PROTEIN. 1027 



patible with the analytical results. It gives the composition of 

 protein, per cent, 



Carbon 55.742 



Hydrogen 6.827 



Nitrogen 16.143 



Oxygen 21.288 



100.000. 



M. Dumas represents the composition of protein differently, 

 I am not aware upon what authority, assigning to it more 

 oxygen, than Mulder and Liebig. His formula is 

 C 48 H 35 N 6 O 17 ; which is 48 atoms of carbon with the elements 

 of 6 atoms of ammonia and of 17 atoms of water. The com- 

 bustion of protein and all its compounds is effected with 

 difficulty in the combustion tube ; to burn the carbon com- 

 pletely, M. Scherer found it quite necessary to mix chlorate 

 of potash with the oxide of copper, or to burn with chromate of 

 lead. 



Protein combines with both acids and bases, and is soluble 

 in all acids when highly diluted. In combining with acids it 

 forms new compound acids ; with sulphuric acid sulpho-proteic 

 add, Pr+SO 3 . It combines also with 2HC1. Chloroproteic 

 acid, Pr + C1O 3 , is formed on passing chlorine gas through a 

 solution of albumen, and precipitates in white flocks. The 

 same compound is formed by the action of chlorine on ammo- 

 niacal solutions of casein and fibrin (Mulder). 



Xanthoproteic acid, 2HO + C 34 H 24 N 4 O 12 (Mulder), is formed 

 when albumen, or any other protein-compound is digested in 

 nitric acid. The albumen, &c., dissolve of a yellow colour, with 

 escape of nitrogen gas, and the formation of oxalic acid and 

 ammonia. Two atoms of protein, 1 of water, and 2 of nitric 

 acid, yielding 3 of oxalic acid, 2 of ammonia and I of hydrated 

 xanthoproteic acid as represented above. After being washed 

 with boiling water, this acid forms a tasteless orange-yellow 

 powder, which combines equally well with acids as with bases. 

 The salts containing the last dissolve in water of a dark red 

 colour. 



Leucin, C 12 H 12 NO 4 , a substance discovered by Braconnot. 

 When boiled with caustic alkali in excess, protein or any pro- 



2 x x 2 



