638 



THE POPULAR SCIENCE MONTHLY. 



crowd, only one other besides myself bestowing any attention upon 

 them. I soon learned in conversation with him that he is a reader of 

 " Knowledge." These cases show one pound of wheat, oats, potatoes, 

 peas, etc., etc., on trays ; by the side of these are bottles, containing 

 the quantity of water in the one pound, and other trays, with the other 

 constituents of the same quantity, the starch, gluten, casein, the min- 

 eral matter, etc., thus displaying at a glance the nutritive value of each 

 so far as chemical analysis can display it. Those Irishmen and others, 

 who think I have been too hard upon the potato, will do well to take 

 its nutritive measure thus, and compare it with that of other vegetable 

 foods. 



They will see that all the leguminous seeds, the ground-nuts, etc., 

 have their nitrogenous constituents displayed under the name of 

 " casein." The use of this term is rather confusing. In many modern 

 books it does not appear at all in connection with the vegetable king- 

 dom, but is replaced by " legumin." Liebig regarded this nitrogenous 

 constituent of the leguminous seeds, almonds, etc., as identical with 

 the casein of milk, and it was a pupil and friend of Liebig's — the late 

 prince consort — who devised and originally supervised this graphic 

 method of displaying the chemistry of food.* 



I will not here discuss the vexed question of whether the analyses 

 of Liebig, identifying legumin with casein, or rather those of Du- 

 mas and Cahours, who state that the vegetable casein is not of the same 

 composition as animal casein, are correct. 



The following figures display my justification for thus lightly treat- 

 ing the discussion : 



The first column shows the results of Dumas for animal casein ; the 

 second those of Dumas and Cahours for legumin ; the third those of 

 Jones for the same ; and the fourth those of Rochleder ; all as quoted 

 by Lehmann. Here it will be seen that the differences upon which 

 Dumas and Cahours base their supposed refutation of the identity of 

 the animal with the vegetable principle are much smaller than the dif- 

 ferences betwen the results of different analyses of the latter. These 



* Shortly after the close of the Great Exhibition of 1851, -when the South Kensington 

 Museum was only in embryo, I had occasion to call at the " boilers," and ttere found the 

 prince hard at work giving instructions for the arrangement and labeling of these ana- 

 lyzed food-products and the eimilarly displayed materials of industry, such as whalebone, 

 ivory, etc. I then, by inquiry, learned how much time and labor he was devoting, not 

 only to the general business of the collection, but also to its minor details. 



