A New Chemical Test for Acid Soils. 
A Miniature Chemical Laboratory. 
.ground limestone will be sufficient. r i’his new test 
is naturally more complicated than the simple plan 
of sticking a piece of litmus paper <lo\yn into the 
soil, hut it is based upon much the same principle 
of determining the degree of acidity by a color test. 
ZINC SULPHIDE AND ACID.—The chemist 
working in his laboratory has known, of course, for 
years that the chemical known as zinc sulphide will 
give off when boiled with an acid a gas with a 
disagreeable smell. This gas is called sulphide of 
hydrogen, and as the name implies, it contains sul¬ 
phur. Any one who has drank the water from a 
sulphur spring, or obtained a very good whiff of rot¬ 
ten eggs. will recognize the smell. Sul¬ 
phide of zinc is a white flour-like sub¬ 
stance, and is known at the mines as 
"black jack.” The pure substance used 
in a test for acid is white, and com¬ 
posed of sulphur and zinc. Now when¬ 
ever this zinc sulphide comes in con¬ 
tact with .an acid, the bad smelling gas 
just mentioned is given off. The chem¬ 
ist found that muriatic acid would 
drive this gas from tin* zinc sulphide, 
and upon noticing this it occurred to 
Prof. Truog that the acid in an acid 
soil might do the same thing. Upon 
experiment il was found that when 
water and this sulphide of zinc were 
added to an acid soil, and the mixture 
boiled together, this evil smelling gas 
was actuallydriven off, just as though 
a common acid such as vinegar had 
been used in place of the acid soil. 
When a sweet soil, or one containing 
no acid was used, none of this gas 
was driven off. This then made tin* 
basis for the test. As you will see, only 
a simple operation was required to con¬ 
duct it. if tlie soil was sour, and this 
zinc sulphide were added to it, and 
heat applied by boiling, this gas would 
be removed. This being demonstrated, 
it was necessary to complete the test 
by some simple method of showing the 
presence of this gas. Of course one 
might hold his nose over tin* boiling 
mixture, and in this way know that the 
gas was formed, but different noses 
happily have different powers of smell, 
and there would be no way of showing 
by such a simple test how much of the 
gas was being given off, and so a bet¬ 
ter way for detecting the gas was util¬ 
ized. In the commercial laboratory 
there has long been a test for this gas 
in the use of what is known as lead 
acetate paper. This paper is produced 
by soaking a white, porous paper, like 
a blotter, in a solution of 10% of ace¬ 
tate of lead. This is a white sub¬ 
stance, looking somewhat like salt. It 
Contains lead, and is used in making the common 
white lead of commerce. When this paper lias been 
dipped into the solution, it is dried, and is then 
ready for use. 
THE FINAL TEST.—Now in making this test, if 
the soil is acid it will send off this bad-smelling gas. 
When this paper covered with the acetate of lead is 
held in the fumes rising from this test, and there is 
any of the sulphide of hydrogen gas arising, the 
paper will be turned more or less dark, according to 
the amount of gas which touches it. The reason for 
this is that the sulphur in this gas combines with 
the lead in the paper and forms a black substance 
L ITMUS PAPER METHOD.—For many years 
we have told our readers about the blue litmus 
paper test for acid soils. This has been freely 
used, and has given a good deal of satisfaction. It 
i> very simple; all you have to do is to get a fair 
ample of the soil to be tested, get it moist enough 
so that it will hold together, and then thrust, a strip 
of blue litmus paper down into the soil where it will 
he held firmly for 10 or 15 minutes. In some cases 
a glass is used with the litmus paper at one side. 
Then the soil is pressed tight around it 
so that you can see any change of color 
in the blue paper through the glass. 
The theory of this litmus test is the 
fact that this paper is very sensitive 
to acid conditions. When packed into 
a soil which is more or less acid, the 
blue color changes all the way from a 
light pink to a bright red, depending 
upon the degree of acidity, and some¬ 
times on other conditions which have 
little to do with the actual condition of 
the soil. The litmus paper has proved 
a great help, but it is not as reliable as 
most farmers would want in order to 
tell the true need of their soils. A 
number of other tests have been de¬ 
vised, such as the use of muriatic acid, 
and other chemicals, but none of them 
has proved entirely satisfactory. Now 
we have a new test, devised by Prof. 
E. Truog, of the Wisconsin Agricul¬ 
tural College. After long experiment¬ 
ing and study this test is now offered 
to the public, and promises to be a 
great help to those who are studying 
the use and value of lime. 
SOIL CONDITIONS.—We think it 
probable that S0% of soils which have 
been under cultivation for 50 years, 
are more or less sour’. With the. ex- 
eep.tion of a few. plants, our leading 
farm crops cannot thrive at their best 
in a sour soil, and the fact that our 
soils have become acid has led again 
and again to crop failures. Various 
causes have been assigned for this 
failure, 1 running all the way down from 
a dispensation of Providence, to a 
growl against the seedsmen for selling 
poor seed. The truth was with most 
"f these failures that the soil had be¬ 
come sour, so sour in fact that it could 
not perform its functions properly, so 
that the failure was not the fault of 
the weather, the fertilizer agent, the 
commission man, the seedsman, or any¬ 
thing else except the failure to use 
lime, or to handle the soil so as to 
overcome its acid condition. It is true that thou¬ 
sands of farmers have rushed to the use of lime, not 
knowing whether their soils were sour or not. Some 
1,1 them have received benefit freely; while others 
have reeived a very slow benefit, for the reason that 
ihey used the wrong kind of lime. We know of 
people who say that they have used half a ton of 
ground limestone to the acre, and found fault be¬ 
cause they did not receive immediate results. The 
truth is that their soil was so very sour that they 
could not expect any particular benefit unless they 
used at least one ton of burnt lime to the acre. 
' "hers found that liming one field in a certain way 
Head of the Herd Hauling Garden Truck. Fig. 244. 
< See page 689.) ‘ '; 
The Pedigreed Gentleman Working With His Ox Brothers. Fig. 245. 
(See page 689. > 
gave them excellent results, while the same process 
in another Held right on the same farm had little 
if any effect. The trouble in these cases was that 
such farmers did not know how sour some of their 
fields were;, for it is a fact that right on the same 
farm one field, or even one part of a field, may be 
as sour as a pickle, while'some rods away another 
held which has been handled in a different manner 
is sweet enough to grow clover and Alfalfa. It will 
be seen from this that no one can hope to handle 
and use lime intelligently without knowing the 
true condition of his soil, and he cannot hope to 
know this without making careful and accurate 
tests to see how sour each field or each piece of 
the farm may be. One trouble with the litmus test 
is that while it will tell you whether your soil is 
sour or sweet, it does not go far enough and give 
you a correct idea about the degree of acidity. If 
>o.u know that, you can tell much better about how 
much lime to use. and also the kind of lime best 
suited to your farm. 
THE NEW TEST.—Now this new test not only 
permits a farmer to know if his soil is sour, but it 
also gives him an idea about how sour it is, how 
much lime he ought to use, and whether an active 
lime is necessary or whether the milder form of 
