Feb. 16, 1914 
Benzene Derivatives in Soils 
363 
In the case of the two acids the method involved considerable loss of 
material and the actual quantity present in the soil is undoubtedly in 
excess of these figures. 
The question as to the form in which these compounds exist in the 
soil is one deserving some consideration, although one not easily an¬ 
swered satisfactorily. It is true of most organic compounds that have 
been obtained from soils through extraction with dilute alkali that they 
are not readily obtained as such by water extraction of the soil. In 
many soils this can be explained, in part at least, by the fact that much 
of the organic matter in soils is of a resinous nature wholly insoluble in 
water, and compounds which when separated are easily soluble in water 
are so incased or protected by the resinous or vamishlike coating effected 
by this resinous material that they are very slowly dissolved, if at all, 
when the soil is leached. This effect is quite apart from any absorptive 
effect and is quite marked in extreme types, such as the sands of Florida 
and some peats, where either fine grinding or previous treatment with 
alcohol will render soluble in water organic material that before this 
treatment was so little soluble as to escape notice. 
In the case of vanillin, grinding the soil and extracting with alcohol 
gave more of the compound than was obtained by extraction with alkali, 
and from the known properties of vanillin it seems unlikely that the 
quantity found is in the soil in any other form than free vanillin. 
Treatment of the soil with hot alcohol after grinding gave extracts 
from which reactions for both benzoic acid and metaoxytoluic acid could 
be obtained, but in the absence of colorimetric methods applicable to 
small quantities and owing to the fact that the extractions with alcohol 
were made with much smaller quantities of soil than the extraction with 
sodium hydroxid, no comparative figures can be given. It is fair to 
conclude, however, that in some of the soils examined some portion of 
both acids is present as free acid. 
