178 ELEMENTARY AGmCULTURAL CHEMISTRY 



preserve the health of animals, to supply them artificially in 

 the form of " licks," which generally consist chiefly of common 

 salt, often with a little sulphur and sometimes some compound 

 of iron — e.g.^ ferrous sulphate. With young ruminants, too, 

 it has been found that a certain quantity of bulky food is 

 essential, and that when entirely fed on rich, concentrated food 

 containing a sufficiency of all necessary constituents they died. 

 The proportion of water to dry food required by animals is 

 apparently greatest in cattle, smallest in sheep, while horses 

 are intermediate in their demands. With sheep the ratio of 

 water to dry matter is said to be about 2:1, with cattle 

 about 4:1. When roots which contain more water than this 

 are taken the economy of adding a little dry food in the shape 

 of cake or meal to the dietary is obvious. With horses in 

 France it was found that the ratio of water to dry food was 

 2*1 : 1 when at rest and 3'6 : 1 when working. With fattening 

 oxen the ratio was found to be from 1*6 to 3*4 lb. of water to 

 each pound of dry matter, the larger amount being consumed 

 when the food was richest in protein. Cows will usually drink 

 from eight to ten gallons of water per day, but much less if 

 roots be taken. 



Money Value of Food Constituents.— It would be 



convenient, if it were possible, to adopt, in valuing food-stuffs 

 from analysis, a method similar to that already described in 

 valuing manures — i.e., to give to the albuminoids, fats, and 

 carbohydrates ^* unit values," so that the value per ton could 

 be computed. Such methods, however, are not completely 

 successful, since some of the properties of food -stuffs — flavour, 

 palatability, &c. — cannot be taken into account, and since 

 animals are much more fastidious as to their food than are 

 plants. 



By taking the market prices (which are necessarily fluctuat- 

 ing) of large numbers of foods it has been estimated that the 

 values of the digestible carbohydrates, fats, and protein are in 

 the ratio 1 : 2-5 : 2-5. 



In England digestible carbohydrates may be taken as worth 



