322 
boys’ department. 
Bags* Sfopartmnit. 
AGRICULTURAL CHEMISTRY.—No. 6. 
Having now completed our examination of the 
atmospheric constituents, hoys, we will next give 
our attention to the soil and its ingredients. But as 
I shall have frequent occasion, in my subsequent 
letters, to mention those classes of compounds de¬ 
nominated acids, alkalies , and salts , and, as a know¬ 
ledge of these substances is of so much consequence 
in all chemical investigations, I will first introduce 
them to your notice. 
1 . Acids. —Most acids may be recognized by the 
sourness of their taste, yet there are certain proper¬ 
ties belonging to this class of substances which are 
possessed by bodies that have not a sour taste ; the 
sourness always depending on the solubility of the 
acid. The property by which they are most usu¬ 
ally distinguished, is that of changing the blue color 
of vegetables to red. It was formerly supposed 
that all acids contained oxygen, but more recent 
investigations have shown a number of exceptions, 
in most of which, hydrogen is found as a substitute. 
Some acfds exist in a fluid state, as sulphuric acid : 
some in a solid state, as oxalic acid ; and one, car¬ 
bonic acid, exists in a gaseous state. Their most 
important property, however, and that which makes 
them peculiarly interesting to the chemist, is their 
uniting with certain substances, and forming an¬ 
other group of compounds called salts. Acids are 
divided into organic and inorganic, the former de¬ 
noting vegetable and animal, the latter, mineral 
acids. 
2. Alkalies. —This class of bodies is possessed of 
properties which seem directly the opposite of those 
belonging to acids. They have a pungent taste and 
change vegetable blue to green. One of the alka¬ 
lies, ammonia, exists in a gaseous state, and is 
called volatile alkali. Potash and soda are the two 
most important, and have been called vegetable al¬ 
kalies, in order to denote their origin, and to distin¬ 
guish them from other alkaline substances. When 
an acid and an alkali are brought in contact, they 
immediately unite, and in combining, so completely 
lose their distinguishing features that no trace of 
their respective natures can afterwards be discov¬ 
ered. In some cases, where the acid and alkali are 
each highly corrosive and poisonous, they become 
go changed by combining as to form a perfectly mild 
and harmless substance, which will not change ve¬ 
getable colors, and which has neither a sour nor a 
pungent taste. The substance thus formed, is 
called a neutral salt. 
3. Salts. — These are very extensively diffused 
through nature, and their num ber of varieties seems 
almost infinite. They are formed by the union of 
an alkali with an acid, an earth, or a metallic oxide. 
The substance with which the acid combines to 
form the salt, is called the base , and the combina¬ 
tion always takes place in certain definite propor¬ 
tions, Although the kinds of salts are so nume¬ 
rous, yet you need never be at a loss to know of 
w T hat any one of them is composed; for chemists 
have adopted a system of naming them, by which 
the composition of any one of them may be known 
by hearing the name. You have only to bear in 
mind that the name of the acid is always made to 
end in ate, while that of the base follows without 
alteration. Thus, a salt formed of sulphuric acid, 
united with lime, is called sulphate of lime ; one 
composed of carbonic acid and potash, carbonate of 
potash , and one composed of acetic acid and lead, 
acetate of lead. 
The termination ite, is sometimes used to denote 
that the acid contains less oxygen than when end¬ 
ing in ate, and in this case the acid ends in ous, in¬ 
stead of ic. Thus, phosphoric acid and potash 
combined, would be called 'phosphate of potash, but 
phosphorous acid, which contains less oxygen, 
combined with potash, would form phosphite of 
potash. 
Formation of Soils. —You have been so accus¬ 
tomed to consider the ground, when the farmer 
turns his furrow and deposites his seed, as having 
always existed in its present state, and to look upon 
rocks and stones as things of eternal duration, that 
you will be surprised when informed that most of 
the matter of which our mellow earth is composed, 
once had the form and appearance of solid rock, 
and that the hardest stones are continually wasting 
away, and adding their particles to those already 
existing in the soil. Such a process is constantly 
going on in nature. The division of these solid sub¬ 
stances, called their degradation . is effected mainly 
by the action of heat, moisture,and frost. You are 
familiar with the expansion of ice, and have un¬ 
doubtedly seen earthern or glass vessels, cracked 
and broken, by having the water in them solidified.- 
It is precisely similar with respect to rocks ; their 
crevices and pores are filled with water, which, by 
repeatedly freezing and thawing, gradually widens 
the interstices, and finally forces asunder the por¬ 
tions between which it had entered. Huge masses 
thus gradually crumble away, until they become 
changed into a soil suitable for the plow. 
Other agencies are also at work in effecting the 
degradation of these solid masses. A chemical 
action is going on, by means of which certain ele¬ 
ments, composing the solid structure of rocks and 
stones, are separated from their original connexions, 
and made to combine with other elements existing 
in the air and water with which they come in con¬ 
tact. 
The science which treats of these peculiar ope¬ 
rations in nature, is called Geology ; but it would 
occupy too much of our time to examine this sub¬ 
ject in detail. I would therefore advise you to 
seek further instruction from some of the excellent 
elementary works that have been written on this 
interesting science. J. MTvinstry. 
Greenport, Columbia Co., N. Y. 
Facts in Hill-side Farming Useful to be 
Known. — 1 . No more houses can be built on a hill 
side than on a plain, the horizontal bases of each 
being equal. 2. It requires no more posts, stakes, 
nor pickets, to fence a hill than would be necessary 
to fence a plain, 3. No more wheat, or any othei 
upright plants, will grow on the hill side than on a 
plain, unless there be a greater surface of air avail 
able as a source of food in the case of the hill side- 
and there is an advantage in that. 4. On a hill 
side, a greater crop of trailing or procumbent plants 
may be produced than on a piain. 
