15 
The nitrogen of humus. 
Humus nitrogen 
Ilumus numus nitrogen 
precipitated by 
Humus 
Total 
Total 
humus 
nitro- 
precipitated by 
Total 
HC1. 
nitro- 
humus 
Humus 
gen not 
HC1. 
nitro- 
,gen in 
soil. 
Per 
cent of 
soil. 
gen 
not 
precipi- 
tated 
nitro- 
gen by 
addi- 
tion 
gen 
deter- 
mined 
di- 
rectly. 
Per 
cent of 
soil. 
nitro- 
gen in 
per 
cent of 
precipi- 
tated 
byHCl. 
Per 
Soil No. 
Non- 
Hydro- hydro* 
Hydro- 
lyzable. 
Non- 
hydro- 
Lysable. 
Per 
lyzable lyzable 
byHCl. 
(a+b+ 
soil 
cent of 
Per 
(a). Per (b). Per 
(c). Per 
c). Per 
nitro- 
total 
cent of 
cent of 
soil. 
cent of 
soil. 
cent of 
soil. 
cent of 
soil. 
gen. 
humus 
nitro- 
humus 
nitro- 
humus 
nitro- 
gen. 
gen. 
gen. 
347 
1.241 
0.362 
0.125 
0.315 
0.802 
0.774 
62.37 
39.28 
4."). 14 
15.59 
428 
.770 
.289 
.051 
.247 
.587 
.590 
76.62 
42.08 
49.23 
8.69 
379 
.592 
.270 
.041 
.129 
.440 
.439 
71. 16 
29.32 
61.36 
9.32 
406 
.456 
.100 
.027 
.117 
.244 
.226 
49.56 
47.96 
40.98 
11.06 
447 
.354 
.094 
.026 
.105 
.225 
.215 
60.79 
46.67 
41.78 
11.56 
345 
.218 
.066 
.019 
.070 
.147 
67.43 
45.16 
42.58 
12.26 
343 
.220 
.061 
.012 
.069 
.142 
.127 
57.73 
48.59 
42.96 
8.45 
405 
.195 
.044 
.012 
.067 
.123 
.123 
63.08 
54.47 
35. 77 
9.76 
292 
.122 
.031 
.012 
.015 
.058 
.058 
67.54 
25.86 
53.45 
20.69 
Average 
64.36 
42. 15 
45.92 
11.93 
1 
The above data show that the humus nitrogen varied with different 
soils, but averaged 64.36 per cent of the total nitrogen. In every 
instance, except two, more than one-half of the nitrogen was dissolved 
by dilute alkali, while in two instances practically three-fourths of it 
was thus extracted. The bodies precipitated with dilute hydro- 
chloric acid also contained nitrogen in varying amounts. The nitro- 
gen bodies precipitated by hydrochloric acid upon subsequent 
hydrolysis yielded by far the greater portion of their nitrogen to the 
solutions, the insoluble residues having been found to contain 11.93 
per cent of the humus nitrogen. By these methods, therefore, the 
nitrogen of soils can be separated into fractional parts. 
AMID XITROGEX. 
The amid nitrogen in the original humus solutions was first deter- 
mined by evaporating the solutions on the water bath, after slightly 
acidifying with hydrochloric acid, then making alkaline with mag- 
nesium oxid and distilling. The relatively high percentages of 
ammonia thus obtained suggested that some hydrolysis had taken 
place during the time of the evaporation on the water bath, possibly 
through the action of the hydrochloric acid present. In order to 
eliminate this possibility, separate portions were distilled directly 
with magnesium oxid, after having been slightly acidified with 
hydrochloric acid. In like manner the solutions, obtained after 
filtering out the humus matter precipitated by hydrochloric acid, 
were distilled with magnesium oxid, and also the solutions obtained 
