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133



Sumatra, Borneo, and other of the
East India Isles. It has been obtained
from thyme {Thyi7ius serpillum,) mar-
jorum {Origanum viajorana,) gino;er
tree {Ammonium zingiber,) sage {Sulvis
officinalis.) Many volatile oils yield i
camphor by being merely exposed to the
air. An artificial substance very similar
to camphor has been formed by M. Kird,
by saturating oil of turpentine with
muriatic acid gas (the gaseous substance
procured from common salt by the action
of sulphuric acid.) The camphor pro-
cured in well conducted experiments
amounts to half of the oil of turpentine
used. It agrees with common camphor
in most of its sensible properties; but
differs materially in its chemical qualities
and composition. It it not soluble with-
out decomposition in nitric acid. From
the experiments of Gehlen, it appears to
consist of the elements of oil of turpentine,
carbon, hydrogen, and oxygen, united to
the elements of muriatic gas, chlorine,
and hydrogen.

From the analogy of artificial to natural
camphor, it does not appear improbable
that natural camphor may be a secondary
vegetable compound, consisting of cam-
phoric acid and volatile oil. Camphor
is used medicinally, but it has no other
application.

15. Fixed oil is obtained by expres-
sion from seeds and fruits ; the olive, the
almond, linseed, and rapeseed afford the
most common vegetable fixed oils. The
properties of fixed oils are well known.
Their specific gravity is less than that of
water; that of olive and of rapeseed
oil is 913; that of linseed and almond
oil 932; that of palm oil 968; that of
walnut and beechmast oil i)23. Many
of the fixed oils congeal at a lower
temperature than that at which water
freezes. They all require for their eva-
poration a higher temperature than that
at which water boils. The products of
the combustion of oil are water and car-
bonic acid gas.

From the experiments of Gay Lussac
and Thenard, it appears that olive oil
contains, in 100 parts,
Carbon - - - - _ 77.213

Oxygen 9.427

Hydrogen . - . . 13.3G0



This estimation is a near approxima-
tion to 11 proportions of carbon, 20 hy-
drogen, and 1 oxygen.

The following is a list of fixed oils, and
of the trees that afford them. — Olive oil,
from tiie olive tree [Olea Europea;) lin-
seed oil, from the common and perennial
flax [Linum usilalissinmm et perenne;)
nut oil, from the hazelnut (Cori/lhis
avellana ;) walnut {Juglans regia ;)
hemp oil, from the hemp {Cannabis sa-
liva;) almond oil, from the sweet al-
mond {Jlmygdalus communis:) beech
oil, from the common beech {Fagus syl-
vatica;) rapeseed oil, from the rapes
{Brassica napiis et campestris;) poppy
oil, from the poppy {Papaver SQrnnife-
rum;) oil of sesamum, from the sesamum
{Sesamiim, orientale;) cucumber oil,
from the gourds {Cucurbit apepo et ma-
lapepo;) oil of mustard {Sinapis nigra
et arvensis;) oil of sunflower, from the
annual and perennial sunflower {Helian-
thus annuus et perennis;) castor oil,
from the palma christi {Ricinus commu-
nis;) tobacco {Nicotiana tabacum et
ruslica;) plum kernel oil, from the plum
tree {Prunus domestica; grapeseed oil,
from the vine ( Vitis vinifera:) butter of
cocoa, from the cocoa tree {Theobram.a
cacoa;) laurel oil, from the sweet bay
tree {Laurus nobilis.)

The fixed oils are very nuti'itive sub-
stances; they are of great importance in
their applications to the purposes of life.
Fixed oil, in combination with soda,
forms the finest kind of hard soap. The
fixed oils are used extensively in the
mechanical arts, and for the preparation
of pigments and varnishes.

16. Volatile o«7, likewise called essen-
tial oil, differs from fixed oil, in being
capable of evaporation by a much lower
degree of heat; in being soluble in al-
cohol, and in possessing a very slight
degree of solubility in water.

There is a great number of volatile
oils, distinguished by their smell, their
taste, and their specific gravity, and other
sensible qualities. A strong and peculiar
odor may however be considered as the
great characteristic of each species; the
volatile oils inflame with more facility than
the fixed oils, and afford by their com bus-



134



SIR H. DAVY S AGRICULTURAL CHEMISTRY.



tion different proportions of the same sub-
stances, water, carbonic acid, and car-
bon.

The following specific grnvitics of the
different volatile oils were ascertained by
Dr. Lewis.

Oil of Sassafras - - - 1094
Cinnamon ^ - - lo35
Cloves - - - 1034

Fennel - - - 997

Dill - - - - 994
Penny royal - - 97S

Cummin - - _ 975
Mint - ... 975
Nutmegs - - - 948
Tansy - - ' - - 94G
Caraway - - _ 940
Criganum - - - 940
Spike - - - - 936
Rosemary ... 934
Juniper - - - 911

Oranges - . - 888
Turpentine - - - 792
The peculiar odors of plants seem, in
almost all cases, to depend on the peculiar
volatile oils they contain. All the per-
fumed distilled waters owe their peculiar
properties to the volatile oils they hold
in solution. By collecting the aromatic
oils, the fragrance of flowers, so fugitive
in the common course of nature, is as it
were, embodied and made permanent.

It cannot be doubted that the volatile
oils consist of carbon, hydrogen, and
oxygen ; but no accurate experiments
have as yet been made on the proportions
in which these elements are combined.

The volatile oils have never been used
as articles of food; many of them are
employed in the arts, in the manufacture
of pigments and varnishes; but their most
extensive application is as perfumes.

17. Woody fibre is procured from the
wood, bark, leaves, or flowers of trees by
exposing them to the repeated action of
boiling water and boiling alcohol. It is
the insoluble matter that remains, and is
the basis of the solid organized parts of
plants. There are as many varieties of
woody fibre as there are plants and organs
of plants; but they are all distinguished
by their fibrous texture, and their in-
solubility.

Woody fibre burns with a yellow flame,
and produces water and carbonic acid in



burning. When it is distilled in close
vessels, it yields a considerable residuum
of charcoal. It is from woody fibre, in-
deed, that charcoal is procured for the
purposes of life.

The following table contains the results
of experiments made by Mr. Mushet, on
the quantity of charcoal afforded by the
different wood.

100 parts of Lignum vitas 26.8 charcoal.
Mahogany 25.4 "
Laburnum 24.5 "
Chestnut 23.2 "

Oak 22.6 "

American black

beech 21.4 "

Walnut 20.60 "

Holly 19.9 «

Beech 19.9 "

A meric. maple 19.9 "
Elm 19.5 "

Norway pine 19.2 "
Sallow 18.4 «

Ash 17.9 "

Birch 17.4 "

Scottish fir 16.4 "
MM. Gay Lussac and Thenard have
concluded from their experiments on the
wood of the oak and the beech, that 100
parts of the first contain :
Of Carbon - . . . 52.53

Oxygen - - _ _ 41.78
Hydrogen - - - - 5.69
and 100 parts of the second :
Of Carbon - - . . 51.45

Oxygen - - - - 42.73
Hydrogen - - - - 5.82
Supposing woody fibre to be a definite
compound these estimations lead to the
conclusion, that it consists of 5 propor-
tions of carbon, 3 of oxygen, and 6 of
hydrogen, or 57 carbon, 45 oxygen, and
6 hydrogen.

It will be unnecessary to speak of the
applications of woody fibre. The dif-
ferent uses of the woods, cotton, the barks
of trees, are sufficiently known. Woody
fibre appears to be an indigestible sub-
stance.

18, The acids found in the vegetable
kingdom are numerous ; the true vege-
table acids, which exist ready formed in
the juices or organs of plants, are the
oxalic, citric, tartaric, benzoic, acetic,
malic, galic, and prussic acid.



ON PROPAGATING FRUIT TREES BY ABSCISION.



135



A NEW SPECIES OP ROOF.
Continued from page l4.

The roofs are much flatter than for
slating, (thecommon proportion being one
.foot in height to twelve in breadth,) the
couples are no more than three inches in
breadth by one and a half deep, and upon
these are laid half inch deals, dressed
with a plane on the edges, so as to pre-
vent intervals at the joints; and the ex-
ternal covering is sheathing paper. The
sheets are prepared by being dipped in
tar, at nearly the boiling point, that it
may the more readily penetrate, and
after drying for two days, are again dip-
ped in tar at a lower temperature ; they are
then nailed on the roof in the same man-
ner as slates, overlapping each other ex-
actly in the same manner; and, above the
whole is laid a coat of tar, boiled to the
consistency of pitch, on which fine smithy
ashes are passed through a seive while
cooling to diminish the combustibility,
and to prevent the liquefaction of the
tar. Mr. William Ramsey, a chemist, of
Glasgow, is related to have used, instead
of common tar, the tar extracted from
wood, in the formation of pyroligneous
acid, and, by a peculiar composition, to
have made it assume as close a texture
and as bright a polish as marble.

Observations. — The species of roof
here described, will soon be extensively
adopted where wood and slates are
scarce, provided its durability can be
ascertained. The building in Greenock,
thus roofed, which has lasted twenty
years, affords a presumption in its favor;
"but we cannot recommend it till it has
stood the test of repeated experiments.



MANGANESE USED IN THE MANUFACTURE
OP IRON AND STEEL.

In the Annales de Chimie, M. Gaze-
ran has given a paper on the subject, in
which he states that in the German
founderies, particularly about Nassau-
Siegen they used the black oie of manga-
nese with the iron ore in making steel;
he advises that from 4 to 5 per cent, of
manganese should be mixed with the ores
that do not contain it naturally, and states
that the best German steel contains 2.16
per cent, of manganese and 1 of carbon.
It is proposed to use manganese with iron



stone in the manufacture of crude iron, •"
various proportions according to the na-
ture of the ore.



It



PROPAGATING FRUIT TREES BY
ABSCISION.
Continued from page 15.

is conceived that a longer period
would be necessary to succeed with this
operation in Europe, because vegetation
is so much slower here than in India,
where Dr. Howison, made his experi-
ments; but he thinks that an additional
month would be adequate to make up
for the deficiency of climate.

The advantages of this method are
stated to be, that a farther growth of
three or four years is sufFicient, when
the branches are of any considerable size
to bring them to their full bearing state;
whereas, eight or ten )'ears would be
otherwise necessary. This he saw prov-
ed from experiment at Prince of Wales*
Island. The writer's experience does not
allow him to speak of the success with
which this method might be applied to
forest trees, but he little doubts of its
succeeding, and the adoption of it is re-
commended at all events in multiplying
such plants, natives of warmer climates,
whose seeds do not come to maturity in
this country. He has besides frequent!}"
remarked that such branches of fruit-trees
as were under the operation of abscision
at the time of bearing, were more laden
with fruit than the rest of the tree,
which is attributed to a plethora or ful-
ness, occasioned by the communication
between the branches and trunk being
cut off by the division of the bark, and
has observed that the roots from a branch
under this operation were longer in
shooting into the ball of straw when the
tree was in leaf, than at another time, on
which account he recommends the spring
as the best season for makingexperiments.

Observations. — This mode of jiropa-
gating trees, which prevails in many parts
of Eastern Asia, is deserving the notice
of our horticulturists at home; and from
the prevailing inclination to pursue that
branch of science, we have no doubt of
being soon able to communicate experi-
ments of this mode of propagation in our
own country.



136



DESCRIPTION OF A FORCING (hOt) HOUSE.



FALSE GILDING AND WHITE-WASHING.

CoMtiniied troin page 15.

The paper thus gilded, is cut into the
shape of the flowers, and pasted on the
walls or columns. The interstices are
filled up with oil-colors; the oil for which
is composed of two parts of linseed oil,
and one of the above mentioned clastic
gum.

At Seringapatam they cover the (chu-
nam) stucco of their walls with a thin
coat of (suday) fine clay, mixed with
size; then a coating of (balapum) pulver-
ized potstone; and finish the wall with a
coating of eight parts of vcr}'^ fine ground
(abracum) mica, with one of pulverized
potstone, anfj one of size. The wall thus
treated, shines like the scales of fishes,
and has a splendid appearance when
lighted up; but, in the day-time, walls
covered with potstone alone look better.



ON THE PRESERVATION OF ANIMAL
SUBSTANCES.

The Chinese are said to prepare their
pork for travelling by pressing out the
juices, and the preparation of brawn is
somewhat similar. If meat were sub-
jected to the action of a screw-press, or,
where that machine is wanting, or a
greater pressure required, it may be
placed between iron plates in a frame of
wood, and the plates brought closer by
wedges, on the principle of an oil mill.
Experiment would soon determine the
necessary pressure for preserving it for
any limited time, without much injury
to its being: dressed as usual.



CAUSES OF THE DECAY OF WOOD, AND
THE MEANS OF PREVENTING IT.

In the Bath Society's papers, Dr. Par-
ry has suggested the cause of decay in
timber, viz : heat and moisture, and pro-
poses that drying oils, either by them-
selves or boiled with metallic oxides, be
used to form & coat to exclude the mois-
ture. As an additional strength to this
varnish, he proposes a mixture of sile-
cious or flinty sand with it; this sand
may be easily procured from the sea-
side, and the currants of roads and rivers;
in using it, however, it should be first
cleared from all saline impregnations, by
washing in several waters, and any sand



may be obtained of any fineness desired'
by mixing it with water in a tub, and
after having stirred the whole well to-
gether, pouring out the muddy (turbid)
water, from which the sand will settle,
by its own gravity, in a state fit for use,
when dried.

Jlnother process recommended, is to
cover the wood with a coat of drying oil,
and immediately drege the coat with a
layer of charcoal, finely pulverized or
powdered, and contained in muslin, and
in a day or two, brushing off what is
loose, and giving the surface a coat of
paint in the usual manner; this forms a
firm and solid crust.

Dry rot is supposed to be produced
by moisture, also combined with a cer-
tain temperature, and a preparation of a
resinous kind, mixed with a certain pro-
portion of bees-wax, is recommended as
a preventive. The proportion of ingre-
dients, and the mode of mixing them,
recommended, are as follows: "Take 12
ounces of rosin, and 8 ounces of roll
brimstone, each coarsely powdered, and
3 gallons of train oil; heat them slowly,
gradually adding 4 ounces of bees-wax,
cut in small bits; frequently stir the li-
quor, which, as soon as the solid ingre-
dients are dissolved, will be fit for use."

It is recommended to dress every part
of wood work, with this composition,
twice over before the parts are put to-
gether, and once afterwards.

While preparing the varnish, it is re-
commended that an earthen vessel be
employed, and that the fire be made in
the open air, for whenever oil is brought
to the boiling point, 600° of Fahrenheit's
thermometer, the vapor immediately
catches fire, and though a lower degree
of temperature than that of boiling should
be used in the process; it is not always
practicable to regulate the heat, or to pre-
vent the overflowing of the materials; in
either of which cases the melting within
doors would be dangerous.



DESCRIPTION OF A FORCING (hOt) HOUSE.

Mr. T. A. Knight pronounces the best
form for the glass roof is that where ij
the rays from the sun fall perpendicu- ^
larly on the root, and as the rays fall
most powerfully on the root when the



ON A METHOD OF TRAINING FRUIT TREES.



137



light comes almost perpendicularly on
the glass, it is important to know by
what elevation of the roof the greatest
quantity of light can be made to pass
through it. Toascertain thispoint,hemade
many experiments, and the result of them
has satisfied him that that the best eleva-
tion in the latitude of 52 degrees, is about
that of 34 degrees, considering the dif-
ferent periods of the year. The vinery
which he has made, is placed at this ele-
vation, and the building, which is forty
feet long, is heated by a single fire place;
the flue goes entirely round without
touching the walls, and in the front, a
space of two feet is left between the flue
and the wall, in the middle of which
space the vines, which are trained to
the roofs, about eleven inches from
the glass, are planted; and as both the
wall and the flue are placed on arches,
the vines are enabled to extend their
roots in every direotion, the air is
usually admitted at the ends only, where
all the sashes are made to slide, but in
the roof only about four feet of the
upper end of every third light is made
to Jift up by hinges, to give air in the
event of very hot, and calm weather, and
this method of giving air is preferred to
the usul one of letting the lights slide
down, because when the former plan is
adopted, no additional shade is thrown
upon the plants.

He recommends that no upright glass
be used, and that, where the roof is ex-
tended, the front part of the interior of
the building may be made sufficiently
low at the floor to give the required room
between that and the roof.

Mr, Knight uses the following sub-
stances to stop the bleeding of vines
when pruned, viz: Four parts of scraped
cheese, and one of calcined oyster shells,
and presses this composition sti'ongly into
the pores of the wood, and it instantly
stops the flowing of the sap; the largest
branches may, of course, be taken ofi" at
any season of the year with safety.

Remarks, — Agreeably to the princi-
ples above stated, which appear to be
founded on the immutable laws of optics,
the elevation most proper for the roof of
a forcing house, may be easily ascertain-
ed in any latitude, by placing it so that



the rays of the sun shall pass through the
glass at about the same relative direction
as that above described.



ON A METHOD OP TRAINING FRUIT
TREES.

The account which is here given by
Mr. Knight, is confined to the Peach-
tree, though he thinks thatthe same mode,
with a little variation, is applicable, even
with superior advantages to the cherry,
plum, and pear; and observes, that
when trees by any means are de-
prived of the motion which their branches
naturally receive from winds, the forms
in which they are trained operate more
powerfully on theirpermanent health and
vigor than is generally imagined.

The peach-trees which are the subject
of this paper were plants of one year old
only, and were headed down as usual
early in the spring, and two shoots only
were trained from each stem in opposite
directions, and in an elevation of above
five degrees; and when either of the
two shoots did not grow with equal luxu-
riance, Mr. K. either depressed the
strongest or gave a greater elevation to
the weakest; by whicli means both were
made to acquire, and to preserve an equal
degree of vigor. These shoots grew
with great luxuriance, as they received
the whole sap of the plant, and in the
pourse of the summer attained the length
of four feet. Many lateral shoots being
also emitted from the luxuriant branches,
which however were all pinched off'at the
second leaf, and in the succeeding winter
were pruned down close. This form, it
is observed, might be advantageously
given to trees in the nursery, as it would
require very little trouble .or expense.

As many branches were suffered to
spring from each shoot in the succeeding
season as could be conveniently trained
without shading each other; and by se-
lecting the strongest and earliest buds to-
wards the points of the last year's
branches, and the weakest and latest near
their base, nearly an equal degree of
vigor was obtained to each shoot in the
year, and by this method also a greater
surface -of leaf was exposed to the light,
without placing any of the leaves so as to
shade others, than could have been effect-



138



ox A METHOD OF TRAINING FRUIT TREES.



ed by any other method of training; and
the growth of the trees was so great from
this arrangement that some of them at
two years old were fifteen feet wide, and_
the young acquired in every part the
most perfect maturity. In the succeed-
ing winter the shoots of the last season
were alternately shortened and left their
whole length, and were then prepared to
afford an abundant and regular blossom
in the succeeding spring. In theautunm
of the third year the shoots of the inter-
nal branches were trained backwards from
the original shoots so that the central part
of each tree was formed of fine bearing
wood; and the size and general health of
the trees afforded evidence of a more re-
gular distribution of the sap than Mr.
Knight had witnessed in any other mode
of training.

It is remarked, tliat in this method of
pruning, little use was made of the knife
during the winter; and, Mr. Knight con-
ceives that winter pruning should be
avoided as much as possible, for the only
advantage gained by laying in a larger
quantity of wood in the summer and au-
tumn, than will be wanted in the spring,
is the choice of good shoots, and there is
no advantage in having more than are
wanted; whereas the health of the tree
always suffers by too much use of the
knife through successive seasons.

As entering into the details of pruning
an the most advantageous manner would
lead him beyond his intended limits, he
merely avails himself of the opportunity
to offer a few observations on the proper
treatment of luxuriant shoots of the
peach-tree; a subject not understood by
either English or foreign writers on
gardening.

Referring to a paper, communicated
by him to the Royal Society, on the
Alburnum or sap of trees, he conceives
that the facts detailed there afford suffi-
cient evidence that the Alburnum of
trees becomes, during winter, a reservoir
of the sap or blood of the tree, as the
bulb of the hyacinth, tulip, and potatoe,
certainly do of the sap or blood of those
plants. Now, a wall tree, from the
advantageous position of its leaves, pro-
bably generates more sap than a standard



tree of the same size, so that the gardener
is compelled to destroy a large portion of
the succulent shoots; the sap in conse-
quence stagnates, and appears to choke
tiie passages through the small branches,
which consequently becomes incurably
unhealthy and stunted in their growth, '
and nature affords means of relief by dis-
tributing the sap in the production of
luxuriant shoots. These shoots, all hor-
ticultural writers have directed to be
shortened in summer, but Mr. Knight,
has found great advantages in leaving
them unshortened, as they have uniformly
produced the finest possible bearing wood
for the succeeding year, arid that the
laterals from these shoots, if stopped at
the first leaf, will often afford strong
blossoms and fine fruit, the succeding sea-
son. He thinks that a luxuriant shoot
should rarely or never be cut out or
shortened, where space for training it can
be found, but it should never be trained
in a perpendicular direction.

Observations. — The intimate know-
ledge which this writer possesses of the
operations of nature in the vegetable crea-
tion, entitles all his suggestions on horti-
cultural subjects to the greatest attention.
The mode of pruning recommended in
this paper, appears to possess all the
advantages attributed to it, besides that
of bringing a fruit-tree into a bearing
state one or two years earlier than by the
common method. For the propriety of
the treatment recommended for the luxu-
riant shoots of the peach-tree, we can
offer our own experience for six or seven
seasons, and the result has uniformly
been, that the trees not only ceased to
produce such shoots (whereas they had
only been multiplied by amputation,) but
have continued to produce fine healthy
bearing wood, and a profusion of blossom
and fruit. As soonasany branch assumes
a more luxuriant appearance than its
neighbors it should be trained if possible
below a horizontal position.

Note. — If fruit trees were trained suffi-
ciently near the ground so as to be cover-



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