46 
Bulletin 65. 
other humus, and is much more like the humus of the Southern and 
Eastern States, as given by Hilgard, than the humus of the prairie 
soils of the arid regions, which are supposed to be rich in nitrogen, 
carrying, according to Hilgard and Jaffa, as high as 18.5 per cent. 
§ 96. A quantity of soil was treated as usual for the prepara¬ 
tion of humus, extracted with ammonia and the solution precipitated 
by acidulation with hydrochloric acid. The precipitated humus 
was washed and dried. It formed a black mass with a strong vitre¬ 
ous lustre and conchoidal fracture. Its reaction was acid with 
litmus. The precipitated humic acids alone were preserved. The 
portion soluble in dilute hydrochloric acid and water was neglected, 
as we thought to obtain the whole of the soluble humic substances 
by evaporating the ammoniacal soil extract to dryness and examin¬ 
ing it, but it was found to contain so much ammonic chlorid that 
the results were unreliable. It seems to be a difficult matter to 
wholly avoid this error when handling larger quantities of soil. 
The results obtained'indicate a very much higher percentage of ash 
in the ammoniacal extract than in the precipitated humus, but on 
the other hand a materially lower percentage of carbon. 
The elementary analysis of the precipitated humus resulted as 
follows: 
TABLE XXL—ELEMENTARY ANALYSIS OF PRECIPITATED HUMUS. 
Per Cent 
Per Cent. 
Carbon. 
. 41.787 
45.727 
Hydrogen. 
. 4.804 
5.267 
Nitrogen. 
.. 5.536 
6.051 
Oxygen . 
... 39.254 
42.955 
Ash. 
. 8.619 
Total. 
.100.000 
100.000 
I have deducted the ash and given the carbon, hydrogen, etc., 
in parts per hundred to make their quantitative relation more evi¬ 
dent, not to indicate that they form a definite compound. It is 
noticeable that the percentages throughout are almost identical with 
those given for humocrenic acid obtained by precipitation as the 
lead salt from a solution prepared from a sample of Russian black 
earth. 
HUMUS AS A SOLVENT. 
§ 97. The ash probably forms an integral part of this precipi¬ 
tated humus, that is the humus carried this inorganic part 
in such a state of solution that it retained it when thrown 
down by the dilute hydrochloric acid. The total sulfur present 
equalled 0.44 per cent, of the precipitated humus, equal to one and 
one tenth per cent, of sulfuric acid (anhydrid). The potash taken 
into solution by the four per cent, ammonia equalled 0.385 per cent, 
of the humus dissolved. The ash obtained from the filtered am- 
