Page:Popular Science Monthly Volume 25.djvu/654

638 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 mineral 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 kingdom, 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 Dumas 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 treating 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 differences betwenbetween [sic] the results of different analyses of the latter. These