CONSTITUENTS OF COTTON-FIBRE. 101 



sisting for the most part of the colouring- matter B. The 

 liquid having been filtered, the powder was treated with a 

 large quantity of boiling alcohol, in which it usually dis- 

 solved almost entirely. A small quantity, however, of 

 a brown flocculent substance was generally left undis- 

 solved; and this substance, which consisted of impure 

 pectic acid, having been filtered off while the liquid was 

 hot, the latter, on cooling, deposited the greatest part of 

 the colouring-matter as a brown powder, which only re- 

 quired to be filtered off", washed with alcohol, and dried. 

 The dark-brown alcoholic liquid, containing the more soluble 

 colouring-matter A, as well as the fatty acid and a portion 

 of the colouring-matter B, was now mixed with ammonia 

 and chloride of barium, which gave an abundant greyish- 

 brown precipitate, consisting of all the organic matter 

 previously contained in the liquid in combination wdth 

 baryta. This precipitate was filtered oflP, and then treated 

 with boiling alcohol. The latter being filtered boiling hot, 

 afibrded, on cooling, a small quantity of a brownish crys- 

 talline deposit. This process was repeated as long as the 

 filtered liquid deposited anything, and until, therefore, the 

 precipitate was thoroughly deprived of everything soluble 

 in alcohol. The crystalline matter deposited from the 

 alcoholic liquid consisted almost entirely of the baryta-salt 

 of a fatty acid. After being filtered ofi", it was treated 

 with warm dilute hydrochloric acid, by which it was de- 

 composed, the fatty acid rising to the surface as a light- 

 brown oil, which became solid on cooling. The latter, 

 after being well washed with hot water, was dissolved in 

 warm alcohol, and the solution, having been decolourized 

 with animal charcoal and filtered, was evaporated spon- 

 taneously, when it left a perfectly white mass of crys- 

 talline needles, consisting of the fatty acid in a state of 

 purity. 



The baryta-precipitate, after treatment with boiling al- 



