364 Wisconsin statu agricultural society . 
has put them up with especial reference to the vegetable kingdom, 
and labeled them as she has put them away in the strata, that the 
farmer may make no mistake when he looks for them for agricul¬ 
tural purposes. 
Is it silica he wants? he will find it nearly pure, put up in sepa¬ 
rate forms and labeled, quartz, hornstone, flint. Wherever these 
minerals form any considerable portion of the rocks, the soil 
formed from them will have a sufficient amount of this element of 
plant food. And this element is essential, for few if any plants 
can live and grow without it. It enters largely into the formation 
of the stalks of most vegetables, and is essential to the formation 
of their seeds. Inasmuch as this substance enters largely into 
most plants, nature has furnished it in abundance and scattered it 
over a large portion of the earth’s surface. It is supposed that 
one-half of the solid substance of the earth is made up of silica. 
If it is lime the farmer needs, he will find it here labeled, car¬ 
bonate of lime. It is combined mostly with carbonic acid, and 
forms a large portion of our strata known as common limestone, 
or dolomite, as already referred to. It is found also forming a 
large portion of some of the minerals composing our granitic rocks, 
consequently is an important ingredient in the soils formed from 
these strata. Indeed there is not a single element of plant food 
that man has to supply, that is not found in the mineral kingdom, 
put up in proper forms and labeled, that the farmer may know what 
it is, and where it may be found. 
It is true, all the elements of plant food do not form a part of 
our common rocks. Nature sometimes puts up what is not found 
in our ordinary bill of fare, and what may be called extras , such 
as our mineral phosphates and sulphates, which, as every intelli¬ 
gent farmer knows, add very much to the health and develop¬ 
ment of plants. These extras nature fixes up by mixing a little 
phosphorus or sulphur with oxygen, forming acids, then by add¬ 
ing a little of these acids to lime, form these compounds so valu¬ 
able to the agriculturists. They are found only here and there 
in the mineral kingdom, and a knowledge of their whereabouts 
would be very acceptable to the farmers of our state. 
It is in the mineral kingdom, nevertheless, among those min¬ 
eral compounds, that the farmer must look for the material to be 
