332 Wells on the Soils of the Scioto Valley, Ohio. 
passing over into carbonates, and remaining fixed, except at a 
high temperature. 
A microscopic examination of the insoluble silicious resi- 
dues of these soils, left after the extraction of all soluble 
organic and inorganic matter, showed them to be composed 
of the detritus of syenitic and porphyritic rocks; consisting of 
minute particles of quartz, feldspar, and yellow jasper, with- 
out the presence of mica. 
'These conclusions I would not present as wholly conclusive 
respecting the origin of the soils of the Scioto. The quartz, 
feldspar, and jasper may have been immediately derived 
from the disintegration of the Waverly and other Ohio Sand- 
stones, and the carbonates may have disappeared by the 
agency of plants, or by long continued draining and filtration. 
Yet the impression left from a careful examination was, that 
the present composition and character of Ohio soils is different 
from what it would have been had their mineral constituents 
been derived from the strata upon which they rest. 
The quantity of organic matter in these soils is generally 
large, varying in the samples examined from two to ten per 
cent. It should be stated that the estimation of this organic 
matter was made upon the finest portion of the soil after sift- 
ing; and in this there is not included the smallest porgjon of 
undecomposed vegetable fibre, which is not unfrequently 
estimated in the organic percentage of other analyses, espe- 
cially where equal care in sifting is not observed. 
amount of nitrogenous compounds contained in this organic 
matter is undoubtedly large, although not determined. The 
peculiar odor of these products while burning, was noticed 
very appreciably in the ignition of some of the samples. 
* Particular attention. was given to the accurate determina- 
tion of the amount of waxy and resinous matters contained in 
these soils; and although it may not be possible to say, that 
they enter unaltered and directly into vegetable systems, yet 
‘we know that as constituents of vegetables they reénter to 
‘form fats in the systems of animals. I cannot, therefore, but 
