35 
In this study total nitrogen, nitrates, ammonia, amids, diamino 
acids, and monamino acids were determined. Nitrates and ammo- 
nia were determined in the soil directly, while the groups f organic 
compounds were determined in solutions obtained by boiling 50 
grams of soil with 750 cubic centimeters of hydrochloric acid under 
a reflux condenser for 10 hours, as outlined by Jodidi, filtering, 
and making the filtrate up to 1 liter. 
The organic nitrogen of soils, having at one time been bound up 
largely in proteid combinations, may reasonably be expected to 
yield hydrolytic products similar to those formed from protein. 
But little is known, however, regarding the specific hydrolysis 
induced by the microflora of the soil. It is not known, for example, 
whether the protein molecule as a whole is broken down with the 
ultimate liberation of ammonia from the several classes of protein 
cleavage products in the same ratio in which nitrogen occurs in 
them or whether certain of these groups yield inorganic or elementary 
nitrogen more readily than others. 
Samples of both heated and unheated soil were studied in this 
connection. The former were subjected to a temperature of 200° 
C. for a period of two hours, after which the same treatment and 
determinations were made as in the unheated portions. The results 
are recorded in the following table: 
Nitrogen compounds in heated and unheated soils. 
i 
to 
o 
i 
o 
a 
1 
2 
Ctj 
1 
£ 
S 
< 
Soluble in hydrochloric acid. 
Composition of hydro- 
chloric acid soluble. 
Soil numbers. 
a 
< 
o 
a 
as 
«8 
o 
a 
as 
a 8 
o 
3 
o 
03 
'3 
o 
a 
a 
< 
W3 
1 
< 
o 
a 
— « 
as 
p 
o 
a 
|| 
a a 
o 
3 
Unheated: 
379 
P.ct. 
0.546 
.179 
.504 
.779 
.396 
.417 
.178 
.419 
.608 
.207 
P.ct. 
0.001 
.0001 
.0015 
.0045 
.0062 
.0 
.0 
.0 
.0 
.0 
P.ct. 
0.001 
.005 
.006 
.022 
.001 
.069 
.036 
.067 
.031 
.020 
P.ct. 
0.096 
.042 
.079 
.129 
.074 
.098 
.055 
.103 
.077 
.039 
P. ct. 
0. 030 
.018 
.055 
.029 
.033 
.034 
.017 
.019 
023 
.022 
P.ct. 
0.298 
.100 
.240 
.363 
.125 
.168 
.044 
.092 
.079 
.028 
P.ct. 
0.426 
.165 
.381 
.558 
.239 
.369 
.152 
.281 
.210 
.109 
78.02 
92. IS 
75. 59 
71.63 
60.35 
88.49 
85.39 
67.05 
34. ,54 
52.65 
P.ct. 
0.23 
3.03 
1.57 
P.ct. 
22.53 
25.45 
20.74 
P.ct. 
7.04 
10.91 
14.43 
5.9 
13.80 
9.20 
11.18 
6.76 
10.95 
20.18 
P.ct. 
69. 95 
405 
406 
66. 06 
62.97 
428 
3.94i 23.12 
.41 30.69 
18.69! 26.56 
23.68 36.18 
23.84' 36.65 
14.76 36.66 
18.35 35.7! 
65.05 
447... 
52 30 
Heated: 
379 
4."> S3 
405 
406 
28.95 
32.74 
428 
37.62 
447 
25.69 
Considering first the unheated soils, the nitrates and ammonia 
are shown to constitute a relatively small percentage of the total 
nitrogen and to vary greatly in the different soils examined. Soil 
447 was found to contain the highest amount of nitrates, while in 
No. 405 nitrates were present to the extent of only one part per 
million. No. 428 contained an abnormally high ammonia content, 
