264 noAv CROPS feed. 



containing pumice, carbonate of lime, and urea, was desti- 

 tute of nitrates. 



Exj^eriments 2, 4, and 5, demonstrate that the concourse 

 of nitrogen gas, a porous hody, and an alkali-carbonate, 

 is insufficient to jjroduce nitrates. Experiment No. 10 

 shows that the highly nitrogenous substance, urea,* dif- 

 fused throughout an extremely porous medium and expos- 

 ed to the action of the air in moist contact Avitli carbonate 

 of lime, does not suffer nitrification. In the brick (ves- 

 sels Nos. 3 and 6), something was obviously present, 

 which determined the oxidation of free atmospheric ni- 

 trogen. Cloez took the brick fresh fi-om the kiln where 

 it was burned, and assured himself that it included at 

 the beginning of the experiment, no nitrogen in organic 

 combination and no nitrates of any kind. Cloez believes 

 the brick to have contained some oxidable mineral sub- 

 stance, probably sulphide of iron. The Gentilly clay, 

 used in making the brick, as well as some iron-cinder, 

 added to it in the manufacture, furnished the elements of 

 this compound. 



The slight nitrification that occurred in the vessels 

 Nos. 7 and 8, containing washed chalk and burned soil, 

 likewise points to the oxidizing action of some mineral 

 matter. In vessel Xo. 9, the simply Avashed soil, which 

 was thus freed from nitrates before the trial began, un- 

 derwent a decided nitrification in remarkable contrast to 

 the same soil calcined (No. 8). The infliience of humus 

 is thus brought out in a striking manner. 



It may be that apocrenic acid, which readdy yields 

 oxygen to oxidable matters, is an important agent in 



Urea (COH4 Na) contains in 100 parts : 



Carbon, 20.00 

 Hydrogen, 6.67 

 Nitrogen, 46.67 

 Oxygen, 26.68 



iiwiot 



