AGRICULTURAL GEOLOGY.—NO. 6. 
85 
far inferior in flavor to the same vegetable 
from Virginia, or even Delaware, or New Jer¬ 
sey. Other vegetables are of like kinds as 
with us. Meats are but on the average; and 
although poultry and eggs are cheap, abundant, 
and good, they show no superiority in quality, 
to ours. 
There is much that is both excellent and su¬ 
perior in the natural production about Cincin¬ 
nati. The soil is rich, the climate mild and 
salubrious; and an abounding supply of all 
edible things for the thronging population 
within and around it. Though neither grand 
in position, nor picturesque in scenery, or where 
grandeur and magnificence are distinguishing 
features in the landscape, can it compare with 
many of the cities of our land; yet it has many 
pleasant surroundings, and is among the most 
useful of our American towns; and in the intel¬ 
ligence, the public spirit, the untiring industry, 
the urbanity and kindness of her people, and 
in the pursuit of the great and essential objects 
which benefit their race and promote the com¬ 
mon prosperity of the state, there is no place 
of its population which takes rank with Cincin¬ 
nati. A Visitor. 
AGRICULTURAL GEOLOGY—No. 6. 
Clay soils, from their peculiar nature, perhaps, 
always retain a certain amount of ammonia 
diffused throughout them. There are very few 
of them that have undergone tillage from which 
ammonia, as a gas, cannot be obtained in small 
quantity. This useful element may have been 
derived from two sources; either from the de¬ 
composition of vegetable roots in the earth 
whereby carbonic acid and ammonia are 
evolved, or from the absorption of atmospheric 
air into the soil, the renewal of its oxygen, and 
the residual nitrogen united with some hydrogen 
escaping • from decomposed mould. This, al¬ 
though a small source, is in all likelihood, a con¬ 
stant one, and when it occurs dn clay soils, the 
alumina acting as a sponge in its moist state, 
absorbs the gas into its pores, and retains it for 
a time. This ammonia escapes on drying the 
soil by a gentle heat, and unless looked for care¬ 
fully is often not estimated as being present. 
The majority of these chemical properties, 
which a clay soil manifests, such as its tendency 
to absorb moisture carbonic acid, ammonia, and 
its affinity for potash, are exhibited with the 
exception of the last, only when it is moderately 
moist When excessively wet, its absorption 
power, of course, ceases; and when it is dry, 
the changes cannot go on; that is, neither air 
nor vegetable matter can be decomposed. This 
is a peculiarity of clayey soils which cannot 
well be remedied. No mixing with sand, or 
gravel, nor lightening its physical texture will 
accomplish it. 
In clayey soils, then, there are periods when 
they are overactive in producing chemical 
changes, such as evolution of oxygen, the forma¬ 
tion of ammonia and carbonic acid; and in a 
few cases, the formation of nitric acid; and there 
are, also, periods of no action, as in time of 
drought. This may he one cause, quite inde¬ 
pendent of its physical texture, why clayey soils 
are favorable to the growth of some plants and 
not others It cannot be the mere tendency to 
retain moisture which would cause this differ¬ 
ence. It possibly may be attributable to the 
impatience of the presence of a large quantity 
of oxygen which injures the roots. 
There is one very striking peculiarity in the 
soils derived from slate rocks, as well as in the 
soils overlying slate districts, namely, the very 
small quantity of lime which exists in these 
soils. In the analyses of slate soils, made in the 
Labratory of the American Agricultural Asso¬ 
ciation, the minute proportion of lime present is 
remarkable; nor is this true of slate merely, 
but it has been observed as true with regard to 
the slate soils of the United States, generally, 
when contrasted with those of Europe. In Great 
Britain, there are few soils to which lime has not 
been added for many years, that still 1 or 2 per¬ 
cent. may not exist, and 4 or 5 per cent, of 
carbonate of lime is often found in stiff clay 
soils. What may have been the cause of this 
difference in the presence of lime in American 
drift and slate soils, compared with those of 
Europe, it is almost out of place here to specu¬ 
late upon. The soils being derived from the 
slate rock, the first question arises, Does the 
slate rock differ on the two continents? The 
answer here is also given in the affirmative. It 
must he due, then, to some causes operating over 
the American hemisphere at the time those rocks 
were deposited, whereby lime did not become 
an element entering into their composition. 
Some difference existed either in the depth of 
ocean which then overlaid this continent, or a 
different race of animals existed in these waters 
which did not separate the lime from the sea 
water to form a bony shell, or probably both 
these causes existed together. In other words, 
the seas, which covered the present slate dis¬ 
tricts, were too deep to allow of coral-forming 
animals to exist, and unfitted for their numerous 
univalve and bivalve mollusca, which form a 
calcareous coat to exist in. This is the usual 
