1038 PEPSIN, HEMATOSIN, GLOBULIN, &C. 



fine Turkey leather is tawed, and afterwards slightly tanned. 5 ' 

 (Aikin's chemical Dictionary, art. Leather, quoted in Brande's 

 Manual). 



Chlorine transmitted through a solution of gelatin throws 

 down a white elastic substance in shreds, which smells of 

 chlorous acid, while humid ; it may be obtained in a dry state, 

 by careful drying, and is a definite compound of unaltered 

 gelatin with chlorous acid. 



The composition of gelatin has also been examined by M. 

 Scherer. He found isinglass, washed with ether to free it from 

 fatty matters, to leave when burned 0.5 per cent of earthy 

 ashes. 



Tendons macerated for a short time in cold water, and after- 

 wards boiled successively in alcohol and ether, and dried at 

 212, left on being burned, 1.6 per cent of ashes. The purified 

 tendons, analysed by combustion with chromate of lead, 

 gave: 



Carbon. . . . 50.774 



Hydrogen. . . 7.152 



Nitrogen. . . 18.320 



Oxygen. . . . 23.754 



100.000 



This result was confirmed on repetition of the analysis. It leads 

 to the following empirical formula for gelatin C 48 H 41 N 15 O 18 . 

 M. Scherer observes that if this formula be doubled, gelatin 

 will contain the elements of 2 atoms of protein, with 3 atoms 

 of ammonia, and 7 atoms of oxygen. 



Products of the alteration or decomposition of gelatin. By 

 long digestion, particularly at a temperature considerably above 

 212, gelatin loses its power of gelatinizing, and when dried by 

 evaporation forms a yellowish gummy mass, which dissolves 

 easily in cold water. 



Concentrated sulphuric acid dissolves gelatin, colourless. If 

 the solution is diluted with water and boiled for a long time, 

 gelatin sugar is obtained from it, on saturating with chalk. 



A concentrated solution of caustic alkali when boiled with 

 gelatin separates ammonia from it, and converts it into leucin 



