38 THE ALBUMINS. 



nitrogen which exists in the albuminous molecule in this form we 

 speak of as diamino-nitrogen. 



We know, further, that sulphur exists in the albuminous mole- 

 cule in at least two forms, as one portion can be readily split off on 

 heating with dilute solutions of the alkalies, as hydrogen sulphide, 

 while the other and larger portion can be obtained only when 

 destruction of the albuminous molecule is carried much further. 



In addition to the bodies which have been mentioned above, still 

 others have been obtained on decomposition of the albumins, such 

 as carbonic acid, oxalic acid, acetic acid, phenol, indol, skatol, 

 methylmercaptan, etc. Some of these, no doubt, result from the 

 further destruction of the substances just considered, while others 

 originate from atomic groups which are as yet but little known. 



A few years ago, Cohn announced the observation that during the 

 decomposition of various albumins with concentrated hydrochloric 

 acid a certain pyridin derivative, dihydroxy-pyridin, may be 

 obtained. This, however, proved erroneous, and Cohn himself 

 later found that the substance in question was a piperazin derivative, 

 dibutyl-diethylene diamin, which is isomcric with a certain leuci in- 

 mid that can be obtained from one of the leucins. 



Besides these various radicles, a carbohydrate group also appears 

 to be present in the albuminous molecule, and may be demonstrated 

 by means of Molisch's test. Its presence, as we shall see, is 

 extremely important, and explains the observation that under cer- 

 tain pathologic conditions sugar can appear in the blood at a time 

 when no carbohydrates are ingested in the food. 



Attempts to gain an insight into the construction of the albumi- 

 nous molecule from a study of its oxidation-products, have on the 

 whole, not yielded encouraging results, but it may be mentioned that 

 Maly apparently succeeded in bringing about oxidation of albumins 

 without causing their destruction. He thus obtained a substance 

 which he termed oxyprotonic acid, or oxyprotosulphonic acid, and 

 which has the character of a polybasic acid. It is apparently closely 

 related to the original albumin from which it is derived, but a re- 

 arrangement of certain atomic groups appears to have taken place, as 

 the sulphur, for example, is held in firm combination in its entirety, 

 and no ty rosin can longer be obtained on decomposing the substance 

 with superheated baryta-water, for example. On further oxidation 

 oxyprotonic acid is transformed into peroxyprotonic acid, which con- 

 tains 34 per cent, of oxygen, as compared with 22 per cent, in the 

 case of the mother-substance. 



Synthesis of the Albumins. The synthesis of a native albumin 

 from the elements has thus far not been accomplished. 



Molecular Size of the Albumins. As it is questionable whether 

 anv albumin has thus far been obtained in chemically pure form, 

 it follows that it is scarcely possible to give formulae which express 

 the true composition of these bodies. Attempts to determine 

 this from an analysis of their compounds with metals have not 



