136 THE CHEMISTEY OF THE FARM 



creased proportion of the nitrogen is in the form of 

 amides. The fat credited to these foods also includes 

 indigestible waxy matter ; in the case of green fodders, 

 chlorophyll ; and in the case of silage, lactic acid ; 

 these substances being all equally dissolved by the 

 ether used to separate the fat. About 30 per cent, of 

 the ether extract of hay consist of unsaponifiable 

 matter. Among the soluble carbohydrates, starch is 

 frequently absent. Meadow hay, according to Gran- 

 deau, contains only 4 — 8 per cent, of starch. The 

 same weight of dry matter in crude foods of this class 

 has thus a decidedly less nourishing value than in 

 foods consisting entirely of matured grain. 



In tubers and roots the supply of albuminoids is but 

 small, a large proportion of the nitrogen existing as 

 amides. The carbohydrates are, however, of much 

 higher nutritive value than in the case of fodder crops 

 or straw. In potatoes, starch forms the principal 

 constituent. In turnips and mangels from one-third 

 to two-thirds of the dry matter consists of sugar. 



Most foods supply a sufficient quantity of the ash 

 constituents which are required for the formation of 

 bone and muscle ; the chief of these are phosphoric 

 acid, lime, and potash. Tht oilcakes and bran are the 

 foods richest in phosphoric acid ; straw and meadow 

 hay are the foods poorest in this constituent. Lime is 

 most abundant in clover hay, bean straw, cabbage, and 

 turnips, and generally in all leafy produce ; it occurs in 

 least quantity in the cereal grains and in potatoes. 

 Potash is abundant in roots, hay, bean straw, bran, and 

 oilcake, and is found in smallest quantity in the cereal 

 grains. The proportion of phosphoric acid and potash 

 in various foods is shown in the table on page 220. 



