THE NITROGENOUS PRINCIPLES OF URINE. 293 



oxidation. So soon as compounds of carbon and hydrogen 

 are formed, which miite but slowly with free oxygen, so 

 that the latter easily maintains itself in excess, then and 

 not before, the nitrogen begins to combine witli oxygen. 

 4. Finally, the sulphur of the albuminoids may be at 

 first partially dissipated as sulphuretted hydrogen gas, 

 while in the slower stages of decay, it is oxidized to suK 

 phuric acid, which remains as sulphates in the soil. 



§8. 

 THE NITROGENOUS PRINCIPLES OF URINE. 



The question " How C'rops Feed " is not fully answered 

 as regards the element Nitrogen, without a consideration 

 of certain substances — ingredients of urine — which may 

 become incorporated with the soil in the use of animal 

 manures. 



Professor Way, in his investigation on the " Power of 

 Soils to Absorb Maiuire," describes the following remark- 

 able experiment : " Three quantities of fresh urine, of 

 2,000 grains each, were measured out into similar glasses. 

 With one portion its own weight of sand was mixed ; 

 with another, its own weight of white c^ay/ the tliird 

 being left without admixture of any kind. When smelt 

 immediately after mixture, the sand appeared to have 

 had no effect, whilst the clay mixture had entirely lost 

 the smell of urine. The three glasses Avere covered light- 

 ly Avith paper and put in a Avarm place, l)eing examined 

 from time to time. In a few honrs it was found that the 

 urine containing sand had become slightly putrid ; then 

 followed the natural urine ; but the quantity with which 

 clay had been mixed did not heeome putrid at all, and 

 at the end of seven or eight Aveeks it had only the pecu- 

 liar smell of fresh urine, without the slightest putridity. 

 The surface of the clay, however, became afterwards coa'- 



