CONSTITUENTS OF COTTON-FIBRE. 113 



SO small that I was hardly able to purify it sufficiently for 

 the purposes of analysis, and the amount of hydrogen 

 which it was found to contain differed accordingly rather 

 widely from that demanded by theory; the presence of 

 some impurity or other in this specimen was also indicated 

 by its rather lower melting-point. 



As regards this fatty acid, the question will naturally 

 arise, whether it is to be considered a natural consti- 

 tuent of the fibre, or whether it is a foreign body intro- 

 duced subsequently to the gathering of the cotton, either 

 before or during the process of manufacture ; but this is 

 a question to which it is not easy to give a satisfactory 

 reply. I am assured by persons practically conversant 

 with cotton-spinning that it is impossible for the cotton 

 to be contaminated with any substance of a fatty nature 

 during the process of its conversion into yarn, provided 

 ordinary care be taken, since it can only in consequence of 

 gross carelessness come into contact with the oil or fat 

 used in greasing the machinery. On the other hand, it is 

 quite possible that after the cotton has been gathered, 

 especially during the process of ginning, a portion of the 

 oil of the seed may escape, diffuse itself among the fibres, 

 and give rise to the formation of fatty acid in consequence 

 of the action on it of the alkali. Be this as it may, I have 

 not failed in any of my experiments, whether made with 

 East-Indian or American cotton, to obtain a small quan- 

 tity of a solid crystalline fatty acid. I have also searched 

 for oleic acid, but without success — though traces of a dark- 

 brown oily substance always presented themselves when 

 the ether with which the colouring-matter A had been 

 treated was evaporated. This oily matter I found it im- 

 possible to purify. 



Colouring-Matter A. 

 This substance is easily soluble in alcohol and is left on 



SER. III. VOL. IV. I 



