88 
The Colorado Experiment Station. 
Percent total nitrogen Milligrams gained 
at the end of 27 days. per 100 grams 
soil in 27 days. 
Sample 
A 
gave 
0.11688 
0.11688 
0.11963 
Average 
0.11779 
10.54 
Sample 
B 
gave 
0.11550 
0.11688 
0.11825 
Average 
0-11688 
9.63 
Sample 
C 
gave 
0.11413 
0.11413 
0.11413 
Average 
0.11413 
6.88 
Sample 
D 
gave 
0.11550 
0.11413 
0.11550 
Average 
0.11504 
7.79 
Sample 
E 
gave 
0.11275 
0.11275 
0.11413 
Average 
0.11321 
5.99 
Sample 
F 
gave 
0.11275 
0.11130 
Lost 
Average 
0.11207 
4.82 
The fixation obtained and given in Bulletin 155, p. 46, is 
given for each 100 c. c. of the culture medium. In order to make the 
figures easily comparable we have given these results in milligrams 
per 100 grams of soil. The soil experimented with was simply 
a good, arable soil collected from the College farm at or near a 
point where I had observed the development of -brown patches. It 
is not one of the soils in which we have observed excessive quan¬ 
tities of nitrates but even here the nitric nitrogen amounts to 3.27 
percent of the total. The quantities fixed in 20 and 30 days in 
a mannite solution inoculated with an infusion of 10 grams of soil 
are exhibited in the following table along with the fixation ac¬ 
complished in these samples of soil in 27 days. The inoculation of 
the two samples seems to have made no difference whatsoever. 
NITROGEN FIXED 
Milligrams in 100 cc. 
Mannite-Solution 
Sample 
In 100 grams of 
in 20 days 
in 30 days 
soil in 27 days 
Sample 1. . . . 
. 0.00000 
1.05075 
A 
10.54000 
Sample 2. . . . 
. 1.19085 
0.56040 
B 
9.63000 
Sample 3. . . . 
. 3.08220 
3.43245 
C 
6.88000 
Sample 4. . . . 
. 6.16440 
12.46890 
D 
7.79000 
Sample 5. . . . 
. 0.84060 
3.08220 
E 
5.99000 
Sample 6 . . . . 
. 0.77055 
3.57265 
F 
4.82000 
Sample 7. . . . 
. 3.50250 
3.01215 
Sample 8 . . . . 
. 2.38170 
2.87205 
Sample 9. . . . 
. 13-02930 
10.15725 
All of the ordinary analytical precautions were taken and 
the nitrogen obtained in the blank test, also run in triplicate, has 
been deducted. Each of the seventeen separate determinations 
made on these six samples show a decided increase in the amount 
