370 CHEMISTRY OF THE PROTEIDS CHAP. 



Ellinger found 15 '5 9 and Magnus -Levy 15 '5 7 per cent nitrogen. 

 Amongst its dissociation - products Spiro found leucin, tyrosin, 

 glutaminic acid, and ammonia, 1 but no glycocoll. Judging by the 

 colour-tests it also contains tryptophane, detachable sulphur, and a 

 carbohydrate. Phosphorus is absent. 



On being heated Bence Jones' albumin behaves in a characteristic 

 way. It becomes coagulated between 50 and 58, but on being 

 heated still more it passes into solution again if there be present an 

 abundance of ammonia-salts or urea. The nitric acid and alcohol pre- 

 cipitates also redissolve in the presence of ammonium chloride, and on 

 cooling the coagulum reappears. As urine constantly contains urea 

 and ammonium chloride, the coagulum disappears on being heated 

 beyond 58, and this happens sometimes even with the 'apparently' 

 pure substance, for which reason Ktihne held the albumin to be an 

 albumose closely related to hetero-albumose. Magnus-Levy, however, 

 has shown that the body coagulates if it be really pure ; further, that 

 it is denaturalised by alcohol and other precipitating agents ; and that 

 it is converted into acid-albumin or alkali-albuminate when it is acted 

 upon by fairly strong acids or alkalies. On being digested with 

 pepsin it yields the ordinary albumoses and peptones, but no hetero- 

 albumose. It must therefore be a genuine albumin. In other respects 

 this body shows the usual reactions towards precipitating agents. The 

 limits for ammonium sulphate are between 4 and 6, and they vary some- 

 what according to the purity of the preparation. Magnesium sulphate 

 does not precipitate, while sodium chloride does so both in neutral and 

 in acid solutions. G-rutterinck and de Graaff obtained this albumin in 

 a crystalline form on using a 10 per cent ammonium-sulphate solution 

 which was subsequently acidified with sulphuric acid. The ammonium 

 sulphate could be replaced by magnesium- or zinc-sulphate, sodium 

 chloride or ammonium chloride, and the sulphuric acid by hydro- 

 chloric acid. In 66 per cent alcohol this albumin is insoluble. It is 

 very readily digested owing to the absence of hetero-albumose and of 

 glycocoll. 



III. THE ALBUMINS OF SEEDS 



The percentage-amount of albuminous substances in plants, taking 

 these as a whole, is so low that these albumins have received very little 

 attention from chemists, if we exclude the investigations of Bokorny. 2 

 The seeds, on the other hand, with their large amount of stored albumin, 



1 A. Magnus-Levy, Zettschr. f. physiol. Chem. 30. 200 (1909). 



2 Th. Bokorny, Pftiiyer's Arch. f. d. ges. Physiol. 80. 48 (1900). 



