- 
 stricted number of coloring agents. The brilliancy results 
 from the oxides being dissolved. 
 
 For opaque enamels, white of tin or arsenic are used. The 
 crystals are faintly colored and rubbed in water only. For 
 deep tones they must be superposed several times, hence the 
 relief observable. These enamels could not adhere upon a 
 hard European glaze. Their adhesion is attributed to the 
 peculiar nature of the glaze. 
 
 The glaze is complex ; kaolin stone, vegetable ashes, and 
 lime are used, resulting in silica 68, alumina 12, lime 14 to 
 21, potash and soda 6. 
 
 The moulds, even for delicately embossed pieces, says 
 Arnoux, are simply clay moulds dried in the sun. 
 
 The walls of the ovens are so thick that the hand laid on 
 outside at no time perceives the heat. The volume of air 
 entering is regulated ; the fuel is dry wood. "When the fire 
 is started the door of the oven is closed, leaving only room 
 enough to insert one piece of wood. The heat is g radually 
 raised for 30 hours. At Sevres, to increase the plasticity, 
 the following body, called " masse Chinoise," is used for 
 large objects (Regnier) : Kaolin clay 43 to 44, plastic clay of 
 Dreux 21 to 25, sand from kaolin 16 to 17, quartz sand 16 
 to 9, chalk 4 to 5. 
 
 PARIAN. 
 
 Parian, like stone-ware and terra-cotta, is composed of clay 
 mixed with vitrifying ingredients, but it differs from these, 
 both in aspect and composition, as being composed of purely 
 
26 
 
 granitic materials. In composition, it lies between stone-ware 
 and English or soft porcelain. Unlike the latter, it contains 
 frequently no calcined bone, and shrinks more. : 
 
 The clay used is the Cornish clay (obtained, as previously 
 described, from decomposed granite) and undecomposed fel- 
 spar, which, being rich in soda or potash, acts as a flux. It 
 is obtained from America or Sweden. The result of firing is 
 a semi-opaque translucent substance known as Parian, and 
 in which every sharp outline is retained. Copeland first 
 made it in 1848. 
 
 Salvetat gives the following composition of Copeland's 
 Parian, before burning and after : 
 
 Silica 58.51 63.74 
 
 Alumina 21 29.71 
 
 Oxide of Iron 1 
 
 Lime 0.14 1.41 
 
 Magnesia 0.05 0.41 
 
 Potash 11.40 
 
 Soda 5.08 4.39 
 
 Loss 6.40 
 
 Ovens for earthen-ware can be used. Continental Parian 
 is often of a bluish white tint ; this arises from the partial 
 exclusion of air from the ovens, and consequent reducing 
 atmosphere (see Blue-bricks). English Parian is of a pleas- 
 ing creamy color, owing to the abundance of air in the oven, 
 which peroxidizes the small quantity of iron salts dissemina- 
 ted through the mass. 
 
 Parian figures are produced from this mixed clay poured 
 in a fluid condition into plaster moulds ; the vitreous nature 
 of the substance renders the subsequent firing a crucial test. 
 The contraction in baking amounts to ^ usually, sometimes 
 even ^ of the original dimensions; due weight should, there- 
 fore, be allowed for the variable allowance the artist has to 
 make for the shrinkage of his work. 
 
 There are many other ways of making Parian. If plaster 
 of Paris, in fine powder, is thrown in a vessel containing a 
 saturated solution of borax, after soaking for some time 
 
27 
 
 witli a solution of alum a hard plaster is obtained (Ansted), 
 wliich is also called Parian, although differing in composition 
 from the above. 
 
 Copeland & Sons exhibit well modelled forms in Parian, 
 showing fine workmanship, as well as material of great merit. 
 
 The Koyal Worcester Works produce pretty statuettes. 
 
 Swedish Parian, made from Cornwall clay, by the Gustaf- 
 berg's Co., is very white and hard. 
 
 Danish Parian statuettes, by Bing & Grondahl, attract at- 
 tention ; the excellent plan of attaching the selling price to 
 each article, which all exhibitors are invited to adopt, has 
 been followed by them and others, in consequence of which 
 many of their products have been sold. 
 
 Parian of inferior texture and form is so common, that its 
 popularity for sculptural works has been much injured ; nor 
 can it be compared with carving or sculpture as an art pro- 
 cess. The Parian of Minton, Worcester, and Copeland is 
 sometimes glazed to facilitate cleaning. For centre-pieces, 
 baskets, teapots, etc., this is an improvement ; but its appli- 
 cation to statuary is frequently objected to. 
 
 ART APPLIED TO USTDUSTRY. 
 
 The excellence of ceramic products in the three essentials 
 of material, form, and decoration, is perhaps most remarkable 
 for the two latter qualities, in the examples where the name 
 of the artist accompanies that of the manufacturer. 
 
 On one hand, the highest skill in manufactures is constant- 
 ly seen connected with the weakest efforts of design, as 
 though mere materials and workmanship were sufficient 
 without the quality of art. On the other, much of the best 
 artistic talent is expended upon objects in which we may seek 
 in vain to discover their utility. Many firms rely too much 
 on the quality of their wares merely on account of mechan- 
 ical excellence of material, rather than upon the artistic 
 treatment which enhances their value. The somewhat 
 cowardly suppression of the names of the artists who design 
 and model the works of various manufacturers, is in a great 
 
28 
 
 measure tlie cause. This practice is less observable in some 
 countries, but it is still only too general. 
 
 Employers of skilled labor, who think it their interest to 
 conceal the origin of the artistic element of their manufac- 
 tures, are doubtless moved by the fear of losing their artists 
 upon revealing their names, or having to increase their pay. 
 But this policy is as narrow as it is ungenerous. 
 
 The interests of the artist and manufacturer are not anta- 
 gonistic ; they are parallel. The stimulus of pubhcity when 
 granted to the carvers in stone, the moulders in clay, the 
 painters on earthen-ware and porcelain, excites their laudable 
 pride and enhances the quality of their work. The mere 
 reward of publicity attracts new artisans to these occupa- 
 tions, and affords the manufacturer a wider choice of art- 
 workmen. An illustrious artist no sooner lends his assist- 
 ance, than his works are at once eagerly sought. 
 
 When an artist has once attained a reputation, the manu- 
 facturer who secures his services is generally not unwilling 
 that his name should appear on his products, but it is essen- 
 tial to the development of artistic merit in current manufac- 
 tures, in its most popular form, that rising art- workmen 
 should have the opportunity of being made known to the 
 public. 
 
 In this view and for those interested, I give the following 
 list of Designers and Modellers in the Department of Pottery, 
 which are all the names I have obtained ; but before leaving 
 this subject, I must name Mr. Henry Cole, C. B., as the one 
 man in England who, by his foundation of art-schools and 
 museums, and creation of a system of art-manufactures, has 
 done the most to provide art instruction for the people : 
 
 LIST OF DESIGNERS AND MODELLERS, 
 
 EI THE DEPARTMENT OF POTTERY. 
 
 B. J. Morris — employe of the S. Kensington Art School — 
 designed a frieze representing pottery manufacture ; 
 also panels representing the months of the year. 
 
29 
 
 Waltee Lonsdale— obtained travelling studentship of Royal 
 Academy — designed art-tile chimney piece. 
 
 W. J. GooDE — designs etchings on the glaze. 
 
 E. Lessoee (late) — original designs for ornaments in mono- 
 chrome, free and bold pencil, painted pottery, majolica, 
 cream-colored ware for Wedgwood & Sons. 
 
 A. Stevens — sculptor of the Wellington Monument for St. 
 Paul's ; designs Graffito ware, great breadth and power. 
 
 Coleman — painted heads on earthen-ware for Minton, also 
 mosaic Head of Isaiah. 
 
 Solon — executes pate-sur-pSte ; received at Paris, in 1867, a 
 bronze medal as " Sculpteur en pate k la Manufacture 
 Imp6riale de Sevres." Was the first artist acquired by 
 Minton & Co., possessing the skill requisite to found 
 this branch of industry. 
 
 H. Daeling and J. Leese — engaged in Minton & Co.'s man- 
 ufactures. 
 
 Yahn — painted for Minton an effective frieze on porcelain 
 vase in turquoise-ware. Flying Cupids and Nymphs in the 
 Bucher style, executed before the final glaze. 
 
 John Gibbs, J. Eyee, J. P Seddon — design tiles for Minton. 
 
 Kate Beayfoed — designed mosaic panel for M. Hollins & Co. 
 
 Lessels — mosaic table designed for Maw & Co. 
 
 De. Deessee — known for his botanical knowledge applied to 
 ornament. Designs conventionalized floral ornaments, 
 ewers, gilt and decorated terra-cotta for Minton & Wedg- 
 wood. 
 
 D. Peaece — of Phillips & Pearce ; effective design for centre- 
 
 piece for flowers in Wedgwood ware. 
 C. F. Hueten — ^flowers, birds, skilfully painted for Copeland. 
 T. H. BoTT (late) — designs after Maclise, for vase, in Limoges 
 
 enamel manner. 
 A. DE MoL — Belgium — Battle scenes on porcelain. 
 
 E. TouETEAU — Belgium — Virgin and Child on porcelain. 
 
 A. Hanstel — Belgium — Descent from the Cross, on por- 
 celain. 
 
 M. Elden — Set of 5 subjects in mosaic, representing the year, 
 for H. Bessemer, Esq. Also art tiles for chimney pieces. 
 Tesserse, by Maw & Co. 
 
30 
 
 Geo. Tinwoeth — modeller, is supposed to liave modelled a 
 fine eagle in terra-cotta for Doulton & Co. 
 
 J. S. KusHTON —painted for Worcester Works, Assyrian and 
 Algerian figures on turquoise ground ; and the Arch- 
 angel Gabriel on a placque. 
 
 Mme, a. Leuzinger — Berne — Smoke painted porcelain. 
 
 Ed. Rischgitz — paints plates cleverly for Copeland. 
 
 Julius Leth — ^Vienna — porcelain with photographic paints. 
 
 Ball — modelled colossal terra-cotta figures for Lecture 
 Theatre of S. K. Museum. Doulton, manufacturer. 
 
 C. Fleuse — designed Gothic parapet of terra-cotta, for E. 
 March, Berlin. 
 
 O. Muller, Professor Wolff, Blankenstein — designers in 
 terra-cotta for E. March, Berlin. 
 
 Mrs. D. O. Hill — a terra-cotta statue of Dr. Livingstone 
 in appropriate travelling costume. 
 
 Aaron Green — painted birds resting on branches of bam- 
 boo, on turquoise porcelain for Minton. 
 
 M. Mussil — Austrian, attained emin ence in Paris ; now 
 paints under the glaze for Minton. 
 
 T. KiRKBY, C. Toft, W. Mellor — design graffito ware for 
 Minton & Co. 
 
 C. J. RowE — designed figures of Shakespeare's heroines for 
 Daniel's dessert plates. Also pierced work, and views 
 of " Mentmore," together with R. P. Daniell. 
 
 A. Waterhouse — designs for Simpson & Sons' art tiles. 
 
 C. Smallwood — designed and modelled a bread tray for R. 
 M. Taylor. 
 
 S. Cooper — mosaic inlaid in alabaster, for M. Hollins & Co. 
 T. Morgan — mosaic " Head of Inigo Jones," in tesserse, by 
 Maw & Co. 
 
 Henry Sherwin — designed dinner plates for Pinder, Bourne, 
 & Go. 
 
 Thos. Allen— modelled majolica vase — Rape of the Sabines, 
 
 for T, Mortlock, paintings after Boucher. 
 J. Slater — paints vases for Minton & Co. Birds, &c. 
 J. H. Wood — designs ewers and basins for Pellatt & Co. 
 
 Milk jugs and dejeuners. 
 
31 
 
 J. Randell — paints birds, fishes, on ewers and basins for J. 
 Rose & Co. 
 
 Kerr & Sons — design and exhibit a breakfast service of 
 Belleek ware. 
 
 Rouse — painted cattle on Rose du Barry ground for card-tray 
 
 for Daniell & Son. 
 J. R. Lees — designed ewers, basins, dessert services for 
 
 Powell & Bishop. 
 J. Ellis — executed the preceding designs of Lees. 
 Williams & Davis — designed " View of Whitley Court " for 
 
 a Tazza of Worcester Works. 
 V. Perling — ^painted dessert services for Royal Worcester 
 
 Works. 
 
 Miss Margaret Tupper — original designs for tiles, card- 
 plates, cups and saucers. 
 
 C. Palmere — ^painted two dejeuner services for R. P. Daniell, 
 one a la pompadour, in turquoise and gold, 1871; the 
 other, " Yiews of Mentmore," Blue de roi and raised 
 gold, from designs by C. J. Rowe. 
 
 Mr. & Mrs. Steele and D. Lucas — design dessert centre- 
 pieces for Thomas Barlow. 
 
 J. Booth and J. Bate — painted roses and pearls on a coffee 
 set, and " the Lorne " for a card-tray. 
 
 E. Bejot — designs and decorates in the Persian style and in 
 Henri II. ware. 
 
 Roberts, Hill, J. Callowhill, J. Williams — landscape ; J. 
 Bradley, spill vases. 
 
 Davies, Webster — flower holders ; Clarke, Jardinieres ; Bolt, 
 J. HoPWiCH, spill vases. 
 
 E. Stephan — spill vases ; all the preceding eleven paint on 
 porcelain for the Worcester Works. 
 
 W. Cooke — painted cups and saucers for R. P. Daniell. 
 
 J. S. Whitty— painted porcelain views of Highgate, Harrow, 
 
 &G. 
 
 KuHN figures and Gorner flowers — ^painted on porcelain for 
 
 Royal Berlin Works. 
 Mitchell — painted cattle for Minton & Co. 
 J. B. Fidler — decorates Graffito ware for Maw & Co. 
 
32 
 
 Babon Davillier — copies Henry II. ware for Theod. Deck of 
 Paris. 
 
 H. S. Marks, A.K.A. — ^painted a Falconer on hexagonal tes- 
 serge. 
 
 E. Monti, J. Hadley, W. Theed, L. A. Malempee, M. Noble, 
 
 R. A., T. Wolner, M. C. Belleuss, J. Durham, Westma- 
 COTT, Papworth, T. Brock, E. M. Miller, Miss S. Teery, 
 P. MacDowell, Professor Molin of Sweden; the preced- 
 ing fifteen model ceramic statuary. 
 J. Gibson, R. A. — ceramic statuary, " Nymph at Bath." 
 
 F. Fuller — of Florence, modelled " Nydia," of Parian gilt, 
 
 for Minton & Co. 
 
 F. Mantel — modelled bust of Bismarck, and vases. 
 Walger — ^modelled bust of Count Moltke, in white biscuit, for 
 
 Royal Berlin Works. 
 Professor Scholander — designs earthen-ware vases for Ros- 
 trands & Co. 
 
 Pienne — models and decorates Faience a la Henri II., for 
 
 Royal Worcester Works. 
 H. Protat — models in the Chinese style for Minton & Co. 
 J. Janda, Itzenplitz, Flancock, Wilmore — model ceramic 
 
 statuettes. 
 
 G. J. Cox, H. HOHLE, C. LUCKHARDT, C. SCHMIDT, SiMPSON 
 
 — paint placques. 
 Godfrey Sykes — modelled an excellent column for Theatre of 
 S. Kensington Museum, and designed art tiles for Simp- 
 son & Co. 
 
 EARTHEN -WARE. 
 
 Earthen- ware possesses a hard, opaque, partly refractory 
 body, covered with a transparent glaze, and withstands cer- 
 tain alterations of temperature. 
 
 It is composed of plastic fire-clay with an addition of fine 
 ground quartz or refractory stone, and occasionally of lime. 
 Thus in England 83 parts of Dorsetshire clay (containing 76 
 silica to 24 alumina) are mixed with 17 of ground flint. The 
 ware is brought to the state of biscuit by one firing, at 60° 
 
33 
 
 to 100° Wedgwood, before the glaze is applied (see Stone- 
 ware Ovens). 
 
 The glaze is a colorless transparent glass of variable com- 
 position, white lead being the base. Borax is used to 
 heighten the lustre of the colors. Silica and alumina (de- 
 rived from kaolin and Cornish stone), flint, felspar, alkalies, 
 saltpetre, and chalk are variously used. To obviate a yel- 
 lowish tinge, less than one thousandth of smalt is added, pro- 
 ducing a bluish hue. The glaze is first burnt (for instance 
 in Bosch's oven) to a glass, the oxide being added before or 
 after the burning ; this glass is ground very fine, tempered 
 with water, and the ware in the biscuit state is dipped in it, 
 and then burnt a second time at a lower heat of 12° to 80° 
 W. to fasten the glaze. The glaze should be hard enough 
 not to be easily scratched by the knife. 
 
 When patterns are printed on the ware, they are applied 
 before the glaze. 
 
 Cowper gives the following glaze : 
 
 Silica 43.66 
 
 Alumina and Iron Oxide 9.56 
 
 Borax 20 08 
 
 Carbonate of Lead 15.19 
 
 Chalk 10.88 
 
 Calcium 0.52 
 
 to form which, Cornish stone, granite, borax and gypsum are 
 used. 
 
 For superior qualities of earthen-ware 16 to 26 per cent, 
 kaolin is added to whiten the body, and a small quantity of 
 Cornish stone (1 to 3 per cent.) to render it denser. This 
 forms the basis of cream-color. 
 
 Part of the Dorsetshire clay is frequently replaced by the 
 Devon, which is somewhat inferior. 
 
 The ground flint is added to whiten the body, and to di- 
 minish the great plasticity of the Dorset and Devon clays to 
 a point more suitable for working. 
 
 The German Feines Steingut and the French fine Fai- 
 ence correspond to English earthen-ware ; they are as white 
 and glossy, but less dense and resisting. 
 
34 
 
 For further details, see Tiles and Majolica. 
 
 Lead Glazes. — Oxide of lead increases the fusibility, 
 adhesion, and elasticity of a glaze, but makes it easier to 
 scratch with the knife, and somewhat yellow. When the 
 glaze contains free lead oxide not saturated with silica, or 
 when the ware is not enough burned, it is deleterious for fire 
 crockery. To detect this, drop vinegar on the ware, after a 
 while insert a piece of clean granulated zinc, and there will 
 be a grey deposit of lead. Before using such crockery, wash 
 it out with hot strong vinegar. 
 
 To make sanitary ware, free from lead, is not easy with- 
 out increasing the cost. A boracic glaze may be used, or as 
 in Berlin the gesundheitsgeschirr, the body glaze, given by 
 Kerl, viz. : 
 
 Body— Kaolin 48 Glaze— Sand 42 
 
 Pipe clay.. 37.5 Kaolin 33 
 
 Felspar. . . . 16.5 Eaw Gypsum. . . . 13 
 
 Ground Porcelain 12 
 
 COLORS FOR ALL KINDS OF 
 POTTERY. 
 
 The color of an object is due to its action upon the light 
 falling on it. 
 
 When white light strikes an object, a fraction of the light 
 is reflected from the surface, without alteration of its white- 
 ness ; the remainder penetrates the surface and is decom- 
 Xoosed, at an exceedingly small depth, into colored rays ; part 
 of the colored rays are absorbed into the body ; the remain- 
 der are reflected, and it is these which we see, and whose 
 color we consider to be the color of the object. Hence the 
 influence which the state of the surface of a body has upon 
 its colors. 
 
 This property of selecting certain colored rays, and re- 
 jecting others, is possessed by metallic oxides in an eminent 
 degree. When these oxides are disseminated through a 
 white mass, they impart their color to the mass. Some ox- 
 ides, and they are the most valuable, are stable in the pres- 
 
35 
 
 ence of other bodies and of high heat ; the colors they im- 
 part do not alter. 
 
 Owing to these qualities, metallic oxides are commonly 
 used, as coloring agents. 
 
 Bodies are transparent, when the light spoken of above as 
 entering the body, traverses it, and is transmitted beyond. 
 
 Bodies are opaque, when the light which enters is quench- 
 ed by the numberless successive reflections it undergoes at 
 the surfaces of the particles of the body, and does not pass 
 beyond. 
 
 By disturbing the perfect contact of the particles, a trans- 
 parent body is rendered opaque. Example : plate glass and 
 glass ground fine. 
 
 By restoring the perfect contact of the particles, by filling 
 the interstices with a transparent substance, the transparen- 
 cy is restored, more or less. Example : paper and paper 
 oiled. 
 
 Partial transparency is likewise obtained, by filling the 
 interstices with a vitreous flux. Example : porcelain. 
 
 The following colors are obtained with the oxides (and 
 sometimes salts) of the metals named. 
 
 Violet — Iron, manganese with soda. 
 
 Purple — Chloride of gold with tin, chloride of silver. 
 
 Black — Iron, manganese, uranium, iridium. 
 
 Indigo — Of violet and blue. 
 
 Blue — Cobalt, carbonate of cobalt, smalt or silicate of 
 cobalt. Zinc brightens blue colors. 
 
 Turquoise — Copper with soda ; cobalt with zinc and soda 
 phosphate. 
 
 Green — Copper, with or without antimony ; chrome with 
 cobalt. 
 
 Bronze green — Nickel. Zinc and its carbonate brightens 
 all greens. 
 
 Olive green — ^Nickel with cobalt. 
 
 Yellow — Antimony, with potash or sulphide, titanium, 
 chromate of lead, chromate of barytes. Zinc brightens yel- 
 low. 
 
56 
 
 Buff— The preceding with iron, sepia, sienna, ochre, um- 
 ber, earths. 
 
 Orange— Uranium ; sulphide of antimony with iron. 
 Bed- Iron, iron sulphate, copper (oxidule), ochre. 
 Carmine — Chloride of silver. 
 Pink — Iron and chrome with potash. 
 
 Brown— Iron, chromate of iron, manganese, with or with- 
 out cobalt, ochre and hammercinder. 
 
 Qrey— Iron, cobalt, iridium, platinum, titanium. 
 
 White— White clay and 5 per cent, tin oxide. 
 ■ In pottery, the colors are either (encaustic) incorporated 
 in the body, or applied upon the surface of the body, which 
 has been previously dried, half burned or fired to receive 
 them, or introduced in the glaze, or applied over the glaze. 
 
 Encaustic Colors. — Encaustic colors possess all the more 
 brilliancy, the nearer the body approaches vitrification. 
 The coloring oxides are introduced in quantities usually of 5 
 to 10 per cent., and sometimes 15 to 20 per cent. They act 
 as fluxes and increase the fusibility of the mass. The com- 
 position of the body must be altered in some cases to coun- 
 teract this. 
 
 When the body is fired at a temperature too low to develop 
 the required color, or when it is not of a sufficiently vitreous 
 nature, the color is fritted before being introduced, i. e., the 
 coloring oxide, by the addition, for instance, of 18 per cent, 
 calcined soda and 75 per cent, silica, is melted up into a 
 glass. This glass is ground fine and mixed with the body m 
 various proportions of i to | and § (see Jasper Ware). 
 
 This colored body may be glazed, or first painted upon in 
 the new opaque enamel colors and then glazed. Transparent 
 colors cannot be used to advantage upon it. 
 
 Colors under the Glaze.— The process consists in dip- 
 ping the dried object in a slip of colored clay, formed 
 usually of 1 colored glass ground and 2 of clay. The clay is 
 introduced to procure the adhesion of the slip. The ware is 
 then burnt, or, after drying, coated with a transparent glaze 
 and then burnt. Subjects may be painted under the glaze, 
 with more or less transparent colors, or with opaque enamel 
 
37 
 
 colors. Before applying the glaze, all oily substances should 
 be removed by a preliminary heating. 
 
 Printing in colors under the glaze, is frequently done. 
 
 Colors in the Glaze. — The ware is dipped in a trans- 
 parent colored glaze. 
 
 The glaze is frequently formed, besides the coloring oxides 
 of: 
 
 Oxide of lead from 40 to 50 per cent. 
 
 Silicious sand " 30 " 40 
 
 Salt " 0 " 12 (see Earthen-ware). 
 
 A. iQode of decoration consists in reserving certain parts 
 from the colored glaze, by which the color of the body or the 
 slip appears in those parts. This is done by covering the re- 
 served spaces, not with oil, which spreads, but with melted 
 tallow and wax, which solidifies on the spot. The ware is 
 then dipped in the colored glaze, heated to expel the grease, 
 and then dipped in a transparent glaze, which adheres to the 
 reserved spaces. 
 
 The appHcation of a colored glaze over a painting is very 
 effective in harmonizing the whole. 
 
 By stamping a depressed pattern in the biscuit, and glaz- 
 ing, the pattern will appear in a deeper tone of glaze. 
 
 Colors over tlie Glaze. — The colors are applied with a 
 brush over the (once fired) glaze ; the ware is heated again 
 to the melting point of the glaze, which in the melted state 
 incorporates the colors, and appears more or less to cover 
 them. To prepare the colors, one method consists in rub- 
 bing the coloring oxides in water, to which gum, or sugar, is 
 added to cause cohesion. Turpentine oil and its fat essence 
 are more often used, also Lavender oil. Only colors which 
 will stand high heat can be thus applied. 
 
 In the case of hard porcelain, the colors melt sooner than 
 the glaze, hence their opaque appearance, as the glaze does 
 not cover them. Another method, applicable to all colors, 
 consists in mixing them with substances (silicates, or borax) 
 which when heated will give a vitreous mass, capable of unit- 
 ing with the glaze or the body of the ware. 
 
38 
 
 The colors thus obtained are transparent. When laid on 
 too thick, they peel off. Colors that are volatile, vegetable 
 and others, can not be used. Color printing can be executed 
 over the glaze. 
 
 Metallic Colors.— For gilding there are several meth- 
 ods. The gold is fine, obtained by precipitation, and 
 amalgamated with oxide of mercury or calomel to spread it. 
 Sometimes gold leaf is rubbed in sugar, salt or honey, and 
 applied. If the glaze is earthy, 8 per cent, of flux of oxide of 
 bismuth, with a little borax, must be added to the gold. 
 
 Silver is applied in a similar way. 
 
 For platinimi, the metallic powder is fluxed with 10 per 
 cent, of a boracic flux, and rubbed in oil on a glass plate. 
 
 The gilding is applied with a brush over the glaze and re- 
 quires high heat to fasten it; it must be applied and fired be- 
 fore other colors. The gilding has a dead appearance until 
 it is polished with agate instruments. There are other 
 methods of gilding less permanent. 
 
 In Egypt, graphite rubbed on gives a black pohsh. In 
 India, gray and copper-colored mica, rubbed on the surface, 
 gives a metallic effect. 
 
 Lustres. — By coating the ware with a glaze, which fur- 
 nishes a thin, adhesive, metallic film, the rays of light are 
 decomposed into prismatic colors, producing a pearly, lus- 
 trous appearance. (See Belleek Ware. ) 
 
 The lustre may be transparent, as with the metals lead, 
 zinc, alumina, bismuth, or colored, as with copper, man- 
 ganese, cobalt, iron, uranium, nickel, cadmium, chrome. 
 
 The transparent lustres are obtained by melting 10 metallic 
 oxide or salt with 80 colophonium, and rubbing in 70 to 140 
 lavender essence. It is applied like a varnish. 
 
 The large amount of carbon in lavender essence acts as an 
 effective reducing agent to produce the thin deposit of un- 
 oxidized metal in the glaze. The most brilliant effects are 
 obtained by using the transparent with the following lustres : 
 
 Copper lustre — Eubi lustre op Georgio — is considered 
 to be silicate of protoxide of copper. Salvetat says nitrate 
 of copper and a reducing gas will produce it. Or else, for 
 
39 
 
 white enamelled ware, throw a paper containing, copper oxide 
 into the muffle. 
 
 Ueanium — MOTHER OP PEARL LUSTRE. — 10 nitrate of ura- 
 nium, 30 colophonium, 50 lavender essence. 
 
 Iron lustre. — Chloride of iron and solution of soda ; the 
 deposit is rubbed in lavender essence. The lustre is red. 
 By adding bismuth lustre it becomes golden yellow. 
 
 Purple gold or Burgos lustre. — Dissolve in acid 25 gold, 
 5 tin ; mix with 50 sulphur and 20 essence of tar, and 50 es- 
 sence of turpentine. 
 
 Cantharides lustre. — A lead glass, with a little oxide of 
 bismuth and chloride of silver, is appHed with the brush. 
 
 The ware is fired ; when red, it is smoked. 
 
 The lustres are brighter when laid over a brilliant glaze. 
 
 To reserve certain spaces, wash off the lustre, by dissolv- 
 ing with linseed oil. 
 
 Printing in Colors. — To print on the glaze : The design 
 is printed in linseed oil colors on damp silk paper. The 
 paper is dipped in water, taken out, the excess of water 
 absorbed, laid on the ware, which has been previously var- 
 nished with turpentine oil and alum or copal, and a woollen 
 roller or ball is passed over it. The ware is then fired. 
 
 To peesit on the biscuit. — The colors are rendered more 
 adhesive by glue. The paper is stronger and dipped in soap- 
 water to prevent absorption of oil. Before laying the paper 
 on the biscuit the parts not colored are cut out. The ware is 
 heated to expel the oil, before glazing. 
 
 Gelatine may be substituted to paper ; the pattern then is 
 only printed in turpentine and nut oil, and the color in pow- 
 der is sprinkled on it. 
 
 preparation of coloring agents. 
 
 Chrome oxide — from bichromate of potash calcined. 
 Iron oxide — from iron sulphate calcined. 
 Uranium oxide — from a blend by chlorhydric acid and ni- 
 trate of iron, used as uranate of ammonia. 
 Manganese oxide — found as such. 
 
40 
 
 Zinc oxide — from a salt of zinc precipitated by carbonate of 
 soda. 
 
 Cobalt oxide — from a cobalt ore, roasted, treated by acids, 
 
 and precipitated by potash carbonate. 
 Antimony oxide — heat 2 of antimony and 5 saltpetre ; anti- 
 
 moniate of potash results. Also from Naples yellow. 
 Copper protoxide — from sulphate of copper, soda carbonate, 
 
 and copper shavings. 
 Copper peroxide — from nitrate of copper calcined. 
 Tin oxide — from tin. The alloy of lead and tin oxidizes 
 
 rapidly. 
 
 Iridium oxide — from a solution of iridium, sal ammoniac, 
 
 potash carbonate. 
 Chloride of silver — silver nitrate, precipitated in the dark by 
 
 chlorhydric acid. 
 Purple gold — At Sevres, 3 gr. tin is dissolved cold in acid (4 
 
 nitric to 1 chlorhydric), and 1 gr. gold in acid. Diluted 
 
 and slowly mixed. Or else, heat gold protoxide with 
 
 stannate of potash. 
 
 EEMAKKS. 
 
 A remarkable pure blue, says Gentelle, is obtained by 
 taking 2 parts of flux (composed of equal sand and lead oxide) 
 and 1 part of color composed of 16 protoxide of cobalt, and 
 84 of the following precipitate : 
 
 To a solution of soda phosphate in excess, add zinc sul- 
 phate ; wash the resulting blue precipitate, which contains, 
 when dried, zinc oxide 42, cobalt protoxide 13, phosphoric 
 acid 33, water 12, and burns to a pure blue. 
 
 For very white opaque enamels, the mixture of 200 oxides 
 of lead and tin, 100 sand, 80 carbonate of potash, must be 
 melted up and pulverized 3 or 4 times successively. When 
 antimony is substituted for tin, the lead must be left out, or 
 it would produce a yellow tint. This antimony enamel is 
 better for blues and purples than the other. Clouet gives 
 as the best : Glass, without lead, 300 ; borax, 100 ; saltpetre, 
 25 ; antimonium diaphoreticum, washed, 100. 
 
 Colored slips for staining the surface of wares vary with 
 
41 
 
 the colors. For common blue and green, some 7 per cent, 
 lead oxide is introduced, while it is left out in others. Thus, 
 for red, ochre is rubbed in water ; for violet, 1 sand, 2 potash, 
 yV manganese, are fritted and mixed with thrice their weight 
 of white clay ; for yellow, 1 sandj 2 potash are fritted, and 
 2 white clay is added. 
 
 DECORATIVE TILES FOR FLOORS, 
 WALLS, ETC. 
 
 The variety of tiles come under the following commercial 
 classification : 
 
 1. Plain Tiles (self-colored) made by pressure from dust 
 clay. "With different colored pieces geometrical patterns can 
 be formed. 
 
 2. Encaustic (figueed) Tiles, having a flat surface with 
 the ornament inlaid, or slipped in various colored liquid 
 clays. These two may have their surface covered with a 
 transparent glaze. 
 
 3. Enamelled Tiles, that is, plain tiles having their sur- 
 face covered with various opaque and transparent colored 
 enamels. 
 
 4. Majolica Tiles, having the ornament in relief, the em- 
 bossed ornament and the ground being covered with various 
 colored enamels. (Palissy ware, more properly speaking.) 
 
 5. Earthen-waee Tiles in plain colors, glazed. — These 
 may have their surfaces decorated by printing or painting. 
 
 PLAIN" TILES. 
 
 These tiles, made from colored dust clay by a sort of coin- 
 ing process (see Tile Presses), are capable of being highly 
 decorative when well made, and are a good instance of the 
 pleasure arising from mere perfection of material. 
 
 The clay or mixture of clays used is usually reduced to a 
 fine powder and made slightly damp before pressing. (See 
 Encaustic Tiles and Colors.) 
 
42 
 
 ENCAUSTIC TILES. 
 
 Encaustic tiles consist of a slab of clay of uniform color, 
 inlaid witli a device of other clays differently colored. 
 
 In this ware the colors are not superficial, but are incor- 
 porated with the body of the clay before burning, either by 
 pugging dry or in the condition of a liquid slip. 
 
 As to the different coloring ingredients : — Many of the 
 clays which contain less iron, such as the Stourbridge and 
 others in proximity to the coal measures, do not come out of 
 the fire red like brick, but white, cane or buff in all varie- 
 ties of tint, and stand the attack of fire and weather. 
 
 Eed, salmon and pink will be produced as the iron pre- 
 dominates, altered by mixtures of other clays in their native 
 condition or by oxides of metals. Nickel, for instance, pro- 
 duces a bronze-green tint ; manganese brown ; protoxide of 
 iron and manganese dead black. Carbonaceous matter 
 gives a dark, dull-looking and rather dirty tint, which may 
 be useful in contrast. 
 
 There is no end to the variety of tints which can be ob- 
 tained by the admixture of earths and metallic oxides. (See 
 Colors.) 
 
 To economize the inlaid colored clay material, the tile is 
 only formed of it to the depth of about 5 of an inch from 
 the surface, the mass of the tile being made of fire-clay. 
 As, however, the fire-clay generally contracts very differently 
 from the surface layer of colored clays, it is usual to apply 
 to the back of the fire-clay, an equal thickness of about I of 
 an inch of the colored clay, in order to preserve the flatness 
 of the tile during the firing. The tile is made with the aid 
 of a press, either by the wet or dry process. (See Tile 
 Presses.) By pressing many small holes in the back of the 
 tile, the drying is facilitated, and also the adhesion of the 
 mortar when subsequently used on the wall. The tiles are 
 dried for a week, then heated in a drying oven for two or 
 three weeks, fired in a stone-ware oven for sixty hours, and 
 left in the oven for six days more, to cool down. The lineal 
 contraction during these operations amounts, in the wet pro- 
 
43 
 
 cess, to twenty -nine per cent, of the size of the tile when first 
 moulded. It is less in the dry process. 
 For glazes, see Earthen-ware and Colors. 
 
 ENAMELLED TILES. 
 
 The bodies are the same as for plaia tiles, which have at 
 most a transparent glaze, while the enamelled tiles are sus- 
 ceptible of great variety of decoration, by the application of 
 transparent or opaque colored enamels. 
 
 By reserving spaces (by oiling or otherwise) and dipping 
 the tile in a slip, or by direct application of the enamels, 
 simple and effective results are obtained. 
 
 For the enamels used see Majolica. 
 
 MAJOLICA AND MAJOLICA TILES. 
 
 The different varieties of Majolica are more easily appre- 
 ciated when its history is recalled. 
 
 The almost total extinction of the arts and sciences which 
 followed the fall of the Roman Empire, left Europe with 
 only the rudest knowledge of the potter's art. The Moors 
 brought with them into Spain, in the eighth century, much 
 of the science and knowledge of the East ; but it took sev- 
 eral centuries for the arts thus introduced to spread over 
 other parts of Europe. The enamelled bricks and tiles of 
 the Moors were of superior taste and coloring, gilding was 
 skilfully used, and the enamel possessed a yellowish lustre of 
 peculiar brilliancy. Their bricks (azulejos), as in the Alham- 
 bra, were formed of a light-colored clay, covered with an 
 opaque white glaze upon which Eastern patterns were traced 
 in colors. This manufacture was continued and is still kept 
 up in Spain. 
 
 In Italy, the art of Pottery, which attained its height 
 during the fifteenth and sixteenth centuries, was introduced 
 in the ninth century by the Moors of Spain and also by 
 Byzantine Greeks. In 1115, an expedition, fitted out from 
 Pisa, conquered the island of Majorca, and brought back as 
 
44 
 
 spoils tlie bricks and tiles of tlie Moors, thenceforward called 
 Majolica. 
 
 The earliest known specimens of Italian majolica presented 
 an arabesque pattern painted in yellow and green upon a 
 blue ground and possessed a yellowish chromatic glaze. The 
 red clay, which formed the body of the ware, was moulded 
 and burnt, then dipped in a white opaque enamel, consisting 
 in oxide of lead, oxide of tin, and a very white earth from 
 Sienna. When dry, the pattern was painted on it, then 
 washed over with a thin lead glaze and burnt a second 
 time. 
 
 From 1450 to 1530 the product is distinguished as mezza- 
 majolica. The outline of the figures were traced in blue 
 upon a black or white ground, and the draperies faintly col- 
 ored ; there were no shadows and the flesh parts were not 
 colored, and the whole was covered with a chromatic mother- 
 of-pearl like glaze which imparted a golden and silvery lustre 
 to its yellows and whites . Under the house of Urbino, the 
 manufacture of mezza-majolica flourished at Pesaro and at 
 Gubbio, where its chief artist, Georgio Andreoli, first applied 
 a transparent ruby-colored lustre, which, with the previous 
 golden and silvery tint, produced a lustre like burnished cop- 
 per, and particularly brilhant over a blue ground. 
 
 At the beginning of this period, the sculptor Luca della 
 Bobbia (born 1400, died 1481), after many trials, discovered 
 that by increasing the proportion of oxide of tin in the glaze, 
 a hard opaque brilliant pure white enamel was produced, 
 which he applied upon terra-cotta statues of Madonnas and 
 saints, and architectural ornaments, and abandoned the pre- 
 vious chromatic characteristics of the ware . His principal 
 decorations were in white, over a blue ground. Several years 
 after his death, this glaze came into general use at Faenza, 
 and at Florence, whence the name of faience, which is now 
 applied to earthen-ware covered with a white enamel. 
 
 From 1530 to 1560, the artistic character of majolica at- 
 tained its highest point, and designs of Raphael and his 
 scholars were frequently used. After 1560, its utility had 
 
45 
 
 been so far sacrificed to decoration, that it rapidly died out 
 upon the introduction of porcelain. 
 
 The manufacture of majolica was carried into Germany by 
 Hirschvogel, who went, in 1603, to Urbino to learn the art, and 
 on his return, erected a manufactory at Nurnberg ; but Ger- 
 many possessed enamelled earthen-ware factories before then, 
 and in Holland the potteries of Delft were already cele- 
 brated. 
 
 The manufacture of faience passed into France with 
 Catherine de Medicis, and the Duke of Gonzago erected, in 
 1570, a majolica manufactory at Nevers, which was so suc- 
 cessful that its products are hardly to be distinguished from 
 the original majolica. Considerably prior to this, however, 
 the potteries of Beauvais were already known in the 12th 
 century ; and in 1555, Bernard de Palissy had discovered for 
 himself the art of enamelling a gray paste. The originality 
 of his decorations, and the skill and humor shown in the 
 modelling, give particular value to his majolica ; but his art, 
 which he kept secret, disappeared with him, until its re-in- 
 troduction from Italy in 1570. The French Henry II. ware 
 also preceded the introduction of faience into France. 
 
 In England, delft ware and colored enamelled tiles from 
 Holland were already imported at the time of Henry IV. 
 The modern revival of majolica there, is due mainly to the 
 labors of Mr. Herbert Minton. In imitating the azulejos of 
 the Alhambra, he was very successful. The tiles of earthen- 
 ware are burnt, then covered with an opaque white tinny 
 glaze, upon which the outlines of the decorations are dis- 
 tinctly traced, and filled in with a thin coat of enamel of 
 various colors, and again burnt. Anihne colors may be used 
 to imitate enamel. 
 
 The Palissy ware, formed of embossed biscuit covered with 
 transparent glazes of various colors, is frequently called 
 majolica, although this term should properly be reserved for 
 biscuit (i.e., burnt earthen-ware) coated with an opaque 
 enamel. 
 
 The majolica of Messrs. Minton & Co. differs in many 
 respects from the modern Italian, French, and Dutch varie- 
 
46 
 
 ties, as well as from the old majolica. The continental ware 
 is formed of limey clays, consisting for white faience of 58 
 silica, 35 alumina, 7 carbonate of lime ; and for brown fai- 
 ence, of 57 sihca, 38 alumina, 5 carbonate of lime. 
 
 The Hme solidijfies the body, makes it more liable to crack 
 over the fire, but facilitates the adhesion of the enamel, by 
 partly melting with it and imparting to it a fat, glossy ap- 
 pearance. Other faiences and old majolicas contain (Pich- 
 enot, etc.) 13 to 22 per cent, of lime, and 1 to 14 per cent, of 
 carbonic acid, the temperature required to fire the biscuit not 
 being sufficient to expel all the carbonic acid. (Palissy ware 
 contains only 1.5 lime.) The silica and alumina are usually 
 in the proportion of 2.5 or 3 to 1. 
 
 In England, the fire-clays used come from the coal forma- 
 tion, contain no lime, are fired at a higher temperature, and 
 produce a denser, harder biscuit, generally of a buff color, 
 but the enamel is less glossy. Its greater power of resisting 
 fire allows of its embellishment with several colors, such as 
 turquoise blue, Chinese yellow, and crimson, requiring great 
 heat for their development. The colors and glazes of Messrs. 
 Minton are of remarkable excellence. Others excel in artistic 
 designs. 
 
 Knausz gives the following opaque white enamel : 
 
 Oxide of lead 23.6 
 
 Oxide of tin 15.6 
 
 Silica 43.5 
 
 Alumina 1.7 
 
 Oxide of iron 0.5 
 
 Lime 3.8 
 
 Magnesia 1.6 
 
 Alkalies 10.0 
 
 The enamel may be fritted, i. e., fired once to a melting 
 heat (about 70° W.) and ground fine. A sudden immersion 
 in water while hot facilitates the grinding and heightens the 
 lustre. Part or all of the coloring metallic oxides can be 
 added after this firing. 
 
 The relative proportions of oxide of lead and oxide of tin 
 
47 
 
 vary. An increase of the lead gives a thinner, more trans- 
 parent, fusible, and brilliant enamel, which sinks too much 
 into the ware under high heat. An increase of the tin gives 
 a whiter, harder, thicker, and less fusible enamel, of greater 
 covering power. Frequently there is 2 to 4 times as much 
 lead as tin. In white enamel these oxides constitute together 
 39 to 48 per cent, of the enamel ; the remainder consists of 
 43 to 47 silica, with 3 to 8 common salt, and 2 to 3 of soda. 
 Sometimes a trace of lime. 
 
 When required to stand a high heat, the silica should be 
 of the cleanest quartz sand. 
 
 In Germany the mixture of oxide is obtained by melting 
 100 lead with 50 sheet tin, in contact with the atmosphere. 
 
 For colored opaque enamels 90 to 97 per cent, of the white 
 enamel is mixed with 10 to 3 per cent, of coloring metallic 
 oxides. 
 
 Stanniferous enamels have sometimes, after a lapse of time, 
 a tendency to peel off, owing to want of affinity of the sili- 
 cates of lead and tin for the body of the earthen-ware. The 
 melting point of the enamel should correspond to an inci- 
 pient softening of the body, when, by a tendency to absorp- 
 tion, it will adhere to the ware. If the enamel is too fusible, 
 it will be too thoroughly absorbed by the ware, and lose its 
 lustre. If wanting in affinity, it will collect in separate drops 
 on the surface, which fall off later. 
 
 The expansion and contraction of the enamel must approx- 
 imate closely to that of the body, or numerous cracks will 
 result. These occur also when the glaze is too thick. 
 
 If the enamel is too refractory, it will be defaced by cavi- 
 ties and points showing only a partial fusion. 
 
 Phosphate of lime can be introduced as a whitening, and, 
 until fluxed, infusible ingredient. Majolica tiles are better 
 for walls, and not so good as encaustic tiles for floors. 
 
48 
 
 EARTHEN-WARE TILES IN PLAIN COLORS, 
 GLAZED. 
 
 They may have their surfaces decorated by printing or 
 painting. By dipping the earthen-ware tile in a slip of white 
 or colored clg,y (see Colors under the Glaze) a smoother and 
 differently colored surface is obtained for the decoration. 
 
 The transparent glaze is colorless or diversely colored (see 
 Colors in the Glaze). It should not be crazed. Also, spaces 
 may be reserved from the slip or the glazes. The Persian 
 patterns of Minton & Co., on a Persian body or slip, for wall 
 tiles, are admired for transparency and the turquoise blue. 
 
 DESIGNS FOR TILES. 
 
 It is generally admitted that flat treatment is the most 
 appropriate for floor designs. Startling contrasts of form or 
 color, which attract our attention to the exclusion of almost 
 everything else in the apartment, fail to produce a harmo- 
 nious effect. Rich and full colors can be so combined as to 
 produce a quiet and unobtrusive pattern. 
 
 Any design presenting the appearance of inequality of sur- 
 face is more objectionable in tiled floors than in carpets even, 
 from the greater rigidity and hardness of the material. Picto- 
 rial imitation seems a waste when destined to be trodden 
 upon. The best result is perhaps observable when a pattern 
 upon a ground of a simple color, or of non-contrasting colors, 
 is used to give repose. The combination of many colors in 
 one pattern is, of course, attended with much greater diffi- 
 culties than the use of a few, as among all the possible com- 
 binations, the concords are much fewer than the discords, 
 and not likely to be hit upon except by careful study. The 
 pleasing effect of Oriental patterns is instructive in this re- 
 spect. Success seems more easily attained when the patterns 
 are distinctly grouped and ornamental borders added. 
 
 The richness of the material should not be concealed by 
 profuse surface coloring, but rather brought out by distinct 
 encaustic colors. 
 
49 
 
 " The attempt to make each tile a decorative unit, and to 
 multiply it over the whole floor, is rarely satisfactory. Forms 
 of this kind occurring over large spaces are likely to prove 
 
 very tedious to the eye The decoration of the floor 
 
 must depend upon the use of the apartment. Large and 
 somewhat empty entrance halls call for more pronounced 
 treatments ; aspect and use also must determine whether 
 the floor should be cool or warm in its coloring." — (Redgrave.) 
 For wall tiles, breadth and quiet are more desirable even 
 than for floors. A design producing diagonal lines, or hori- 
 zontal lines, is not as good as vertical lines. 
 
 Messrs. Minton's Persian designs and Maw & Go's Eosette 
 patterns are particularly admired. 
 
 TESSERiE.-MOSAIG BRICKS. 
 
 TesserfB or blocks for mosaic brick are made by a machine 
 exhibited by M. Hollins & Co. The small squares are made 
 by this process in a diy condition. Formerly the clay was 
 wet when shaped, which caused many of them to warp, as 
 they dried before baking. They are now formed of dry- 
 powdered clay, stamped together with great force in small 
 moulds, so that the particles adhere together. 
 
 Minton & Go's stamping press for producing mosaic bricks, 
 makes slabs from 1| inches square, used for flooring tiles, 
 down to the minute pieces used for delicate mosaics. It is a 
 vertical screw press ; dies of the required shape pass through 
 openings in a circular metal table, into matrices below. The 
 clay finely pulverized and colored by difi'erent pigments, as 
 desired, is heaped upon the table, and a small portion is 
 swept into the matrices by hand at each downward stroke of 
 the press. The cubes are arranged and dusted, and then 
 baked. The heat vitrifies them, and they appear with an 
 opaque glazed surface. Various pigments are adedd to the 
 clay. The picture is made by reversing the tesserae and 
 gumming them on a board ; the back is then covered with a 
 cement composition, and the board taken away from the 
 face. 
 
50 
 
 The clay is not that used at tlie Potter's wheel, nor the 
 same as is used for fine china. It is "Cornwall clay," a 
 white substance obtained along the edge of a granite forma- 
 tion, where the rock has been oxidized and disintegrated for 
 ages by the atmosphere. The thickest veins are to be meas- 
 ured in inches. When this disintegrated granite has been 
 obtained, the particles of mica and other impurities are 
 washed away, and the residue of converted quartz is " Corn- 
 wall clay." (For fine china, there is in England an addition 
 of bone dust and other ingredients.) This clay, when baked 
 without the addition of coloring ingredients, forms pure white 
 earthen-ware, of which material the tesserae are made. 
 
 TERRACOTTA. 
 
 Terra-cottain its application to architecture still has its ad- 
 vocates and opponents. When properly manufactured it is 
 one of the most durable materials which can be employed ; 
 but, like stone or any building material, it requires inspection 
 before use. 
 
 Very fine specimens of terra-cotta made in London one 
 hundred years ago, and exposed to the weather since, are 
 Btill perfect. In Northern Italy many fine examples of brick 
 and terra-cotta exist, and the extensive revival in England 
 and Germany of this method of building, is worthy of note. 
 
 The strength of well made terra-cotta is surprising. A 
 piece of four-inch column, made by Jas. Pulham, and tested 
 at the 1851 Exhibition, required a pressure of 400 tons to the 
 square foot to crush it, or as much as good granite, and two 
 to three times as much as most building stone. In a paper 
 recently read at the Architectural Conference in London, Mr. 
 C :barry gave some valuable results of experiments on terra- 
 cotta, showing the crushing strength of this material to be 
 seven and a half times greater than that of average brick. 
 
 The difficulty of obtaining a really durable buHding stone, 
 is well known to architects, and practical experience is re- 
 quired in its selection ; architects do not agree, some prefer- 
 ring limestones to sandstones, others sandstones, nor is it 
 
61 
 
 settled which are the best beds. Stone varies much in every 
 quarry ; an instance in point is the Geological Museum in 
 London and the Houses of Parliament, both of the same 
 magnesian limestone ; the first lasts well so far, but the latter 
 is rapidly decaying, and many protecting coats have been 
 tried upon it, to arrest decay. 
 
 The test of the amount of water absorbed, is conclusive 
 neither for terra-cotta nor for stone, as some materials ab- 
 sorb more water, and yet withstand frost better than others, 
 owing to their great cohesive strength. 
 
 The quality of a stone is so difficult to discover, that the 
 most durable stones are not unfrequently rejected. Even 
 granites are not all durable, particularly those with a soapy 
 fracture, which, by weathering, decompose, and furnish the 
 china and pipe-clays so extensively used in the industries. 
 The difficulty of finding a material that will stand heavy 
 frosts is seen in St. Petersburg ; the Alexander Column, a 
 granite monoHth 84 feet high, is split in several places from 
 this cause, and in the public monuments some of the largest 
 granite blocks are rent in two . 
 
 In erecting large buildings it is difficult to supply quickly 
 enough stone of a durable quality from one quarry. Nearly 
 all stone is not fire-proof, but cracks when exposed to high 
 heat. 
 
 These causes, without deprecating the use of stone, point 
 to the desirabihty of finding a durable fire-proof building 
 material, which can be relied on always and supplied in large 
 quantities. This presents an opening for the use of terra- 
 cotta — a material which has stood the crucial test of firing. 
 
 A simple test of the texture of terra-cotta is the point of a 
 pen-knife, which should not penetrate the surface, and will 
 sometimes strike fire upon it. A clear and bell-like ring is 
 also an evidence of homogeneity and compactness, and a 
 clean close fracture shows strength. The texture of the body 
 and tlie precision of the forms are further indications of ac- 
 curate firing and homogeneous material. 
 
 The true qualities of terra-cotta in its application to archi- 
 tecture consist in its merit? , as a, decorative fire-proof material, 
 
52 
 
 spbssessing the three essentials of color, durability, and econ- 
 omy. 
 
 When treated with due regard to construction, so as to 
 '^fulfil its part in the building as honestly as the brickwork of 
 the wall itself, the high capacities of the material to receive 
 artistic treatment admit of the impress of original art being 
 reproduced for the uses of the architect, in an almost im- 
 perishable substance. 
 
 Fine works in hard stone are exceedingly difficult of execu- 
 tion, and in soft stone soon crumble away ; the labor of the 
 artist may be saved by taking a mould of his work, and re- 
 producing it in terra-cotta as often as may be required ; in- 
 deed, the great economy in the use of terra-cotta lies in 
 producing a great number of articles of the same pattern. 
 
 Where original art is required, the subject can be modelled 
 in the actual terra-cotta clay, and passed through the kiln, 
 from which it issues an original work of the sculptor, with- 
 out the intervention of mechanical copying, moulding, point- 
 ing, or carving. 
 
 Modern examples of the extensive use of terra-cotta are 
 seen in the Dulwich School, (from designs by C. Barry, Jr.), 
 costing $500,000, and accommodating 700 boys ; the Ken- 
 sington and other Museums ; various hotels and stores, and 
 the great Albert Hall, which cost one million dollars. This 
 building is of brick and terra-cotta, contains seats for 8,000 
 persons, and is capable of accommodating 16,000 without 
 discomfort. The mMe structures, decorated in stone, would 
 have cost much more. 
 
 An example of successful decoration is the permanent brick 
 and terra-cotta arcading at the International Exhibition. In 
 the successful use of these materials, the architect, Col. 
 ' Scott, deserves praise. 
 
 TERRA-COTTA MATERIALS. 
 
 Terra-cotta, or literally " burnt clay," would seem from its 
 name to be very simple in its manufacture; yet to produce 
 a material as strong, more durable, and less expensive than 
 
58 
 
 stone, requires an exact scientific knowledge of the properties 
 of many varieties of clay, and accurate observations upon 
 their behavior in the oven. 
 
 The improvements visible in many species of ceramic pro- 
 duction, may be attributed to the increasing regard paid to 
 the chemistry of the manufacture and the physical phenom- 
 ena involved. In the same way, success in terra-cotta is in 
 proportion to the exact experimental knowledge possessed 
 of the natural properties of the various clays ; for there is no 
 such thing as a terra-cotta clay, ready for use under condi- 
 tions that are always applicable. By judiciously selecting 
 and combining different clays, the best results are obtained. 
 We will, therefore, review the natural materials which the , 
 manufacturer of terra-cotta has to choose from. 
 
 Pure clay — the hydrous silicate of alumina of chemists- 
 is absolutely infusible in the greatest heat to which we can 
 subject it. But pure clay is rarely found in nature ; it is 
 usually combined with other substances. 
 
 The common clays consist of silicate of alumina in coarse 
 admixture with sand, lime, iron, carbon, alkalies, and not 
 unfrequently much organic matter. The variety found in the 
 composition of common clay is not surprising, when we ex- 
 amine its origin, and see that it results from the decomposir 
 tion of felspathic rocks and soils by weather and water, and is 
 found lining the banks of rivers and the bottom of valleys 
 ajid seas. Nearly all the common clays contain much lime , 
 andiron, and are fusible at an ordinary furnace heat. The 
 better varieties are soft to the touch, but want unctuosity. 
 
 Some of these clays are adapted to brick-making ; they^ 
 are the brick clays, and consist of silicate of alumina with 
 admixture of silica sand, which is essential, and may even 
 reach a proportion of 90 per cent, of silica, and still formi 
 excellent brick. Silica in the mealy state is injurious to clay. 
 intended for brick-making (excepting Bath brick). Also^ 
 any considerable quantity of lime, iron, potash or soda, is 
 unfavorable, and in a good brick clay there should not be> 
 more than two per cent, of limei or potash, for these sub- 
 
54 
 
 stances cause the brick to run into glass when in the 
 kiln. 
 
 Fire-clay is a variety that will bear intense heat without 
 meltin^T in the kiln or in furnaces. The fewer different ele- 
 ments it contains the more infusible it generally is, following 
 in this respect the rule applicable to metallic alloys, which 
 are fusible in proportion to the greater number of different 
 elements they contain. This rule, which is not absolute, also 
 accounts for the melting qualities of fluxes in general, and is 
 applicable to common clays. 
 
 The alkaline earths, iron oxide, etc., which would help to 
 form a flux, are therefore absent in fire-clays. Many excel- 
 lent varieties of fire-clays are found in the coal measures, and 
 they usually result from the decomposition of the older rocks, 
 exposed at the time of the coal period. They often contain 
 carbon and hydrocarbons. 
 
 Pottery clays are more compact, unctuous, and plastic 
 than brick clays ; they are very tenacious and ductile, and 
 form with water a semi-translucent mass. When pure they 
 are practically infusible and burn white. They contract 
 much in burning, as they part with their water only under 
 exposure to the furnace. The more oxide of iron they con- 
 tain the deeper is their red color after burning, and the more 
 fusible they are . They contain ten to twenty per cent, of 
 water, and very little lime or magnesia, while the remainder 
 is silica and alumina, in proportions varying from two to one, 
 to equal parts. Pottery clays seem to result from a natural 
 separation of the objectionable parts of common clay, by the 
 action of water and long exposure to the weather, and are 
 found in deposits. 
 
 Pipe clay is a variety of potter's clay, containing very little 
 iron, and, like china clay, is formed from the decomposed fel- 
 spar of certain granite rocks, either by natural or artificial 
 washing. 
 
 In terra-cotta manufacture, one of the most important 
 clays is the potter's clay from North Devon and Dorsetshire 
 (see Fire-Clay Analysis) ; the neighborhood of Poole sup- 
 plies the great Staffordshire potteries, the " stone-ware " pot- 
 
55 
 
 teries of all parts of England, and even the Continent. These 
 clays contain a small percentage of alkalies. 
 
 Also the clays of the coal measures, technically known as 
 ** fire-clays," are greatly employed. 
 
 In the terra-cotta manufactures of the North of England and 
 Scotland, the purest lumps of fire-clay are selected by their 
 color and texture, and used alone without any other clay, 
 while the firms near London prepare more carefully a mixture 
 of clays, which produces a body of better texture. 
 
 The precise mixture of clays used varies with the appear- 
 ance aimed at for the terra-cotta, and in this respect manu- 
 facturers appear to seek different results. Some try to ob- 
 tain the texture and pale straw-color of stone ; others a red 
 brick color ; others again a warmer buff tint. 
 
 There seems to be in every case advantage in using a mix- 
 ture of clays, as 1a more compact, homogeneous, and better 
 vitrified body is obtained, although at the cost of extra labor 
 and care. One of the chief difiiculties met in manufacturing 
 terra-cotta figures and ornamental works is the contraction 
 the clay suffers after it has left the mould — first, in drying, 
 and still more in the subsequent process of firing. By mix- 
 ing the clays, a further advantage is gained in the diminished 
 shrinkage, as fire-clay terra-cotta (i. e., unmixed) shrinks in 
 lineal dimensions about 12 per cent from the time it leaves 
 the mould until it leaves the kiln ; the mixed clay terra-cotta 
 shrinks 6 per cent or less, and red clays shrink 3 per cent. 
 
 To enhance the durability of the body of terra-cotta a par- 
 tial vitrification of the mass is aimed at, by adding clays 
 which, like the Dorset, contain a small amount of alkalies, 
 which act as a flux to fuse the body harder. 
 
 Also vitrifying ingredients, pure white river sand, old fire- 
 brick ground fine, previously burned clay, called " grog," 
 are added in various proportions, amounting even to twenty- 
 five per cent. They counteract excessive shrinkage, act as 
 vitrifying elements, and keep the color lighter. 
 
 The efflorescence of the alkaline salts in the clays, acting 
 on the silicates of the surface, tend to vitrify more particu- 
 larly the exterior of the block, and to form a harder surface, 
 which should be left intact. 
 
MANUFACTURE. 
 
 The mixture of clays is ground under an edge runner to 
 the consistency of flour. The mills have either revolving or 
 stationary pans ; the former do the most work. 
 
 In order thoroughly to mix and incorporate the different 
 clays, a subsequent careful pugging is required, for which 
 hot water is sometimes used. 
 
 The mixture, when brought to the proper homogeneous cjon- 
 sistency, is placed in a plaster mould, withdrawn, dried near 
 the kilns, or otherwise, and baked in a kiln for 5 to 7 days,^ 
 dxiring which time it is slowly brought to a white heat, and 
 as gradually cooled down again. 
 
 There are several varieties of kilns, such as th^ Hoffman 
 kiln, which serve for terra-cotta and stone-ware. They are 
 improvements only to the extent which they economize fuel, 
 disseminate the heat uniformly, and allow of its perfect gra- 
 dation to any desired degree. 
 
 In order to avoid twisting and warping during the firing, 
 it is necessary, besides complete mixing of clays, that the 
 mould be shaped so as to give a uniform thickness of mate- 
 rial throughout, and if the temperature of the kiln be well 
 graded, the homogeneous body will not warp. 
 
 To cheapen terra-cotta building blocks, they are made 
 hollow, and filled, during the construction, with concrete or 
 cement. 
 
 Although in the kilns the products of combustion are 
 separated from the wares, it is found that the use of sulphur- 
 ous fuel darkens and tarnishes the surface, and it is to be 
 avoid© 
 
 DESIGNS. 
 
 In treating the clay material, several fundamental princi- 
 ples may serve as guides. 
 
 In the design of an object, construction has the first claim 
 upon our attention, and utility has precedence of decoration. 
 T^his requires a study of the strength of materials, and where- 
 
57 
 
 it has been neglected, as in some of the architectural pottery 
 exhibited, the result is a prevailing sense of weakness. 
 
 The general form of a piece having been determined on 
 sbund constructive principles, its details remain to be com- 
 pleted, in a manner that will make the object ornamental 
 in the position it is destined to occupy. It is essential that 
 the ornament should harmonize with the purpose of the ob- 
 ject. This part of the design requires an artist for its 
 execution ; the schools of design throughout England, of 
 which there are 110, have been largely used to procure these 
 designs, by premiums offered and competitions. 
 
 In the representation of objects taken from nature, it is an 
 efror, for decorative purposes, to attempt an exact imitation 
 of the natural object ; the forms should be conventionalized 
 and adapted to the material dealt with, in a way to bring out 
 fully its true nature and qualities. 
 
 The rale of not attempting to conceal the true material, 
 arises from the pleasure which mere merit of material affords, 
 and from the general unsatisfactory effect of all attempts at 
 imitation. 
 
 The imitation of stone in terra-cotta is an error for which 
 manufacturers are less responsible than the buyers who re- 
 quire it ; but the majority have happily avoided this extreme. 
 When the pale straw stone color is produced by the addition 
 of ingredients whose object is to increase the vitrification of 
 the body, it is perfectly legitimate. 
 
 The rich buff color of terra-cotta is usually considered the 
 most pleasing ; it requires twenty-four hours longer firing. 
 Although more difficult to obtain uniformity in tint, when 
 produced it is good evidence of hard firing and homogeneous 
 material. 
 
 KEPRODUCTIONS. 
 
 One of the advantages of terra-cotta is the facility with 
 which it lends itself to the reproduction at home of features 
 of architectural merit, wherever found in distant countries. 
 By taking on the spot a plaster cast of a detail of cornice, 
 bracket, column, or other object, and sending this cast from 
 
68 
 
 abroad, it may be used for the reproduction of as many 
 similar objects in terra-cotta as the architect requires for a 
 new building. 
 
 A practical difficulty is met in taking many casts from one 
 plaster cast, as it requires some skill, and deteriorates the 
 model. This difficulty is overcome by the process of gelatine 
 moulding, as follows : 
 
 The plaster model is coated with oil and soap, to prevent 
 adhesion, and covered with a canvas for protection. Rolls of 
 modelling clay are then laid on over the canvas, until the 
 whole surface is covered to a suitable thickness, say 4 to 6 
 inches ; and against this a plaster coating or wall is built up, 
 in, say, two parts, to form a backing for the mould. The two 
 parts are then opened, the canvas and clay are taken out and 
 thrown away, the two parts are replaced, and a hollow inter- 
 val of the thickness of the clay will exist, into which hot 
 liquid gelatine is poured. After twelve hours, the gelatine 
 will have attained a semi-solid elastic consistency, which will 
 allow of the mould being opened, and the gelatine impression 
 peeled from the face of the model. The gelatine impression 
 is replaced on the plaster wall which previously supported it, 
 and a plaster cast is taken from it. From the latter, about 
 four terra-cotta reproductions can be made without sensible 
 deterioration. 
 
 The advantnge of gelatine is that it re-produces minutely 
 without deterioration every mark of the plaster model ; its 
 elastic nature makes it especially useful for " undercut " carv- 
 ing, as it yields while being released from the cut, and im- 
 mediately again resumes its shape with perfect accuracy. 
 The process as now used, for instance, for the reproduction 
 of 64 brackets of the New Museum, Kensington, works ad- 
 mirably. 
 
 USES OF TERRA-COTTA. 
 
 This material finds a ready application to architectural dec- 
 oration, especially in connection with brickwork. It is used 
 for : 
 
 String Courses, Cornices, Vertical Separations, Terminals 
 
59 
 
 for walls, Window Heads, "Window Mullion Tracery, Key- 
 stones, Wall Copings, Pier Caps, Capitals and Bases of Col- 
 umns, either in connection with marble or granite columns, 
 or of terra-cotta columns plain or twisted, Friezes, Bas Ke- 
 lievos. Figures and Busts, Medallions for insertion in walls 
 Festoons, Chimney Pots and Chimney Shafts, Ventilators and 
 Ridges. 
 
 Ornamental and Plain Facing Tiles and Building Blocks, 
 from 1 to 4| in. thick, formed into Quatrefoil and other 
 Panels, Chequered and Vermiculated Eustics, and Diaper 
 Work. 
 
 Fire-proof Ornamental Stair Cases with Newels and Balus- 
 trades, perforated or plain Risers, and inlaid with Majolica 
 and other Tiles . The strength of terra-cotta gives it partic- 
 ular value for this purpose. 
 
 Garden Decorations of all kinds. Fountains, Basins, Bal- 
 ustrades, Bridges, Tazzse, Vases, Pendant Flower Baskets, 
 Ferndelabras, Garden Stej)s, Statuettes, Garden Edging 
 (fixed so as not to get displaced by digging), made also with 
 Encaustic Tile Panels, Horticultural appliances, and Window 
 Flower Enclosures. 
 
 Ornamental Conservatories, Lodges, Summer Houses, 
 Aviaries and Dairies. 
 
 Mural and other Monuments. 
 
 (See list of Exhibitors.) 
 
 STONE-WARE. 
 
 In the fifteenth and sixteenth centuries, stone-ware, charac- 
 terized by its dense, opaque, vitreous fracture and imper- 
 meable and refractory nature, was already abundantly manu- 
 factured in Germany and Holland, whence the industry was 
 imported into England, and encouraged there by Queen 
 Elizabeth. 
 
 The materials made use of in England are the refractory 
 white and greyish plastic pipe clays of Devon and Dorset- 
 shire (see Fire-Clays), which are used, alone or mixed, for 
 small articles. For larger objects, white river sand, ground 
 
60. 
 
 fire-bricks and flint are added to counteract shrinkage and 
 warping. 
 
 Salvetat's analysis of stone-ware shows a composition of; 
 
 Silica from 62 to 75 per cent. 
 
 Alumina " 19 "29 " 
 
 Iron oxide " 1 "8.5 " 
 
 Lime " 0.25" 1.0 " 
 
 Magnesia " 0 "0.9 " 
 
 Alkalies " 0.5 " 1.5 " 
 
 The shaping of large masses, such as tanks to hold several 
 hundred gallons, takes place on the potter's wheel. A diffi- 
 ciilty arises from the length of time (some ten days) required 
 to build up a tank, in the unequal drying of the parts first 
 formed. This is counteracted by wet cloths wrapped around 
 them. While drying subsequently for ten days, it is protected 
 against unequal currents of air. More intricate forms are 
 made in plaster moulds. 
 
 The heat required is greater than for terra-cotta, above the 
 melting point of silver, and is one of the highest required for 
 any kind of pottery (100° to 120° Wedgwood). The texture 
 of the body produced is more vitreous and dense. The man- 
 ufacture of terra-cotta and stone-ware are advantageously 
 carried on together, as the refuse materials from the one can 
 be used in the other, and the less heated story of stone-ware 
 kilns, used for terra-cotta. 
 
 The consumption of fuel is a heavy item and depends 
 largely on the kiln. In some, the Siemens regenerator is 
 applied. 
 
 In Germany, Bosch's oven is considered economical. The 
 flame enters through apertures at the sides and centre of the 
 floor, is reverberated, descends through other openings in 
 the fldor, and reascends through upright flues at the circum- 
 ference, to a central conical chimney. The objects remain 
 about ten days in the oven, in some cases three weeks. 
 Bonnet recommends the following refractory concrete for 
 introduction in oven walls as a separating lining to retain 
 
61 
 
 heat: "Mix 2^ parts clay, 1| river sand and pebbles, 1 un- 
 slacked fat lime in powder ; water slightly and ram well." 
 
 The ware is usually glazed, although its imperviousness 
 does not require it, for better protection and smooth appear- 
 ance. The glaze is either a salt glaze or a liquid glaze. 
 
 The salt glaze, which is the cheapest, is applied when the 
 ware has nearly reached its highest temperature in the kiln ; 
 the fire is then managed, and when the right temperature is 
 reached, common salt is thrown uniformly with shovels 
 through holes at the top of the kiln. A moderate sized oven 
 requires about 150 lbs. salt. The steam in the smoke de- 
 composes the volatilized salt into chlorhydric acid and soda, 
 which unites with the silica of the clay, and forms a thin film 
 of soda glass on the surface of the ware. Silicious clays 
 take the glaze best and become the most lustrous. When 
 nearly half the salt has been thrown in, the fire is increased 
 for a moment, then again reduced and some of the specimens 
 examined. Then the remainder is thrown in, part at the top 
 and part over the fire. All openings are then carefully closed 
 and the oven cooled off for four or five days. 
 
 The liquid glaze, containing oxide of lead, clay, and fel- 
 spar, sometimes borax, and diversely colored by metallic ox- 
 ides, is applied by dipping the vessel in it before burning. 
 This constitutes the Bristol ware of smoother surface. 
 
 Berthier mentions a glaze containing : 
 
 SiHca 56 per cent. 
 
 Alumina 7 " 
 
 Lime 21 " 
 
 Magnesia , 1 " 
 
 Oxide of iron 12 " 
 
 Oxide of manganese 3 
 
 Ground cinder, and slag from iron furnaces and mills are 
 sometimes used. 
 
 Potash, saltpetre, soda, basalt powder, have been recom- 
 mended. 
 
 The glaze is applied sometimes on the inside of vessels 
 
m 
 
 only, as making them less liable to crack under alternations 
 of temperature. 
 
 At Quimper, a felspathic body is used, and the glaze con- 
 tains no lead, as follows : Sand, 62 ; carbonate of soda, 20 ; 
 kaolin, 8 ; lime, 8 ; borax, 2. Felspar, when introduced, 
 opposes shrinkage, less flint can be used, it is easier ground, 
 and the firing requires less heat. 
 
 The washing of impure kaolins gives a fusible felspathic 
 sand, which may be used. 
 
 Felspathic bodies have an affinity for boracic glazes. The 
 stone-ware on exhibition is remarkable for the perfection to 
 which the industry has been brought, and the new practical 
 uses to which this^ material is put with advantage. 
 
 The machinery used is represented only by two potter's 
 wheels, several crushing machines, and Boulton's patent 
 jigger. Drain pipes up to 30 inches in diameter are made 
 by forcing a piston by steam or otherwise through a mass of 
 clay enclosed in an iron box, in the bottom of which is an 
 opening of the exact external section of the pipe. The sock- 
 ets are afterwards added on by hand. Siphons and intricate 
 fitments are made in moulds. 
 
 The water cisterns, acid pumps and tanks, distilling appa- 
 ratus, egg-shaped sewer pipe, Doulton's lipped invert-blocks 
 for sewers, with channels to separate the surface wash from 
 the sewage when the latter has to be pumped in order to 
 utilize it ; a revolving churn, said to act rapidly ; pipes to be 
 built up in towers for the storage of muriatic acid, are all 
 worthy of particular mention. (For further details see list 
 of Exhibitors.) The impermeability of the material, its power 
 to withstand the action of most acids, and, to some extent, 
 of sudden changes of temperature without cracking, and the 
 possibility of grinding the surface perfectly true, are its chief 
 qualities for these uses. 
 
 Stone-ware and earthen-ware manufacturers will be inter- 
 ested in the following account from the Staffordshire Adver- 
 tiser, of the New Over House Manufactory, Burslem : 
 
 "It stands upon about an acre of ground, and all the 
 buildings are en suite — that is to say, from the clay bank to 
 
63 
 
 the pacldng-house all the processes are carried on in build- 
 ings which are arranged in consecutive order. This leads to 
 a great economy of space, time, and labor. Commencing at 
 the slip-house, we found the machinery arranged in two 
 stories, and driven by a 30-horse power engine, supplied from 
 two boilers fitted with smoke-consuming doors. All the 
 materials required are ground upon the premises, and there 
 
 are two 24-chamber clay presses in constant operation 
 
 The slip-house communicates direct with the clay workshops, 
 a range of buildings 143 ft. by 27. On the ground floor occur 
 the throwing, turning, and handling shop, the throwers' hot- 
 house, and the flat-pressers' workroom. It is in these de- 
 partments that some of the most ingenious and useful of 
 recent scientific inventions appear, and for these, producer 
 and consumer (for the benefit is shared by both) are indebted 
 to the engineering ability of the patentee, Mr. Wm. Boulton, 
 of Burslem. For the first time, Mr. Boulton has applied a 
 
 new invention to the throwers' wheel It is exceedingly 
 
 ingenious, and is under perfect control by means of a treadle. 
 In the flat-pressers' room, there are 12 jiggers and 2 whirlers 
 driven by a supplementary engine of 6-horse power. The 
 whole of these appliances are worked by an invention of Mr. 
 Boulton, which may be thus described : An endless band 
 passes down each side of the workshop under the floor, and 
 is operated upon by means of two descriptions of grooved 
 pulleys. There is beneath each jigger a driving pulley, and 
 there is also nearly opposite to that a friction pulley, and this 
 lattet IS attached to the upright spindle which communicates 
 the motive power to the jigger. When the workman desires 
 to set the jigger in motion, he presses his left leg slightly, 
 and after a time, almost involuntarily, against a lever, which 
 action has the effect of curving the endless band, and bring- 
 ing it into contact with the friction pulley. The jigger, of 
 course, revolves at once, but the workman, by means of the 
 lever just mentioned, has the speed under complete control, 
 and can regulate it to the greatest nicety. If necessary, ai 
 treadle can be used in place of the knee lever. By this inven- 
 tion the workmen are delivered from the annoyances insep- 
 
64 
 
 arable from the employment of unpunctual and inattentive 
 boys as jigger turners ; there is also a moral and physical 
 advantage as compared with the old plan of engaging women 
 to work the treadles, and assist the workmen . Provision is 
 made in the second story for nineteen hollow-ware pressers, 
 •whose workshop runs nearly the whole length of the range, 
 and is probably the finest workroom in the Potteries, the 
 height to the apex of the roof being 23 ft. We were not at 
 all surprised to hear from Mr. Hammersley that the mere fact 
 of such a noble room being provided enabled him to secure, 
 without difficulty, the most respectable workmen. Lap stoves 
 
 are used, and they are heated by exhaust ste^im Mr. 
 
 Boulton has succeeded in warming and heating the whole of 
 the works by means of iron pipes, along which the exhaust 
 
 steam is conveyed There are two biscuit ovens and three 
 
 glost ovens, the latter of which are built on the cone princi- 
 ple. There are four warehouses : the hollow biscuit ware- 
 house, 121 ft. by 28 ; the flat biscuit warehouse, 60 ft. by 28 ; 
 a smaller warehouse for sorting, and the principal warehouse, 
 a room of 164 ft. by 33. Provision is made for twelve print- 
 ers ; and in the sagger-house, which is the last place reached 
 by the steam pipes, 40 scores of saggers are dried at one 
 time. The manufactory has an extensive frontage to the 
 
 road The tympanum is filled in with E. Minton, Taylor 
 
 & Co.'s encaustic tiles. All the roads and footpaths on the 
 factory are paved and bricked, and, indeed, it may be stated 
 summarily, that no expense has been spared to make this 
 factory one of the most complete, substantial, and in some 
 parts handsome, buildings in the district." 
 
 The decoration of stone-ware by grotesque figures moulded 
 separately and superimposed before burning is well-known. 
 Decoration in colors is hard to obtain on account of the de- 
 structive action of the intense heat and the glaze employed. 
 Messrs. Doulton & Co. produce a " Claret " stone-ware, by 
 the use of oxide of chromium, which is green before burning. 
 Also, by tracing a design with a steel point on the clay itself, 
 and applying oxide of cobalt with a fine brush, they obtain 
 
65 
 
 an effective method of decoration, in keeping with the char- 
 acter of the ware. 
 
 (See list of Exhibitors.) 
 
 TERRO-METALLIC WARE—BLUE 
 BRICKS. 
 
 Terro-metallic ware is of a dense, vitreous, non-absorbent, 
 very hard and durable bodj. It is for some purposes su- 
 perior to the best stone, and is particularly adapted for road 
 and stable pavements, copings, tiles, channel courses, solid 
 walls and hydraulic constructions. The tiles resemble cast 
 iron in hardness and exceed it in durabihty, as incapable of 
 rusting. 
 
 The material used is a natural clay, highly impregnated 
 with iron, and sometimes with lime, and is more fusible than 
 ordinary brick-clay. Clays which contain a large portion of 
 elements soluble in chlorhydric acid are good for this pur- 
 pose. Where these are not obtainable, lime and iron, in the 
 shape of slag ground, are mixed with a fat clay. In England, 
 chalk dust, sifted coke dust, and mill cinder are used. Pug- 
 ging and moulding is done by machinery. 
 
 The firing requires a high vitrifying temperature, and fuel 
 is a heavy item, unless kilns on the continuous principle are 
 used. A kiln with down-draught flame, from which the waste 
 gases are conducted to a second kiln, is found economical by 
 Eckhardt. 
 
 The same substance will produce an ordinary red brick, 
 blue ware, or a glass, according to the mode and degree of 
 firing. For terro-metallic ware, the heat is first brought 
 to a point at which the ware begins to soften and run to- 
 gether, then lowered to dark red, again raised and. lowered 
 many times. 
 
 Wood and clean peat are best; coking coal is hard to 
 manage, as the intermittence in heat is obtained by succes- 
 sive heavy charges of fuel which are allowed to burn low.. 
 
 In Holland, the firing is roughly done in open kilns, with 
 walls 6 feet thick and 12 feet high.. 1DQ,00Q bricks are burnt 
 
66 
 
 at a time, requiring often six weeks. This metliod gives con- 
 siderable loss in melted and unburnt bricks. 
 
 In Germany, a rectangular kiln, witli arched roof, contain- 
 ing 90,000 bricks, is used. The walls are 4 feet thick. There 
 are 60 flue openings in the roof, and 20 fire-place openings at 
 the sides, without grates ; peat is used as fuel, continuously 
 at first for 8 days, then charged intermittently every 4 hours 
 for 4 days, and finally every 2 hours for 2 days. During the 
 last period the flame issues abundantly from the roof. 
 
 At Kouen, the Hoffman annular kiln is used. 
 
 Blue-bricks are abundantly made in Staffordshire from a 
 ferruginous clay which fuses at a china biscuit heat. 
 
 The blue color does not permeate the body as for terro- 
 metalHc ware, but only extends to about one-eighth of an 
 inch from the surface. The fire is managed in a series of 
 " pinches," but requires to be less intense. The blue color 
 is obtained by repeatedly submitting the ware when highly 
 heated to a reducing atmosphere of smoke, which reduces the 
 red peroxide of iron to protoxide, all the salts of which are 
 bluish and greenish. Sulphur assists this action. 
 
 In Holland the process consists in closing the dampers, 
 and throwing bundles of wood into the fire shortly before the 
 end of the firing. 
 
 FIRE-CLAY WARES. 
 
 The extensive use of fire-clay wares in most of the arts 
 gives peculiar interest to their manufacture. The obtainable 
 quahty of refractory goods has, in certain industries, a con- 
 trolling influence upon the economic results. 
 
 The fire-brick industry of England is chiefly centred in the 
 productions of Stourbridge and New Castle, which together 
 make 110 milHons fire-bricks per annum, and export over 
 $500,000 of fire-clay and 10 millions fire-bricks. 
 
 Fire-Clays. — In the present state of knowledge, the physi- 
 cal tests of clays give us better indications of its value than 
 the chemical. 
 
 Clays of the same chemical composition are sometimes of 
 
67 
 
 opposite refractory qualities, while clays of different com- 
 position may be equally refractory. 
 
 When Brongniart and Malaguti mixed the correct chemi- 
 ical elements of porcelain together, and tried to reproduce 
 that substance, they failed signally, and obtained only a non- 
 plastic and very fusible substance. This also shows how 
 greatly the properties of a body depend on the mode of 
 grouping of the elements. The analyses of fire-clays, in 
 chemical works, give merely the elements, and are therefore 
 not presented in a practical shape to the manufacturer. 
 
 In examining a refractory clay, the purpose for which it is 
 intended should be considered, for a material will answer for 
 certain conditions that will not for others. Lightness of 
 color indicates little ; when owing to lime, it is generally a, 
 source of fusibility. , Experiment should be made whether 
 the clay is best alone, or mixed with other clay, raw or burnt, 
 and in what proportion ; what size to give to the fragments 
 of burnt clay or quartz added ; the finer it is the more it 
 tends to combine chemically, especially quartz. The addi- 
 tion of large fragments produces a more porous and brittle 
 brick, which stands better changes of temperature, and is 
 preferred for blast-furnace boshes, &c. ; fine burnt clay makes 
 a denser brick, which retains heat better, and is preferred for 
 coke-ovens, &c. 
 
 The corroding influence of the metals and slags to whicl^ 
 the fire-brick is exposed, must be combated by careful preparr 
 ation of the clay, to produce a denser brick, by giving super- 
 ficial smoothness, and by hard burning. 
 
 In building with fire-brick, the use for joints of cement 
 containing free silicic acid (quartz) should be avoided, by 
 previously saturating the cement with a basic burnt clay. 
 Bricks analyzed before and after use, have shown a loss of 
 half the silica they contained. A test of the power 'of brick 
 to withstand these corrosive influences, is the number of 
 times it can be melted up with oxide of lead, without being 
 eaten through. 
 
 In examining the analysis of fire-clays, attention should be 
 paid to the proportion of iband, which makes them more 
 
68 
 
 icaeagre, and opposes rupture, while burning. An excess of 
 sand renders them more brittle and porous, yet they stand 
 heat better. The sharpness and size of the grains facilitates 
 a homogeneous composition by rubbing when being worked 
 up. Clean quartz sand is the best; ground sandstone is 
 good, but expensive. 
 
 A high proportion of alumina increases the plasticity of 
 clay, and, at high temperatures, also the refractory power. 
 Thus monosilicates are more refractory than bi or tri-silicates. 
 Free sihca, i. e., in crystals mechanically mixed, must be dis- 
 tinguished from combined silica. 
 
 Increasing the proportion of combined silica, augments 
 ttie resistance in the fire only at lower temperatures, which, 
 however, may often suffice in industry. But above the point 
 of melting steel, the more combined «ilica there is, the 
 greater is the fusibility. Also, the ware then requires a longer 
 burning in the kiln. 
 
 Clean free silica will not melt in our melting heats, unless 
 -fluxed. A high proportion of free siHca is less injurious than 
 when the silica is combined. Silica which has been long in 
 tiie fire is more refractory and incorrodible. 
 
 Bischof finds that any addition of fluxes above 4 per cent, 
 rapidly increases the fusibility of the clay, in the following 
 order : lime, magnesia, alkali, and oxide of iron least. Eichter 
 finds them damaging, as follows : magnesia most, lime next, 
 then iron oxide and alkali. 
 
09 
 
 •uaaHOf) 
 Iff '(viaxsav) zxiaag 
 
 C O r-< 1-1 
 
 •iviHAivy iff 'xassiapi 
 
 20.92 
 61.52 
 
 1^25 
 
 1.75 
 
 •aaxHoig; ia 'flvavvg 
 
 05 O O « 1-1 i-( o> 
 S^I^TJIO .OrH --^ • • • 
 
 OD W TjJ S * ^ rH oi 
 
 •oxa 'uavK^; ia 'avssY<j 
 
 T-l O • rH iH <M eO • • • • 
 
 eo t-o • • i-( • • • 
 
 
 M I> U5 1-1 'tl eO ri i-i 
 
 o o _o o o _o _o o o !_o : 
 
 lO (N O O O O O O U5 O 
 1-1 CO 
 
 •aaiHX 
 -aag ia 'avaaaxuopi 
 
 24.6 
 64.4 
 
 trace 
 
 lo'" ■ 
 
 •xazvpi 
 
 25 
 52 
 
 9.0 
 
 trace 
 12.' 6 
 
 •aaiHvj, 
 
 . o o o 
 
 1-1 
 
 *aac[iioj3 ia iinov]^ 
 
 M< <M CO t- 00 
 
 t~ CO • CO <M • .ceo • • 
 
 C5 CO O O O !M <M 
 CO tH fH 
 
 •Noxsa^'^ ia 
 
 'KOAad 'HXilOKNOiaX 
 
 00 CO CO (M t~ 05 CD 
 
 COO • O CO <N lO (M • . . 
 
 05 IM O O (M (M (M O 
 
 •KOXsaAV 
 la 'aaiHsxasaoQ 'aiooj 
 
 rHOi eo'M-^.-ieoco 
 
 1-1 05 • Tf( (M CO CO CO CO • • • 
 
 cico O O (M CO IM OS 
 CO T)* 
 
 •oxa 'xvxaATYg 'laay 
 'aoaiaaanoxg 
 
 19 to 38 
 63 to 70 
 
 0 to 6^7 
 0 to 0.2 
 2 to 7 
 0 to 3 
 
 10 to 16 ] 
 
 0 to'i'.S 
 
 •ZaVAiHOg 
 
 ia 'aiaaaHsxavQ 
 
 28.95 
 59.48 
 
 trace 
 
 l!65 
 
 11.05) 
 
 a 
 
 S § 
 
 •s 
 
 •2 2^ 
 
 CJ .fl 
 
 3§ 
 
70 
 
 The Gamtirk clay (near Gartsherrie, Scotland) is bitu- 
 minous and mixed with some sulphur and almost free of 
 sand. After weathering for two or three years, it is used 
 almost dry and without addition of burnt clay. It is the 
 most refractory clay known. 
 
 The Stourbridge clays, also of the coal formation, are care- 
 fully sorted at the pit into three numbers. The best is for 
 glass-house pots and blast-furnaces, and costs fifty-five shil- 
 lings a ton on the spot. The second is for cupolas and fine 
 wares. The ordinary clay costs ten shillings a ton, and four 
 tons of it make a thousand nine-inch brick. The two first 
 are mixed with "grog" before use. The first, after grind- 
 ing, is kept under cover. 
 
 The Cornwall fire-bricks are made of : 1 clay of Poole, 1 
 clay of Teignmouth, and 2 of clean sand. 
 
 Belgian fire-clay (the best are Tahier and Mazet) is found 
 in the chalk formation, in pockets of some 200 feet diameter. 
 The best is white, grey and black. It is sometimes used 
 without grog. It has superior qualities for zinc distilleries. 
 
 France — Montereau and others are good. 
 
 Germany — The clays are inferior for some uses. The 
 graphite crucibles of Passau clay (Bavaria) are excellent. 
 100 Silesian clay of Saarau, with 150 of sand, makes excel- 
 lent fire-brick. 
 
 Austrian clays resemble the English in qualities and com- 
 position. 
 
 Sweden possesses, near Hogenas, clays superior to the 
 Stourbridge, and nearly equal to the Garnkirk. 
 
 i MANUFACTURE. 
 
 In England, the clay, after weathering, is ground to ^ of 
 an inch by passing between or under crushing rollers weigh- 
 ing tliree tons, and sifted at six meshes to one inch for brick, 
 and fourteen to one inch for glass pots. 
 
 The grog is then added, and it is tempered with water. 
 The pugging is done by treading and beating, or generally in 
 a cast-iron pug-mill driven by steam (2.5 to 3 horse-power 
 
Tl 
 
 will pug eight tons of clay in ten hours, the clay remaining 
 three or four hours in the machine. 
 
 The bricks are moulded by hand. Steam-presses have 
 been devised (Daelen's.) 
 
 Fire-bricks, when too porous, may allow molten slag to 
 filter through. This is obviated by increasing the density 
 by homogeneous preparation, beating, kneading, and hard- 
 firing ; but this also increases brittleness. 
 
 Clays rich in silica are to be avoided for glass manufac- 
 ture, as they are sooner attacked by the glass, are more 
 brittle, and burn less hard. Fatter clays, with the addition 
 of burnt clay, are better. 
 
 The fuel, and the mode of applying the flame, from below 
 or from the side, has different effects. 
 
 The addition of serpentine, talc, graphite, coke, coal, char- 
 coal, etc., heightens the refractory power of brick. 
 
 By treating with acids, inferior qualities of fire-clay, they 
 have been much improved, by the solution and removal of 
 detrimental parts. 
 
 The burnt clay added, should be burnt as hard as possible, 
 so that it may not again contract in firing. In Belgium, for 
 ordinary fire-brick, the burnt clay is reduced to i- or of an 
 inch ; for muffles to ^ or i, and well beaten in. At An- 
 dennes the sieves have twenty-five to eighty-eight openings 
 per square inch. 
 
 For best brick, in Westphalia, to 1 of fire-clay, 2 of burnt 
 clay are added. In Belgium, to 31 of clay, are added 52 
 burnt clay, and 17 clean quartz. 
 
 The drying of bricks, in Scotland and at Stourbridge, 
 takes place in sheds or rooms, with hot air flues in the floor. 
 For zinc retorts, the drying is verj^ gradual, lasting several 
 months, and the temperature increasing from 80° to 120° F. 
 For certain uses (zinc retorts, &c.) the wares are only dried, 
 and not burnt. A glaze composed of 40 white lead, 36 gran- 
 ite, 12 flint, 4 glass, is sometimes applied to one side of the 
 ware. 
 
 Walls and arches of large glass ovens are made of Stour- 
 
bridge clay, shaped into large slabs, and dried for a year or 
 more, but not burnt. 
 
 The burning takes place at Garnkirk, in rectangular kilns ; 
 the flame enters and ascends at the side, between the bricks, 
 descends in the centre, and thence enters two chimDeys. 
 At Stourbridge the kilns are circular-domed cupolas. The 
 flame is everywhere separated from the ware by thin walls ; 
 it enters at the circumference, from 8 or 10 steep inclined 
 grates, passes first under the floor, ascends into an annular 
 Bpace, which is separated by a thin wall from the middle of 
 the oven, and passes to the chimney through a vertical flue 
 and holes in the floor. The inner shell of the oven is closed 
 top, and has one door at the side. From 12,000 to 35,000 
 bricks are introduced ; the temperature is raised gradually, 
 maintained 80 hours at a white heat, and cooled down for 7 
 days. The capacity of the kiln is such that one cubic foot of 
 space is allowed per 10 bricks. The coal is obtained from 
 the same pits as the clay. 
 
 In Belgium two kinds of kiln are in use. Those with a, 
 fire under an arched floor, having openings through it, work 
 the fastest, and consume 8 or 10 pounds fuel for 100 pounds 
 brick. Hoffman's kilns are also used. The duration of the 
 firing varies, large grained w^are burning more rapidly. 
 
 Plumbago Crucibles — Graphite is added to the fire-clay, 
 that of Ceylon is used in England ; it gives the most refrac- 
 tory product, is used for melting crucibles, and withstands 
 changes of temperature. It is essential to purify it from 
 oxides or fluxes ; this is done by alkaline, followed by acid 
 washes. Old plumbago crucibles ground up are also used. 
 
 The Passau crucibles are made of ^ to ^ Passau clay and 
 ^to ^ graphite. The Patent Plumbago Crucible Co., Lon- 
 don, manufacture ware containing 52.6 carbon, 2.08 hygro- 
 scopic water, and 45,40 earthy parts, which consist of 68 per 
 cent, silica, 31 alumina, 0.5 iron oxide, and a trace of lime. 
 They are burned without contact of the flame. 
 
 Plumbago crucibles withstand great alternations of tem- 
 perature, and absorb metals much less than fire-clay. 
 
 Coke, coal, and charcoal are used as substitutes for graph- 
 
73 
 
 ites, but more than 10 per cent, can not be used, as it is 
 burnt out more easily than graphite, and makes a too porous 
 ware. 
 
 In Hanover, at Sollingerhutte, excellent crucibles are made 
 of 9 parts fire-clay, 14 burnt clay, 6 charcoal. In Bavaria, a 
 good crucible is made of 14 clay, 10 old brick, 8 quartz, 2 
 coke. 
 
 For lining lead furnaces and brick kilns, sifted coke dust 
 shpped with clay is used. 
 
 Very refractory crucibles are also made, without any clay, 
 of coal, or coke powder alone, with glue, and burnt without 
 contact of the air. 
 
 At Beaufay dense crucibles are made of clay raw and clay 
 burnt, and being poor in sihca, they withstand corrosion. 
 Although dense, they withstand sudden changes of heat. 
 They contain silica 64.6, alumina 34.4, iron oxide 1. (Ber^ 
 thier.) 
 
 Silicious Fire-Brick.. — The Dinas fire-bricks, which con- 
 sist of 96 per cent, pure silica, with a little lime and iron, 
 possess the highest refractory powers, but will not stand al-. 
 ternations of temperature nor the action of basic slags, such 
 as those of metals or lead ores. 
 
 The Dinas sandstone consists of 98 to 96 silica, 1 alumina, 
 0.2 lime, 0.5 iron oxide, 0.2 alkali, 0.5 water. This stone is 
 heated in quantities of 15 tons in a Rumford oven. A con- 
 tinuous kiln, as for Hme, may be used to advantage and 
 brought in 12 hours to a red heat, then thrown at once into 
 water ; the fragments are washed by a hand machine and 
 sorted by hand, the cleanest being chosen for first quality of 
 bricks. They are next crushed to a rough powder between 
 iron rollers, and 1 per cent, of lime and water is added. Th$ 
 workmen with gloves put this paste into moulds, placed on 
 an iron table, where it is firmly compressed by a stamp. 
 
 After drying, the bricks are burned hard for 7 days. They 
 expand in burning, yet are very dense. The introduction of 
 large fragments of quartz in bricks, causes rupture from ex- 
 pansion. The fracture is rough and presents grains of quartz 
 imbedded in a yellowish cement. 
 
The manufacture is newly carried on at Stolberg, near Aix, 
 and the Templeton Silica Works exhibit bricks analogous to 
 the Dinas. 
 
 Excellent bricks are also made of clean quartz with an ad- 
 dition of a little clay. The Martin Bros., England, make 
 brick of refuse kaolin and selected washed sand. They are 
 formed of 76 silica, 21 alumina, 1.7 iron oxide. Vygen & Co. 
 (Duisburg) make excellent brick, containing 85 silica, 13 
 alumina, 2 lime. 
 
 Eor lining Bessemer converters, a Sheffield sandstone is 
 mixed with 1 or 2 per cent, of alumina and oxide of iron. 
 
 Otlier Fire-Bricli To avoid the introduction of silicium 
 
 and carbon, so detrimental to many metals, fire-bricks and 
 crucibles are made with success by adding to fire-clay, either 
 magnesite, haUoisite, asbestin (a plastic magnesian silicate) 
 or bauxite. 
 
 Deville obtains excellent crucibles by mixing equal parts of 
 sulphurous or cryolitic clay and marble. To 1 part of this 
 mixture burnt very hard is added 1 alumina and 1 gelatinous 
 silica saturated with ammonia and alum, and when burnt 
 once, withstands all changes of temperature. 
 
 A novelty in fire-clay gas retorts, are the internal ribs of 
 Eraser, for strengthening and conducting the heat rapidly ; 
 • made by the Earnley Iron Co. (See Exhibitors.) 
 
 BRICKS. 
 
 Somewhat meagre clays, containing a certain amount of 
 oxide of iron and lime, are usually chosen. Although fatter 
 clays are easily moulded, they shrink more, and even crack 
 in the fire. The fluxes, iron, lime, &c., are useful, as they 
 produce a solid brick at a lower temperature. 
 
 Although the clays of each particular locality are almost 
 of necessity used for brick-making, a knowledge of their 
 adaptability to each kind of brick is essential. 
 
 Sandy clays, containing 60 to 96 per cent, of sand, besides 
 some lime and iron, produce bricks which are cheap, and 
 stand fire better than weather, for they are absorptive and 
 
75 
 
 brittle. These clays may be differently used, according to 
 the nature of the silica they contain : 
 
 1st. If in the mealy or finely divided state, it will not make 
 brick, except for polishing, as Bath brick and Tripoli stone. 
 
 2d. If the silica is amorphous and fusible (such clays then . 
 possess more parts soluble in acids) the clay will run together 
 in the fire, and may be eminently adapted for making terro- 
 metallic ware (which see). 
 
 3d. If the silica is in the shape of crystalline sand, by wash- 
 ing out some | of it, the remainder will be unctuous and fatj 
 and, with or without an addition of sand, it can be worked 
 into a good brick (more fuel is then required). Or else it may 
 be used unwashed, but mixed with a fat clay. 4th. If the 
 clay contains much mineral dust, washing will not separate 
 it, and the bricks will not be durable, unless burnt to vitrifi- 
 cation, as in terro-metallic and blue ware. 
 
 Brick clays contain not too much sand (5 to 60, some- 
 times 80, usually about 25 per cent.), the silica and alumina 
 are about in the ratio of 3 to 1, and there is 1 to 2 per cent, 
 of lime. When they contain 20 per cent, lime they become 
 limey clays and are not used for ordinary brick, as they would 
 fall to pieces by slaking of the lime. A certain percentage 
 of lime and iron is, however, useful. To make use of limey 
 clays for brick, as it would be too expensive to wash out the 
 lime, the only resource is to mix them with other clays, so as 
 to reduce the percentage below 20 per cent., or else use them 
 for terro-metallic and blue ware. If the use of limey clay 
 alone, cannot be avoided, it should be burnt at a temperature 
 low enough not to expel the carbonic acid ; the brick will 
 then contain carbonate of lime, which does not slake ; but 
 such bricks are treacherous. 
 
 Lumps of gypsum in a brick will destroy it. Pebbles and 
 fragments of flint cause the brick to fly in firing. 
 
 Pottery clays are expensive for brick, as their shrinkage 
 must be combated by the addition of sand, meagre clays, 
 etc. For thin ware, such as roofing tiles, they may be used 
 advantageously alone. 
 
76 
 
 Fat brick clay also requires sand, meagre clay, anthracite 
 cinders, etc., to be added. 
 
 Test of Clays for Brick-making. — Several bricks are 
 made and placed at various points of the oven. The econo- 
 mical medium between fusibility on the one hand, and suffi- 
 cient facility of working on the other, is sought for. 
 
 Clay that feels slippery between the teeth and cracks in 
 the oven is too fat. Clay that feels gritty and burns to a 
 porous, crumbly brick, is too meagre ; in this case, it can be 
 improved by applying pressure, and if at the same time it 
 contains the right amount of lime, which will combine chemi- 
 cally at a higher heat, a most durable brick results, which 
 may contain even 85 per cent. sand. 
 
 A good brick is known by its hardness, soHdity, perfect 
 faces and edges. Cold and dampness will not split it off in 
 scales. It must not be too heavy and dense. Striking with 
 the hammer in one direction affords an essential test of 
 homogeneity by the fracture, which should occur in that direc- 
 tion, and when machine-made bricks will not stand this test, 
 they are not durable. For flooring and vaulting, lightness is 
 very desirable. Hydraulic masonry and pavements require 
 greater density and superior vitrification. 
 
 A clear ringing tone when struck, indicates solidity. A 
 dull sound, weakness. The fracture should be homogeneous. 
 Kesistance to crushing, to acids, to scahng off when plunged 
 in Glauber salts, and to weathering, are further tests. 
 
 Bricks stand weathering best when they contain but little 
 lime (unless highly burnt) and are not laid in lime-mortar. 
 
 The durability of Eoman brick is attributed to their great 
 homogeneity. 
 
 A simple chemical analysis assists greatly in ascertaining 
 the value of a clay for brick. 
 
 Manufacture. — The quality of a brick depends largely 
 upon the preparatory processes of weathering, crushing, mix- 
 ing, pugging with cold or hot water, by hand or steam. 
 
 Long weathering in winter is sometimes replaced by sun- 
 drying or by heating the clay artificially and then watering 
 
77 
 
 it, or by pugging with water at 160° F. in a steam-heated 
 cylinder. 
 
 Crushing rolls, first used in England and now spread 
 through Germany, are essential. 
 
 Moulding toy Hand. — In Germany 7 men mould in a day 
 10,000 bricks, l^ear Paris, 4 men make 7,000 bricks in 12 
 hours. 
 
 In the London brick-field, 4 men and 3 boys, constitute a 
 "stool." Of these, only one is at the mould, the others are 
 engaged in bringing the clay from the pug-mill (driven by 
 one horse per stool) and in carrying off and stacking the 
 bricks. 7,000 bricks per day of 12 hours is considered good 
 work for one stool. This labor is paid about $1.25 per 1,000. 
 
 In Westphalia, an iron mould is fastened to a table ; an 
 iron piston connected with a lever worked easily by the 
 moulder's foot, empties the contents of the mould upon a 
 board. The brick is carried off between two boards, and set 
 up on edge to dry. One man moulds 8,000 per day. The 
 German bricks are larger than the French or Dutch. 
 
 In France an iron mould with hinged sides is used ; it 
 makes a smooth brick, as the mould is opened sideways and 
 is never drawn off. 
 
 When the brick is moulded close to the lower opening of 
 the pug-mill, and wheeled off on a track, one moulder Avith 
 two men to fill the pug-mill, one man to rough-shape and 
 hand him the clay, and one man to wheel off the moulded 
 bricks, can make and stack 3,500 German bricks per day. 
 
 If the clay is worked too stiff, the bricks may look better, 
 but are less homogeneous and durable. In England the clay 
 is worked in a more plastic state than in Germany. 
 
 Macliine-made Bricks. — Machines have to compete 
 with the preceding elements of hand-moulding. 
 
 The advantage of machine over hand labor may be con- 
 sidered fully established in all departments of brick-making 
 except digging the clay and moulding the brick ; the latter 
 seems the only debatable operation. 
 
 Meagre clays and those requiring much working up are 
 better adapted to machine work. 
 
78 
 
 Bricks made from fat and mixed clays seem more apt to 
 crack when machine-made. 
 
 The relative merits of machine and hand make are not 
 settled. Eesistance to crushing has been investigated and 
 found equal, by a Bavarian Commission, and in favor of the 
 machine, by an English Commission. In point of economy, 
 the following are obstacles to moulding by machinery : 
 
 1st. A stationary machine requires excessive transporta- 
 tion of raw and finished material. 
 
 2d. Interest, and sometimes wages, on machinery idle six 
 months. Also repairs. 
 
 3d. Some 15 per cent, more raw material is required, if 
 bricks are denser, as often occurs. 
 
 dth. Protection from unequal wind and sun in drying is in- 
 dispensable. 
 
 With a large production and a well-chosen machine these 
 difficulties are overcome. 
 
 Briclt-Macliiiies. — Salvetat, Malpeyre, etc., have classi- 
 fied these machines differently. The most comprehensive 
 division seems to be into : 1st. Compressive, 2d. Expressing 
 machinery. 
 
 The first class imitates hand-work by driving the clay into 
 moulds, and subdivides itself into the dry and moist pro- 
 cesses. 
 
 The second class forces cla}^ through a die, in a continu- 
 ous stream, which is cut into separate bricks by a cutter. 
 
 The first method only presses, the second only shapes the 
 brick. Each has its advocate ; a combination of the 
 two may be desirable (Duberg), as for hand-made bricks, 
 namely, first shape the brick and then press it. 
 
 The dry process (Gregg, Durand, Davis, McHenry) is 
 adapted to sandy and meagre clays, when they are homo- 
 geneous, and is then cheapest. Otherwise, the moist process 
 gives a more uniform and durable brick. For the moist 
 process, expression is cheaper and better than compression. 
 
 Besides the expressing machines exhibited, which are de- 
 scribed further on, those of Hertel, Schlickeysen and Sach- 
 senberg have obtained some success in Germany. 
 
79 
 
 The Hertel macliine works up the clay more and delivers 
 it best of the three. The clay is crushed, cut up, and ex- 
 pressed by screw motion (Clayton expresses by a piston), and 
 with eight or ten-horse power, 1000 bricks per hour are 
 made. 
 
 Drying, in the open air, requires a material that will 
 stand unequal sun, rain and winds. Bricks dry faster when' 
 set on edge. In England, two layers of bricks three inches 
 thick are set up daily, until they are walled eight or twelve 
 high. Drying by artificial heat produces uniformity of shape, 
 and is economical when waste heat is applied. Fans are 
 sometimes used for the purpose (see Annex). 
 
 Facing bricks may be smoothed and stained red uniformly, 
 by dipping when dry in a clay slip containing iron oxide, or 
 lead oxide and dextrine ; black, as practised in Germany, by 
 dipping hot in boiling tar. Pressing, when dry, improves the 
 surfaces. 
 
 Glazed bricks. — A glaze of a nature more fusible than the 
 body, is applied to the surface of the dried brick (see Earthen- 
 ware). A salt glaze can be applied in the same way as for 
 stone-ware. Salt, followed by oxide of lead thrown into the 
 oven, produces a more brilliant glaze. 
 
 Burning. — For kilns, etc., see description of those exhibited. 
 According to the temperature of the oven, the same material 
 gives a brick, blue-ware, or glass. 
 
 At a certain temperature the silica combines with the lime, 
 iron, etc., and forms stable silicates. Sometimes 2200° F. is 
 required. The color of the brick (see Blue- ware) depends 
 much upon the firing. By dipping in a clay slip a uniform 
 color can be obtained. Insufficiently burnt bricks are known 
 by their solubility in acids, showing the non-formation of the 
 durable silicates. 
 
 The walls of the kiln should be air-tight, to prevent air 
 from entering and lowering the temperature. To realize this, 
 an isolating layer of sand or concrete may be introduced in 
 the wall, which will also retain heat. Porous walls 3 to 7 
 feet thick, of meagre or sandy clay mixed with coke or coal 
 
80 
 
 dust, coated witb 4 inches of sand, and cased outside with 
 brick, are recommended for their non-conductibility of heat. 
 
 By setting the bricks close together inch apart) in the 
 kiln, fuel and space is saved, fusible bricks are less apt to 
 run, and the color is more uniform. If bricks have not been 
 thoroughly dried, they crack in the oven. The required draught 
 is usually obtained more cheaply by a chimney than by a fan. 
 Nevertheless Buhrer & Hamel and Muller & Gillardoni use 
 kilns composed, like Hoffman's, of a series of chambers, com- 
 municating with a central flue, with the difference that a fan 
 exhausts the gases thence and delivers them into drying 
 rooms. 
 
 DIMENSIONS OF BRICKS. 
 
 It is questionable whether the size of 8 X 4 X inches, 
 commonly used in the United States, is really adapted to 
 form the most solid walls. 
 
 10 X 4 X 2f in. is considered a proper size in Germany. 
 In Austria, the bricks and joints are much larger than with 
 us. In modern Italy, besides the size of 9 X X 2^ a 
 larger one of 12 X 5 X I5 is much used for arches and cor- 
 nices and the mortar joint is ^ to | in. thick. 
 
 The solidity of the constructions of ancient Eome may owe 
 something to the size of the brick, which for arches are 16 
 inches in length and more. 
 
 The ancient Babylonian bricks are 13 in. square and 3 in. 
 thick. The paving bricks are 18 to 24 in. square. The 
 wedge-shaped bricks with curved tops and bottoms, used by 
 the ancient Chaldeans for arches, are well adapted for 
 strength and finish, besides saving labor in turning the 
 arches. 
 
 An 8 inch brick will produce by its bond a stronger wall, 
 only if the wall be thin. But 24 and 30 inch walls would 
 perhaps be stronger as well as easier to build, with larger 
 bricks. 
 
 Arches made of single 16 inch bricks are more solid than 
 when made of two concentric arches each 8 inches thick, and 
 are also more easily built. 
 
81 
 
 TUBULAR OR PERFORATED BRICKS. 
 
 Whether for light floor vaulting and partitions, for ventila- 
 tion and chimney flues, or to exclude cold by the layers of 
 air they contain, the property of saving some 33 per cent, in ■ 
 raw material, in coal, in time of drying, and in weight, makes ' 
 these bricks invaluable. 
 
 They are stronger than solid brick for the same section 
 Numerous small holes, say 24 to 48, are better for strength 
 than a few large ones. 
 
 To diminish the consumption of mortar, and present a 
 smooth face, the holes are sometimes closed up on five faces 
 and left open only on the sixth. Expressing brick machines 
 are used. The clay requires more preparation than for solid 
 brick. Hexagonal hollow tubes are a variety of this ware. 
 
 LIGHT POROUS BRICKS. 
 
 Being light and poor conductors- of heat, they serve for 
 vaulting, flooring and chimney stacks. 
 
 They hold mortar, and stand fire well, but weather ill,' un- 
 less made of infusorial silex. 
 
 Infusorial silex, found near Luneburg (80 silica and 20 
 water, besides a few impurities), mixed with 4 per cent, of fat 
 clay, makes a good brick. This infusorial silex, when raw, 
 is a trifle lighter than water, but washed and dried, it weighs 
 less than half; the bricks weigh | of ordinary brick, shrink 
 and are much used for arching in Berlin (Kerl). 
 
 By mixing organic substances, such as peat, coal, sawdust, 
 straw, flax, and sometimes hgnite ashes, etc., with clay, the 
 firing consumes these, leaving numerous pores in the brick. 
 According to the desired lightness and strength, 1 volume of 
 fat or plastic clay is mixed with ^ to 3 volumes of coal dust, 
 etc . Sandy clay will not answer. A high porcelain heat 
 is required, and the substances added to the clay assist 
 greatly in producing this heat. 
 
82 
 
 WATER COOLERS. 
 
 In Alcarazzas, Goolahs, etc., the porous body allows water 
 to filter slowly through, which in hot climates evaporates 
 rapidly and cools the jug. The pores should be fine enough 
 to produce only a moist surface. The material used is either 
 clay alone, or mixed with sand, organic and vegetable fibres, 
 animal dung or salt Clay or river slime requires only a 
 feeble firing. 
 
 Seven volumes clay powder, 7 volumes burnt fire clay, i 
 volume saw dust, mixed and burned at a white heat gives a 
 strong and porous body. 
 
 Cells for galvanic apparatus are similarly made, but limey 
 clay is inadmissible. 
 
 Flower-pots, which, if glazed or impervious, are worth 
 little, are made porous in the same way. 
 
 DEAIN PIPES. 
 
 They are made permeable, for draining wet ground, or im- 
 pervious, for conducting water. 
 
 To produce a permeable channel two methods are avail- 
 able. The v/orst consists in selecting a meagre clay and half 
 burning it ; the porous body thus produced is weak and the 
 pores soon fill up. The better way is to burn a stifi:' and 
 fatter clay mixed with sand to a semi-vitreous state, and in 
 putting together, leave passages for the water. The clay 
 should be sifted through | inch holes. 
 
 The impervious ware has a fat or fire-clay body, covered 
 internally with a glaze formed of 50 lead oxide, 45 sand, 2 
 bioxide of manganese. 
 
 Expressing brick machines are available for making drain 
 pipes. Whitehead & Williams' machines are used in England 
 and Germany for 4 in. and smaller pipes ; they rest while 
 the hopper is being charged. Clayton's machines are used 
 for large pipes. 
 
 The pipes are dried slowly, and when sti£f enough, are 
 
83 
 
 rolled with a core upon a table and then set up. For large 
 pipes, a semicircle of wood is worked in the ends to make 
 them circular and true. Thej are burnt in brick ovens. 
 
 EOOFING TILES. 
 
 In many countries earthen-ware tiles are used ; for dura- 
 bility and cost they are often preferable to slate. 
 
 The clay is stiffer, fatter, and more carefully worked than 
 for brick ; it requires to stand weather better. Limey clays 
 are excluded unless burnt to vitrification. 
 
 Imperviousness is essential. As \dtrified ware is apt to 
 warp, glazing is the readiest method of producing impervi- 
 ousness. Salt and lead glazes last less than those made 
 with oxides of iron and manganese, or with iron slag. Old 
 tiles are less absorptive than new, as the pores become grad- 
 ually filled. 
 
 The selection of the best form is important. Some shapes 
 require more pitch to the roof. 
 
 The tiles are moulded by hand or by machine. The flat 
 stream of clay issuing from the die is cut into plates, and 
 these are pressed in a plaster mould. Plastic clay produces 
 a more finished tile ; stiff clay, pressed in metal moulds, dries 
 faster and requires no boards. 
 
 The preparation of stiff clay consists chiefly in passing 
 between rolls I- of an inch apart, heaping up, re-rolling sev- 
 eral times between rolls of an inch apart, and treading 
 under foot. 
 
 The tiles, being thinner than brick, require less heat to fire 
 them. Six days in a simple closed kiln or in the less heated 
 portions of a brick kiln, suffices. For vitrified tiles, they 
 must not be piled up in the kiln or the shape will suffer. 
 
 Leaving tiles under water for several days is a test ; limey 
 tiles will appear scaly and be rejected. 
 
 The tiles may be stained red by an iron clay slip, or by 2 
 minium and 1 dextrine. Blue may be obtained as for blue 
 bricks (which see). Black, by dipping the tile while hot in 
 boiling tar. For blue-black tiles, see Ferro-metallic Ware. 
 
84 
 
 A good dark brown glaze consists of 85 lead oxide and 15 
 manganese oxide slipped with clay. If two per cent, copper 
 oxide be added the glaze will be black. They are applied 
 upon the dry ware before burning. 
 
 Colored glazes applied upon burnt tiles that have stood the 
 test of water are analogous to those for earthen-ware. They 
 must be adapted by experiment to the composition of the 
 tile ; 4:0 to 60 per cent, lead oxide, with 10 to 20 quartz sand, 
 10 to 16 glass ground, and 10 to 20 of clay, salt, saltpetre, 
 etc., gives a white glass, which may be variously colored by 
 2 to 5 per cent, of metallic oxides (see Colors), and applied 
 as a glaze. By replacing ^ of the lead, by tin, an opaque 
 efiamel results. 
 
 ANCIENT AKCHITECTURAL 
 POTTERY. 
 
 The researches of Layard, Rawlinson, Rassam, Loftus, 
 Place, Wilkinson, and others, have revealed much of the 
 architecture and materials used by the ancient Assyrians, 
 Chaldeans, and Egyptians. 
 
 The durability of earthen-ware and its colored glazes, the 
 great use which can be made of colored decoration, and 
 special-shaped bricks, in architecture, may be considered 
 well established by their labors. 
 
 Durability — The Assyrians kept minutely inscribed pub- 
 lic records of conveyances of lands, deeds, <fec., on cylinders 
 and tablets of clay, which was afterwards baked. These 
 furnish complete materials for deciphering the history and 
 cuneiform writing of those times ; a selection from these in- 
 scriptions is now being pubHshed by the Trustees of the 
 British Museum. Perfect impression of seals pressed on the 
 moist, and afterwards baked clay, are also found. 
 
 Inscribed earthen bowls from Babylon assist in historical 
 researches on the Jews. 
 
 " To this day," says Layard, " there are men who have 
 no other trade, than that of gathering bricks from this vast 
 heap (the ruins of ancient Babylon), and taking them for 
 sale to the neighboring towns and villages, and even to 
 
85 
 
 Bagdad. There is scarcely a house in Hillah that is not 
 almost entirely built with them. . . . . . Many bricks 
 
 found in this ruin are coated with a thick enamel or glaze. 
 The colors have resisted the effects of time, and preserve 
 their original brightness." 
 
 Brick. — The three varieties of red, blue, and yellow, or 
 fire-brick, were well known to the ancient Chaldeans ; crude 
 or sun-dried brick were used in large quantities. 
 
 In the tombs at Thebes, the process of brick-making is 
 represented. The crude bricks were made with a simple 
 wooden mould, stamped with the name of a king or high- 
 priest, and then dried in the sun ; and although no pressure 
 was used while drying, their structure is most compact, and 
 some have been found by Wilkinson as firm as when first 
 made. 
 
 The Babylonian baked bricks are 13 in. square, and 3 in. 
 thick. The sun-dried bricks are 6 to 16 in. square, and 2 to 
 7 in. thick. Besides these, which resemble the square thin 
 shapes later used by the Eomans, there were triangular 
 bricks for corners of walls, and wedge-shaped bricks for 
 arches, which are sometimes concave below and convex on top. 
 For the casing of walls, burnt bricks were used ; the crude 
 bricks were reserved for the interior mass. The casing is 
 often as much as 10 ft. thick . 
 
 The masonry was striped horizontally by thick layers of 
 reed matting steeped in bitumen, inserted at every 4 or 5 
 ft. of height, to form the bond when crude brick were used, 
 but never for burnt brick. 
 
 The crude bricks were laid in clay, sometimes mixed with 
 chopped straw ; the burnt bricks, in bitumen. 
 
 In the palace of Nimroud, sculptures are set on a crude 
 brick platform, with an intervening layer of bitumen one inch 
 thick. 
 
 The Assyrians at Kouyunjik used large kiln-burnt bricks, 
 about 2 ft. square, for paving. 
 
 The lUahoon pyramid is of crude brick, also that of 
 Dashoor. 
 
 The Hawara pyramid is of large brick, cased with stone. 
 
86 
 
 Limestone was used for foundations, as it resists salts bet- 
 ter tlian granite or sandstone. 
 
 Vaults are found, covered with a single piece of terra-cotta, 
 of about 7 ft. by 4 ft. 
 
 Colored Decoration. — The distinctive feature of Baby- 
 lonian architecture is the profuse employment of colored dec- 
 oration. The Temple-towers of the Chaldeans were built in 
 many stories, faced with enamelled bricks of colors corre- 
 sponding to the planets, connected with each story. Copper 
 bolts were used to fasten stone to brickwork, and copper nails 
 for tiles. 
 
 In the Temple of the Moon at Mugheir, brick or tiles 
 glazed with a blue enamel were fastened externally to walls 
 of burnt brick. The building practice of to-day may study 
 this temple with fruit. In the matter of cements, witness the 
 care with which the whole lower story and the N. W. faces 
 of the superstructure are laid in bitumen (to resist dampness); 
 the other faces are laid in good lime-mortar (which hardens 
 well, only when exposed to the air), while all the bricks of 
 the inner masses (except foundation) are laid in cement of 
 lime and ashes (ashes tend to make lime hydraulic, and as 
 lime-mortar remains moist in the interior of walls, for years 
 even, it would appear that the ashes were added to hasten 
 the hardening of the interior). 
 
 The domestic dwellings of the Chaldeans, were ornamented 
 externally by diapered patterns of colored bricks, sometimes 
 moulded into half columns, with a variety of wavy patterns. 
 Internally the plaster walls were embellished with colored 
 cones of terra-cotta, imbedded in the plaster, so as to show 
 either their bases, or their points, or a part of their sides, 
 combined in lines. 
 
 The following process of painting on enamelled and em- 
 bossed brickwork was also used. A subject was modelled on 
 a large sheet of clay ; the clay was cut up into bricks, which 
 were stamped with guide-marks, The bricks were coated 
 with the desired colored enamels, which vitrified in burning, 
 and the whole bas-relief subject was then set up according to 
 the guide-marks. 
 
87 
 
 In ancient Egyptian decoration, the colors were primary 
 colors — red, yellow and blue ; only one secondary — green ; 
 to which black and white were added. By avoiding the 
 mixture of tints, pleasing conventional effects, similar to 
 Chinese decoration, were obtained. 
 
 Bold decided lines were the aim of Egyptian draughtsmen ; 
 broken dotted lines are not met with. Some of the lines of 
 figures done at a single stroke are 15 inches long. The de- 
 signs were first traced in red lines, and corrected in black. 
 
 EXHIBITORS OF ARCHITECTURAL 
 TERRA- COTTA, STONE -WARE, 
 FIRE-CLAY GOODS, TILES, AND 
 MOSAIC BRICKS, Etc. 
 
 Blanchaed & Co., 74 Blacldriars Koad, London, exhibit 
 in terra-cotta a complete angle of the main cornice of the 
 Wedgwood Memorial Institute, Burslem. The architect, R. 
 Edgar, and the manufacturer deserve credit for particularly 
 artistic treatment of material. Also portions of main cornice 
 of New Schools of Science, and of Lecture Theatre of S. Ken- 
 sington Museum. There is a rough and ready stamp about 
 their products. 
 
 DouLTON & Co., High street, Lambeth, London, exhibit a 
 terra-cotta " Amazon Vase " of colossal dimensions, elaborate- 
 ly modelled and skilfully moulded. Also an elegantly de- 
 signed fountain. Their material is in every case of excellent 
 manufacture. The designs are often comparatively deficient. 
 They obtained medals in 1851, '62 and '67. Their stone-ware 
 crucibles and blue bricks are well known. Their lipped in- 
 vert blocks for sewers are a new feature. They exhibit 
 stone-ware taps 9 inches in diameter. Also a remarkable 
 plumbago crucible 6 feet high and 4 feet diameter. 
 
 Jas. Pulham, Broxbourne, exhibits a built window setting 
 in moulded blocks of pale terra-cotta, equal in appearance to 
 stone, ornamented by a mask of conventionalized floral orna- 
 
«8 
 
 ments in red clay. Also a Preston vase and pedestal, all of 
 good partly vitrified material. 
 
 Jas Stiff <fe Son, Lambeth, London, make a pretty effect 
 of red colored clays inlaid on a buff body, for arch blocks . 
 The difficulty of difference in shrinkage they appear to have 
 overcome. They exhibit also highly vitrified chemical ap- 
 paratus, sewer pipes, chimney finials, etc. 
 
 J. Cliff k Son, Wortley, near Leeds, make large egg- 
 shaped stone-ware drain pipes, gas retorts, crucibles, etc., 
 a,nd terra-cotta. 
 
 The Watcombe Tebra-Cotta Clay Co. have found an ex- 
 cellent red clay material near Torquay. The specimen- 
 shown are of pure unmixed clay. The surface is hard and 
 somewhat slippery. The clay will not stand as much fire as 
 buff terra-cotta, nor the test of the point of a knife. Two 
 remarkable baskets of flowers in terra-cotta are shown, which 
 indicate unusual plastic qualities in the clay, and may be 
 considered a triumph of the potter's art. 
 
 E. March, Charlottenburg, near Berlin, makes a fine ex- 
 hibit of pale biscuit tint terra-cotta, of excellent body and 
 firing. Also photographs proving the extensive use of terra- 
 cotta at Berlin. His statuettes, capitals, consoles, are good, 
 and a large fluted ornamented column of great merit, price 
 $50, are noticeable. Also a tablet with incised ornament in 
 dark clay. 
 
 V. Brausewetter, Wagram, Austria, exhibits some ad- 
 mirably moulded terra-cotta brackets and vases ; the body is 
 of a rich deep buff color, and of superior texture. This ex- 
 hibitor distances his competitors in excellence of design and 
 color of material. 
 
 GiBBS & Canning, of Tamworth, have supplied a large 
 amount of terra-cotta for the Albert Hall and Arcades of 
 Eoyal Horticultural Gardens. The color is excellent. They 
 adhere closely to the models given them. The firing is some- 
 what unequal. Their hexagon pots of thin terra-cotta to fill 
 in the spandrels of vaulting are light and excellent, and ex- 
 tensively used at Manchester. 
 
 J. Blackmore, Manchester, has a patent glazed earthen- 
 
89 
 
 ware cistern for both hot and cold water, which is better for 
 the purpose than metal, since it will not injure the water like 
 lead, or rust like iron. 
 
 LiLLiEHiLL Teeba-Cotta Co., of Dumfermline, have a bust 
 of Apollo, and a terra-cotta vase of some merit. 
 
 J . Knowles, of Wooden Box, Gothic tracery and chimney 
 pots, of well burned Derbyshire fire-clay, and remarkably 
 lustrous stone-ware. 
 
 W. T. Holland, Ynisymuda, Swansea, Wales, exhibits 
 chimney tops, ridge tiles, vases, and fountains, all good. 
 
 Whitewick Colliery Co., Coalville, near Leicester, exhibit 
 a material of mixed clays, called Glypto terra-cotta. The 
 body is too soft and porous to compete with other terra- 
 cottas. The designs of chimney finials have some merit. 
 
 H. Pether, Belvidere Road, Lambeth, Surrey, exhibits 
 some patent bricks which resemble terra-cotta. A simple 
 pattern is stamped on them . 
 
 I. C. Bailey, Fultham Pottery, London, exhibits chemical 
 stone-ware, ale bottles, and terra-cotta goods in abundance. 
 Also a terra-cotta gas stove 2 ft. 6 in. high, price $3.50. 
 
 The Patent Plumbago Crucible Co., Battersea, London 
 exhibit Morgan's crucibles for melting and refining metal, 
 and nests of round and triangular clay crucibles for refining 
 and gold-beater's use. Also muffle furnaces and flint glass 
 crucibles. 
 
 B. Looker, of Kingston-on-Thames, exhibits horticultural 
 appliances of earthen-ware and glass, without putty, cheaper 
 much than wooden frames, lead, or bell glasses, more durable 
 and portable, and retaining more heat. The glass covering 
 is held in its place by grooves in the brick, top and bottom, 
 easily removed and ventilated ; it is adaptable to the growth 
 of early vegetables, strawberries in borders, and forcing 
 grapes. Growers all prefer for ripening fruit a double roof 
 to a lean-to. 
 
 W. E. Eendle has an arrangement like Looker's, which 
 has the advantage that the pit may be easily raised. 
 
 The Farnley Works, near Leeds, exhibit gas retorts of 
 ribbed fire-clay, and glazpd bricks of excellent material. 
 
90 
 
 These bricks are either salt-glazed, or the face is dipped in a 
 white " slip," and a transparent or opaque enamel glaze is 
 added, as for majolica, all in one firing. The white body 
 glaze does not always adhere well. These glazed bricks are 
 well adapted for lining the walls of dark courts that require 
 lighting, and for shops, closets, &c., which require a material 
 easily kept clean. 
 
 B. N. NoErdAN, Hurtspierpoint, bricks of deep plum color, 
 well modelled. 
 
 E. C. Gibbon's, Ipswich, red and white ornamental bricks 
 and tiles are much used. 
 
 Faeeham red brick. This brick is easily cut and rubbed 
 and has high qualities of finish and color. A window of rub- 
 bricks shown by Wm. Cawte, is well executed ; but rubbing 
 or cutting bricks, and in general all fire-clay goods, is highly 
 injurious to their durability, as it removes the hard non- 
 absorbent and semi-vitrified surface. 
 
 Davison, of Egton, Yorkshire, shows good terra-cotta bricks 
 stained. 
 
 Geo. Gunton, of Corsey Brickfield, Norwich, exhibits red, 
 white and moulded bricks of good color and well fired. Tex- 
 ture somewhat sandy. 
 
 V. Laigneaux, Mons, Belgium. — SiUcious fire-brick, at 
 $5.50 per thousand. 
 
 Steam Beick Co., Reading, and Alexandea Beickwoeks, 
 Suffolk, exhibit excellent moulded work in red and buff clay. 
 
 Thos. Peake's terro-metallic clay, Tunstall, Staffordshire, 
 for roofing, ridge tiles, floor tiles, consists of fire-clay charged 
 with as much iron as it will hold, and burnt at a high vitrify- 
 ing temperature. 
 
 Beoomhall Tile and Beick Co., Blackfriars, London, make 
 tiles of a peculiar shape to form a face to concrete walls. 
 These tiles possess an appendage which beds into the con- 
 crete while the wall is being built. 
 
 Heaton, Butlee & Co. — Art tiles ; figures in outline, fairy 
 tales, lightly sketched on a white ground and successful in 
 effect. 
 
 Maw & Co., Broseley, Salop. — Architectural majolica. 
 
91 
 
 Tiles with raised pattern and colored enamels. Their pat- 
 terns are good. 
 
 George Jones, Stoke-on-Trent. — Earthen-ware and ma- 
 jolica vases, price, $10 to $60; well executed and highly 
 glazed. 
 
 MiNTON & Co., Stoke-on-Trent. — Majolica garden flower- 
 pots, $70 to $250. This firm makes every variety of earthen- 
 ware except tiles, and is referred to elsewhere. 
 
 JosiAH Wedgwood & Sons, Stoke-on-Trent. — Majolica 
 vases. Already noticed. 
 
 MiNTON, HoLLiNS & Co., Stoke-on-Trent. — Tile works. 
 Many patterns, raised or gilt, or in clays of two colors. 
 
 Egbert Minton Taylor, Fenton. — Variety of tiles. 
 
 MACHmEEY IN THE POTTERY 
 ANNEXE. 
 
 To exhibit in this building the machinery of all descrip- 
 tions employed in the manufacture of every kind of pottery, 
 required more space and time than could be afforded at the 
 first of the series of Annual Exhibitions. 
 
 The following machines which were shown at work at- 
 tracted considerable attention : 
 
 Clayton's improved three-process brick-making machine. 
 
 Clayton's double chamber hand-power brick press. 
 
 Clayton's hand-power lever brick-pressing machine. 
 
 Clayton's self-delivery brick-cutting apparatus. 
 
 Clayton's screw-construction ornamental tile press. 
 
 Large's semi-dry moulding and pressing machine. 
 
 Potter's wheel by Doulton & Watts. 
 
 Blake's crusher (for pottery and claj^ price £40, by H. E. 
 Marsden). 
 
 Process of making tesserae and tiles (by Minton, Hollins 
 &Co. 
 
 Pollock's brick-making machine. 
 Camroux's stone-crusher (for clay, &c., for potters). 
 Needham & Kite's filter-press (used by potters to extract 
 water from the slip and reduce it to clayj. 
 
93 
 
 E. Page's drain-pipe, brick and tile machine. 
 
 J. P. Pinfold's brick-making machines, with self-acting 
 feed and cutter, price £155, and with hand feed and cutter, 
 price £55, 
 
 Wm. Boulton's patent potter's wheel. 
 
 Wm. Boulton's jigger for moulding. 
 
 Malkin Edge's encaustic tile-press. 
 
 B. Bewley's machine for grinding colors for pottery. 
 
 J. Johnson's crusher (for flints, <fec., for potters). 
 
 G. H. Goodman's crusher (a model of), for flints, &c., for 
 potters. 
 
 Also models of patent kilns and drying-rooms, by Clayton, 
 John Knowles, Mo rand, and Hoffman. 
 
 The above machinery is driven by two engines, viz.: 
 Manning, Waedle & Co., of Leeds, portable engine, and 
 Tangye Beos. & Holman's engine. 
 
 BRICK-MAKING, DRAIN-PIPE, AND TILE 
 MACHINES. 
 
 The points upon which the three principal brick-machines 
 of Pinfold, Clayton, and Pollock agree, are worthy of note. 
 
 As to the state in which the clay is worked, the plastic is 
 preferred. In this condition the clay is drier than for hand 
 labor. The working of clay in a dry state, besides re- 
 quiring more power, is only suitable to clays which par- 
 tially vitrify in firing, and even then the edges are brittle 
 and crumbly. 
 
 The clay is first thrown into a hopper, containing either 
 one or two shafts revolving in opposite directions, provided 
 with a series of knives and scrapers arranged to form sections 
 of a screw. In this hopper the clay is cut and mixed while 
 it is being driven forward to a pair of smooth horizontal 
 rollers, placed either one above the other (as in Pinfold's, a 
 quarter of an inch apart, with cheeks to guide the clay, and 
 through which water passes to lubricate it), or side by side 
 (as in Clayton's, the interval being regulated by shifting the 
 
93 
 
 bearings of one of them by means of set screws), which 
 effectually crush the lumps of clay. 
 
 From the rollers the clay passes into the pug cylinder, 
 which has a central rotating shaft provided with pug knives, 
 by which the clay is cut, turned over, and pugged while being 
 carried forward. (In Pinfold's machine there is simply a 
 compressing chamber here.) 
 
 So far the machines are alike in principle. But the clay 
 which has been prepared by crushing and pugging, is sus- 
 ceptible of two different treatments, in order to shape it into 
 bricks. The " compressive " and the " expressing " principle 
 have each their advocates. 
 
 The older method of compression, which was first sug- 
 gested by the ordinary hand process, consists in compress- 
 ing the clay, with a piston, into metal moulds arranged in a 
 sliding or rotating table, expelling it from the mould and 
 pushing it on to a delivery apparatus. 
 
 The more recent method of expression, which required 
 more thought for its invention, consists in expressing the 
 clay in a continuous stream, through an orifice shaped like 
 the cross-section of the required brick, and on to a travelling 
 band, where the operation is completed by cutting the bar 
 of clay across into separate and complete bricks. This 
 method is superior to the other, in requiring less cumbrous 
 and complex machinery and less motive power. The motion 
 being continuous is not abrupt or concussive, and avoids the 
 consequent strains and breakages, and the production is more 
 rapid. Finally, by rolling, the air is expelled from the clay, 
 while compression tends to force it in, causing bricks to 
 blister, crack, and fly in firing. 
 
 Pollock's machine (Leeds) is on the compressive prin- 
 ciple. The clay prepared in the machine, is delivered into 
 moulds arranged in a revolving table, and compressed by a 
 simultaneous movement of top and bottom plates, connected 
 directly to a steam piston. The bricks are pushed on to a 
 delivery table, and passed under a rotary brush. The lubri- 
 cation of the moulds with oil is self-acting from an oil cis- 
 tern cast in the frame work of the machine. The moving 
 parts which work against the clay and the shafts are of steel. 
 
04 
 
 The whole is compact and massive. Production, 9,000 
 bricks in 10 hours. 
 
 Pinfold's Machine (Kugby) is on the expressing principle ; 
 from the compressing chamber, already spoken of, the clay 
 issues through a die or mould on to an endless travelling 
 band, carried over rollers. Water issues in a thin film from 
 the sides and corners of the mould near its mouth and lubri- 
 cates the clay to produce a smooth surface . The stream of 
 clay is cut while in motion by thin piano wire tightly stretched 
 along the radii of a wheel. This wheel has a central bear- 
 ing, but it is kept in position by three friction pulleys on its 
 inner rim. The wires are guided obliquely across the mov- 
 ing clay, so as to cut' the bricks square. By changing the 
 mould and using cone bars the machine will make perforated 
 bricks, coping, cornices, etc. The bricks are stiff enough to 
 be walled at once — 6 high, for drying. Production, 15,000 to 
 20,000 bricks ; price X155. The machine is commendable 
 for its simplicity ; it obtained a medal at Oxford in 1870. 
 
 Pinfold exhibits a smaller machine, in which the bricks 
 are cut by hand with wires. Production, 10,000 bricks, or 
 16,000 drain pipes per day ; price ,£55. 
 
 In Clayton's Machine (Harrow Road, London), as pre- 
 viously described, the clay is crushed and pugged. A piston 
 expresses the clay through a moulding orifice or patent 
 rotary orifice dies, and lubrication with water produces clean 
 edges on the bar of clay. A similar stream of clay issues in- 
 termittently from the opposite side of the machine, and 
 while one stream is in motion the other is at rest and being 
 cut by steel wires into separate bricks. All shapes of bricks 
 and drain pipes can be made. The bricks are strong. Pro- 
 duction, 20,000 to 30,000 bricks per day, with 16 horse- 
 power ; price .£330. Medals at all the Exhibitions. 
 
 Clayton's Double-chamber Hand-power Brick-press. — 
 This machine, also on the expressing principle, is one of 
 the most practical on exhibition, and consists of two com- 
 pression chambers, in which the prepared clay is introduced, 
 and two pistons acting alternately press the clay out through 
 lubricating dies. The brick, tiles, or drain pipes are then 
 ctf S with a wire ; the machine stands on four wheels ; one man 
 
95 
 
 works it by a crank. Production, 5,000 bricks per day; 
 price £28. 
 
 Clayton's Hand-power Lever Brick-press, also portable, 
 stands upon a barrow carriage. Tlie principle is that of 
 compression, the brick being first roughly made, then placed 
 in the press-box of the machine and pressed by means of a 
 powerful lever and cam motion, which also empties the mould 
 and delivers the brick in a highly finished state, and more 
 salable than hand-mould bricks. The piston is self-lubri- 
 cating ; one man and a boy can make 5,000 bricks per day ; 
 price £] 7 to £25. 
 
 Clayton's Self-delivery Brick-cutting Apparatus is intend- 
 ed to be applied to any machine working oh the expressing 
 principle, even those in which the motion of the bar of clay 
 is continuous, and consequently not arrested long enough to 
 allow the bricks to be cut. This is effected by severing a 
 certain length (say for 10 bricks) of the stream of clay, 
 drawing it forward and then cutting it by a number of par- 
 allel wires tightly stretched on a sliding frame. This move- 
 ment also removes the plate on which the bricks rested, and 
 substitutes a board, upon which the bricks are then re- 
 moved to the drying ground ; any length can be cut. The 
 machine works accurately ; price £20. 
 
 Large's Semi-dry Moulding and Pressing Machine, manu- 
 factured by Clayton, for making bricks or blocks of concrete 
 or fire-clay. The machine is driven by steam. The bricks 
 are compressed by a plunger in a movable mould, which is 
 slid forward and emptied by a second plunger ; price £80. 
 
 E. Page's Brick Drain-pipe and Tile Machine (Bedford). 
 This is also one of the most practical machines exhibited, as 
 it produces brick, tile, etc., by the expressing method ; is 
 worked by hand-power (one man at a crank), and is set on 
 4 wheels. The clay being prepared, i. e., crushed and pug- 
 ged, it is put by hand into a compression chamber, possess- 
 ing a lubricated die orifice, through which a piston drives 
 the brick or drain pipe on to a cutting table, where it is cut 
 by wires. Production, 2,500 brick or 6,500 two-inch drain- 
 pipe per day; price £20. 
 
 Experiments made for the Commissioners of Sewers gave 
 
96 
 
 26 tons as the crushing pressure of an ordinary hand-made 
 brick, and 41 tons for bricks made by expression in a ma- 
 chine. The pressures to crack were respectively 13 and 16 
 tons. 
 
 Bawden's Brick and Tile Machine (Notting Hill, London), 
 model on ^ scale exhibited. This machine works by the 
 compressive method, and the clay is pugged and moulded in 
 a state as soft as for hand-moulded bricks. One horse will 
 supply power for 12,000 or 15,000 bricks per day. A medal 
 awarded ; price £60. 
 
 TILE PRESSES. 
 
 The manufacture of encaustic tiles was until lately carried 
 on by the wet method, as follows : The clay tile in a plastic 
 condition was put under a plaster mould containing a pattern, 
 a pressure was appHed, and the plaster removed. The tile 
 was then put in a frame and hquid colored clay poured into 
 the pattern. After drying, the superfluous clay was scraped 
 off and the tile burned. This method has been superseded 
 by the dry system, in which the clay is reduced to the state 
 of a dry powder and made slightly damp. The colored clay 
 for the pattern is first placed in the press and forced into a 
 device cut out in a brass plate about I of an inch thick. The 
 superfluous clay is scraped off and the device plate removed, 
 leaving the clay in the shape of the pattern. The clay for 
 the ground is then thrown in upon it and strongly pressed. 
 The tile thus formed is removed and the device in colored 
 clay is found firmly inlaid in its face. Several colored clays 
 can be used, requiring only more care in filling the pattern. 
 
 Clayton's Screw Construction Ornamental Tile-press. — 
 This machine, mounted on 4 wheels, operates by a vertical 
 screw, worked by swing levers, which act on a self-lubricated 
 piston, working in guides. It is intended for ornamental and 
 tessellated paving and roofing tiles. DeUcate devices can be 
 impressed. Two men work the press easily ; price £25 to 
 £42. 
 
 Minion, Hollins & Co.'s Hand-press for Tesserae and Tile. — 
 This is a screw press also . For tesserae a number are made 
 
97 
 
 at a time, in a die block, by small square punclies or pistons. 
 
 Malkin, Et)GE & Co.'s Encaustic Tile-press consists of a 
 screw press with heavy fly-wheel, and is of solid compact 
 make. The momentum of the fly-wheel presses the tile and 
 pushes it up out of the mould. 
 
 POTTER'S WHEELS. 
 There are two exhibitors. 
 
 DouLTON & Watts, Lambeth, London, show one driven by 
 steam power and under control of the workman's foot. 
 
 William Boulton, Burslem, Staffordshire, exhibits a patent 
 potter's wheel, in which the velocity is varied at will, within 
 certain limits, by transmitting the movement through two 
 vertical friction cone pulleys which are brought in contact at 
 various points of their height. The inclination of the spin- 
 dle which accomplishes this is regulated by a lever under 
 the potter's foot, giving different ratios of velocity, without 
 wasting the motive power by friction, as in the ordinary belt 
 method of varying the velocity. Mr. Boulton has also a 
 patent jigger and a system of heating factories by exhaust 
 steam without back pressure on the engine, which has ob- 
 tained some success. 
 
 COLOR-GRINDING MACHINE. 
 
 R. Bewley, of Uttoxeter, exhibits a patent machine for 
 grinding gold and colors used by potters for china, or for 
 paint or printing ink, or any substance that requires to be 
 ground very fine. As a labor-saving machine, it is of parti- 
 cular interest, one person at a crank handle doing the work 
 of eight. Seven glass mullers, inserted in a frame possessing 
 a horizontal eccentric motion, press by means of india-rubber 
 springs, and rub against a slowly revolving horizontal glass 
 table. The colors are placed on the table, and scrapers at 
 the circumference prevent them from wasting over the edge. 
 The transmission movement is simple and solid ; price £30. 
 
98 
 
 CRUSHINa MACHINERY. 
 
 There are four exhibitors in this specialty. 
 
 Blake's stone-breaker is too well known to require descrip- 
 tion. Testimonials give 2| cents per ton as the cost of break- 
 ing limestone in England, including labor, fuel, and furnish- 
 ings. Is also used for emery stone. H. R. Marsden, Leeds, 
 makes them for £75 to £350, according to weight (36 to 
 376 cwt.). When placed on four wheels (£5 to £15 additional), 
 their utility is greatly increased, as it overcomes the objec- 
 tion of having to transport large heaps of ore to one spot. 
 
 Camroux's machine (by tl-ardiner & Mackintosh) operates 
 by the continuous rotation of two angle-grooved circular discs 
 of chilled cast iron, placed upon two shafts shghtly inclined. 
 There is a heavy fly-wheel. The machine will crush to any 
 size, ores, quartz, granite, emery, &c. 
 
 Jas. Johnson exhibits his patent pulverizing machine. It 
 consists of a horizontal polygonal cylinder of wood lined 
 with iron. In the interior angles near the heads of the 
 cylinder are fastened angular obstructions, which, when the 
 cylinder revolves, strike against the ore or stones it contains, 
 and, according to the testimonials, are very effective in pul- 
 verizing the materials. 
 
 G. H. Goodman, 53 Penrose-street, Walworth, London, ex- 
 hibits a model of a machine for crushing clay or stones, in 
 which the grinding is done by a heavy ram which travels 
 loosely on an eccentric ; price £40 to £120. 
 
 KILNS AND DRYING-ROOMS. 
 
 As clay becomes hard and solid, only by the application of 
 heat, this department of pottery deserves particular study. 
 
 A great variety of kilns are used, of forms governed chiefly 
 by habit, and which are often easy to replace by others, bet- 
 ter adapted to the purpose, i. e., which waste neither fire- 
 proof materials nor heat. 
 
 The chief progress has consisted in abandoning the square 
 forms for oval and circular ones, in the introduction of Lan- 
 
99 
 
 gen's and other grates, of chambers and flues for the use of 
 powdered fuel and gas fuel ; also in applying more fully the 
 reverberatory principle, and finally in substituting the con- 
 tinuous system of firing to the previous intermittent method, 
 wherever the amount of the production would justify its 
 use. 
 
 Wood is considered the best fuel, and non-sulphurous 
 gas coal the next best. Peat is also used. For the manufac- 
 ture of superior wares, the products of combustion are usually 
 not allowed to come in contact with the ware. 
 
 The flame required is a somewhat reducing one, in the 
 case of porcelain, and highly reducing for stone-ware. Al- 
 though there is loss of heat in creating a reducing flame, 
 since oxide of carbon only is produced, yet this flame dis- 
 seminates the heat with much greater uniformity than an in- 
 tense oxidizing flame. It also partly reduces the oxide of 
 iron in the clay. Transparent glazes are easily dimmed by 
 the bituminous substances present in highly reducing flames. 
 
 There are four models of kilns exhibited : 
 
 Hoffman's Patent Annulab Kiln, a model shown by H. 
 Chamberlain. This kiln is on the continuous system, applied 
 by Hoffman & Licht to a series of brick chambers forming 
 an oval, each chamber communicating with the con- 
 tiguous ones by a short direct flue, and also with a central 
 chimney ; each flue-opening is provided vdth a damper which 
 can effectually close it. The products of combustion, after 
 heating the objects in one chamber, pass to the next, and so 
 on until it reaches a chamber containing green bricks or 
 pottery, where they are turned off into the chimney, until the 
 contents of this chamber are dry, when they are admitted to 
 the next. The chambers are filled from the top through an 
 arched roof. This oven is excellent, and its use is spreading. 
 The saving in fuel over open kilns is 80 per cent. At the Ber- 
 lin Porcelain Works, a kiln (see Hard Porcelain) is erected 
 in which gas fuel will be used. The older oven of Gibbs & 
 Maille, on the same principle, failed chiefly from the intricate 
 zigzag circulation of the products of combustion. Agents in 
 the United States, Messrs. Wedekind & Duberg, Baltimore. 
 
too 
 
 Moeand's Patent Kiln for Ceeamic "Wares- -A model by 
 T. S. Derham.^ — A series of chambers communicating witli 
 each other and with a central chimney, operating also on the 
 continuous system. There is a particular disposition of ver- 
 tical flues traversing each chamber. They are intended to 
 produce a high heat by the economical use of powdered fuel, 
 which is dropped through them after a preliminary period of 
 heating from a bottom fire. 
 
 John Knowles. — A model of patent kiln. — This disposition 
 consists of three circular reverberatory kilns, placed in a tri- 
 angle and communicating with each other, so as to make the 
 operation to a certain extent continuous. The kilns are 
 divided into chambers, provided with fire-holes at the bottom, 
 on the outside, and an entrance into each. 
 
 Clayton & Son, London, show a patent kiln for drying 
 bricks, by which brick-making may be carried on all the year 
 round. Hot dry air enters the kiln at the top, passes down 
 through the " hacks " of brick and is drawn out below by 
 exhausting fans or otherwise. The smoke and heat of the 
 furnace pass through the walls of the building. There are 
 no underground flues. These kilns are cheap to build and 
 economize space, as the bricks are piled in them in walls 6 
 or 8 feet high. 
 
 CONCLUSION. 
 
 It will be seen from the preceding how varied and compre- 
 hensive was the Exhibition of Pottery this year, and the 
 more interesting for being the only one of the kind to take 
 place, in conformity with the programme, for ten years. 
 
 The official reports which are being published in London, 
 will be instructive and read with interest, being in every case 
 the work of men well-known in the specialties they have 
 undertaken. 
 
 The oportunities afforded to study the products, and to 
 some extent the processes, must result in imparting a fresh 
 impulse to all the departments of this industry. 
 
101 
 
 In matters of taste, a preference was manifest for subdued 
 decoration, lively but not excessive coloring, and construc- 
 tive utility. 
 
 In matters of invention, the successful application to new 
 purposes, of materials previously known, and the extended 
 use of labor-saving machinery, attracted particular notice. 
 
 The mechanical excellence of horticultural and chemical 
 appliances, building materials, and sanitary ware, was often 
 remarkable. 
 
 And finally, the superior technical qualities, facility of uni- 
 form and rapid production, and great artistic merit and 
 beauty, of many of the products in this department, deserved 
 and received general approbation. 
 
INDEX. 
 
 Page. 
 
 Preface 3 
 
 Introduction 5 
 
 Pottery Wares 6 
 
 Porcelain— Body and Glaze 7 
 
 Soft Porcelain 8 
 
 English do 8 
 
 Hard do 9 
 
 Porcelain exhibited 12 
 
 Pate-sur-P4te 15 
 
 Pate changeante 17 
 
 Graffito Ware .... 17 
 
 Henri Deux Ware 18 
 
 Pottery mounted in Damascened 
 
 metals 19 
 
 Cloisonne Epamel 19 
 
 Under-the-glaze Painting in enamel 20 
 
 Persian Ware 21 
 
 Campbell's Mosaic Wall Decoration . . 22 
 
 Belleek Ware 22 
 
 Jasper, or Wedgwood Ware 23 
 
 Chinese Porcelain 24 
 
 Parian 25 
 
 Art applied to Industry 27 
 
 List of Designers and Modellers 28 
 
 Earthenware — Body and Glaze 32 
 
 Colors for all kinds of Pottery 34 
 
 do. in the body, encaustic 36 
 
 do. on the body, under the glaze. 36 
 
 do. on the body, in the glaze 37 
 
 do. over the glaze 37 
 
 do. Metallic 38 
 
 Lustres 38 
 
 Printing in colors 39 
 
 Preparation of coloring agents 39 
 
 Remarks 40 
 
 Decorative Tiles for floors, walls, 
 
 etc 41 
 
 Plain Tiles 41 
 
 Encaustic Tiles 42 
 
 Enamelled Tiles 43 
 
 Majolica and Majolica Tiles 43 
 
 White and brown faience 44 
 
 Minton's Majolica 45 
 
 Opaque white and colored enamels . . 47 
 Earthen-ware Tiles, in plain colors, 
 
 glazed 48 
 
 Designs for Tiles 48 
 
 Tesser» — Mosaic Bricks 49 
 
 Page. 
 
 Terra-Cotta 50 
 
 Durable building stone 50 
 
 Decorative and Fire-proof 51 
 
 Terra-Cotta Materials, Clays 52 
 
 Manufacture 56 
 
 Designs 56 
 
 Reproductions by gelatine moulding. 57 
 
 Uses of Terra-Cotta 58 
 
 Stone-ware — Body and Glaze 59 
 
 do. on Exhibition 62 
 
 Manufactory at Burslem 62 
 
 Decoration 64 
 
 Terro-Metallic Ware, Blue Bricks 65 
 
 Fire-Clay Wares — Fire-Claj's 66 
 
 Analysis of fire-clays 69 
 
 Manufacture 70 
 
 Plumbago Crucibles 72 
 
 Silicious fire-brick 73 
 
 Other fire-brick 74 
 
 Bricks 74 
 
 Test 76 
 
 Manufacture 76 
 
 Moulding bj' hand 77 
 
 Machine-made bricks 77 
 
 Brick-Machines 78 
 
 Drying, facing, glazing, burning 79 
 
 Dimensions 80 
 
 Tubular or Perforated Bricks 81 
 
 Light porous bricks 81 
 
 Water-Coolers 82 
 
 Drain-Pipes 82 
 
 Roofing Tiles 83 
 
 Ancient Architectural Pottery. . 84 
 
 Durability 84 
 
 Bricks '. 85 
 
 Colored decoration 86 
 
 Exhibitors of Terr \ -Cotta, Stone- 
 ware, Fire-clay goods. Tiles, 
 
 Bricks, etc 87 
 
 Machinery in t n e Pottery Annex. . 91 
 Brick-making, Drain-pipe and Tile 
 
 Machines , 92 
 
 Tile Presses 96 
 
 Potters' Wheels 97 
 
 Color-grinding machine 97 
 
 Crushing machinery 98 
 
 Kilns and drying-rooms 98 
 
 Conclusion 100 
 
 f 
 
Scientific Books. 
 
 I 'RANCIS' (J. B.) Hydraulic Experiments. Lowell Hydraulic Ex- 
 ■* periments — being a Selection from Experiments on Hydraulic 
 Motors, on the Flow of Water over Weirs, and in Open Canals of 
 Uniform Rectangular Section, made at Lowell, Mass. By J, B, 
 Francis, Civil Engineer. Second edition, revised and enlarged, in- 
 cluding many New Experiments on Gauging Water in Open Canals, 
 and on the Flow through Submerged Orifices and Diverging Tubes. 
 With 23 copperplates, beautifully engraved, and about 100 new 
 pages of text, i vol., 4to. Cloth. $15. 
 
 Most of the practical rule* given in the books on hydraulics have been determined from ex 
 periments made in other countries, with insufficient apparatus, and on such a minute scale, that 
 in applying them to the large operations arising in practice in this country, the engineer cannot 
 but doubt their reliable applicability. The parties controlling the great water-power furnished 
 by the Merrimack River at Lowell, Massachusetts, felt this so keenly, that they have deemed it 
 necessary, at great expense, to determine anew some of the most important rules for gauging 
 the flow of large streams of water, and for this purpose have caused to be made, with great care, 
 several series of experiments on a large scale, a selection from which are minutely detailed in 
 this volume. 
 
 The work is divided into two parts— Pakt I., on hydraulic motors, includes ninety-two exper. 
 ments on an improved Fourneyron Turbine Water- Wheel, of about two hundred horse-power, 
 with rules and tables for the construction of similar motors ; — Thirteen experiments on a model 
 of a centre-vent water-wheel of the most simple design, and thirty-nine experiments on a centre 
 vent water-wheel of about two hundred and thirty horse-power. 
 
 Part II. includes seventy-four experiments made for the purpose of determining the form ot 
 the formula for computing the flow of water over weirs ; nine experiments on the efl'ect of back 
 water on the flow over weirs ; eighty-eight experiments made for the purpose of determining 
 the formula for computing the flow over weirs of regular or standard forms, with several tal)les 
 of comparisons of the new formula with the results obtained by lOrmer experimenters ; five ex- 
 periments on the flow over a dam in which the crest was of the same form as that built by the 
 Essex Company across the Merrimack River at Lawrence, Massachusetts ; twenty-one experi- 
 ments on the effect of observing the depths of water on a weir at different distances ft-om th« 
 weir ; an extensive series of experiments made for the purpose of determining rules for gaug- 
 ing streams of water in open canals, with tr Mes for facilitating the same ; and one hundred and 
 one experiments on the discharge of water i trough submerged orifices and diverging tubes, the 
 whole being lYilly illustrated by twenty-three double plates engraved on copper. 
 
 In 18.55 the proprietors of the Locks and Canals on Merrimack River, at whose expense most 
 of the experiments were made, being willing that the public should share the benefits of the 
 scientific opeications promoted by them, consented to the publicatioei of the first edition of this 
 work, which contained a selection of the most important hydraulic experiments made at Lowell 
 up to that time. In this second edition the principal hydraulic experiments made there, subse- 
 jueut to 1855, have been added, including the important series above mentioned, for determia- 
 mg rules for the gauging the flow of water in open canals, and the interesting series on the flo\» 
 through a sabmwged Venturi's tube, in which a larger flow was obtained than any we find r& 
 eordod. 
 
 FRANCIS (J. B.) On the Strength of Cast-iron Pillars, with Tables 
 for the use of Engineers, Architects, and Builders. By James B. 
 Frances, l..ivil Engineer, i vol., 8vo. Cloth. $2. 
 
24 
 
 D. Van Nbstrand^s Publications. 
 
 HOLLEY'S RAILWAY PRACTICE. American and Earopean 
 Railway Practice, in the Economical Generation of Steam, in- 
 cluding the materials and construction of Coal-burning Boilers, 
 Combustion, the Variable Blast, Vaporization, Circulation, Super- 
 heating, Supplying and Heating Feed-water, &c., and ihe adaptation 
 of Wood and Coke-burning Engines to Coal-burning ; and in Per- 
 manent Way, including Road-bed, Sleepers, Rails, Joint Fastenings, 
 Street Railways, &c., &c. By Alexander L. Holley, B. P. With 
 77 lithographed plates, i vol., folio. Cloth. $12. 
 
 "This is an elaborate treatise by one of our ablest civil engineers, on the construction and iisa 
 of locomotiveB, with a few chapters on the building of Railroads. * * * All these subjects 
 are treated by the author, who is a first-class railroad engineer, in both an intelligent and intelli- 
 ^ble manner. The facts and ideas are well arranged, and presented in a clear and simple style^ 
 accompanied by beautiful engravings, and we presume the work will be regarded as indispens- 
 able by all who are interested in a knowledge of the construction of railroads and rolling stock, 
 or the working of locomotives." — Scientific American. 
 
 HENRICI (OLAUS). Skeleton Structures, especially in their Appli- 
 cation to the Building of Steel and Iron Bridges. By Olaus 
 Henrici. With folding plates and diagrams, i vol., 8vo. Cloth. 
 
 WHILDEN (J. K.) On the Strength of Materials used in En- 
 gineering Construction. By J. K. Whilden. i vol., i2mo. 
 Cloth. $2. 
 
 " We find in this work tables of the tensile strength of timber, metals, stones, wire, rope, 
 hempen cable, strength of thin cylinders of cast-iron ; modulus of elasticity, strength of thick 
 cylinders, as cannon, &c., effects of reheating, &c., resistance of timber, metals, and stone to 
 crushing; experiments on brick- work; strength of pillars; collapse of tube ; experiments on 
 punching and shearing ; the transverse strength of materials ; beams of uniform strength ; table 
 of coefficients of timber, stone, and iron ; relative strength of weight ie cast-iron, transverse 
 ptrength of alloys ; experiments on wrought and cast-iron beams : lattice girders, trussed cast- 
 Iron girders ; deflection of beams ; torsional strength and torsional elasticity."— ^7rt6rica» Ar- 
 tisan. 
 
 C AMPIN (F.) On the Construction of Iron Roofs. A Theoretical 
 and Practical Treatise. By Francis Campin. With wood-cuts and 
 plates of Roofs lately executed. Large 8vo. Cloth. $3. 
 
 BROOKLYN WATER-WORKS AND SEWERS. Containing a 
 Descriptive Account of the Construction of the Works, and also 
 Reports on the Brooklyn, Hartford, Belleville, and "Cambridge 
 Pumping Engines. Prepared and printed by order of .(.e Board of 
 Water Commissioners. With illustrations. i vol., folio. Cloth. 
 $15. 
 
 ROEBLING (J. A.) Long and Short Span Railway Bridges. By 
 John A. Roebling, C. E. Illustrated with large copperplate en- 
 gravings of plans and views. Imperial folio, cloth. $25, 
 
 CLARKE (T. C. ) Description of the Iron Railway Bridge across 
 the Mississippi River at Quincy, Illinois. By Thomas Curtis 
 Clarke, Chief Engineer. Illustrated with numerous lithographed 
 plans. I vol., 4to. Cloth. $7.50. 
 
Scientific Boohs. 
 
 25 
 
 \1/'ILLIAMS0N (R. S.) On the Use of the Barometer on Surveys 
 . . Reconnaissances. Part I. Meteorology in its Connection 
 with Hypsometry. Part II. Barometric Hypsometry. By R S 
 Williamson Bvt^ Lieut. -Col. U. S. A., Major Corps of Engine'ers! 
 With Illustrative Tables and Engravings. Paper No. 1 5, Professional 
 Papers, Corps of Engineers, i vol.. 4to. Cloth. $15. 
 
 ». » . Tx " ^-^^^ Francisco, Cai,., Feb. 27, 1867 
 
 Gen. A. A. Humphreys, Chief of Engineers, U. S. Army • . , . 
 
 J«H T"^"^^ ^*r' ^ y^"' ^ following pages, the results of my ia 
 
 Testisa ions in meteorology and hypsometry, made with the view of ascertaining how far ihe 
 barometer can be usea as a reliable instrument for determining altitudes on extended line, of 
 survey and reconnaissances. These investigations have occupied the leisure permitted me from 
 my professional duties during the last ten years, and I hope the results will be deemed of s.iffl. 
 c^nt value to have a place assigned them among the printed professional papers of the Unilc<J 
 States Corps of Engineers. Very respectfully, your obedient servant, 
 
 "R. S. WILLIAMSON, 
 "Bvt. Lt.-Col. U, 8. A., Major Corps of U. 8. Engineers." 
 
 T^UNNER (P.) A Treatise on Roll-Turning for the Manufacture of 
 Iron. By Peter Tunner. Translated and adapted. By John B 
 Pearse, of the Pennsylvania Steel Works. With numerous engrav- 
 ings and wood-cuts, i vol., 8vo., with i vol. folio of plates. Cloth °$io 
 CHAFFNER (T. P.) Telegraph Manual. A Complete History and 
 ^ Description of the Semaphoric, Electric, and Magnetic Telegraphs 
 of Europe, Asia, and Africa, with 625 illustrations. By Tal P 
 bHAFFNER, of Kentucky. New edition, i vol., 8vo. Cloth. 850 pp! 
 50. 
 
 \/f INIFIE (WM.) Mechanical Drawing. A Text-Book of Geomet- 
 \ ncal Drawing for the use of Mechanics and Schools, in which 
 the Definitions and Rules of Geometry are familiarly explained ; the 
 Practical Problems are arranged, from the most simple to the more 
 complex, and in their description technicalities are avoided as much 
 as possible. With illustrations for Drawing Plans, Sections and 
 Elevations of Buildings and Machinery ; an Introduction to Isomet- 
 ncal Drawing, and an Essay on Linear Perspective and Shadows. 
 Illustrated with over 200 diagrams engraved on steel. By Wm 
 MiNiFiE, Architect. Seventh edition. With an Appendix on the 
 Theory and Application of Colors, i vol., 8vo. Cloth. $4. 
 
 • ft is the best work on Drawing that we have ever seen, and Is especially a text-book of Geo- 
 metrical Drawing for the use of Mechanics and Schools. No young Mechanic, such as a Ma- 
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 American. 
 
 " One of the most comprehensive works of the kind ever published, and cannot but possesi 
 great value to builders. The style is at once elegant and substantial. "-Pe/i/wy^cania Inquirer 
 
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 Index to technical t^rm^ .""—Glasgow Mechamcs' Journal. 
 
 The British P^vernment has authorized the use of this book In tiieir echoote of art at 
 Somerset House, London, and throughout the kingdom. 
 
 V/T INIFIE (WM.) Geometrical Drawing. Abridged from the octavo 
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 New edition, enlarged, i vol., i2mo, cloth. $2. 
 
 "It is well adapted as a tex^book of drawing tc be used in our High Schools and Academiet 
 wfcwe th .8 useful branch of the fine arts has b«e' hitherto too much ne«lected. Boston Joumcu 
 
26 T). Van NostrancVs Publications. 
 
 PEIRCE'S SYSTEM OF ANALYTIC MECHANICS. Physical 
 and Celestial Mechanics, by Benjamin Peirce, Perkins Professoi 
 of Astronomy and Mathematics in Harvard University, and Con- 
 sulting Astronomer of the American Ephemeris and Nautical Al- 
 manac. Developed in four systems of Analytic Mechanics, Celestial 
 Mechanics, Potential Physics, and Analytic Morphology, i vol., 
 4 to. Cloth. $io. 
 
 GILLMORE, Practical Treatise on Limes, Hydraulic Cements, and 
 Mortars. Papers on Practical Engineering, U. S. Engineer De- 
 partment, No. 9, containing Reports of numerous experiments con- 
 ducted in New York City, during the years 1858 to 1861, inclusive. 
 By Q. A. GiLLMORE, Brig. -General U. S. Volunteers, and Major U. 
 S. Corps of Engineers. With numerous illustrations. One volume, 
 * octavo. Cloth. $4. 
 
 ROGERS (H. D.) Geology of Pennsylvania. A complete Scien- 
 tific Treatise on the Coal Formations. By Henry D. Rogers, 
 Geologist. 3 vols., 4to., plates and maps. Boards. $30.00. 
 
 BURGH (N. P.) Modern Marine Engineering, applied to Paddle 
 and Screw Propulsion. Consisting of 36 colored plates, 259 
 Practical Woodcut Illustrations, and 403 pages of Descriptive Matter, 
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28 
 
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 29 
 
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30 
 
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