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QUALITIES OF LIME AND ITS COMPARATIVE VALUE FOR AGRICULTURAL PURPOSES. 
QUALITIES OP LIME AND ITS COMPARATIVE 
VALUE FOR AGRICULTURAL PURPOSES.— No. 2. 
Lime is slightly soluble in wqter, a property 
which is so essential to enable it to undergo in 
itself and effect in other matter, those chemical 
and mechanical changes before alluded to. The 
solvent power of water upon lime is in the in- 
verse ratio of its temperature. At 32,° water dis- 
solves -g-fg- of its weight of lime ; at 60° 7 ^ ; and 
at 212,° only -^Vo-; and as the ordinary temper- 
ature of water In soils seldom exceeds 60°, and 
frequently is near 32,° it follows that in this 
condition, it acts with nearly its maxium influ- 
ence on lime. 
Another properly of lime, we have no doubt is 
true, though in the yet imperfect state of agri- 
cultural science, we are not absolutely certain 
of it; and if true, it is of incalculable advantage 
in promoting the growth of vegetation and that 
too from the gratuitous supplies derived from 
the atmosphere. When lime is mixed with 
damp manure and rich vegetable loam, in the 
shade, it condenses nitric acid, which immedi- 
ately combines with the potash of the manure, 
forming nitrate of potash (saltpetre). ' That this 
operation is going forward in rich calcareous 
soils, hardly admits of a doubt, especially when 
shaded by a rank vegetable growth, and occa- 
sionally stirred in the process of cultivation. 
The value of both nitric acid and nitrate of pot- 
ash to vegetable nutrition, has too often been 
tested to admit of doubt. Professor Johnston 
in his ingenious and valuable essay on lime, 
published in the Highland Quarterly Journal 
of Agriculture, in which many of the prob- 
able beneficial operations of lime are detailed 
corroborates this opinion and attributes not only 
the formation of nitric acid, but ammonia, also, 
" at the expense of the free nitrogen of the at- 
mosphere, from the presence of calcareous mat- 
ter in the soil." 
There is a great difference in the value of the vari- 
ous limestones for agricultural purposes. When 
burnt, some contain considerable proportions of 
phosphate of lime, the remains of innumerable 
infusoria, coprolites, and some species of the 
coral, the aggregation of ages of insect and oth- 
er animal remains, in the indefinite past. Phos- 
phate of lime is the principal fertilising mate- 
rial of bones, and enters into the composition of 
every vegetable ; its importance must therefore 
be readily appreciated. And this is the reason 
why one species of limestone yields what is 
termed lime, but which is really quicklime as- 
sociated with the phosphate, so much more 
valuable for agricultural uses than others, which 
approximate more nearly 1o a pure carbonate. 
Many of the limestones of Kentucky and other 
parts of the Union, and more frequently the 
marls, yield a large per centage of phosphate of 
lime ; and wherever such are attainable, their 
application to soils is attended with the best re- 
sults. The yield of fertile lands is augmented, 
and the resuscitation of worn-out soils is speedily 
accomplished where such a dressing is used. 
There are other limestones which yield only an 
impure lime, mixed with considerable quantities 
of other minerals or earth, of no utility for agri- 
cultural purposes. 
Oyster-shell lime, or that derived from other 
shell fish, both of marine and fresh-water origin, 
is generally superior for agricultural purposes, 
to such as is derived from other sources ; not 
only from its containing nothing but what is 
useful, but especially as yielding a noticeable 
quantity of phosphate. 
Magnesian lime has its value in agriculture. 
This is apparent from the analysis of the ashes 
of all vegetables. None are without magnesia. 
Wheat contains about 0.9 per cent.; barley 
almost 2 ; the bean and pea nearly as much, and 
their straw and the clovers and lucern, from 2 to 
3.5. Besides contributing to the food of plants, its 
alkaline properties act on soils and manures in 
a manner similar to lime, but in a more intense 
degree. Wherever applied, therefore, ft must 
be in quantity considerably less then when the 
pure lime is used. 
The effect of lime upon crops is to mature them 
earlier, and give a fuller, healthier growth. The 
best sugar plantation in Louisiana, which gives 
the largest average yield of sound, convertible 
juice, has great quantities of muscle shells, in 
every stage of decomposition, scattered through- 
out the soil. Wheat is found to be fuller and 
heavier when grown on well-limed or calcare- 
ous soils. The stalk is not so liable to rust, or 
mildew, and it yields a brighter, cleaner straw. 
The potato rot, which has devastated not only 
fields, but whole countries, has in many instan- 
ces, been checked or wholly prevented by the 
use of lime. Lime seldom or never does injury 
either to the soil or crop, unless applied in ex- 
cess ; and in nearly all cases, its application is 
attended with the best results. 
Tlie application of lime may be made either 
after burning or grinding, but the former is by 
far the most speedy in its effects. In this case, 
it is reduced to an impalpable powder, it may 
be a thousand times finer than by the most effi- 
cient artificial grinding, so much more perfect 
are the chemical operations of nature than the 
mechanical ones of man. In consequence of 
this minute division, every particle of the lime 
is brought into intimate contact with the soil 
and exerts its full influence ; while the unburned 
though finely-divided limestone may require 
many years, and probably centuries of them to 
yield all its benefits. The difference to the soil 
is analogous to that of an animal swallowing 
unbroken grain and cooked meal. In the former 
case, the grain may possibly be voided before 
digested; in the latter, every particle of the 
farinaceous nutriment has been developed by 
the expanding heat, and is thus ready for imme- 
diate assimilation by the stomach. 
It is important to secure the maximum benefit of 
lime, that it be kept near the surface. Air, moist- 
ure, heat and light are all important agents in 
effecting chemical changes in the soil ; and these 
are only to be found at or near the surface. 
From its greater weight, there is a constant ten- 
dency to sink, not only from the operations of 
the plow, spade, &c, but from the washing of 
rain, the operations of moles, earth worm*-', and 
