80 
THE CULTIVATOR. 
becomes the same chemical substance as chalk or limestone. Ver$ 
few limestones or chalks consist entirely of lime and carbonic acid. 
The statutary marbles, or certain of the rhomboidal spars, are al¬ 
most the only pure species; and the different properties of lime¬ 
stones both as manures and cements, depend upon the nature of 
the ingredient mixed with the limestone ; for the true calcareous ele¬ 
ment, trie carbonate of lime, is uniformly the same in nature, in 
properties, and effects, and consists of one proportion of carbonic 
acid, 41.4, and one of lime, 55. When a limestone does not copi¬ 
ously effervesce in acids, and is sufficiently hard to scratch glass, it 
contains siucious, [sandy,] and probably aluminous, [clayey,] earths. 
When it is deep brown or red, or strongly coloured of any of the 
shades of brown or yellow, it contains oxide of iron. When it is 
not sufficiently hard to scratch glass, but effervesces slowly, and 
makes the acid in which it effervesces milky, it contains magnesia. 
And when it is black, and emits a foetid smell if rubbed, it contains 
coaly or bituminous matter. Before any opinion can be formed of 
the manner in which the different ingredients in limestones modify 
their properties, it will be necessary to consider the operation of 
pure lime as a manure. 
Quick-lime , in its pure slate , wffiether in powder or dissolved in 
water is injurious to plants. In several instances grass has been 
killed by watering it with lime-water. But lime, in its state of com¬ 
bination with carbonic acid, is a useful ingredient in soils. Calca¬ 
reous earth is found in the ashes of the greater number of plants ; 
and exposed to the air, lime cannot long continue caustic, for the 
reasons that were just now assinged, but soon becomes united to 
carbonic acid. When newly burnt lime is exposed to air, it soon 
falls into powder ; in this case it is called slaked lime ; and the same 
effect is immediately produced by throwing water upon it, when it 
heats violently, and the water disappears. Slaked lime is merely a 
combination of lime, with about one-third its weight of water ; i. e. 
fifty-five parts of lime absorb seventeen parts of water, and is called 
by chemists hydrate of lime; and when hydrate of iime becomes 
carbonate of lime by long exposure to air, the water is expelled, and 
the carbonic acid gas takes its place. When lime, whether freshly 
burnt or slaked, is mixed with any moist, fibrous, vegetable matter, 
there is a strong action between the lime and the vegetable matter, 
and they form a kind of compost together, of which a partis usually 
soluble in water. By this sort of operation, lime renders matter 
which was before comparatively inert, nutritive; and as charcoal 
and oxygen abound in all vegetable matters, it becomes at the same 
time converted into carbonate of lime. 
Mild lime, powdered lime-slone, marls or chalks, have no action 
of this kind upon vegetable matter; they prevent the too rapid de¬ 
composition of substances already dissolved, but they have no ten¬ 
dency to form soluble matters. It is obvious from these circum¬ 
stances, that the operation of quick-lime, and marl or chalk, de¬ 
pends upon principles altogether different. Quick-lime in being ap¬ 
plied to land, tends to bring any hard vegetable matter that it con¬ 
tains into a state of more rapid decomposition and solution, so as to 
render it a proper food for plants. Chalk, and marl, or carbonate of 
lime, will only improve the texture of the soil, or its relation to ab¬ 
sorption ; it acts merely as one of its earthy ingredients. Chalk 
has been recommended as a substance calculated to correct the sour¬ 
ness of land. It would surely have been a wise practice to have 
previously ascertained the certainty of this existence of acid, and 
to have determined its nature, in order that it might be effectually 
removed. The fact really is, that no soil was ever yet found to con¬ 
tain any notable quantity of uncombined acid. The acetic and car¬ 
bonic acids are the only two that are likely to be generated by any 
spontaneous decomposition of animal or vegetable bodies, and nei¬ 
ther of these have any fixity when exposed to the air. Chalk hav¬ 
ing no power of acting on animal or vegetable substances, can be 
. no otherwise seviceableto land than as it alters its texture. Quick¬ 
lime, when it becomes mild, operates in the same manner as chalk, 
but in the act of becoming mild, it prepares soluble out of unsoluble 
matter. Bouillon La Grange says, that gelatine oxygenized be¬ 
comes insoluble, and vegetable extract becomes so from the same 
cause ; now lime has the property of attracting oxygen, and, conse¬ 
quently, of restoring the property of solubility to those substances, 
which have been deprived of it, from a combination of oxygen.— 
Hence the use of lime on peat lands, and on all soils containing an 
excess of vegetable insoluble matter.— Grisenthwaile. 
Effect of lime on wheat crops. —When lime is employed upon land 
where there is present any quantity of animal matter, it occasions 
the evolution of a quantity of ammonia, which may, perhaps, be im¬ 
bibed by the leaves of plants, and afterwards undergo some change 
so as to form gluten. It is upon this circumstance, that the opera¬ 
tion of lime in the preparation for wheat crops depends ; and its effi¬ 
cacy in fertilizing peat, and in bringing into a state of cultivation all 
soils abounding in hard roots, or dry fibres, or inert vegetable mat¬ 
ter. 
General principles for applying lime. —The solution of the ques¬ 
tion whether quick lime ought to be applied to a soil, depends upon 
the quantity of inert vegetable matter that it contains. The solu¬ 
tion of the question, whether marl, mild lime, or powdered lime- 
si one ought to be applied,depends upon the quantity of calcareous mat¬ 
ter already in the soil. All soils are improved by mild lime, and ulti¬ 
mately by quick-lime, which do not effervesce with acids, and sands 
more than clays. When a soil, deficient in calcareous matter, con¬ 
tains more soluble vegetable manure, the application of quick-lime 
should always be avoided, as it either tends to decompose the solu¬ 
ble matters by uniting to their carbon and oxygen so as to become 
mild lime, or it combines with the soluble matters and forms com¬ 
pounds having less attraciion for water than the pure vegetable sub¬ 
stance. The case is the same with respect to most animal manures, 
but the operation of the lime is different in different cases; and de¬ 
pends upon the nature of the animal matter. Lime forms a kind of in¬ 
soluble soap with oily matters, and then gradually decomposes them 
by separating from them oxygen and carbon. It combines likewise 
with the animal acids, and probably assists their decomposition by 
abstracting carbonaceous matter from them combined with oxygen; 
and consequently must render them less nutritive. It tends to di¬ 
minish, likewise, the nutritive power of albumen from the same 
causes ; and always destroys, to acertain extent, the efficacy of 
animal manures, either by combining with certain of their elements, 
or by giving to them new arrangements. Lime should never be ap¬ 
plied with animal manures, unless they are too rich, or for the pur¬ 
pose of preventing noxious effluvia. It is injurious when mixed 
with any common dung, and tends to render the attractive matter 
insoluble. According to Chaptal, Jime forms insoluble composts, 
wilh almost all animal or vegetable substances that are soft, and 
thus destroys their fermentative properties. Such compounds, how¬ 
ever, exposed to the continued action of the air, alter in course of 
time, the lime becomes carbonate, the animal or vegetable matter 
decompose, by degrees, and furnish new products as vegetable 
nourishment. In this view, lime presents two great advantages for 
the nutrition of plants; the first, that of disposing of certain insolu¬ 
ble bodies to form soluble compounds, the second, that of prolonging 
the action and nutritive qualities of substances, beyond the term 
which they would retain them if they were not made to enter into 
combination with lime. Thus the nutritive qualities of blood, as it 
exists in the compound of lime and blood, known as sugar bakers’ 
scum, is moderated, prolonged, and given out by degrees;—blood 
alone applied directly to the roots of plants will destroy them, with 
few or no exceptions. 
Lime promotes fermentation. —In those cases in which fermenta¬ 
tion is useful to produce nutriment from vegetable substances, lime 
is always efficacious. Some moist tanner’s bark was mixed with 
one-fifth of its weight of quick-lime, and suffered to remain toge¬ 
ther in a close vessel for three months ; the lime had become coloured 
and was effervescent; when water was poured upon the mixture, it 
gained a tint of fawn colour, and by evaporation furnished a fawn co¬ 
loured powder, which must have consisted of lime united to vegetable 
matter, for it burnt when strongly heated, and left a residuum of mild 
lime.— Loudon’s Enc. Ag. 
GYPSUM. 
Besides being used in the forms of lime and carbonate of lime, cal¬ 
careous matter is applied for the purposes of agriculture in other 
combinations. One of these bodies is gypsum or sulphate of lime. 
This substance consists of sulphuric acid, the same body that exists 
combined with water in oil of vitriol, and lime, and when dry is com¬ 
posed of 55 parts of lime and 75 parts of sulphuric acid. Common 
gypsum or selenite, such as that found at Shotoverhill, near Oxford, 
contains, besides sulphuric acid and lime, a considerable quantity of 
water, and its composition may be thus expressed : sulphuric acid 
one proportion 75; lime one proportion 55; water two proportions 
34 - 
The nature of Gypsum is easily demonstrated: if oil of vitriol be 
I added to quick-lime, there is a violent heat produced ; when the 
