THE TECHNOLOGIST. [July 1, 1865. 



544 ON DYEING. 



true nature of fats, their composition, &c, which up to this period had 

 been veiled in obscurity ; he separated fat into solid and liquid con- 

 stituents, and placed at the disposal of the manufacturer the solid in- 

 gredients of fat, stearine, and margarine, possessing the required 

 properties, and as the result, we see in the present day the tallow 

 candle almost entirely superseded by a variety of candles called palm, 

 composite, Belmont sperm, stearic acid, and many others, which almost 

 equal wax and spermaceti in appearance and illuminating power, and 

 from the cheap rate at which they can be manufactured the best varieties 

 are open to all. 



In very few cases has chemistry been more successful in its applica- 

 tion than in those of dyeing and calico printing. Dyeing is strictly a 

 chemical art. The great object of the dyer is to be enabled to impart 

 to fabrics of various materials, whether of silk, cotton, or wool, certain 

 colouring matters, the colours being derived either from the animal 

 vegetable, or mineral kingdom, and so imparting these colours that 

 they cannot be removed by washing. This art being so dependent upon 

 chemical science, we shall expect to find that its development has taken 

 place of late years only, and that amongst the nations of antiquity it 

 existed in a very imperfect state. Amongst the Greeks and Romans 

 indigo was known, but was used only as a pigment, not as a dye, the 

 nations being ignorant of its proper solvent, it being insoluble in water, 

 though in Egypt and in India this dye was known and used. Madder 

 was also used as a dye, and the kermes insect, for the production of a 

 crimson colour, by these nations; but it is well known the most 

 renowned dye in ancient times was the imperial Tyrian purple, a most 

 costly colour, and worsted dyed with this in the time of Augustus, sold 

 for 36Z. the pound weight ; it was used in dyeing the imperial robes, 

 and exclusively employed for that purpose. It was procured from two 

 shell fish, buccinum and purpura ; a puncture was made in the neck of 

 the animal, and when squeezed two or three drops exuded ; or the entire 

 shell-fish was pounded in a mortar, and the fluid thus obtained, col- 

 lected, mixed with water, and used. The fluid thus extracted was at 

 first colourless, but by exposure to air and light, became yellow, then 

 green, afterwards red, and in twenty-four hours, of a beautiful purple 

 colour. By adding to this dye various alkalies, &c, the Tyrians 

 managed to get shades of this colour. The process for obtaining the 

 Tyrian purple was kept secret and lost, but of late years some .French 

 chemists have obtained from these shell-fish, the beautiful purple of 

 ancient days. When America was discovered, several dyeing materials 

 were added to the list, such as logwood, arnatto, cochineal, Brazilwood, 

 and quercitron. But the great improvement in modern times in dyeing, 

 (and this improvement owing to the rapid strides of chemistry) is the 

 addition of colours derived from the mineral kingdom. Thus, about 

 the end of the 17th century, Prussian blue, chrome yellow, chrome 

 orange, manganese brown, prussiate of copper, green, &c, &c, were 



