90 
The Colorado Experiment Station. 
Percent of total nitrogen in soil at Milligrams nitrogen gained by 
the end of 48 days. 
100 grams soil in 4 8 days 
1 
0.12276 
A 
2 
0.12144 
Average 0.11968 
12.43 
3 
0.11484 
1 
0.11484 
B 
2 
0.11748 
Average 0.11748 
10.18 
3 
0.12012 
1 
0.11616 
C 
2 
0.11880 
Average 0.11792 
10.60 
3 
0.11880 
1 
0.11484 
D 
2 
0.11748 
Averpge 0.11660 
9.30 
3 
0.11748 
1 
0.11616 
E 
2 
0.11880 
Average 0.11924 
12.00 
3 
0.12276 
1 
0.11484 
F 
2 
0.11356 
Average 0.11529 
7.99 
3 
0.11748 
Sample E, which contained 17.5 percent of water at the end 
of the experiment and had received direct sunlight every day, 
developed quite a growth of algae, showing on the surface as green 
and brown spots. These proved to be, for the most part,oscillaria 
and diatoms, which became very evident in a culture of these made 
on sand. The incubator samples of course showed no growth of 
this sort, but sample A made even a larger gain in total nitrogen 
and the same gain in nitric nitrogen as sample E on which the 
algae grew. So it is not clear whether the algae exercised any 
influence upon the result or not. The gain in both total and nitric 
nitrogen was, however, much more marked in sample E during 
the second period of the experiment than in any other sample dur¬ 
ing this period. The order of the samples in regard to gain during 
the second period is E, C, F, A, D, B, but in no case had reverse 
changes set in to such an extent as to wholly conceal the increase. 
It is, perhaps, unfortunate that I did not extend the examination 
of the soil to include the ammoniacal and nitrous nitrogen at the 
beginning and end of the experiment as well as the total and nitric 
nitrogen. 
Returning to the increase of total nitrogen in the soil it may 
be well to state it in terms of percentage, calculated on the amount 
of nitrogen originally present. Such a statement gives us for A, 
1 4.589; E, 11.188 ; C, 9.883; B, 9.492;. D, 8.671 and for F, 7.449 
percent. The maximum gain calculated on the amount of nitrogen 
present at the beginning of the experiment is 11,589; the minimum 
7.49 and the average for the six samples is 9.712 percent. 
The gain of the total nitrogen in the case of sample F, is 
worthy of special note. This sample was the original just as it 
