334 Wells on the Soils of the Scioto Valley, Ohio. 
In these analyses, for the first time, has the amount of 
organic /matter combined with the iron, alumina, and manga- 
nese been carefully estimated by itself. This organic matter 
is undoubtedly combined with the above-mentioned bases as 
an acid, and as such may have an important bearing upon the 
fertility of a soil. In some of the New England soils this acid 
has been ascertained by Dr. Hayes to be oxalic acid ; and the 
soil, as might be expected, was adapted to the growth of sor- 
rels and acid plants. I have tested the soils from Pike county 
carefully for oxalates, but have not been able to detect them. 
What other acid may be present I am unable to say; the 
subject in this connection is new and requires considerable 
investigation. It has heretofore been generally omitted in 
the analysis of soils. 
Manganese was present in all the specimens examined. It 
appears to be present, accompanying iron in almost all soils, 
and very frequently in the waters of lakes, ponds, and rivers. 
Its quantitative determination, unless present in large quanti- 
ties, as well as the separate estimation of the amount of iron, 
and the amount of alumina soluble in acid, I consider of no 
consequence in a soil analysis. 
The method of extracting and determining the amount of 
organic matter contained in a soil by means of alkalies, seems 
to possess advantages over that of any other. The plan pur- 
sued in the analyses presented is essentially as follows: — 
All matters contained in the soil capable of solution in water 
or dilute acid having been removed, the portion remaining i$ 
digested in a small quantity of caustic ammonia; the matter 
rendered soluble is washed out, precipitated by an acid, dried 
at 250° F., and determined. The quantity thus obtained is 
considered as representing that portion of organic matter 
which is immediately available for the use or nourishment of 
plants. The same portion of soil is then digested in a stronger 
alkali, caustic soda, and treated as before. The product so 
obtained is considered as representing that portion of organic 
matter Which is in a less advanced stage of decomposition ; 
