Year: 1859

The penetration of water into rocks upon
mountains covered with snow is cause wnlch
destroys the cohesion of their clements II
is known that as water passes into ice it di-
lates and this explains why walls, saturated with
water and exposed to intense cold in severe
nights, exfolate and sometimes even crumblc
down if they contain much humidity; and II
explains also why masons cover recent con-
structions, With straw. Now water in solidl-
flying in the superficial beds of rocks produces
the same effect, that is to say, separates their


parts, which with the thaw come off, are dis


persed and carried away by the waters.


But this mechanical and incidental cause of
disintegration is not the most powerful; there
are others which act constantly during centu-
ries, minute by minute or rather second by
second, and which not being limited by time,
triumph over the resistance which bodies ap-
parently the most unalterable, oppose to them;
l speak of the combined chemical actions, by
which oxygen, water and carbonic acid decom-
pose rocks and stones. Silica (AinD and the
silicates despite their seeming insolubility, re-
siSt not the slow and continued action of wa
ter sharpened with carbonic acid. Porcelain
clay (Kaolin) owes its property only to the sec
ular decomposition which had dissolved the
silicate of potassa and reduced the stone TO
the condition of siicate of alumina. An aka


line siicate put near water saturated with car


bopic acid and in the vicinity of the roots of
plants, is decomposed, dissolved in the water
and in the end passes in the liquid state into
the tissue of the plants.


The phosphate of lime is not soluble in
pure water, but it is soluble in water contain
ing Sea salt ammonical salt such as the
Sulphate of ammonia. 1t also dissolveS very
well in water acidulated with carbonic acid !;


it is the same with limestone carbonate of


lime which becomes easily soluble through


an excess of carbonic acid.


Since tillable land is constituted of the waste


of certain rocks its properties must depend on
the principles which predominant in the de-
bris. If the earth is composed of silica or Of
pure limestone it is absolutely sterile, but if
clay is mixed with it in proper proportions
there results fruitful soil. Clay is the result
of disintegration of silicate of alumina and al


kalies, feSpar, granite, gniess: Sc.); its in
fiuence upon the life of plants is due to the al
kalies, alkaline earths and phosphates and sui
pilates which it contains. This influence is


such that single cubic metre of felspar. (sil-
icate of alumina and of potash) which con-
tains seventeen hundredths of alkalies, can


furnish potash during $50 years for forest of
oaks containing $500 square metres.


The alumina of clay takes part in the devel-
! opment of plants only by its property of ie-
| tanning water and ammonia; and ii is rarely
found in the ashes of plants. a soil as fertile
as possible is that where clay is mixed with
calcareous matter and sand in such proportions
as to give a free passage to air and moisture.
The soil in the vicinity of Vesuvius is type
of fertile lands. They never manure it and


they there cultivate corn without returning to
the soil that which they take from it, but they
let the land rest one year in three. Thus they
subject it to all the vicisstHdes of the season.
and certain quantity of the alkalies which


it contains set at liberty by the decompo-


sition of the superficial bed of minerals which


constitute the soil.


Why is tillage useful? Only in this that it
separates the earth and multiplies the surfaces


which should be brought in contact with car
bonic acid, air and moisture, that the re-


mains Of rocks constituting the. tiilable land
shall receive the property of being disSoluble


of water. Stirring the soil by mechanical op-
erations is not the only means of rendering the
nutritious principles there contained soluble
and fit for vegetables. The employment of
lime, spread over the surface, produces the
same result. This base combines with a part
of the elements of clay and sets free the other
parts, soluble and fit to promote vegetation.
This explains the efficiency of marls. which
are mixture of clay and lime. The lime thus
mixed with clay, favors the action of water
sharpened with carbonic acid upon the silica,


an action which we have explained.


Lastly we shall name another method, more
expensive, but not less powerful than the 9TH
ers for increasing the fertility of argilaceous


lands, which is, to subject them to a slow cal


cination. The silicates then dissolve with the
greatest facility.


To resume, should We employ the piow or
the harrow, should we mix lime with clayey


land or should we calcine it, all these means
concur in the same end. that is to say the dis


integration of the slicates of alumina and al
kalies. If clayey land offers compact con-
sistaucy, it will resist the development and


multiplication of roots. Then it will suffice
to mix with this earth certain quantity of fine
sand, which will render il sufficiently light
and accessible; to air and water, that which
frequent tillage could not effect.


They call fatLoW that period of culture when
the soil is abandoned to atmospheric Influences
so that it can enrich itself of certain soluble
substances. Fallowing is, then an effort anal
agous to tillage addition of lime and calcina-
ton. Since the concurrence of soluble silica
and alkalies is one of the principal conditions
for the prosperity of cereals, if they are not
added to the soil, greater or less repose
should be given to it so that it may regain the
mineral substances proper for absorption. If
during the time of resting the land that they
wish to prepare for the cereals, they cultivate
another vegetable on the same land the har-
vest of which draws not silica from the soil.
this preserves its fertility for the corn which
they wish to cultivate later. This suffices to
make us comprehend the importance of rota-
tion liz crops by which the agriculturist can
draw from the same earth, without adding ma
ny successive crops of different vegetables
which he alternates according to the difference
in the quality of mineral, substances which
each OF them extract from the soil in develop
ing themselves.


THE WAY TO DO TIFF you want to keep
your town from thriving, turn cold shoulder
to your mechanics, or new beginners in busi-
ness look upon every newcomer with jeal-
ous scowl; discourage all you can last, tho