May 21, 1917 
Solubility of Certain Inorganic Soil Constituents 
259 
developed by boiling the extract in the presence of phenolphthalein. 
However, it required from 0.8 to 2.8 c. c. of normal hydrochloric acid per 
100 c. c. of extract to develop an acid reaction in the extracts, using 
methyl orange as an indicator. Table V shows the results of the titra¬ 
tions of the first set of organic solvents both before and after passing 
through the soils. 
Table V.— Titration of solutions of organic substances before and after extracting soils 
Decomposing substance from which organic solution was obtained. 
Normal hydrochloric acid required 
to develop an add reaction in 100 
c. c. of solution, using methyl or¬ 
ange as an indicator. 
Organic 
solution. 
After extracting. 
Clay 
loam. 
Sandy 
loam. 
Barley hay. 
C.c. 
0. 80 
2. 80 
2. 40 
I. 70 
C. c. 
1. OO 
2. 60 
. I. 90 
I. 70 
C. c. 
1. 00 
2. 40 
2. 60 
I. 70 
Sweet-clover hay... 
Alfalfa hay. 
Cow manure. 
There were substances, probably of organic nature, present in both 
the organic solvents and the soil extracts obtained with these solvents, 
that were neither alkaline to phenolphthalein nor acid to methyl orange. 
These substances, however, were capable of combining with a consider¬ 
able amount of hydrochloric acid before an acid reaction was shown, 
using methyl orange as indicator. The amount of acid thus required 
varied approximately with the amount of calcium present in the sol¬ 
vents and extracts. This latter fact, however, does not account en¬ 
tirely for the comparatively large amount of acid required to make these 
solutions acid. Solutions from hydrolyzed organic substances contain¬ 
ing none of the elements under investigation required about the same 
amount of acid to develop an acid reaction, using methyl orange as an 
indicator. 
ARTIFICIALLY PREPARED MANURES 
During the summer'of 1915 various green-manure substances, includ¬ 
ing barley hay, sweet clover, bean straw, and alfalfa, were dried, placed 
in 4-gallon glazed jars, saturated with water, and allowed to ferment. At 
the same time a jar was filled with dry cow manure and similarly treated. 
Dried hay, leaves, weeds, etc., soon break down under these conditions, 
and in a surprisingly short time decompose into a mass closely resem¬ 
bling manure. Six months after these substances had been placed in the 
jars decomposition had evidently gone to an end, except for the slow 
changes which ordinarily follow the first rapid bacterial action in any 
manure kept in tanks. 
