mixture with them till they bring it back to the 
ground in the first fall of rain or snow. Rain- 
water, in consequence, must always contain am- 
monia, and possess a decidedly manurial power ; 
yet less in winter or spring than in summer,— 
less on the second day of any constant rain than 
on the first,—less after a brief than after a long 
interval of drought,—and most of all in a thun- 
der-shower at the end of a long tract of dry and 
sunny weather. Dr. Liebig supposes the quan- 
tity of ammonia in a pound of rain-water to 
amount, on the average, to about one-fourth of a 
grain ; while the reviewer of his “ Organic Chem- 
istry” in the Quarterly Journal of Agriculture, 
computes it to amount to only ‘092 of a grain; 
and they very probably differed in their esti- 
mates, solely on account of the former having 
used the rain-water of occasional showers, and 
the latter the rain-water of frequent rains. On 
Dr. Liebig’s computation applied to the rain- 
gauge of Germany, the quantity of ammonia an- 
nually deposited by rain upon every 26,910 square 
feet of land is upwards of eighty pounds; and 
according to his reviewer’s computation applied 
to the rain-gauge of Scotland, the quantity of 
ammonia and of common salt annually deposited 
by rain upon every acre of land is respectively 
71'8 and 641°4 pounds. Some portion of the am- 
monia which falls, indeed, will be re-evaporated 
with the water; but quite enough of it must 
sink into the soil and operate upon vegetation, 
to act as both a stimulating and an alimentary 
manure,—at once preparing the materials around 
it for the plant’s assimilation, disposing the spon- 
gioles to absorb the food presented to them, and 
entering the interior of the plant chiefly to con- 
tribute its azote to the plant’s nitrogenous secre- 
tions, partly to undergo other transformations in 
the economy of the plant’s growth and matura- 
tion, and partly to remain unaltered and act as 
an interior stimulant. 
The quantity of azote in each eighty pounds 
of ammonia, which Dr. Liebig computes to be 
annually deposited by rain upon every 26,910 
square feet of land, is so great as seventy pounds ; 
and this is much more than the quantity con- 
tained in all the gluten and vegetable albumen 
of any average crop of wood, hay, or beet-root 
which that extent of land can produce, yet less 
than the gluten and vegetable albumen of the 
straw, roots, and grain of a crop of corn. The 
mere ammonia of rain-water, therefore, affords 
an ample supply of azote for trees, grasses, and 
green crops, but must be supplemented with ni- 
trogenous manures, such as those of the farm- 
yard, for all cereal crops; yet, in every case, it 
is so strongly and even necessarily alimentary as 
to afford a very broad and easy explanation of 
the fact, that artificial waterings with the water 
of streams are generally a miserable substitute 
for the rains of heaven. [See also the articles 
Anration and Azotz.] The juices of maple-trees, 
birch-trees, and beet-root, when mixed with lime, 
AMMONIA. 
emit a strong odour of ammonia; the products 
of the distillation of flowers, herbs, and roots 
with water, and all extracts of plants made for 
medicinal purposes, contain ammonia; the trans- 
‘parent, gelatinous pulp of the unripe almond and 
peach, when treated with alkalies, emits a large 
proportion of ammonia; the fresh or unwithered 
leaf of the tobacco plant, contains ammoniacal 
salts; the juice of a wounded vine, evaporated 
with a few drops of muriatic acid, evolves much 
ammonia; and, in short, the juice of the roots, 
the stem, the blossoms, and the fruit of all albu- 
minous plants, in an unripe stage, have been 
proved by experiment or may be inferred from 
analogy, to contain both ammoniacal and sac- 
charine matters, and to be in consequence under 
the precise chemical conditions for forming azo- 
tised secretions and products. 
plants are ripening, the juices gradually dry up, 
the ammonia diminishes in quantity, the sugar 
disappears along with the ammonia, and the per- 
manent nitrogenous products of the plants, such 
as albumen, gluten, and vegetable casein, com- | 
prising all the most nutritious and valuable con- 
stituents of most cultivated crops, are evolved. 
Animal manure exerts a very complex action | 
upon plants; yet, as regards its supply of nitro- 
gen, or its agency in assisting the formation of 
nitrogenous products, it acts only by its contri- 
butions of ammonia. Hither an increased quan- 
tity of any one kind of it, or the use of any vari- 
ety of it which is richer in ammonia than varie- 
ties previously used, occasions both an increase 
in the number of grains or seeds in a crop, and 
an enlargement of the proportion which their ni- 
trogenous contents, such as gluten and albumen, 
bear to their other constituent elements. Wheat 
grown on a soil manured with cow-dung—a man- 
ure which evolves less ammonia than most other 
animal manures—has been found to contain only 
11:95 per cent. of gluten, and 62°34 per cent. of 
amylin or starch; while wheat grown, in the 
same circumstances, on a soil manured with hu- 
man urine—a manure remarkably rich in ammo- 
nia—has been found to contain 35'1 per cent. of 
gluten, or nearly three times the proportion con- 
tained in the other. Urea, the most prominent 
ingredient in urine, is converted by putrefaction, 
or under the influence of heat and moisture, into 
carbonate of ammonia, or the very form of am- 
moniacal salt which exists so largely in solution 
in rain-water ; native urine contains also a pro- 
portion of both the phosphate and the muriate 
of ammonia; so that putrid urine is a singularly 
powerful combination of ammoniacal forces, and 
may easily be understood to elicit the formation 
of threefold more gluten in a grain crop than 
can result from the action of so comparatively 
feeble an ammoniacal manure as cow-dung. Gu- 
ano operates as a mighty manure almost exactly 
on the same principle; for, when genuine, it con- 
sists solely of the urate, the oxalate, the phos- 
But while the | 
