34 
THE CULTIVATOR. 
tion, or the mixture of two substances, which, when chemically com¬ 
bined, occupy less volume than when separate, tends to expel the ca¬ 
loric which interposed between them, and by destroying the chemical 
union which existed between those atoms and the caloric, and to cause 
sensible heat. Thus hammering cold iron upon the anvil, will force out 
the caloric, and the metal will in time become red hot. By rubbing two 
pieces of dry hard wood, fire is produced, which existed before in a 
latent state, but which by friction is set free. Water thrown upon quick 
lime or boiled gypsum, often produces a heat which sets fire to build¬ 
ings. In this case the caloric comes from the water. Fifty pounds of 
lime will take up and solidify seventeen pounds of water. The caloric 
which the water contained is thereby set free, and becomes sensible 
heat. The air too, readily elicits fire, and ignites spunk, on being vio¬ 
lently compressed in a metal tube. Caloric is also disengaged from the 
atmospheric air by combustion. As condensation produces heat, so ex¬ 
pansion or evaporation produces cold, by imbibing caloric from sur¬ 
rounding objects. Spontaneous combustion arises from the chemical 
union of matters, which occupy, in their combined form, less space than 
when separate. Both heat and cold are artificially produced by mix¬ 
tures, one kind abstracting heat from the surrounding objects, and pro¬ 
ducing cold, and the other giving it off, and producing heat. Hence the 
coolness which is produced by watering or sprinkling during the heats 
of summer. By the evaporation which ensues, the volume of water 
employed becomes greatly enlarged, and the heat of the atmosphere 
interposes between its particles, becomes latent, and is carried off with 
the vapor. The more volatile the liquid, the greater the coolness in¬ 
duced. Ether, ammonia, camphor, and alcohol, produce more sudden 
changes in temperature than water. Ether is volatalized at a tempe¬ 
rature of 98, ammonia at 140, camphor at 145, sulphur at 170, alcohol 
at 176, and water at 212°, or boiling heat; muriate of lime becomes 
volatalized at 230, and mercury at 660° of Fahrenheit; but when the 
heat is abstracted, all these matters return to their natural state.— 
“Whenever a body changes its chemical state, (says Dr. Black,) it 
either combines with, or separates from, caloric.” Fix a small tin cup 
with ether in a large watch-glass containing a little water, and place 
both under the receiver of the air pump. The exhaustion of the re¬ 
ceiver will cause one of the fluids to boil, and the other to freeze, at 
the same instant,— Parke. Mix three parts of snow with four parts of 
potash, immerse the bulb of a thermometer in the mixture, and the 
quicksilver will show an artificial cold of 83 degrees. When water is 
poured upon dry pulverized plaster of Paris, in order to form cornices 
in rooms, great heat is produced by the mixture. This is owing, as in 
slaking lime, to the water giving out its caloric as it becomes solidi¬ 
fied in the plaster or lime. When the cream in a churn changes from 
a fluid to a solid, a considerable degree of heat is produced from the 
same cause. 
Although a universally pervading element, and essential to all the 
purposes of organic life, caloric is subservient to the artificial use of 
man in innumerable ways; and those who understand best its proper¬ 
ties and laws, will best know how to apply it to the useful purposes 
of life. Heat is necessary to the germination of the seed, the develop¬ 
ment of the plant, and the maturity of the fruit; it is also necessary 
to the fermentation of manures. Some plants grow, and some fruits 
ripen, in a temperature of 45 to 50, while others require a heat of 60 
to 80 to perfect their maturity. Light porous soils, as sands and 
gravels, become heated by the sun’s rays much sooner than compact 
heavy clays, and they part with their heat more readily, particularly 
sands, when the sun is obscured or withdrawn. The colour of soils 
has also an influence upon their capacity for absorbing or retaining 
heat. Davy found that a black soil, containing nearly one-fourth of ve¬ 
getable matter, when exposed to the sun, acquired in one hour an in¬ 
creased temperature of 23 degrees, while white soil, whose base was 
chalk, under a similar exposure, acquired an increased temperature 
of only 4 degrees. But the black earth, removed into the shade, lost 
again, in half an hour, 15 degrees of its acquired heat; and the white 
earth, in the same time and position, lost 4 degrees, or all it had ac¬ 
quired. In green houses, the walls are sometimes blackened, and the 
soil spread with soot, in order to concentrate and fix the heat, and 
this has been known to raise the temperature in the house several de¬ 
grees. On the table lands of the Alps, it is not uncommon to throw 
black earth upon the snow, to hasten its thawing, and expedite its pre¬ 
paration for tillage. Aspect has also a great influence in determining 
the influence of the sun’s rays upon the soil. All slopes to the south, 
south-east, and south-west, are warmer than those in opposite direc¬ 
tions, The nearer to a right angle the sun’s rays fall upon a surface, 
the greater the heat they impart. Thus in constructing green houses, 
it is the rule to give the glass that slope which will bring it at right 
angles with the rays of the meridian sun, at the season its heat is most 
needed to excite rapid growth. 
The practical benefits which the farmer may draw from the conside¬ 
ration of the preceding facts, are many and important. We shall con¬ 
fine ourselves to a notice of a few of them. 
1. They show the importance of draining. Water is a bad conduc¬ 
tor of heat. Land well drained may be worked and planted ten days 
or a fortnight earlier than if in a wet condition. If there is an excess 
of water in the soil, or reposing upon the subsoil, it prevents the ground 
acquiring the heat, in summer, necessary to the healthy growth and 
early maturity of farm crops, and necessary, also, to the decomposi¬ 
tion of vegetable manures. If the water comes from springs, it is al¬ 
ways of a cold temperature ; if it is surface water reposing upon the 
subsoil, it becomes stagnant—in both cases it is unfriendly to an early 
or healthy growth of-plants. 
2. They show that the capacities of soils for heat may be increased, 
by mixing with those which are light coloured, darker earths, as swamp 
muck, wash of the roads, earth from head lands and ditches, and dark 
manures ; and also, when flat and moist, by throwing them into ridges, 
and thereby rendering them more dry. 
3. They suggest the propriety of adapting the crop to the soil, in re¬ 
ference to texture, colour and aspect—of placing those which are na¬ 
tives of warmer latitudes, or which are liable to be injured by early 
autumnal frosts, as Indian corn, pumpkins, barley, red clover, &c. in Ihe 
most favored situations; and of assigning to less favored soils, those which 
come from higher latitudes, or which are indigenous with us, as wheat, 
rye, timothy, peas, and particularly turnips, oats and potatoes. The 
temperature of soils is often so different on the north and south slopes 
of a hill—on white and dark soils—on those‘that are porous and adhe¬ 
sive—and on those which are wet and dry, as to make a material dif¬ 
ference in the products of crops of the first class. 
4. They suggest the value of pulverization, particularly of the sur¬ 
face, among hoed and drilled crops—the heat penetrating much more 
readily a surface that is frequently stirred, than one which has become 
compact ana baked. 
5. The most important means of benefiting the corn crop, by increas¬ 
ing the temperature of the soil, is the use of unfermented manure. 
This benefits in a two fold way: the fermentation itself generates heat, 
and, by rendering the soil loose and porous, it renders it more permea¬ 
ble to the warmth imparted by the sun and the atmosphere. 
6 . They show that seeds may be buried too deep. Few seeds vegetate 
at a temperature below 45 degrees. They should therefore be deposited 
as near the surface as a proper regard to moisture will permit, to brmg 
them as much as possible within the influence of the heat of the at¬ 
mosphere. 
Seed Corn, that is steeped preparatory to planting, should not be suf¬ 
fered to dry on the surface of the ground, or by exposure too long to the 
sun, but should be buried in the earth while moist. In our last spring’s 
planting, after finishing one field, which came up well, the seed was 
left exposed a day, in a basket, to the sun, and planted the day follow¬ 
ing. Much of the seed failed to vegetate, and some of that which grew, 
had a sickly, dwarfish appearance through the season. The like hap¬ 
pened to Mr. Weston, of Washington, and Mr. Brewster, of Oneida, 
Another gentleman has informed us, that he planted steeped seed; that 
the three first rows were covered immediately, but the residue was not 
covered until the whole field had been dropped, and the seed become 
dry. The three rows came up and grew well; the residue came up but 
imperfectly, and the plants they produced were inferior and dwarfish. 
The cause of these failures may be thus explained: Germination had 
commenced in the steep—a chemical change had taken place in the 
cotyledons, in the matter which feeds and sustains the young plant till 
it develops its leaves, and can take care of itself,—and by the subse¬ 
quent drying, this nutriment was partially or wholly destroyed, and the 
corn failed to grow, or grew but feebly, for want of it. Where germi¬ 
nation is stopped, after it has commenced, for want of moisture, the 
vitality of the seed cannot be again resuscitated. We have had seed 
corn, after it had been steeped, keep good in a basket five days, in a 
cellar, where it sprouted, and was afterwards planted and grew well. 
AN ESSAY' ON GRASSES.— {Continued from page 24.) 
OF THE CULTIVATED GRASSES. 
The forage, hay and pasture grasses, of which we are now about to 
treat, are found clothing the surface in every zone, attaining generally 
a greater height, with less closeness at the roots, in warm climates; 
and producing a low, close, thick, dark green nutritive herbage, in the 
cooler latitudes. The best grass pastures are found in countries that 
have least cold in winter, and no excess of heat in summer, as in Ire¬ 
land, England, Holland and Denmark. In every zone, where there are 
high mountains, there are certain positions between the base and sum¬ 
mit, where, from the equilibrium of the temperature, turf may be found 
equal to that in marine islands. 
The universal presence of the forage grasses, and the rapidity with 
which all soils become covered with them, when left uncultivated, is 
the obvious reason why their selection and systematic culture is but of 
recent date. This branch of culture originated in England, about the 
middle of the seventeenth century, and at first embraced only rye-grass, 
was afterwards extended to cocks-foot, timothy, foxtail, &o. The Duke 
of Bedford made the latest and most laborious efforts towards attaining 
