CONSTITUENTS OF COTTON-FIBRE. 121 



The reactions just described are of themselves almost 

 sufficient to prove that the acid obtained from cotton is 

 one of the derivatives of pectine. All uncertainty on this 

 point_, however, was removed by an examination of its 

 composition, which led to the following results : — 



I. 0-4100 grm. obtained from East-Indian cotton, and 

 purified by the chloride-of-lime process, gave, after being 

 dried at ico° C, 0*6070 grm. carbonic acid and 0*1755 

 grm. water. 



0*7x70 grm., burnt with soda-lime, gave 0*0385 grm. 

 chloride of platinum and ammonium, containing 0*0024 

 grm. nitrogen=o*33 per cent. 



I-02I0 grm. left 0*0135 grm. of ash=i*32 per cent. 



II. 0*4635 grm. from American cotton, purified by the 

 same process and dried at 100° C, gave o*666o grm. car- 

 bonic acid and 0*1945 grm. water. 



0*8375 grm. gave 0*0370 grm. chloride of platinum and 

 ammonium, containing 0*0023 nitrogen = o*27 per cent. 

 0*3215 grm. left 0*0065 grm. of ash = 2*02 per cent. 



III. 0*5000 grm. from American cotton purified by 

 means of caustic soda, in the manner above described, 

 gave 0*6675 grm. carbonic acid and 0*2015 gi'ni. water. 



0*7545 grm. gave 0*0525 grm. chloride of platinum and 

 ammonium, containing 0*0033 nitrogen = o*43 per cent. 



0*5125 grm. left. 0*0440 grm. of ash= 8*58 per cent. 



If the ash be deducted and the small amount of nitrogen, 

 which evidently belonged to some slight impurity, be neg- 

 lected, these numbers lead to the following composition : 



I. II. III. 



C 40*91 3998 39*82 



H 4*8i 475 ...... 4-88 



O 54*28 55-27 55-30 



lOO'OO lOO'CO lOO'OO 



The results arrived at by different chemists in examin- 

 ing the composition of pectine and its derivatives vary so 



