| parts of the matured plant. 
| the part in which the absorption and decomposi- 
118 
the ascending sap, they part with nearly all their 
own alkaline juices for continued elaboration 
with the ammoniacal and carbonic acid gases, 
till they cease to have a sufficient quantity for 
the maintenance of their own health and ver- 
dure; and they, in consequence, sicken, fade, and 
die. Hence, the withered leaves are found to 
contain mere traces of soluble alkaline salts, 
while the buds and sprouts are remarkably rich 
in these substances. “The reverse of this pheno- 
menon is seen in the case of many kitchen-plants, 
when they are supplied with rich manure con- 
taining an excess of mineral ingredients; salts 
| are separated from the surface of their leaves, 
| and cover them with a thin white crust. In con- 
sequence of these exudations, the plant becomes 
sickly, the organic activity of the leaves dimin- 
ishes, the growth of the plant is destroyed, and 
if this condition lasts, the plant finally dies. 
These observations are best made on plants with 
leaves of large dimensions, through which large 
quantities of water are evaporated. This disease 
generally attacks turnips, gourds, and pease, when 
the soil is drenched with sudden and violent rain, 
after continued dry weather, at a time when the 
plants are near, but have not attained, maturity ; 
| it is also necessary for its occurrence, that dry 
weather should again happen after the rain. By 
the rapid evaporation of the water, absorbed by 
| the roots, a larger quantity of salts enters the 
plants than they are able to use. These salts 
effloresce on the surface of the leaves, and when 
they are juicy, act as if the plants had been 
treated with solutions of salts, in greater quantity 
than their organism could bear. Of two plants 
of the same kind, the one nearest maturity is 
most liable to this disease ; if the other plant has 
either been planted at a later period, or if its de- 
velopment has been restrained, the causes which 
exercised injurious effects upon the first plant 
accelerate the development of the latter. The 
germ springing out of the earth, the leaf on com- 
ing out of the bud, the young stem, and the green 
sprouts, contain a much larger quantity of salts 
with alkaline bases, and give ashes on incinera- 
tion much richer in alkaline ingredients, than 
The leaves, being 
tion of carbonic acid is effected, are much richer 
in mineral ingredients than other parts of the 
plant. The simple fact that a plant is restrained 
in growth by the want of rain to convey to it 
alkalies, proves completely that these alkalies 
play a most important part in vegetation.” 
The formation of sugar, starch, and other non- 
azotised constituents of plants is effected by means 
of soluble alkaline salts, or of vegetable acids in 
chemical combination with alkalies; it does not 
take place in such fruits and seeds as contain 
vegetable acids in a free state, or uncombined 
with alkalies, as in the lemon and the chick-pea, 
_ which contain respectively citric acid and oxalic 
acid in a free or uncombined condition; and it 
ALKALIS. 
takes place on the largest scale, and accumu- 
lates the greatest stores of sugar, starch, and 
similar substances, in those plants which are 
richest in soluble alkaline salts, or in the bases 
and the acids of which these are formed. A de- 
ficiency in sugar, starch, and woody fibre, in the 
plant, is the necessary consequence of a deficient 
supply of alkaline matter in the soil; and a luxu- 
riant produce in these, or a large amount of the 
vegetable elements of nutrition for animals, is a 
general consequence of an abundant supply of 
alkalies. Hence an excellent crop, as to either 
the vigour of its growth, the soundness of its 
organism, or the large amount of its food for the 
use of man, can be obtained only when the soil 
possesses alkaline bases in sufficient quantity for 
the plant’s use, and in a condition suitable for 
absorption. “The compounds containing nitro- 
gen and sulphur, as well as the alkalies and phos- 
phates,” remarks Dr. Liebig, “are constituents of 
the blood of animals; but the conversion of the 
former into blood cannot be conceived without 
the presence and co-operation of the latter. Ac- 
cording to this view, the power of any part of a 
plant to support the life of an animal, and to in- 
crease its blood and flesh, is in exact proportion 
to its amount of the organic constituents of the 
blood, and of the materials necessary for their 
conversion into blood,—viz., of alkalies, phos- 
phates, and chlorides (common salt or chloride of 
potassium). It is highly worthy of observation, 
and of great significance to agriculture, that the 
vegetable compounds containing sulphur and 
nitrogen, which we have designated as the or- 
ganic constituents of the blood, are always ac- | 
companied, in the parts of the plants where they | 
occur, with alkalies and with phosphates.” The 
tubers of the potato and the roots of the beet 
contain vegetable albumen, alkaline salts, and 
soluble phosphate of magnesia ; the seeds of pease, | 
beans, lentils, oats, rye, barley, and wheat contain 
starch, alkaline phosphates, and earthy salts; and 
the parts of these plants which are poor in the 
properties of food for animals, are proportionally | 
poor both in the substances which result from 
the combined action of alkalies and organic acids, 
and in those which result from the joint presence | 
of alkalies, phosphates, nitrogen, and sulphur. As 
regards, therefore, either the azotised or the non- 
azotised adaptations of cultivated vegetables for 
the uses of man and the domestic animals, one 
invariable and most important condition of every 
good crop is the presence in the soil of an ample 
supply of soluble alkaline matter. But this great 
topic, under certain modifications, will again and 
again meet us in a number of our future articles, 
and hence must not be regarded as at present 
fully discussed. See, in particular, the articles Am- 
moNIA, Porasu, Sopa, Sauts, Manure, Nitrates, 
SuLPHATES, Gypsum, Limg, PHospHates, ALKA- 
Lorps, ALKALINE Bases, and ALKALINE SALTS. 
Alkalies and alkaline earths, when mixed with 
various substances which do not absorb oxygen, 
