1849. 
THE CULTIVATOR. 
107 
Iron is present in the blue and grey rock partly in the 
form of protoxide,* there is also some sulphuret of iron 
(Mused throughout it, which by oxidation produces 
sulphate of lime or gypsum. Sulphur, it is well known, 
is an important element of plants, especially of the 
most nutritious kinds, as the cabbage; it is also found 
in the mustard, the turnip, and in almost all the animal 
tissues. 
Our limestone therefore contains all the mineral in¬ 
gredients necessary to organic nutrition; viz. phospho¬ 
rus, sulphur, lime, magnesia, oxide of iron, silex and 
potash, and soda in small quantities. 
Some specimens appear to contain a larger propor¬ 
tion of phosphoric acid than is stated above; one analy¬ 
sis gave me as much as 2.57 per cent, as estimated by 
the precipitated phosphate of iron. As the presence 
of this acid, in the rock, is a fact of great importance, 
and the processes for its correct estimation require 
great care, I have taken unusual pains to arrive at po¬ 
sitive certainty in regard to it; and in consequence of 
my desire to separate it fully from all impurities, my 
estimation of its per centage is, no doubt, below the 
truth, from the unavoidable loss which this substance 
sustains in the various processes used. The chemist 
will understand this when I describe these processes. 
1. The ground limestone was dissolved in hydrochlo¬ 
ric acid, with a little nitric, and the solution filtered 
from the sand and silicates. 
2. Pure ammonia, and chloride of ammonium, were 
added to the boiling solution, and the precipitate was, 
after careful washing, re-dissolved in a little hydrochlo¬ 
ric acid. This contained oxide of iron, alumina and 
the phosphates. 
3. Acetate of soda was boiled with the solution (2,) 
sometimes with the addition of some chloride of iron, 
which threw down all the phosphoric acid as phosphate 
of iron. There was generally enough oxide of iron in 
the limestone to combine with all the phosphoric acid. 
4. The precipitated phosphate of iron was re-dissol¬ 
ved in hydrochloric acid, with tartaric acid and ammo¬ 
nia, and the phosphoric acid was thrown down from the 
solution by sulphate of magnesia. 
5. This precipitated ammonio-phosphate of magnesia 
was re-dissolved in hydrochloric acid, and precipitated 
again by ammonia, and, after thorough washing, was 
ignited and weighed, and the phosphoric acid estima¬ 
ted. 
Not content with this, the phosphate was dissolved 
in nitric acid, and the phosphoric acid carefully preci¬ 
pitated by nitrate of silver and ammonia: from the pre¬ 
cipitated phosphate of silver the silver was removed as 
chloride, and by the evaporation of the liquid, the phos¬ 
phoric acid was obtained in the glacial state, by gentle 
ignition in a platinum capsule. 
The original precipitate (2) containing the phosphates, 
was also treated in another way. Dissolved in ni¬ 
tric acid, acetate of lead was added to its solution, un¬ 
til all the phosphoric acid was thrown down as phos¬ 
phate of lead; which, after being well edulcorated, was 
ro-dissolved in a little nitric acid, and the lead separa¬ 
ted by means of sulphuretted hydrogen. The filtered 
liquid evaporated as above, yielded the glacial phos¬ 
phoric acid; which, re-dissolved in water, was estima¬ 
ted as pyro-phosphate of magnesia. 
In the glacial form, by this last process, the phos¬ 
phoric acid weighed 3 per cent, after moderate ignition. 
But this acid is so hygrometric that it cannot be cor¬ 
rectly estimated in the uncombined state. 
In the estimation of the magnesia, the usual mode is 
to precipitate it from the filtrate* (2) by adding phos¬ 
phate of soda; but as the ammonio-phosphate of mag¬ 
nesia is not wholly insoluble in a solution of chloride 
* Filtrate, i. e. the liquid filtered from the precipitate. 
of ammonium, I used the process of Berzelius, viz: 
ignition with the oxide of mercury; or, what is still 
more convenient, a modification of the process of 
Boothe, as follows:—Sulphuric acid in sufficient amount 
was added to filtrate (2,)and the mixture was concen¬ 
trated by evaporation. Alcohol, in equal volume was 
then added, and the precipitated sulphate of lime was 
washed with diluted alcohol. The sulphate of lime, ig¬ 
nited and weighed, gave the proportion of lime, while 
the filtrate gave on evaporation, the magnesia in the 
form of sulphate. 
The proportion of carbonic acid was ascertained by 
the process of Fresenius. 
I give this abstract of chemical processes that com¬ 
petent persons may be enabled to judge as to the value 
of the analyses. 
It must be evident, from the foregoing facts, that the 
Blue Limestone of Kentucky, should it generally be 
found to resemble that above described, will be a valu¬ 
able agricultural resource, when the soil begins to show 
the inevitable consequences of the constant exportation 
of its products; and that, with this immense source of 
fertilizing materials beneath our feet, we need never 
fear the thorough exhaustion of our soil. 
One bushel of lime, such as specimen No. 1, containing 
about 1| lb. of phosphoric acid, will yield phosphates 
enough for 5 bushels of corn; while 2 or 3 bushels of 
lime would supply all that are carried away in the bones 
and body of a hog. 
By actual experiment, within my own knowledge, of 
burning 2700 bushels of lime in one rude kiln;—the 
rock having been purchased at 50 cents per perch of 
24f cubic feet;—the wood at $3 per cord, and the la¬ 
bor estimated at 75 cents per day,—it is found that 
lime can be obtained for 10| cents per bushel. 
Our farmers, with their own wood, and farm hands, 
can burn it much cheaper, and I do not doubt that if 
they make the experiment on a sufficiently large scale, 
they wall find their labor and expenditure well repaid; 
whether they use it in the cornfield, on their wheat, or 
clover, or on the orchard. All vegetables require the 
elements which are found in it, and it cannot come amiss 
any where, when applied in the proper manner. 
It may be used in the proportion of from 20 to 50 
bushels to the acre; spread in the fall, on the surface, 
in the dry slacked state. 
It is especially recommended for the potato crop. 
Potatoes, and particularly the stalks, are found to con¬ 
tain a very large proportion of phosphoric acid in their 
ashes, and it is probable that their liability to u the 
rot ” may have some relation to the deficiency of phos¬ 
phates in the soil. Jan. 31, 1849. 
Suggestions for jFcxnmrs. 
System, Order, and Economy. 
In - the last number of The Cultivator, it was shown 
how the absence of Order in relation to the plow, 
worked a loss to the farmer of more than three dollars 
per acre; and allusion was made to the necessity for 
sound judgment in the selection of tools, implements, 
and machinery for our farm purposes. To make this 
discretion more apparent, the following list of plows 
with their relative position as to merit, is selected from 
the various volumes of Transactions of the State Agri¬ 
cultural Society—the list cannot fail to be useful to eve¬ 
ry farmer, exhibiting a wide range in the force required 
for working them, and so far, is a guide to the selec¬ 
tion, provided the material of which they are respect¬ 
ively made, is equally strong and good. It will be no¬ 
ticed t|iat the resistance offered to our horses in plow 
ing, varies according to the construction of the plow, 
