616 COMPOSITION OF PEAS, BEANS AND LENTILS. 



which are easily collected on a filter. The addition of an excess of acid 

 will re-dissolve the coagulated Icgumin, vvliich is again thrown down by 

 a few drops of a solution of carbonate of soda or of ammonia ; a slight 

 excess of either of the latter, however, will cause the precipitate a second 

 time to disappear. The legumin of the pea and bean, therefore, differs 

 from the gluten of wheat, in being soluble in water (Dumas), and in very 

 dilute acid or alcaiine solutions. 



The solution of legumin in water is coagulated when heated nearly to 

 boiUng, in which respect it resembles albumen (white of egg), and it is also 

 coagulated by rennet, in which, and in its relations to acids and alcalies, 

 it resembles casein, the curd of milit. Legumin has, indeed, by Liebig, 

 been called vegetable casein, from an impression that it is identical in 

 composition and properties with the pure curd of milk. 



The semi-transparent solution of legumin in water, obtained directly 

 from beans or peas, gradually becomes opaque, and slowly deposits the 

 legumin in an insoluble state. This is owing to the production of a 

 small quantity of acid by the decomposition of the sugar or other sub- 

 stances present in the liquid. This acid slowly coagulates the legumin 

 in the same way as when dilute acids are artificially added to the solu- 

 tion. It is proper to mention that other chemists consider legumin, like 

 casein, [see the following lecture,] to be nearly insoluble in water, and 

 that in tlie solutions from the bean and the pea it is rendered soluble by 

 the presence of a little potash, soda, or lime — the liquid becoiriing turbid 

 as soon as a quantity of acid is formed to combine with these alcaiine 

 substances. According to Dumas, pure legumin dried in vacuo at 284° 

 F. consists of — 



100 100 100 100 100 



For the pur])ose of comparison, I have inserted the composition, ac- 

 cording to the same chemist, of the several nitrogenous compounds ex- 

 isting in wheat. 



If these analyses be correct,- legumin contains more nitrogen than the 

 fibrin, the albumen, the glutine, or the casein of wheat, and is almost 

 identical with the gelatine of bones. The important consequence deduced 

 from this fact, by Dumas, in reference to the feeding of animals, we shall 

 consider in a subsequent lecture. 



Above, I have given the composition of legumin, the nitrogenous 

 principles contained in peas and beans, as found by Dumas, from which 

 it would appear to contain more nitrogen than any of the other vegetable 

 principles hitherto found in cultivated grains. The legumin analysed by 

 Dumas was extracted from sweet almonds. 



Since the preceding sheet was prepared for press, a further analysis of 

 legumin, extracted from beans, has been published by Rochleder,* which 



* AnnaUn der Chem. et Pharmacie, x\\i., p. 155. 



