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injuring the skin or bending the limbs.
These precautions are necessary, as rough
treatment may easily occasion dislocations
of the joints, or fractures of the bones.
Next, the whole naked frame, excepting
the face, should be covered with a bed of
snow from twelve to eighteen inches in
thickness, or if this cannot be procured,



cold water and ice may be substituted,
and clothes successively dipped in it may
be spread over the whole body, especially
the head and breast. After continuing
these affusions, gentle frictions with flan-
nel or soft brushes, likewise immersed
in cold fluids, should be commenced,
alternately making use of the shower bath,
and persevering in these attempts for an
hour at least, when the body ought to be
left undisturbed for some minutes. If no
signs of life appear, clysters of cold water,
with oil and vinegar, or six ounces of
brandy, are to be given, and the former
process again and again repeated; so that
five or six hours sometimes elapse, before
any symptoms of animation are per-
ceptible. As soon, however, as there is
the least prospect of recover}^, warm
fomentations must be resorted to; the de-
gree of friction cautiously increased, and
the patient placed in bed between two
robust persons ; emollient clysters pre-
pared; and when he is able to swallow,
a cup of tea with a little vinegar, wine or
brandy, may be allowed. In many des-
perate instances, however, it will perhaps
be proper to perform venesection, or in-
troduce air into the lungs by means of
common bellows ; or to have recourse to
the electrifying machine, or the earth
bath, &c. but such cases must be submit-
ted to the judgment of a physician. In
Russia, frozen parts of the human system
are kept constantly covered with goose
grease until a cure is effected, and in the
United States, that of common fowls is
used. — Preparations of camphor, either
that of camphorated spirits or opodeldoc,
has also been used with beneficial re-
sults.

Fasts, a term used to denote abstinence
from food,particularly for religious reasons.
Fasting is injurious to delicate and debi-
litated habits, particularly in the early
part of the day, because the fluids of the
body, after circulating several hours with-
out any alimentary refreshment, at length
acquire a putrid tendency, which is ex-
tremely injurious to the whole human
system.

Fermentation

Is strictly speaking a chemical process,
and of considerable importance in domes-
tic economy; particularly in the fermen-



122



SIR H. DAVY S AGRICULTURAL CHEMISTRY.



tatioii of bread, wine, beer, and cider,*
The most essential requisites in every
process of fermentation, are,

1. That the substance be in a fluid
state.

2. That there be a proper degree of
warmth, that is, in general between 70°
and 80° of Fahrenheit's thermometer;
and

3. That the atmosphere be not entirely
excluded from the fermenting bodies, nor
that they be exposed to a current of air.

Filtration in chemistry as well as
domestic economy, is the process of
straining or filtering liquors, by means
of woolen, cotton, or linen, paper, or
other materials. The common filters
are of two kinds, namely: simple pie-
ces of paper or cloth, through which
the fluid is passed ; or similar mate-
rials are twisted up in the same manner
as skeins or wicks; they are first v^etted,
then squeezed, and one end put into the
vessel which contains the liquor to be
filtered; the other end is to be suspended
out of the vessel, lower than the surface
of the liquor, the purest parts of which
drop gradually out of the vessel, leaving
behind the coarser particles. Sometimes
they are made to operate while the liquor
is passing upwards in an inverted sy-
phon.



SIR H. DAVY S AGRICULTURAL CHEMISTRY'

(Continued from page 112.)

5. Gluten may be obtained from
"wheaten flower by the following process :
The flower is to be made into a paste,
which is to be cautiously washed, by
kneading it under a small stream of water,
till the water has carried ofi" from it all
the starch ; what remains is gluten. It is



*As the value of fermented liquids depend upon the
retention of the largest possible quantity of carbonic
acid. It is suggested for the consideration of brewers
and cider manufacturers, that in vessels containing
liquids, whilst undergoing vinous fermentation, the
vent for the escape of the gas shall be as small as pos-
sible, consistent with the safety of the vessel ; that the
gas be made to pass through a tube in form of a syphon,
and discharged under the surface of water, in such a
manner that atmospheric air shall not supply the place
of carbonic acid gas in the vessel, and that in the pas-
sage of the gas the largest possible quantity shall be
retained in water for domestic purposes, so as to par-
take of the properties of spring water.



a tenacious, ductile, elastic substance. It
has no taste. By exposure to air it be-
comes of a brown color. It is very
slightly soluble in cold water, but not so-
luble in alcohol. When a solution of it
in water, is heated, the gluten separates in
the form of yellow flakes ; in this respect
it agrees with albumen, but difiers from it
in being infinitely less soluble in water.
The solution oi albumen does not coagu-
late when it contains much less than 1000
parts of albumen, but it appears that gluten
requires more than 1000 parts of cold
water for its solution.

Gluten, when burnt, affords similar pro-
ducts to albumen, and probably differs
very little from it in composition. Gluten
is found in a great number of plants;
Proust discovered it in acorns, chesnuts,
horse chesnuts, apples, and quinces ; bar-
ley, rye, peas, and beans ; likewise in the
leaves of rue, cabbage, cresses, hemlock,
borage, safiVon, in the berries of the elder,
and in the grape. Gluten appears to be
one of the most nutritive of the vegeta-
ble substances ; and wheat seems to owe
its superiority to other grain, from the
circumstance of its containing it in larger
quantities.

6. Gum Elastic or Caoutchouc, is pro-
cured from the juice of a tree, which
grows in the Brazils, called Haeva. When
the tree is punctured, a milky juice ex-
udes from it, which gradually deposites a
solid substance, and this is gum elastic.

Gum elastic is pliable and soft, like
leather, and becomes softer when heated.
In its pure state, it is white ; its specific
gravity is 9335. It is combustible,and
burns wdth a white flame, throwing off a
dense smoke, with a very disagreeable
smell. It is insoluble in water and in al-
cohol; it is soluble in ether, volatile oils,
and in petroleum ; and may be procured
from ether in an unadultered state, by
evaporating its solution in that liquid.
Gum elastic seems to exist in a great
variety of plants ; amongst them are,
Jatropha elastica, Ficus indica, Jirto-
ccirpus integrifolia, and Urceola elas-
tica.

Bird lime, a substance which may be
procured from the holly, is very analo-
gous to gum elastic in its properties. Spe-
cies of gum elastic may be obtained from



SIR H. DAVY S AGRICULTURAL CHEMISTRY.



123



tlic misletoe, from gum mastic, opium,
and from the berries of the smilax cadii-
ca, in which last plant it has been lately
discovered by Dr. Barton.

Gum elastic, when distilled, affords
volatile alkali, water, hydrogen and car-
Ijon, in diflerent combinations. It there-
fore consists principally of azote, hydro-
u;cn, oxygen and carbon ; but the propor-
tions in which they are combined, have
not yet been ascertained. Gum elastic is
an indigestible substance, not fitted for the
food of animals ; its uses m the arts are
well known.

' 7. Extract, or the extractive princi-
ple, exists in almost all plants. It may
be procured in a state of tolerable purity
from saffron, by merely infusing it in
water, and evaporating the solution. It
may likewise be obtained from catechu, or
Terra Japanica, a substance brought
from India. This substance consists prin-
cipatly of astringent matter, and extract ;
by the action of water upon it, the astrin-
gent matter is first dissolved, and may be
separated from the extract. Extract is
always more or less colored ; it is solu-
ble in alcohol and water, but not soluble
in ether. It unites with alumina when
that earth is boiled in a solution of extract,
and it is precipitated by the salts of
alumina, and by many metallic solutions,
particularly the solution of muriate of tin.

From the products of its distillation, it
seems to be composed principally of hy-
drogen, oxygen, carbon, and a little azote.

There appears to be almost as many
varieties of extract as there are species of
plants. The diflference of their proper-
ties, probably in many cases depends upon
their being combined with small quanti-
ties of other vegetable principles, or, to
their containing diflerent saline, alkaline,
acid, or earthy ingredients. Many dying
substances seem to be of the nature of ex-
tractive principle, such as the red color-
ing matter of madder, and the yellow dye,
procured from weld.

Extract has a strong attraction for the
fibres of cotton or linen, and combines
with these substances, when they are
boiled in a solution of it. The combina-
tion is made stronger by the intervention
of mordants, which are earthy or metallic
combinations, that unite to cloth, and ena-



ble the coloring matter to adhere more
strongly to its fibres.

Extract, in its pure form, cannot be
used as an article of food, but it is proba-
bly nutritive when united to starch, mu-
cilage, or sugar.

8. Tannin, or the tanning principle,
may be procured by the action of a small
quantity of cold water, on bruised grape
seeds, or pounded gall-nuts ; and by the
evaporation of tlic solution to dryness. It
appears as a yellow substance, possessed
of a highly astringent taste. It is difficult
of combustion. It is very soluble, both
in water and alcohol, but insoluble in
ether when a solution of glue, or isinglass
{gelatine) is mixed with an aqueous solu-
tion of tannin, the two substances, i. e.
the animal and vegetable matters, fall down
in combination, and form an insoluble pre-
cipitate.

When tannin is distilled in close ves"
sels, the principal products are charcoal?
carbonic acid, and inflammable gases,
with a minute quantity of volatile alkali.
Hence its elements seem the same as those
of extract, but probably in diflerent propor-
tions. The characteristic property of tan-
nin is its action upon solutions of isinglass
or jelly ; this particularly distinguishes it
from extract, W'ith which it agrees in most
other chemical qualities.

There are many varieties of tannin,
which probably owe the diflference of their
properties to combinations with other
principles, especially extract, from which
it is not easy to free tannin. The purest
species of tannin is that obtained from the
seeds of the grape; this forms a white
precipitate, with a solution of isinglass.
The tannin from gall-nuts resembles it in
its properties. That from sumach aflbrds
a yellow precipitate ; that from kino a
rose colored ; that from catechu a fawn
colored one.

The coloring matter of Brazil wood?
which Mr. Chevreul considers as a pecu-
liar principle, and which he has called
Hematine, differs from other species of
tannin, in affording a precipitate with gela-
tine, which is soluble in abundance of hot
water. Its taste is much sweeter than
that of the other varieties of tannin, and
it may perhaps be regarded as a substance
intermediate between tannin and extract.



124



SIR H. DAVY S AGRICULTURAL CHEMISTRY.



Tannin is not a nutritive substance, but is
of great importance in its application to
the art of tanning. Skin consists almost
entirely of jelly or gelatine, in an orga-
nized state, and is soluble by the long con-
tinued action of boiling water. When
skin is exposed to solutions containing
tannin, it slowly combines with that prin-
ciple ; its fibrous texture and coherence
are preserved ; it is rendered perfectly
insoluble in water, and is no longer liable
to putrefaction ; in short, it becomes a sub-
stance in chemical composition, precisely
analogous to that furnished by the solution
of jelly and the solution of tannin.

In general, in this country, the bark of
the oak is used for affording tannin in the
manufacture of leather ; but barks of some
other trees, particularly the Spanish ches-
nut, have lately come into use.

The following table will give a general
idea of the relative value of different
species of barks. It is founded on the
result of experiments made by myself.

Table of numbers exhibiting the quanti-
ty of tannin afforded by 480 lbs. of differ-
ent barks, which express nearly their rela-
tive values:
Average of entire bark of middle

sized Oak, cut in spring.
Average of Spanish chesnut,

Leicester willow, large
size.

Elm,

Common willow, large 11

Ash,

Beech,

Horse chesnut,

Sycamore,

Lombardy poplar,

Birch,

Hazel,

Black thorn,

Cappice oak.

Oak cut in autumn.

Larch cut in autumn.

White interior cortical
layers of old bark.
The quantity of the tanning principle
in barks, differs in diflerent seasons ; when
the spring has been cold, the quantity is
smallest. On an average, 4 or 5 lbs. of
good oak bark are required to form 1 lb.
of leather. The inner cortical layers in
all barks contain the largest quantity of



29 lbs


21


((


33




13




11




16




10




9




11




15




8




14




16




32




21




8





72



tamiin. Barks contain the greatest propor-
tion of tannin, at the time the buds begin
to open — the smallest quantity in winter.

The extractive or coloring matters found
in barks, or in substances used in tanning,
influence the quality of the leather. Thus
skin tanned with gall-nuts, is much paler
than skin tanned with oak bark, which
contains a brown extractive matter. —
Leather made from catechu is of reddish
tint. It is probable that in the process of
tanning, the matter of skin and the tanning
principle first enters into union, and that
leather, at the moment of its formation,
unites to the extractive matter. In general,
skins in being converted into leather, in-
crease in weight about one third*; and the
operation is most perfect when they are
tanned slowly. Whenskins are introduced
into very strong infusions of tannin, the
exterior parts immediately combine with
that principle, and defend the interior
parts from the action of the solution. Such
leather is liable to crack and to decay by
the action of water.

The precipitates obtained from infusions
containing tannin by isinglass, when dried,
contain, at a medium rate, about 40 per
cent, of vegetable matter. It is easy to
obtain the comparative value of different
substances for the use of the tanner, by
comparing quantities of precipitate afford-
ed by infusions of given weights mixed
with solutions of glue or isinglass.

To make experiments of this kind, an
ounce, or 480 grains of the vegetable sub-
stance in coarse powder, should be acted
upon by half a pint of boiling water. The
mixture should be frequently stirred, and
suffered to stand 24 hours ; the fluid should
then be passed through a fine linen cloth,
and mixed with an equal quantity of solu-
tion of gelatine, made by dissolving glue,
jelly, or isinglass in hot water, in the pro-
portion of a drachm of glue or isinglass,
or six table spoons full of jelly, to a pint
of water. The precipitate should be col-
lected by passing the mixture of the solu-
tion and infusion through folds of blotting
paper, and the paper exposed to the air
till its contents are quite dry.

If pieces of paper of equal weights are
used, in cases of which different vegetable



* This estimation must be considered as applying
to drif siviii and dry leather.



SIR H. DAVY S AGRICULTURAL CHEMISTRY.



125



substances are employed, the difference of
the weights of the papers when dried,
will indicate with tolerable accuracy, the
quantities of tannin contained by the sub-
stances, and their relative value, for the
]iurposes of manufacture. Four-tenths of
the increase of weight in grains must be
taken, which will be in relation to the
weights in the table.

Besides the barks already mentioned?
there are a number of others which con-
tain the tanning principle. Few barks
indeed are entirely free from it. It is
likewise found in the wood and leaves of
a number of trees and shrubs, and is one
of the most generally diffused of the vege-
table principles. A substance very simi-
lar to tannin has been formed by Mr.
Hatchett, by the action of heated diluted
nitric acid on charcoal, and evaporation
of the mixture to dryness. From 100
grains of charcoal, Mr. Hatchett obtained
120 grains of artificial tannin, which, like
natural tannin, possessed the property of
rendering skin insoluble in water.

Both natural and artificial tannin form
compounds with the alkalies and the alka-
line earths; and these compounds are not
decomposible by skin. The attempts
that have been made to render oak bark
more efficient as a tanning material by in-
fusion in lime water, are consequently
founded on erroneous principles. Lime
forms with tannin a compound not solu-
ble in water. The acids unite to tannin,
and produce compounds that are more or
less soluble in water. It is probable that
in some vegetable substances tannin exists,
combined with alkaline or earthy matter;
and such substances will be rendered more
efficacious for the use of the tanner; by the
action of diluted acids.

9. Indigo may be produced from wood
{Isatis tinctoria,) by digesting alcohol on
it, and evaporating the solution. White
crystalline grains are the substance in
question. The indigo of commerce is
principally brought from America. It is
procured from the Indigo/era argentea,
or wild indigo, the Indigofera disperma,
or Gautimala indigo, and the Indigofera
tinctoria, or French indigo. It is pre-
pared by fermenting the leaves of those
trees in water. Indigo in its common
form appears as a fine, deep blue powder,



it is insoluble in water, and but slightly
soluble in alcohol; its true solvent is sul-
pliuric acid: 8 parts of sulphuric acid dis-
solve 1 part of indigo; and the solution
diluted with water forms a very fine blue
clye.

Indigo, by its distillation, affords car-
bonic acid gas, water, charcoal, ammonia,
and some oily and acid matter: the char-
coal is in very large proportion. Pure
indigo, therefore, most probably consists
of carbon, oxygen, hydrogen, and azote.

Indigo owes its blue color to combina-
tion with oxygen. For the uses of the
dyers it is partly deprived of oxygen, by
digesting it with orpiment and lime water,
when it becomes soluble in the lime water,
and of a greenish color. Cloths steeped
in this solution combine with the indigo;
they are green when taken out of the
liquor, but become blue by absorbing
oxygen when exposed to air.

Indigo is one of the most valuable and
most extensively used of the dying ma-
terials.

10. The narcotic principle is found
abundantly in opium, which is obtained
from the juice of the white poppy [Papu-
rea album.)

To procure the narcotic principle, water
is digested upon opium: the solution ob-
tained is evaporated till it becomes of the
consistence of a syrup. By the addition
of cold water to this syrup, a precipitate
is obtained. Alcohol is boiled on this
precipitate ; during the cooling of the
alcohol, crystals fall down. These crystals
are to be again dissolved in alcohol, and
again precipitated by cooling : and the
process is to be repeated till their color is
white; they are crystals of narcotic prin-
ciple. The narcotic principle has no taste
nor smell. It is soluble in about 400
parts of boiling water ; it is insoluble in
cold water: it is soluble in 24 parts of
boiling alcohol, and in 100 parts of cold
alcohol. It is very soluble in all acid
menstrua.

It has been shown by De Rosne, that
the action of opium on the animal economy
depends on this principle. Many other
substances besides the juice of the poppy,
possess narcotic properties; but they have
not yet been examined with much atten-
tion, — The Lactuca sativa, or garden let-



126



COUNTERFEIT COINS.



tuce, and most of the other lactucas yield
a milky juice, which when inspissated has
the characters of opium, and probably con-
tains the same narcotic principle.

11. The hitter principle is very ex-
tensively diffused in the vegetable king-
dom; it is found abundantly in the hop
{Humiuhts lupilus ;) in the common
broom {^Spartiinn scopariimi;) in the
chamomile [Jintheniis noblis ;) and in
quassia, amara, and exrelsa. It is ob-
tained from those substances by the action
of water or alcohol, and evaporation. It
is usually of a pale yellow color; its taste
is intensely bitter. It is very soluble,
both in water and alcohol, and has little
or no action on alkaline, acid, saline or
metallic solution. An artificial substance,
similar to the bitter principle, has been
obtained by digesting diluted nitric acid,
on silk, indigo, and the wood of the white
willow. This substance has the property
of dying cloth of a bright yellow color; it
differs from the natural bitter principle in
its power of combining with the alkalies;
in union with the fixed alkalies it consti-
tutes crystallized bodies, which have the
property of detonating by heat or per-
cussion.

The natural bitter principle is of great
importance in the art of brewing; it checks
fermentation, and preserves fermented
liquors; it is likewise used in medicine.

The bitter principle, like the narcotic
principle, appears to consist principally
of carbon, hydrogen, and oxygen, with a
little azote.

12. Wax is found in a number of
vegetables; it is procured in abundance
from the berries of the wax-myrtle [My-
rica cerifera,) it may be likewise obtained
from the leaves of many trees; in its pure
state it is white. Its specific gravity is
9.662; it melts at 155 degrees; it is dis-
solved by boiling alcohol, but it is not
acted upon by cold alcohol; it is insoluble
in water; its properties as a combustible
body are well known.

The wax of the vegetable kingdom
seems to be precisely of the same nature
as that afforded by the bee.

From the experiments of M.M. Gay
Lussac and Thenard it appears that 100
parts of wax consist of —



Carbon 81.784

Oxogen 5.544

Hydrogen 12.672
or otherwise. Carbon 81.784

Oxygen and hydrogen in
the proportions neces-
sary to form water 6. 300
Hydrogen 11.916— which
agrees very nearly with 37 proportions
of hydrogen, 21 of charcoal, 1 of oxygen.



Fly {Hessian or wheat). — The follow-
ing are the remarks of Joseph Cooper,
Esq., of New Jersey, on the subject of
guarding wheat from this insect; after
stating the advantages of late sowing in
fertile soil, he says:

"/«?72 convinced, from the above and
other experiments, that if the farm,ers
all through a neighbourhood would
prevent us much us possible such grain
as is nutritive to the Hessian Fly from
vegetating in the period between harvest
and. the latter end of September, have
their land in a good state of cultivation,
and sow about the beginning of Oc-
tober, or even later, and of the kind of
grain which comes forward most rapid-
ly in the spring, they loould receive
little injury from wheat fly;^^ and as the
early Virginia wheat was produced from
a plant selected by an observant farmer
from his other wheat, there is no doubt
that other sorts of grain might be im-
proved by a selection of such particular
plants as ripen earliest and are superior
in other respects.



EASY METHOD OF DETECTING THE COUNTER-
FEIT COIN NOW IN CIRCULATION.

The following simple experiment, which
has laid the foundation of one of the most
splendid of modern sciences, readily ena-
bles any person to discover spurious coin.
Take a clean slip of common sheet zinc,
about two inches by one-half, and lay it
upon the tongue; place a genuine silver
coin under the tongue, and on bringing
the silver and zinc together a pungent
and disagreeable taste will be perceived.
Substitute now a coin suspected to be
counterfeit in place of the genuine coin,
and a very slight, if any, taste will be per-
ceived. The false coin of half dollars,
dimes, and half dimes, is made mostly of



SUPERIORITY OF ELASTIC CABLES.



127



German silver, and produces scarcely any
galvanic action with a piece of zinc. The
above test is almost infallible, and recom-
mends itself from its simplicity. — National



Intelligencer.



SWIFTNESS OF BIRDS.



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