388 PROTEIN-COMPOUNDS. 



has a yellow, transparent appearance, and is brittle. It coagulates 

 like albumen from its aqueous solution, but is precipitated from it 

 by acetic and phosphoric acid like casein, from which, however, it 

 differs, in the first place, in not dissolving in concentrated acetic 

 acid, and, secondly, in the circumstance that when it is precipitated 

 by an acid, the precipitate does not dissolve when digested with 

 carbonate of lime or of baryta. It is coagulated by rennet. It dis- 

 solves readily in ammonia and other alkalies. 



Composition. No definite results have as yet been obtained 

 from the analyses of legumin. The following numbers have 

 been found by the chemists whose names are attached to each 

 analysis : 



Dumas & Cahours.* Jones.-]- Rochleder.!}! Ruling. 



Carbon ........ 50'50 .... 55-05 .... 56'24 .... 50'59 



Hydrogen ........ 6'78 .... 7'59 .... 7'97 .... 6'83 



Nitrogen ........ 18'17 .... 15'89 .... 15'83 .... 16- 54 



25 ' 5 ? 



.... 24-55 .... 21-47 .... 19-96 

 Sulphur I 0-47 



100-00 100-00 lOO'OO 100-00 



The differences presented by these analyses are so great that 

 it is obvious that we have not yet succeeded in obtaining this sub- 

 stance in a state of purity, and fit for elementary analysis. 



Preparation. This body is chiefly found in peas and beans, 

 and other leguminous seeds, from which it may be easily obtained ; 

 the watery extract of these seeds has an acid reaction, and on 

 neutralisation the legumin is precipitated ; it is purified by solution 

 in ammonia, from which it is again precipitated by an acid, and 

 finally by extraction with alcohol and ether. 



Besides these substances, there are in the vegetable kingdom, 

 and especially in seeds, other substances which approximate more 

 or less closely to the protein-compounds of the animal kingdom. 

 In the first place there is vegetable albumen, which Liebig calls 

 vegetable fibrin ; it is insoluble in water, and similar in its com- 

 position to coagulated animal albumen ; it remains undissolved, 

 when we have separated the starch from flour by washing, and the 

 gluten by alcohol. Of the diastase or mucin which is formed 

 during the germination of grain, and which is a product of the 

 metamorphosis of the previous substances, we know even less, both 



* Ann. de Chim. et de Phys. T. 6, p. 409. 

 t Ann. d. Ch. u. Pharm. Bd. 40, S. 67. 

 I Ibid. Bd. 46, S. 155. 

 Ibid. Bd. 58, S. 301-315. 



