THE CHEMISTRY OP ALBUMINS 193 



The solution containing the mixture of amino-acids is 

 carefully evaporated at reduced pressure and at a temperature 

 not exceeding 40° C. The syrupy residue is dissolved in 

 absolute alcohol, and gaseous hydrochloric acid passed into 

 the solution to saturation, the hydrochlorides of the esters 

 being thus formed. The excess of alcohol is evaporated off 

 under diminished pressure. Strong caustic soda solution is 

 carefully added to the residue, until the hydrochloric acid is 

 neutralised. 



The esters thus set free are separated by solution in ether. 

 The etherial solution is then fractionally distilled in a specially 

 designed apparatus in which the pressure is reduced to less 

 than 1 mm. 



A number of precautions in detail are necessary if the best 

 yields are to be obtained. 



2. The acids are converted into their /3-naphthalene-sulpho 

 derivatives, which are sparingly soluble compounds. 



The following equation indicates the formation of the 

 y8-naphthalene-sulpho derivative of serin by the action of 

 ^-naphthalene-sulpho-chloride : — 



CH2OH 



CioH^SOgCl + HjNCh/ 



COOH 



CHgOH 

 = HCl + C10H7SO2NHCH/ 



COOH 



3. The acids are combined with phenyl isocyanate, which 

 gives characteristic compounds. 



The equation representing the formation of the glycocoll 

 compound is as follows : — 



CsH^-NCO + NH2CH2COOH = CoHgNHCONHCHijCOOH 



The chief end products obtained by taking to pieces, as 

 it were, the molecule of albumin, may be roughly classified as 

 follows : — 



