THE NITROGENOUS PRINCIPLES OF URINE. 293 
oxidation. So soon as compounds of carbon and hydrogen 
are formed, which unite but slowly with free oxygen, so 
that the latter easily maintains itself in excess, then and 
_not before, the nitrogen begins to combine with 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 sul- 
phuric acid, which remains as sulphates in the soil, 
§ 8 
THE NITROGENOUS PRINCIPLES OF URINE. 
The question “ How Crops 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 Manure,” describes the following remark- 
able experiment: “Three quantitics 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 clay ; the third 
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 smellof urine. The three glasses were covered light- 
ly with paper and put in a warm place, being examined 
from time to time. In afew hours 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 become putrid at all, and 
at the end of seven or eight weeks it had only the pecu- 
liar smell of fresh urine, without the slightest putridity. 
The surface of the clay, however, became afterwards cov- 
