DIFFERENT PROPORTIONS OF GLUTEN. 515 



b. Again, upon the barley, oats, and rye, the sheep's dung produced 

 little more effect than the horse's dung. It might be said that this was 

 because these two manures contain nearly the same proportions of nitro- 

 gen. But if so, why did they not produce like effects also upon the 

 wheat ? — and why did pigeon's dung impart less gluten than either, to 

 all these varieties of grain ? 



c. The unsatisfactory nature of these experiments is still more clearly 

 seen when we compare the relative proportions of nitrogen, contained in 

 the several manures applied, with the proportions of the same element 

 contained in the several crops to which these manures had been added. 



This comparison is made in the following table — the quantity of nitro- 

 gen in sheep's dung and in the crops manured with it being called 

 100 :— 



Proportions of Proportions of nitrogen added to the 



.r „ „ ,.„ . nitrogen, in crop by earth manure.* 



Manure applied. the manure. , ^^— . 



Wheat. Barley. Oats. Rye. 

 Sheep's dung ... 100 100 100 100 100 



Horse dung ... 102 16 75 100 66 



Pigeon's dung . . 300 9 48 43 55 



Cow dung ... 97 6 1 66 22 



The relation which exists among the numbers in the first of the above 

 columns, is totally unlike that which exists among those in any of the 

 others. In none of the crops does the quantity of nitrogen in the manure 

 bear a perceptible relation to that contained in the grain that was reaped. 

 The theory, therefore, that the quantity of gluten in the crop is always 

 determined by that in the manure, and that the amount of gluten in the 

 grain we reap may at pleasure be increased by the use of manures 

 which are rich in nitrogen — this theory derives in reality no solid support 

 from the experiments of Hermbstadt. The theory may indeed be correct, 

 but it is not sustained by any rigorous experiments hitfierto made — and 

 the prudent man will place little reliance upon it, until its correctness 

 shall have been proved by future and more rigorously conducted investi- 

 gations. 



§ 19. Composition of peas, beans, and vetches. 



The seeds of leguminous plants in general contain a large quantity of 

 a substance — very analogous to the gluten of wheat — to which the name 

 of legumin has been given. 



To extract this legumin, bruised beans, peas, or vetches, are steeped 

 in tepid water for some hours, then rubbed to a pulp in a mortar with 

 their own weight of warm water, and, after an hour, strained through 

 linen. The strained liquid deposits, at first, a quantity of starch, but is 

 obtained nearly clear by filtration. To the filtered solution diluted 

 acetic acid (vinegar) or sulphuric acid is added in small quantity, when 

 the legumin coagulates and falls in the form of nearly insoluble flocks, 



• These columns are calculated by multiplying together the increase of crop and the ia- 

 crease in the per centage of gluten and albumen. Thus in the case of wheat- 

 Increase of crop. Increase of gluten. Product. Proportions; 



Sheep's dung 9 fold X 24-3 per cent. = 218-7 = 100 



Horse dung 7 fold X 49 per cent. = 34-3 = 16 



Pigeon's dung 6 fold X 3-2 per cient. = 19 2 = 9 



Cow dung 4 fold X 31 per cent. = 124 = 8 



