262 
Journal of Agricultural Research 
Vol. IX, No. 8 
effective in dissolving the minerals as the alcohol-soluble portion, and the 
organic residue from the dialyzer was the least effective. As stated above, 
this material when taken up with distilled water was chiefly in a state of 
colloidal suspension, and a strong solvent action could hardly be expected. 
The amount of inorganic elements added to the soils with these dif¬ 
ferent organic solvents was about the same in all cases. It would there¬ 
fore appear that the solvent action of these different organic solvents 
was due largely to the effect of the different organic constituents present 
in the solvents. 
The untreated organic liquid was strongly ammoniacal, requiring 
4.2 c. c. of normal hydrochloric acid per 100 c. c. of solution to dispel the 
red color of phenolphthalein at room temperature. 
HYDROLYZED ORGANIC MATTER 
It is recognized that in the preceding experiments the inorganic salts 
present in the organic solvents may have exerted a solvent action on the 
soil minerals. In order to eliminate this effect, soluble organic extracts 
were prepared free from the inorganic elements under investigation. 
Dried alfalfa, sweet clover, barley hay, and sugar were digested for 
about 24 hours on the water bath with hydrochloric acid of about 1.115 
specific gravity. The acid was then washed out, the residue extracted 
with 4 per cent ammonia, and the solid insoluble material filtered out. 
The ammonia extract was then heated on the water bath, the water lost 
by evaporation being occasionally partly replaced, until all free ammonia 
was driven off. The solutions were found by analysis to be free from iron, 
calcium, magnesium, and phosphoric acid. They were then standardized 
gravimetrically. In addition to the above solutions, an organic solution 
was also prepared from horse manure. It was washed thoroughly with 
hydrochloric acid until no more calcium came through the filter. The 
acid was then washed out and the residue extracted with ammonia. 
The ammonia was driven off and the resulting organic solution standard¬ 
ized and used in soil extraction. 
It will be seen from Table IX that the mineral-free organic solvents 
here used were quite effective as solvents. The sugar humus was most 
effective in dissolving magnesium and calcium. It also increased the 
solubility of the iron slightly. Its effect on the solubility of the phos¬ 
phoric acid in the soils was negligible. Some of the other solvents, 
however, exerted a marked solvent action on the phosphoric acid in the 
soil. 
The results obtained with the mineral-free humus solutions show 
clearly a solvent action on the iron, calcium, magnesium, and phosphoric 
acid in the soil. 
