420 



EXHIBITION, BRITISH INDUSTRIAL. 



chloroform and castor oil, which produces a 

 substance as hard as horn, but as flexible as 

 leather capable of being cast or stamped, 

 painted, dyed, or carved, and which, above all, 

 can be produced, in any quantity, at a lower 

 price than gutta percha. 



Here may be mentioned the principal im- 

 provements during the past ten years in France, 

 in chemicals and pharmaceutical products and 

 perfumery, including colors. Such improve- 

 ments are, the use of pyrites in place of sulphur, 

 which has caused reduction in the price of sul- 

 phuric acid ; the extension of the indigenous 

 production of potash by the calcination of the 

 residues of the distillation of beet-root juice ; 

 and the preparation of potasse du mint; the 

 development, in the process of extraction from 

 the waters of saltmarshes, of the sulphate of 

 soda and the salts of manganese which are con- 

 tained in them ; the improvements in the pro- 

 duction of ammonia, and its salts, from the con- 

 densed fluid collected during distillation of coal ; 

 the development of the industries of the distil- 

 lation of coal tar, and the preparation of Ben- 

 zine and certain acids; the application, more 

 and more frequent, of the silicates of soda and 

 potash, to the conservation of monuments and 

 sculpture; the new industry of the salts of 

 alumina with a soda base, and of pure alumina ; 

 the experiments for the industrial production 

 of the prussiates and ammoniacal salts by am- 

 monia and carbonate of barytes ; increase of 

 the production of pyroligneous acid and its 

 compounds ; development given to the fabrica- 

 tion of the vegetable alkaloids; extension in 

 the manufacture of white lead, and artificial 

 ultramarine ; introduction of the yellow, red, 

 violet, and blue coloring matters, resulting from 

 the transformations of aniline ; and the use of 

 sulphuret of carbon for the extraction of fatty 

 substances and perfumes. 



Coal Tar and Lichen Dyes. Strange and cu- 

 rious were the illustrations exhibited of the 

 coal tar dyes, and their wonderful effects al- 

 ready mentioned. Coal tar is the basis of all 

 the new colors we have lately got, such as 

 mauve and magenta, and this field of chemical 

 research seems boundless in extent. Thus, 

 coal tar is gradually refined upon and improved 

 till the dirty mass becomes a liquid of glowing 

 tints, the dye of which is shown by exquisite 

 silks, feathers, and moire 1 antiques, tinted of the 

 now so fashionable colors. The way in which 

 the color is produced may be told in a few 

 words. Coal tar r when distilled, yields a color- 

 less fluid called benzole, much used for remov- 

 ing grease stains from silk or cloth. This when 

 mixed with nitric acid forms nitro-benzole, 

 which when again distilled with acetic acid and 

 iron filings forms those exquisite green crystal- 

 izations called aniline. This when distilled 

 again with diiferent salts, produces dyes of dif- 

 ferent colors, such as mauve and magenta ; and 

 thus the coal tar, which was of such little 

 value that it almost puzzled gas- factories to get 

 rid of it, has become the basis of a most impor- 



tant manufacture. Aniline was but a few years 

 ago so rare as to be known among chemists al- 

 most only by name. Now it is an article of 

 commerce. A few grains of it suffice to dye 

 many yards of fabric, and it is well that 

 it has this power, for two gallons of coal tar 

 only yield ten grains of aniline. One circular 

 block of aniline about twenty inches high by 

 nine inches wide was shown, which was the 

 whole product of no less than 2,000 tons of coal. 

 This specimen is sufficient to dye 300 miles of 

 silk fabric. Where two quantities are given it 

 is easy to find a third. With the data which 

 we have stated, therefore, as to two gallons of 

 coal tar yielding ten grains of aniline, and the 

 product of 2,000 tons of coal being capable of 

 dyeing 300 miles of silk, any lady of a calcu- 

 lating turn of mind can reckon to a bushel the 

 precise amount of coal consumed to color the 

 mauve dress in which she is attired. A grain 

 of the aniline dissolved in water tinges it at 

 once of that reddish violet, the delicate color 

 of which can only be compared to the bright- 

 ness of a flash of electricity. 



Near these were shown the products of the 

 lichen dyes, the beautiful blues and purples 

 which are made from the common mosses and 

 lichens. This was accidentally discovered, for 

 the mosses have to undergo a particularly offen- 

 sive course of treatment before they yield their 

 tints. Where the specimens of the mosses 

 used were shown, the fabrics dyed with their 

 colors were displayed above them, so that, ex- 

 cept in witnessing the actual process, the whole 

 modus operandi was told to the visitor clearly 

 enough. Near these were shown some speci- 

 mens of indigo and indigo dyes ; while round 

 about were displayed all the wonderful forms 

 of crystallization, from masses of alum as big 

 as grottos, down to groups of crystals of soda, 

 of salt, and saltpetre. Some of the single block 

 crystals of alum weighed from five to seven tons. 



Substances used for Food. The collection of 

 these articles was numerous and interesting. 

 Sugar, long considered a neutral substance 

 without congeners, has, in consequence of 

 chemical research, become the parent of a nu- 

 merous and increasing family. Fourteen speci- 

 mens were exhibited by Derby and Gosden, 

 including not only beautiful forms of cane and 

 grape sugar, but also sugars derived from 

 acorns, &c., muscular fibre, beets, and other 

 animal and vegetable substances. 



Mr. Hallett exhibited his wonderful examples 

 of "pedigree wheat." He has applied to the 

 growth of wheat the rules which every stock- 

 breeder in the country knows namely, that 

 from the largest and best animals the largest 

 and best progeny may be expected, and that, 

 therefore, the agriculturist should proceed to 

 develop the productive powers of wheat as if 

 it were altogether a new species of cereal which 

 he was trying to bring to perfection for the 

 first time. Mr. Hallett, in 1857, planted only 

 from ears 4i inches long, containing 47 grains. 

 In 1858 his finest ear was 6J inches long, con- 



