QUESTION OE THE SOURCES OF THE NITROOEN OF VEOETATTON. 
45 
and for all of these comparative results are given for the period from April 30 to 
October 10, 1885. It maybe mentioned that at the commencement of this period the 
initial amounts of nitrogen in these materials were very much lower than in any 
cultivated soils, being respectively O'OOOl, O'OlllO, 0'0021, and O’OIOGS per cent. 
Each of these descriptions of soil was exposed under the following conditions :— 
1. From 50 to 60 kilog., in open glazed pots, in a closed chamber free from 
emanations. 
2. From 0’08 to O'lO mm. depth of soil, in open pots, on a trestle 0‘7 metre above 
the ground, in a meadow, with a roof protecting from vertical, but not from 
oblique rain, or from free air. 
3. In similar pots, uncovered, placed on a plank on a tower 29 metres high, 
4. 1 kilog. soil, placed in a 4-litre flask, moistened, and closed with a ground 
stopper; one set being exposed to diffused day light, and a duplicate set kept 
in a closed cupboard. 
5. 1 kilog. of soil put into a 4-litre balloon, heated at 100° C. for 2 hours, steam 
passed through for 5 minutes, and cooled in filtered air previously heated 
to 130° C. ; then closed and exposed from July 10 to October 6, 1885. 
The following tabular statement, summarises the results obtained in the first, 
second, third, and fourth series of experiments. The upper division shows the actual 
percentages of nitrogen found, before and after exposure, and the lower division, the 
gains in the percentage of nitrogen. We give the results in percentages, instead of 
in parts per kilogram, to compare the better with the figures given relating to our 
own experiments. 
Initial. 
In closed 
chamber. 
In meado-sv. 
On tower. 
In closed 
flasks in light. 
Nitrogen found—j^er cent. 
Yellow argillaceous sand I. 
,, ,, ,, 11 ... 
White clay. 
Crude kaolin.'. 
0'00910 
0-01119 
0-00210 
0-01065 
0-01179 
0-01639 
0-00407 
0-00983 
0-01295 
0-00353 
0-01144 
0-01396 
0-00557 
0-01497 
0-01289 
0-01503 
0-00494 
0-01236 
1 
Gain of nitrogen—per cent. 
Yellow argillaceous sand I. 
>> )) )) 11. 
White clay. 
Crude kaolin. 
0-00269 
0-00520 
0-00197 
0-00073 
0-00176 
0-00143 
0-00079 
0-00277 
0-00347 
0-00432 
0-00379 
0-00384 
0-00284 
0-00171 
Thus, although the actual amounts of gain are small, there is in every case some 
gain. Determinations of nitric acid and ammonia showed that the gains were not 
