144 CHEMICAL STATICS 



orthophosphoric acid prepared by treating crystallized egg- 

 albumin, dissolved in NaOH, with POC1 3 . 



3. Compounds of the Proteins with Carbonic Acid. Siegfried 

 (113) has described a special form of combination between inor- 

 ganic salts and amino- or polyamino-acids which is probably 

 destined to assume considerable importance in the eyes of physi- 

 ologists. He observed that if CO 2 be passed through solutions 

 of various amino-acids in barium hydrate, provided that the 

 total concentration of Ba(OH) 2 is not greater than twice that 

 of the amino-acid no precipitate of barium carbonate is obtained. 

 Similar results are obtained with Ca(OH) 2 , and the peptones 

 and the proteins of the blood behave in a manner analogous to 

 the simple amino-acids. On standing, BaC0 3 or CaC0 3 , as the 

 case may be, is slowly liberated, and this process is accelerated 

 by heating. Direct analysis of the products obtained when 

 CaC0 3 acts upon glycocoll and other amino-acids showed that the 

 compounds can be represented by the general formula 



H 



R 



I I 



COO -- Ba 



being the barium salts of carbamino-acids. 

 For the monoamino-acids the ratio 



molecules C0 2 bound 

 atoms of N 



is 1, indicating that the NH 2 group reacts quantitatively with 

 the carbonate. For diamino-acids, such as lysin, the ratio is 

 also 1, showing that both NH 2 groups react quantitatively. 

 For arginin, which contains 4 atoms of nitrogen, the ratio is J, 

 indicating that only one of the NH 2 groups and neither of the 

 imino-groups react. For the different dipeptids the ratio varies 

 between 



1 , 1 

 L63 and L79* 



If the N.HOC groups. did not react at all the ratio would be 

 i, if they reacted quantitatively it would be 1. For tripeptids 



the ratio is -==, whereas it would be if the N.HOC groups 



