COMPOSITION OF UEINE. 



Phosphoric acid is present in the urine of the farm 

 animals in the most minute traces ; practically, it may 

 be considered to be wanting in the urine of the horse 

 and the cow, and is present only in small quantities 

 in sheep's urine. The pig's urine, indeed, contains it in 

 larger quantities, but the percentage is still so small 

 as to justify the statement that the urine of the 

 common farm animals is not a complete manure, and 

 must be supplemented by phosphates, if it is to be 

 used alone. The incomplete nature of urine as a 

 manure constitutes a strong argument in favour of 

 its being applied along with the solid excreta, which 

 contain, as we have seen, considerable quantities of 

 phosphoric acid. It is on this account that the 

 drainings of rotten manure-heaps are more valuable, 

 from a manurial point of view, than urine itself, since 

 these contain the soluble portion of the phosphates in 

 the solid excreta. 1 The urine of all animals, however, 



1 See Appendix, Note XV., p. 64. 



