COMPOSITION OF URINE. 9 



is not equally poor in phosphates. In the case of 

 flesh-eating animals, such as the dog, the urine is 

 found to contain them in considerable quantities. 



The above tables show that the most valuable urine, 

 weight for weight, is that of the sheep, as it contains 

 the largest amount of alkalies (including potash) and 

 nitrogen ; that the urine of the horse comes next ; 

 then that of the cow ; while, as has already been 

 pointed out, that of the pig is the poorest. 



In order to make our survey of the composition of 

 urine uniform with that of the dung, let us see how 

 the urine of the common farm animals compares in 

 the matter of the composition of its dry substance. 

 The following results (basing our calculations on 

 Stoeckhardt's figures, previously given) show this : 



Nitrogen, Phosphoric acid, Alkalies 

 per cent. per cent. per cent. 



Pig ... 12.0 5 8 



Horse . . . 10.9 trace 13.6 



Sheep . . . 10.4 3.7 14.9 



Cow . . . 10.0 trace 17.5 



From these figures we see that the dry substance of 

 the urine of the pig is richest in nitrogen and phos- 

 phoric acid, but poorest in alkalies, of the four common 

 farm animals ; that of the horse comes next in the 

 amount of nitrogen it contains, but that, on the whole, 

 there is very little difference between the horse, cow, 

 and sheep in this respect. 1 



As in the case of the dung, this subject is best 

 studied in relation to the food consumed. We are 



1 See Appendix, Note III., p. 54. 



