CONSTITUENTS OF COTTON-FIBRE. 123 



improbable that this may be the case with cotton-fibre 

 also ; but I have as yet made no experiments to decide 

 this point. The mere fact of the presence of pectine in 

 cotton-fibre need not excite surprise, since it is a common 

 constituent of various parts of plants, and probably stands 

 in some close relation to cellulose, from which it is perhaps 

 derived by decomposition, or which it may, on the con- 

 trary, serve to form by that process of building up con- 

 stantly going on in the vegetable cell. 



Pectic, parapectic, and metapectic acids have recently 

 been discovered by Divers and Abel among the products 

 of the spontaneous decomposition of gun-cotton ; and the 

 latter maintains that " these substances have been so fre- 

 quently obtained, that they must be regarded as general 

 products of the gradual decomposition of gun-cotton/^ If 

 from this we are to infer that the acids named are derived 

 from nitro-cellulose itself, I think it will be granted that 

 there is little probability in the supposition, and that it is 

 safer to assume that these acids preexisted in the cotton- 

 fibre, in the form of pectine or pectic acid, before the action 

 of nitro- sulphuric acid on it. 



According to Fremy, the pectic acid of plants is always 

 accompanied by a small quantity of an albuminous sub- 

 stance. It seemed to me not improbable that this might 

 also be the case with the pectic acid of cotton ; but as the 

 preparation in a state of purity of a body of this class when 

 occurring along with the other constituents of cotton-fibre 

 would without doubt have been a very difficult task, I de- 

 termined to ascertain whether, by the action of caustic 

 alkalies on the impure pectic acid of cotton, I could pro- 

 cure any of the products of decomposition of albumen, 

 some of which are bodies of very characteristic properties. 

 For this purpose I took a quantity of the brown precipitate 

 thrown down by acid from an alkaline extract of cotton ; 

 and after having exhausted it as far as possible with boil- 



