Plaster of Paris, 
37 
Plaster of Paris, 
Gents. —We have neard many complaints among 
our farmers who use this important stimulant, and 
particularly from those who have but recently com¬ 
menced its application, that it failed in numerous in¬ 
stances last year in developing its usual benefits. 
They doubt the goodness of the article, or its adapta¬ 
tion to their soils. 
Our solution to their complaints and inquiries is, 
that it requires rains to dissolve or decompose the 
plaster, without which its application to crops is 
fruitless. The spring and summer of 1841 were un¬ 
usually dry throughout a great part of the Northern 
States. For two or three months, we had little or no 
rains, and the grass, and early grain crops were un¬ 
commonly short. This we apprehend is the principal 
cause of the failure. We advise our agricultural 
friends, however, to repeat their regular course, and 
soon the present season may give a good account of 
the last year’s application. At all events, our confi¬ 
dence is in no way impaired in the virtue of this 
stimulant. 
Yours truly, F. 
As the application of Sulphate of Lime 
more familiarly known as Selenite , Gypsum, 
or Plaster of Paris , is extensively and most 
beneficially made in this country as a manure, 
perhaps we cannot occupy the attention of our 
readers more advantageously, than by throwing 
together some facts connected with it. Of 
theories , we have many; but as they have not 
yet attained that certainty which we deem es¬ 
sential to any subject claiming the attention of 
practical farmers, the rule we have adopted for 
our present limits, will not allow our communi¬ 
cating them. 
The materials of gypsum, 
are 
lime, chemically combined with sulphuric 
or 
acid; commonly known as oil of vitriol 
vitriolic acid; which is one of the strongest 
mineral acids, and consists of sulphur and 
oxygen, with the addition of a little water. 
This combination is essential to be understood 
by such as are making experiments on its use, 
and will serve to throw much light on the 
reasons for the different results obtained. 
And, 1? It generally has little or no effect on 
strong clay lands; unless applied in large quan¬ 
tities, say 15 or 20 bushels to the acre, when 
it has been known to change the character of a 
stiff clay in a single season, to a loose, friable, 
mellow and rich soil. 
2? It is used with great effect on dry, sandy, 
(not a barren sand,) or loamy soils. 
3? One to two bushels per acre, is considered 
a sufficient quantity to apply at once, though as 
high as six, have been sown with marked ad¬ 
vantage. 
4? Its effects last through two seasons, and 
frequently much longer. 
5? It should be sown generally in April or 
May; (and always applied when the ground is 
dry,) thus affording an opportunity for dissolving 
it by the rains. Its application to crops as late 
as June, have frequently been attended with 
decided advantages, though the large quantity 
of water required for dissolving it, being about 
500 parts of water, at a temperature of 60° to 
one of gypsum, renders the advantage much 
more conspicuous when sown earlier. 
6? The effects are much more striking when 
applied with manure, and sometimes with lime. 
7? It is.a stimulant, as well as manure, and 
has a tendency to exhaust the humus or geine 
already in the ground, which renders it neces¬ 
sary to add manures occasionally, when the 
crops are carried off' the ground; when they 
are consumed on it, the soil is constantly im¬ 
proving without the addition of manure. 
8? It is in some instances a specific food of 
vegetables, by this means greatly increasing the 
quantity of some plants, as clover, sainfoin, and 
other of the broad leaf grasses; peas, corn, 
roots, &c.; while some of the narrow leaf 
grasses, and wheat, barley, oats, &c. are scarcely 
benefited by it. 
9? In opposition to the suggestion of our cor¬ 
respondent, we have well attested experiments 
of its immediate beneficial effect on crops suffer¬ 
ing from drought, before any rains had come to 
its aid; it having been in some slight degree 
dissolved by copious dews. 
10? Its application in the neighborhood of 
salt water, has seldom been attended with bene¬ 
fit, owing undoubtedly to its combining with the 
saline vapor, wafted to it by the sea breezes. 
11? Frequent benefit is derived from its use, 
on vines and other plants infested with insects, 
for though the diluted acid constituting a por¬ 
tion of it, may be highly beneficial to the vege¬ 
table, it is poison to the insect. 
12? Wet lands are not improved by it. 
13? Many soils are already so highly charged 
with gypsum in their natural condition, as to 
derive no benefit from an additional quantity. 
There is scarcely any saline substance more 
generally diffused, it constituting a portion of 
almost every soil, and is contained to a greater 
or less extent, in all river and spring water; 
and giving to the latter especially, when in 
onsiderable quantity, the character of hardness, 
From this cause, (its general and large diffu¬ 
sion), is unquestionably owing the want of effect 
on clay lands. These almost invariably con¬ 
tain considerable portions of sulphur and lime ; 
we have then but to add a portion of oxygen to 
the sulphur, which is abundantly found in the 
soil, and water, and atmosphere, and we have 
the sulphuric acid, which brought into com¬ 
bination with the lime, gives us the gypsum. 
This enters directly into the substances of some 
plants, as we have seen above j. and on others^ 
it acts favorably, by its subsequent decomposi¬ 
tion, and union with other substances, as pot- 
