COMPOSITION OF URINE. 191 



a property which they themselves possess only in a 

 very slight degree. 



When we examine what substances we add to a 

 soil by supplying it with urine, we find that this 

 liquid contains in solution ammoniacal salts, uric 

 acid, (a substance containing a large quantity of 

 nitrogen), and salts of phosphoric acid. 



According to Berzelius 1000 parts of human 

 urine contain : 



Urea . . . . . 30-10 

 Free Lactic acid, Lactate of Ammonia, and 



animal matter not separable from them 17*14 



Uric acid .... 1-00 



Mucus of the bladder . . . 0-32 



Sulphate of Potash . . . 3- 71 



Sulphate of Soda . . . .3-16 



Phosphate of Soda . . . 2'94 



Phosphate of Ammonia . . 1 65 



Chloride of Sodium . . . 4-46 



Muriate of Ammonia . . .1-50 



Phosphates of Magnesia and Lime . . 1*00 



Siliceous earth .... 0*03 



Water .... 933-00 



1000.00 



If we subtract from the above the urea, lactate of 

 ammonia, free lactic acid, uric acid, the phosphate 

 and muriate of ammonia, 1 per cent, of solid mat- 

 ter remains, consisting of inorganic salts, which 

 must possess the same action when brought on a 

 field, whether they are dissolved in water or in urine. 

 Hence the powerful influence of urine must depend 

 upon its other ingredients, namely, the urea and 

 ammoniacal salts. The urea in human urine exists 



