76 
Journal of Agricultural Research 
Vol. VIII, No. 3 
Other comparisons might be made, but these are sufficient to illustrate 
the point mentioned and to emphasize the position taken in the intro¬ 
duction that the chemical investigation of soils should not stop with 
determining their ultimate composition, but should be directed toward 
ascertaining so far as possible the nature of the compounds in the soil. 
It has been well established, with regard to the organic matter in soils, 
that it is made up of a great variety of compounds and that it is not 
enough simply to determine the quantity of organic matter or humus, 
but that research should be extended to the kinds of organic compounds. 
It is common to find two soils with approximately the same organic con¬ 
tent, but containing quite different organic compounds. So it is not in¬ 
conceivable to have two soils alike in content of calcium, potassium, and 
phosphorus, and yet, because of the different character of the compounds 
containing these elements, to be quite different physically, biologically, 
and agriculturally. 
Any discussion of the form of lime in soils naturally should include some 
reference to soil acidity, and without entering into any discussion of this 
much-discussed subject, at this time mention will merely be made of 
some observations on the behavior of the soil samples under discussion 
toward litmus paper. 
The litmus-paper test as an indication of the acid, neutral, or alkaline 
condition of a soil, in spite of the condemnation expressed in some quarters 
is still in use by a large number of field observers and laboratory workers 
who have need for a quick, simple method that will give such indications 
of a soil's condition as will furnish a basis for advice regarding its treat¬ 
ment or will suggest further investigation. When properly carried out, 
the authors believe the litmus-paper test affords this. The essentials 
for the proper performance of the test are good litmus paper and some 
experience in correlating the results obtained with other observations. 
It is the experience of the authors that when good litmus paper is pressed 
in contact with a moist soil and gives a color change indicating an acid 
condition, a filtered water extract of that soil, on concentration in 
platinum, will very frequently give a concentrated extract acid to litmus, 
or will loose volatile acids which by proper means can be recovered and 
the acid nature demonstrated. 
The soil samples included in this investigation were carefully tested 
with litmus paper, with the result that only samples 49, 50, 51, 62, and 63 
were found to be acid. No claim is made that the litmus-paper test as 
applied to moist soil is at all delicate, and it is quite likely that other 
samples of this series would be found acid if subjected to a determina¬ 
tion of the hydrogen-ion concentration, which is the only true test of 
reaction. Of those samples found to be acid to litmus, samples 49, 50, 
and 51 are from one location, and are samples of Cherokee silt loam, 
62 and 63 are samples of Pheba fine sandy loam. All are rather low in 
total calcium content, and in calcium as easily decomposable silicates, 
and are the lowest of the series in content of calcium carbonate. 
