210 
On the Tlieoretical and Practical Value of 
rule, food rich in nitrogen is also rich in phosphate of lime 
and other animal matters ; and hence the excrements of cattle 
fed upon such food are both richer in phosphates and in nitrogen, 
and possess a greater fertilising value, than the excreta voided 
bj cattle fed upon less nitrogenous and more carbonaceous 
food. 
Money- Value of the Constituents of Artificial Food. 
Having considered the functions of the several constitHent& 
of food in the animal economy, I will offer a few remarks on 
their comparative practical or money-value. 
Oil and Fatty Matters. — As indicated already, oil and fatty 
matters are by far the most valuable and expensive ingredients 
of feeding-stuffs. In round numbers, one part, by weight, of fat 
or oil is worth as much for feeding purposes as 2\ parts of 
starch or sugar. In examining various articles of food for the 
purpose of obtaining an insight into their nutritive value, it is 
necessary, therefore, to determine accurately the amount of oil 
or fatty matter which they contain. The fattening value of 
some kinds of cattle-food in a great measure depends upon the 
amount of ready-made fat which they contain. For instance, the 
feeding and commercial value of palm-nut meal or cake, rises 
or falls with the percentage of fatty matter which the oil-crusher 
leaves in the meal or cake. Some crushers extract the fat from 
palm-nut kernels much more perfectly than others ; and as the 
commercial value of this kind of food is regulated in a large 
measure by the percentage of fatty matters, palm-nut meal is 
sold at from 5Z. 5s. to 8/. 8s. per ton, the difference in the price 
being caused solely by the smaller or larger proportion of fatty 
matter which has been left in the expressed palm-nut kernels. The 
cheaper kinds of palm-nut meal, selling at from 5/. 5s. to 6/. 10s. 
per ton, usually contain from 3 to 6 per cent, of fatty matter, 
whilst the more expensive and more valuable palm-nut meals 
contain from 15 to 18 per cent, of fat, and no more, or rather less, 
albuminous compounds than the cheaper kinds. Assuming- 
ready-made fat to be worth ?>d. per lb. for fattening purposes — 
and this perhaps is too low an estimate, considering that 1 lb. 
of fat is worth as much as 2\ lbs. of starch or sugar, and that 
the latter cannot be bought in the cheapest kinds of food at a 
clieaper rate than l\d. to \^d. per lb. — the difference in the 
fattening and commercial value of the poorest samples of palm- 
nut meal, containing only 3 per cent, of ready-made fat,, and 
tlie richest yielding 18 per cent., amounts to about 4/. per ton, 
or 1/. more per ton than the difference in the actual soiling 
price of the cheapest and most expensive samples. It therefore 
