488 SEPARATION OF PHOTO- AND DEUTERO-ALBUMOSE. [BOOK II. 



II. 



ON THE SEPARATION OF PHOTO- FROM DEUTERO- 

 ALBUMOSE. 



(Supplementary to pages 125 and 129.) 



The methods which have been described at pages 125 to page 129 

 for separating deutero-albumose have been shewn by Neumeister to 

 be incapable of yielding the substance in a pure condition, as shewn 

 by the fact that the product obtained always gives a precipitate, or at 

 least a turbidity, when treated with a 2 per cent, solution of copper 

 sulphate, whereas a solution of pure deutero-albumose is not pre- 

 cipitated by this reagent. 



When a mixture of primary (proto- and hetero-) albumoses and of 

 deutero-albumose is saturated with sodium chloride, the precipitate 

 is composed of the primary albumoses. The precipitation of proto- 

 albumose is not however a complete one, so that if acetic acid (or 

 better still acetic acid saturated with sodium chloride) be added to 

 the nitrate, the body which is thrown down is a mixture of proto- 

 and deutero-albumose. When acetic acid saturated with NaCl no 

 longer occasions a precipitate, the nitrate still contains deutero- 

 albumose, which is now, however, entirely free from proto-albumose. 

 In order to obtain the pure body, the solution, which contains free 

 acetic acid as well as sodium chloride, is freed from these bodies by 

 long-continued dialysis. On concentrating the aqueous solution and 

 then adding alcohol, deutero-albumose is precipitated; the precipitate 

 may then be dried by further treatment with absolute alcohol, the 

 alcohol being allowed to evaporate spontaneously 1 . 



1 Eefer to the following papers : R. Neumeister, 1. ' Zur Kenntniss d. Albumosen,' 

 Zeitsch. f. Biologie, Vol. xxm. (1887), pp. 381401 ; 2. ' Ueber die Reaktionen der 

 Albumosen und Peptone,' Ibid. Vol. xxvi. (1890), pp. 324 348. 



