144 CHEMICAL STATICS 



orthophosphoric acid prepared by treating crystallized egg- 

 albumin, dissolved in NaOH, with POCI3. 



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 assmne considerable importance in the eyes of physi- 

 ologists. He observed that if CO2 be passed through solutions 

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

 total concentration of Ba(0H)2 is not greater than twice that 

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

 Similar results are obtained with Ca(0H)2, and the peptones 

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

 the simple amino-acids. On standing, BaCOa or CaCOs, as the 

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

 by heating. Direct analysis of the products obtained when 

 CaCOs acts upon glycocoll and other amino-acids showed that the 

 compounds can be represented by the general formula 



R ^COO 

 I I 



COO Ba 



being the barium salts of carbamino-acids. 

 For the monoamino-acids the ratio 



molecules CO2 bound 

 atoms of N 



is 1, indicating that the — NH2 group reacts quantitatively with 

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

 also 1, showing that both — NH2 groups react quantitatively. 

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

 indicating that only one of the — NH2 groups and neither of the 

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

 between 



and 



1.63 1.79 



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 i if the —N.HOC— groups 

 ^.0/ 



