The Litmus-paper Test
Categories:
THE NEED OF LIME
A test of fair reliability may be made with
litmus paper. A package of blue litmus paper can be bought for a few
cents at any drug store. This paper will turn pink when brought into
contact with an acid, and will return to a blue if placed in
lime-water. A drop of vinegar on a sheet of the paper will bring an
immediate change to pink. If the pink sheet be placed in lime-water,
the effect of the lime in correcting the a
idity will be evidenced by
the return in color to blue.
To test the soil, a sample of it may be put into a basin and moistened
with rain-water. Several sheets of the blue litmus paper should be
buried in the mud, care being used that the hands are clean and dry.
When one sheet is removed within a few seconds and rinsed with
rain-water, if any pink shows, there is free acid present. Another
sheet should be taken out in five minutes. The rapidity with which the
color changes, and the intensity of the color, are indicative of the
degree of acidity, and aid the judgment in determining how much lime
should be used. If a sheet of the paper retains its blue color in the
soil for twenty minutes, there probably is no lime deficiency. The test
should be made with samples of soil from various parts of the field,
and they should be taken beneath the surface. One just criticism of
this test is that while no acidity may be shown, the lime content may
be too low for safety.