ARTIFICIAL MANURING. 143 



faces, silica, if it was contained in the food, earthy carbo- 

 nates, and phosphates, are the principal ing-redients. 



The cpiantity of alkaline carbonates bears a certain pro- 

 portion to the amylum, sugar, pectine, or the gam of the 

 food. The urine of an animal which has been fed with 

 potatoes or turnips, is rich in alkaline carbonates. The 

 potatoes, however, consist principally of amylum ; the chief 

 ingredients of the turnips are sugar and pectine. The urine 

 of a horse which has been fed with hay and oats is relatively 

 poor in alkalies, if compared with the former. 



It is further shown that the ammonia, or the nitrogen of 

 the excrements, bears a certain proportion to the phosphates ; 

 the azote increases or decreases with the C[uantity of the 

 phosphates, in a manner that both can serve as a measure 

 for each other, although not cpiite as an accurate one. It is 

 not cpiite accurate, because the gum and the amylum also 

 contain a certain, though small cpiantity of phosphate of 

 lime, as has been proved in my laboratory. 



The ammonia of the excrements is of course derived from 

 the nitrogenous substances in the food ; the phosphates are 

 likewise constituents of the latter. In the composition of 

 the food, an equally constant proportion exists between both, 

 A given weight of gluten or casein, in peas or in grain, 

 always corresponds with a certain weight of phosphates. If 

 the grain or the vegetable is rich in those azotic products of 

 vegetable life, it is also rich in phosphates. If it is deficient 

 in them, the equality of the latter decreases in an equal 

 ratio. 



As the amount of nitrogen in manure is a measure for its 

 amount in phosphates, and as manure contains, besides these, 

 also the other ingredients of the soil which are required by 

 the grain or by the other vegetables for their development, 

 and taken up by them from the soil, it is easily conceived 

 what was the cause of the error in regarding the azote of the 

 manure as the principal cause of its efficac}'. The reason 

 was, that the ammonia of the manure is always accompanied 

 by the mineral elements which aflect its nourishing quali- 

 ties, because they render its assimilation into the organism 

 of the plant, and its transition into a nitrogenous constituent, 

 possible. Without jihosphates, and without the other mineral 

 elements of the food of pknts, the ammonia exercises no 

 influence whatever upon vegetable life. 



If it has been shown that the fertility of the soil depends 

 on certain mineral substances ; if the restoration of the fer- 



