CONSTITUENTS OF COTTON-FIBRE. 97 



compounds being only used to impart to them the highest 

 degree of whiteness. Now, I have confined myself in this 

 investigation to those natural constituents of cotton-fibre 

 which are insoluble in water, but soluble in alkaline lye, 

 and which are afterwards precipitated from the alkaline 

 solution by acid. Whether cotton contains naturally any 

 substance soluble in water, or which, being originally in- 

 soluble, is rendered soluble therein by the prolonged action 

 of alkalies, is a question on which I pronounce no decided 

 opinion, though I am inclined to believe that there exists 

 in it at least one such body. 



For the purpose of procuring the substances which I 

 proposed to myself to examine, I might have taken raw 

 cotton, treated it to exhaustion with alkaline lye, and then 

 operated on the liquor thus obtained. But to this ap- 

 parently simple course serious objections presented them- 

 selves. In the first place, unspun cotton is a very bulky 

 article, difiicult to treat in vessels of ordinary size. Se- 

 condly, after treatment with alkaline liquids, the cotton 

 might have been rendered useless as an article of manu- 

 facture, and consequently unsaleable, which, considering 

 its high price at the time I commenced my experiments, 

 and the very large quantity required in order to obtain 

 definite results, would have entailed a very heavy expense. 

 Thirdly, raw cotton generally contains a quantity of me- 

 chanical impurities, chiefly fragments of seed-vessels, which 

 might have yielded up to the alkali substances not properly 

 belonging to the fibre. I therefore preferred employing 

 for my purpose cotton-yarn made from definite unmixed 

 kinds of cotton. Apart from financial considerations, yarn 

 presents certain advantages as compared with raw cotton. 

 It is much freer from mechanical impurities, which are to a 

 great extent removed during, or rather previously to, the 

 operations of spinning ; while, on the other hand, in a well- 

 ordered manufactory, little or nothing of a foreign nature 



SER. m. VOL. IV. H 



