The Middlebury register. [volume] (Middlebury, Vt.) 1850-1882, 1875-06-29
About Gypsum.

VIII hon. george Geu9eS, OF SOME
other of your correspondents who know
from experience, tell me which Is best
for the money, If there is any differ
ence, Nova Scotia plaster, or what is
called western plaster? Nova Scotia |
plaster is about two dollars more per
ton, and some say no better. / have
had no experience in using either, but
intend using one or two tons this sea-
son, and would like to know which to
purchase. u. s, b.
REPLY BY HON. GEORGE GEEDEs.
The foregoing note of inquiry giving
no place from which 1t was written, |
cannot tell what is meant by "western
plaster"-perhaps Michigan, perhaps
Fort Dodge. But let us have little
general discussion of this matter.
Sulphate of lime - known in the
books as gypsum, in common converse
ton as plaster-consists of sulphuric
acid, 46 parts, lime, 32, and water %, in
all lOO and Is found in many countries,
and in many varying forms of color
and structure, and in combination with
other minerals, such rs carbonate of
lime, alumina, slick or oxide of iron.
We have in the books various names
given to varieties of gypsum, among
them selenite of several varieties, and
tibrous, granular compact, branchy,
snowy gypsum, etc We get the term
plaster of Paris from the fact that ex-
tensive beds are found at and near Par
is, France, OF peculiar combination,
having (at Montmartre) II per cent. of
carbonate of lime, which makes the
plaster (cement) that is made from this
stone stronger than it would be with
out this admixture of carbonate of lime
(Cleaveland's Mineralogy, p. 20s), For
agricultural purposes, this carbonate of
lime would do harm or, to state the
case in few words, the stone that will
make the best plaster to put on the
walls of houses would not make the
best gypsum to put on land.
Many persons judge of the value of
gypsum for agricultural purposes by its
color, and, think that the whittier it is,
the BETTER This is not so /; very little
oxide of iron is sufficient to give con-
siderable color to otherwise very pure
sulphate of lime. A person who is not
chemist will form very safe opinion
as to the value, for manure, of speci-
men of the rock, by its softness-
scratching by the thumb nail-by per-
feet equalization and freedom from
earthly matter, such as alternate layers
of gypsum and slate rock, so mixed
that the whole mass must be ground to-
gether. A very old analysis of Onon-
daga gypsum gave, lime 32, sulphuric
acid AZ, water q, For agricultural uses
1 suppose that this specimen was as
good as exists-that is, it was as pure
and free from all foreign substances
But was that fair specimen of all that
goes into the markets from the Onon-
daga beds?
Living as l do, where can go either
west, north, east or south, within ten
miles, and find mill where it IL
ground, take some pains to know
from personal observation the charac
ter of the bed from which the gypsum
is taken, that buy; and having large
masses OF the ROCK " iovh at, 1 can
very readily see whether the whole
mass is uniform in its formation, free
from slate rock, and all gypsum. The
next thing is, so into the mill and look
at the grinding, and see that power is
not spared In the work. The finer the
stone is ground, the better, and if the
rock is really soft, pure gypsum, the
flour will have no sharp feeling, but
will be smooth and soft between the
fingers. Our farmers and our dealers
in gypsum are generally good judges OF
this whole matter; and while some
persons prefer some beds over others
and the work of some mills over that OF
others, yet go generally Is the quality
good, and the grinding good that nc
man that does not have good rock, and
grind 1t fine, can succeed against the
competition of the many parties who
offer only good article in the market
Thus it is to be hoped that this very
value able fertilizer will escape the fate
that overtakes many of the costly ma.
nures that are urged upon farmers, and
that the abundance of the rock and the
great publicity that must attend the
quarrying and manufacture, will pro
tect against serious frauds.
do not believe that it is necessary tc
60 to Nova Scotia to get pure article,
but / do believe that through most O.
the MISUNDERSTANDING part of this
state, and in many places west of thi.
state, real sulphate of lime is found il
large deposits, and sold to the farmer,
properly manufactured. And withou
going farther into the discussion of it
value, than to say that l fully concu
IN an opinion that l once heard tina
wise farmer, John Johnston, express
That II gypsum could moi be purchased
for less than $40 per ton, still its us,
would be profitable on some lands ant
in some places. For even at that pric,
1t would cost less than ~ to apply
bushel to AN acre of clover, and tn
Michigan Agricultural College proved
by actual experiment, that bushe
sown on an acre of clover, did produc
an increased yield of ton of hay dur
ing the two following years. Countr,
Gentleman.