FAT OIL MANUFACTURE._A Dictionary of Arts, Manufactures and Mines containing a clear exposition of their principles and practice

It is the practice of almost all the proprietors in the neighbourhood of

Aix, in Provence, to preserve the olives for 15 days in barns or

cellars, till they have undergone a species of fermentation, in order to

facilitate the extraction of their oil. If this practice were really

prejudicial to the product, as some theorists have said, would not the

high reputation and price of the oil of Aix have long ago suffered, and

have induced them to change their system of working? In fact all depends

upon the degree of fermentation excited. They must not be allowed to

mould in damp places, to lie in heaps, to soften so as to stick to each

other, and discharge a reddish liquor, or to become so hot as to raise a

thermometer plunged into the mass up to 96° F. In such a case they would

afford an acrid nauseous oil, fit only for the woollen or soap

manufactories. A slight fermentative action, however, is useful, towards

separating the oil from the mucilage. The olives are then crushed under

the stones of an edge-mill, and next put into a screw-press, being

enclosed in bullrush-mat bags (_cabas_), laid over each other to the

number of eighteen. The oil is run off from the channels of the

ground-sill, into casks, or into stone cisterns called _pizes_,

two-thirds filled with water. The pressure applied to the _cabas_ should

be slowly graduated.

What comes over first, without heat, is the virgin oil already

mentioned. The _cabas_ being now removed from the press, their contents

are shovelled out, mixed with some boiling water, again put in the bags,

and pressed anew. The hot water helps to carry off the oil, which is

received in other casks or _pizes_. The oil ere long accumulates at the

surface, and is skimmed off with large flat ladles; a process which is

called _lever l’huile_. When used fresh, this is a very good article,

and quite fit for table use, but is apt to get rancid when kept. The

subjacent water retains a good deal of oil, by the intervention of the

mucilage; but by long repose in a large general cistern, called

_l’enfer_, it parts with it, and is then drawn off from the bottom by a

plug-hole. The oil which remains after the water is run off, is of an

inferior quality, and can be used only for factory purposes.

The marc being crushed in a mill, boiled with water, and expressed,

yields a still coarser article.

All the oil must be _fined_ by keeping in clean tuns, in an apartment,

heated to the 60th degree Fahr. at least, for twenty days; after which

it is run off into strong casks, which are cooled in a cellar, and then

sent into the market.

_Oil of almonds_, is manufactured by agitating the kernels in bags, so

as to separate their brown skins, grinding them in a mill, then

enclosing them in bags, and squeezing them strongly between a series of

cast iron plates, in a hydraulic press; without heat at first, and then

between heated plates. The first oil is the purest, and least apt to

become rancid. It should be refined by filtering through porous paper.

Next to olive oil, this species is the most easy to saponify. Bitter

almonds being cheaper than the sweet, are used in preference for

obtaining this oil, and they afford an article equally bland, wholesome,

and inodorous. But a strongly scented oil may be procured, according to

M. Planché, by macerating the almonds in hot water, so as to blanch

them, then drying them in a stove, and afterwards subjecting them to

pressure. The volatile oil of almonds is obtained by distilling the marc

or bitter almond cake, along with water. See PRESS, HYDRAULIC, and

STEARINE.

Linseed, rapeseed, poppyseed, and other oleiferous seeds were formerly

treated for the extraction of their oil, by pounding in hard wooden

mortars with pestles shod with iron, set in motion by cams driven by a

shaft turned with horse or water power, then the triturated seed was put

into woollen bags which were wrapped up in hair-cloths, and squeezed

between upright wedges in press-boxes by the impulsion of vertical rams

driven also by a cam mechanism. In the best mills upon the old

construction, the cakes obtained by this first wedge pressure, were

thrown upon the bed of an edge-mill, ground anew, and subjected to a

second pressure, aided by heat now, as in the first case. These mortars

and press-boxes constitute what are called Dutch mills. They are still

in very general use both in this country and on the Continent; and are

by many persons supposed to be preferable to the hydraulic presses.

[Illustration: 770 771]

The roller-mill, for merely bruising the linseed, &c., previous to

grinding it under edge-stones, and to heating and crushing it in a Dutch

or a hydraulic oil-mill, is represented in _figs._ 770. and 771. The

iron shaft _a_, has a winch at each end, with a heavy fly-wheel upon the

one of them, when the machine is to be worked by hand. Upon the opposite

end is a pulley, with an endless cord which passes round a pulley on the

end of the fluted roller _b_, and thereby drives it. This fluted roller

_b_, lies across the hopper _c_, and by its agitation causes the seeds

to descend equably through the hopper, between the crushing rollers _d_,

_e_. Upon the shaft _a_, there is also a pinion which works into two

toothed wheels on the shafts of the crushing cylinders _d_ and _e_, thus

communicating to these cylinders motion in opposite directions. _f_, _g_

are two scraper-blades, which by means of the two weights _h_, _h_,

hanging upon levers, are pressed against the surfaces of the cylinders,

and remove any seed-cake from them. The bruised seeds fall through the

slit _i_ of the case, and are received into a chest which stands upon

the board _k_.

Machines of this kind are now usually driven by power. Hydraulic presses

have been of late years introduced into many seed-oil mills in this

country; but it is still a matter of dispute whether they, or the old

Dutch oil-mill, with bags of seed compressed between wedges, driven by

cam-stamps, be the preferable; that is, afford the largest product of

oil with the same expenditure of capital and power. For figures of

hydraulic presses, see PRESS, and STEARINE.

This bruising of the seed is merely a preparation for its proper

grinding under a pair of heavy edge-stones, of granite, from 5 to 7 feet

in diameter; because unbruised seed is apt to slide away before the

vertical rolling wheel, and thus escape trituration. The edge-mill, for

grinding seeds, is quite analogous to the gunpowder-mill represented in

_fig._ 531., page 630. Some hoop the stones with an iron rim, but others

prefer, and I think justly, the rough surface of granite, and dress it

from time to time with hammers, as it becomes irregular. These stones

make from 30 to 36 revolutions upon their horizontal bed of masonry or

iron in a minute. The centre of the bed, where it is perforated for the

passage of the strong vertical shaft which turns the stones, is enclosed

by a circular box of cast iron, firmly bolted to the bed-stone, and

furnished with a cover. This box serves to prevent any seeds or powder

getting into the step or socket, and obstructing the movement. The

circumference of the mill-bed is formed of an upright rim of oak-plank,

bound with iron. There is a rectangular notch left in the edge of the

bed, and corresponding part of the rim, which is usually closed with a

slide-plate, and is opened only at the end of the operation, to let the

pasty seed-cake be turned out by the oblique arm of the bottom scraper.

The two parallel stones, which are set near each other, and travel round

their circular path upon the bed, grind the seeds not merely by their

weight, of three tons each, but also by a rubbing motion, or attrition;

because their periphery being not conical, but cylindrical, by its

rolling upon a plane surface, must at every instant turn round with

friction upon their resting points. Strong cast-iron boxes are bolted

upon the centres of the stones, which by means of screw clamps seize

firmly the horizontal iron shafts that traverse and drive them, by

passing into a slit-groove in the vertical turning shaft. This groove is

lined with strong plates of steel, which wear rapidly by the friction,

and need to be frequently renewed.

The seeds which have been burst between the rolls, or in the mortars of

the Dutch mills, are to be spread as equably as possible by a shovel

upon the circular path of the edge-stones, and in about half an hour the

charge will be sufficiently ground into a paste. This should be put

directly into the press, when fine cold-drawn oil is wanted. But in

general the paste is heated before being subjected to the pressure. The

pressed cake is again thrown under the edge-stones, and, after being

ground the second time, should be exposed to a heat of 212° Fahr., in a

proper pan, called a steam-kettle, before being subjected to the second

and final pressure in the woollen bags and hair-cloths.

[Illustration: 772 773]

_Fig._ 772. is a vertical section of the steam-kettle of Hallette, and

_fig._ 773. is a view of the seed-stirrer. _a_, is the wall of masonry,

upon which, and the iron pillars _b_, the pan is supported. It is

enclosed in a jacket, for admitting steam into the intermediate space

_d_, _d_, _d_, at its sides and bottom. _c_, is the middle of the pan in

which the shaft of the stirrer is planted upright, resting by its lower

end in the step _e_; _f_, is an opening, by which the contents of the

pan may be emptied; _g_, is an orifice into which the mouth of the hair

or worsted bag is inserted, in order to receive the heated seed, when it

is turned out by the rotation of the stirrer and the withdrawal of the

plug _f_ from the discharge aperture; _h_, is the steam induction pipe;

and _t_, the eduction pipe, which serves also to run off the condensed

water.

The hydraulic oil-press is generally double; that is, it has two

vertical rams placed parallel to each other, so that while one side is

under pressure, the other side is being discharged. The bags of heated

seed-paste or meal are put into cast-iron cases, which are piled over

each other to the number of 6 or 8, upon the press sill, and subjected

to a force of 300 or 400 tons, by pumps worked with a steam engine. The

first pump has usually 2 or 2-1/2 inches diameter for a ram of 10

inches, and the second pump one inch. Each side of the press, in a

well-going establishment, should work 38 pounds of seed-flour every 5

minutes. Such a press will do 70 quarters of linseed in the days’ work

of one week, with the labour of one man at 20_s._ and three boys at

5_s._ each; and will require a 12-horse power to work it well, along

with the rolls and the edge-stones.

I am indebted to my excellent friend Mr. E. Woolsey, for the following

most valuable notes, taken by him at sundry mills for pressing oil; and

remarks upon the subject of seed-crushing in general.

“The chief point of difference depends upon the quality of seed

employed. Heavy seed will yield most oil, and seed ripened under a hot

sun, and where the flax is not gathered too green, is the best. The

weight of linseed varies from 48 to 52 lbs. per imperial bushel;

probably a very fair average is 49 lbs., or 392 lbs. per imperial

quarter. I inspected one of the seed-crusher’s books, and the average of

15 trials of a quarter each of different seeds in the season averaged

14-1/2 galls. of 7-1/2 lbs. each; say, 109 lbs. of oil per quarter. This

crusher, who uses only the hydraulic press, and one pressing, informed

me that

Archangel seed will yield

from 15 to 16 galls. (of 7-1/2 lbs. each)

Best Odessa 18 and even 19 galls.

Good crushing-seed 15-1/2 do.

Low seed, such as weighs 48

lbs. per bushel 13-1/2 do.

“The average of the seed he has worked, which he represents to be of an

inferior quality, for the sake of its cheapness, yields 14-1/2 galls.

per quarter. I had some American seed which weighed 52-1/4 lbs. per

imperial bushel, ground and pressed under my own observation, and it

gave me 111 lbs. oil; that is to say, 418 lbs. of seed gave 111 lbs. oil

= 26-56/100 per cent. A friend of mine, who is a London crusher, told me

the oil varied according to the seed from 14 to 17 galls.; and when you

consider the relative value of seeds, and remember that _oil_ and _cake_

from any kind of seed is of the _same value_, it will be apparent that

the yield is very different; for example,

25th July, 1836, {E. India linseed worth 52_s._ per quarter.

prices of seed. {Petersburg linseed 48 to 52 do.

{Odessa 52 -- --

The difference of 4_s._ must be paid for in the quantity of oil which at

38_s._ 6_d._ per cwt. (the then price) requires about 11-1/2 lbs. more

oil expressed to pay for the difference in the market value of the seed.

Another London crusher informed me that East India linseed will produce

17 gallons, and he seemed to think that that was the extreme quantity

that could be expressed from _any seed_. The average of last year’s

Russian seed would be about 14 galls.; Sicilian seed 16 galls.

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“_Rape-seed._--I have not turned my attention to quantity of oil

extracted from this seed; but a French crusher (M. Geremboret), on whom

I think one may place considerable dependence, told me, that

3-1/2 lbs. of best Cambray rape-seed yielded 1 lb. oil.

3-3/4 -- common rape-seed 1 lb. oil.

4-1/4 -- -- poppy-seed 1 lb. oil.

“Rape-seed weighs from 52 to 56 lbs. per imperial bushel.”

The following are the heads of a reference of machinery for a seed

oil-mill:--

1. Two pairs of cast-iron rollers, 19 inches long, and 10 inches in

diameter, fixed in a cast-iron frame, with brasses, wheels, shafts,

bolts, scrapers, hoppers, shoes, &c.

2. Two pairs of edge-stones, 7 feet diameter each, with two bottom

stones, 6 feet diameter each, cast-iron upright shafts, sweepers,

wheels, shafts, chairs, brasses, bolts, and scrapers, with driving

spur-wheels, &c.

3. Five steam kettles, with wheels, shafts, and brasses, bolts,

breeches, and steam pipes, an upright cast-iron shaft, with chairs and

brasses at each end; and a large bevel wheel upon the bottom end of

upright shaft, and another, smaller, upon fly-wheel shaft, for the first

motions.

4. Five stamper presses, with press plates of cast iron, cast-iron

stamper shaft with 10 arms and 10 rollers, with bosses, brasses, bolts,

driving bevel-wheels.

A well made oil-mill, consisting of the above specified parts, will

manufacture 200 quarters of seed per week.

I have been assured by practical engineers, conversant in oil-mills,

that a double hydraulic press, with 2 ten-inch rams, will do the work of

no more than two of the stamper presses; that is to say, it will work 22

quarters in 24 hours; while three stamper presses will work 33 quarters

in the same time, and produce one half more oil.

_Castor oil, quantity of_,

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| 1835. |1,109,307| 670,205 | 61,296 |

| 1836. | 981,585| 809,559 | 68,515 |

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Duty, from British possessions, 2_s._ 6_d._ per cwt.; from foreign,

1_s._ per lb.

_Cocoa-nut oil, quantity of,_

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| 1835. | 19,838 | 14,015 | 2,238 |

| 1836. | 26,058 | 26,062 | 3,158 |

| 1837. | 41,218 | 28,836 | |

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_Olive oil, quantity of,_

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| 1835. | 606,166| 554,196 | 283,734 |

| 1836. |2,682,016| 1,844,622 | 150,561 |

| 1837. |1,720,397| 1,499,122 | |

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Duties on olive oil, not of Naples and Sicily, 4_d._; of Naples and

Sicily, 8_d._; and, if in ships of these countries, 10_d._ per gallon.

_Train oil, spermaceti, and blubber, quantity of,_

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| 1835. | 24,197 | 16,114 | 8,035 |

| 1836. | 19,489 | 18,722 | 1,365 |

| 1837. | 21,823 | 21,286 | |

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Duties on oil taken by British ships, 1_s._; by foreign fishers, _£_26

18_s._ per tun.

OILS, VOLATILE OR ESSENTIAL; Manufacture of. The volatile oils occur in

every part of odoriferous plants, whose aroma they diffuse by their

exhalation; but in different organs of different species. Certain

plants, such as thyme and the scented _labiatæ_, in general contain

volatile oil in all their parts; but others contain it only in the

blossoms, the seeds, the leaves, the root, or the bark. It sometimes

happens that different parts of the same plant contain different oils;

the orange, for example, furnishes three different oils, one of which

resides in the flowers, another in the leaves, and a third in the skin

or epidermis of the fruit. The quantity of oil varies not only with the

species, but also in the same plant, with the soil, and especially the

climate; thus in hot countries it is generated most profusely. In

several plants, the volatile oil is contained in peculiar orders of

vessels, which confine it so closely that it does not escape in the

drying, nor is dissipated by keeping the plants for many years. In other

species, and particularly in flowers, it is formed continually upon

their surface, and flies off at the moment of its formation.

Volatile oils are usually obtained by distillation. For this purpose the

plant is introduced into a still, water is poured upon it, and heat

being applied, the oil is volatilized by the aid of the watery vapour,

at the temperature of 212°, though when alone it would probably not

distil over unless the heat were 100° more. This curious fact was first

explained in my _New Researches upon Heat_, published in the

Philosophical Transactions for 1818. Most of the essential oils employed

in medicine and perfumery are extracted by distillation from dried

plants; only a few, such as those of the rose and orange flower, are

obtained, from fresh or succulent salted plants. When the mingled

vapours of the oil and water are condensed into the liquid state, by the

refrigerator of the still, the oil separates, and either floats on the

surface or sinks to the bottom of the water. Some oils of a less

volatile nature require a higher heat than 212° to raise them in vapour,

and must be dislodged by adding common salt to the water, whereby the

heat being augmented by 15°, they readily come over. If in such

distillations too much water be added, no oil will be obtained, because

it is partially soluble in water; and thus merely an aromatic water is

produced. If on the other hand too little water be used, the plant may

happen to adhere to the bottom of the still, get partially charred, and

thus impart an empyreumatic odour to the product. But as the quality of

water distilled depends less upon the quantity employed, than upon that

of the surface exposed to the heat, it is obvious that by giving a

suitable form to the still, we may get rid of every inconvenience. Hence

the narrower and taller the alembic is, within certain limits, the

greater will be the proportion of oil relative to that of the aromatic

water, from like proportions of aqueous and vegetable matter employed.

Some place the plants in baskets, and suspend these immediately over the

bottom of the still under the water, or above its surface in the steam.

But the best mode in my opinion is to stuff an upright cylinder full of

the plants, and to drive down through them, steam of any desired force;

its tension and temperature being further regulated by the size of the

outlet orifice leading to the condenser. The cylinder should be made of

strong copper tinned inside, and encased in the worst conducting species

of wood, such as soft deal or sycamore.

The distillation is to be continued as long as the water comes over of a

milky appearance. Certain plants yield so little oil by the ordinary

processes, notwithstanding every care, that nothing but a distilled

water is obtained. In this case, the same water must be poured upon a

fresh quantity of the plants in the still; which being drawn over, is

again to be poured upon fresh plants; and thus repeatedly, till a

certain dose of oil be separated. This being taken off, the saturated

water is reserved for a like distillation.

The refrigeratory vessel is usually a worm or serpentine plunged in a

tub of water, whose temperature should be generally cold; but for

distilling the oils of anise-seed, fennel, &c., which become concrete at

low temperatures, the water should not be cooler than 45° F.

The liquid product is commonly made to run at the worm end, into a

vessel called an Italian or Florentine receiver, which is a conical

matrass, standing on its base, with a pipe rising out of the side close

to the bottom, and recurved a little above the middle of the flask like

the spout of a coffee-pot. The water and the oil collected in this

vessel soon separate from each other, according to their respective

specific gravities; the one floating above the other. If the water be

the denser, it occupies the under portion of the vessel, and continually

overflows by the spout in communication with the bottom, while the

lighter oil is left. When the oil is the heavier of the two, the

receiver should be a large inverted cone, with a stopcock at its apex to

run off the oil from the water when the separation has been completed by

repose. A funnel, having a glass stopcock attached to its narrow stem,

is the most convenient apparatus for freeing the oil finally from any

adhering particles of water. A cotton wick dipped in the oil may also

serve the same purpose by its capillary action. The less the oil is

transvased the better, as a portion of it is lost at every transfer. It

may occasionally be useful to cool the distilled water by surrounding it

with ice, because it thus parts with more of the oil with which it is

impregnated.

There are a few essential oils which may be obtained by expression, from

the substances which contain them; such as the oils of lemons and

bergamot, found in the pellicle of the ripe fruits of the _citrus

aurantium_ and _medica_; or the orange and the citron. The oil comes out

in this case with the juice of the peel, and collects upon its surface.

For collecting the oils of odoriferous flowers which have no peculiar

organs for imprisoning them, and therefore speedily let them exhale,

such as violets, jasmine, tuberose, and hyacinth, another process must

be resorted to. Alternate layers are formed of the fresh flowers, and

thin cotton fleece or woollen cloth-wadding, previously soaked in a pure

and inodorous fat oil. Whenever the flowers have given out all their

volatile oil to the fixed oil upon the fibrous matter, they are replaced

by fresh flowers in succession, till the fat oil has become saturated

with the odorous particles. The cotton or wool wadding being next

submitted to distillation along with water, gives up the volatile oil.

Perfumers alone use these oils; they employ them either mixed as above,

or dissolve them out by means of alcohol. In order to extract the oils

of certain flowers, as for instance of white lilies, infusion in a fat

oil is sufficient.

Essential oils differ much from each other in their physical properties.

Most of them are yellow, others are colourless, red, or brown; some

again are green, and a few are blue. They have a powerful smell, more or

less agreeable, which immediately after their distillation is

occasionally a little rank, but becomes less so by keeping. The odour is

seldom as pleasant as that of the recent plant. Their taste is acrid,

irritating, and heating, or merely aromatic when they are largely

diluted with water or other substances. They are not greasy to the

touch, like the fat oils, but on the contrary make the skin feel rough.

They are almost all lighter than water, only a very few falling to the

bottom of this liquid; their specific gravity lies between 0·847 and

1·096; the first number denoting the density of oil of citron, and the

second that of oil of sassafras. Although styled volatile oils, the

tension of their vapour, as well as its specific heat, is much less than

that of water. The boiling point differs in different kinds, but it is

usually about 316° or 320° Fahr. Their vapours sometimes render reddened

litmus paper blue, although they contain no ammonia. When distilled by

themselves, the volatile oils are partially decomposed; and the gaseous

products of the portion decomposed always carry off a little of the oil.

When they are mixed with clay or sand, and exposed to a distilling heat,

they are in a great measure decomposed; or when they are passed in

vapour through a redhot tube, combustible gases are obtained, and a

brilliant porous charcoal is deposited in the tube. On the other hand,

they distil readily with water, because the aqueous vapour formed at the

surface of the boiling fluid carries along with it the vapour of the oil

produced in virtue of the tension which it possesses at the 212th deg.

Fahr. In the open air, the volatile oils burn with a shining flame,

which deposits a great deal of soot. The congealing point of the

essential oils varies greatly; some do not solidify till cooled below

32°, others at this point, and some are concrete at the ordinary

temperature of the atmosphere. They comport themselves in this respect

like the fat oils; and they probably consist, like them, of two

different oils, a solid and a fluid; to which the names _stearoptène_

and _eleoptène_, or stearessence and oleiessence, may be given. These

may be separated from each other by compressing the cooled concrete oil

between the folds of porous paper; the stearessence remains as a solid

upon the paper; the oleiessence penetrates the paper, and may be

recovered by distilling it along with water.

When exposed to the air, the volatile oils change their colour, become

darker, and gradually absorb oxygen. This absorption commences whenever

they are extracted from the plant containing them; it is at first

considerable, and diminishes in rapidity as it goes on. Light

contributes powerfully to this action, during which the oil disengages a

little carbonic acid, but much less than the oxygen absorbed; no water

is formed. The oil turns gradually thicker, loses its smell, and is

transformed into a resin, which becomes eventually hard. De Saussure

found that oil of lavender, recently distilled, had absorbed in four

winter months, and at a temperature below 54° F., 52 times its volume of

oxygen, and had disengaged twice its volume of carbonic acid gases; nor

was it yet completely saturated with oxygen. The stearessence of

anise-seed oil absorbed at its liquefying temperature, in the space of

two years, 156 times its volume of oxygen gas, and disengaged 26 times

its volume of carbonic acid gas. An oil which has begun to experience

such an oxidizement is composed of a resin dissolved in the unaltered

oil; and the oil may be separated by distilling the solution along with

water. To preserve oils in an unchanged state, they must be put in

phials, filled to the top, closed with ground glass stopples, and placed

in the dark.

Volatile oils are little soluble in water, yet enough so as to impart to

it by agitation their characteristic smell and taste. The water which

distils with any oil is in general a saturated solution of it, and as

such is used in medicine under the name of distilled water. It often

contains other volatile substances contained in the plants, and hence is

apt to putrefy and acquire a nauseous smell when kept in perfectly

corked bottles; but in vessels partially open, these parts exhale, and

the water remains sweet. The waters, however, which are made by

agitating volatile oil with simple distilled water are not apt to spoil

by keeping in well-corked bottles.

The volatile oils are soluble in alcohol, and the more so the stronger

the spirit is. Some volatile oils, devoid of oxygen, such as the oils of

turpentine and citron, are very sparingly soluble in dilute alcohol;

while the oils of lavender, pepper, &c. are considerably so. De Saussure

has inferred from his experiments that the volatile oils are the more

soluble in alcohol, the more oxygen they contain. Such combinations form

the odoriferous spirits which the perfumers incorrectly call waters, as

_lavender water_, _eau de Cologne_, _eau de jasmin_, &c. They become

turbid by admixture of water, which seizes the alcohol, and separates

the volatile oils. Ether also dissolves all the essential oils.

These oils combine with several vegetable acids, such as the acetic, the

oxalic, the succinic, the fat acids (stearic, margaric, oleic), the

camphoric, and suberic.

With the exception of the oil of cloves, the volatile oils do not

combine with the salifiable bases. They have been partially combined

with caustic alkali, as in the case of Starkey’s soap. This is prepared

by triturating recently fused caustic soda in a mortar, with a little

oil of turpentine, added drop by drop, till the mixture has acquired the

consistence of soap. The compound is to be dissolved in spirits of wine,

filtered, and distilled. What remains after the spirit is drawn off,

consists of soda combined with a resin formed in the oil during the act

of trituration.

The volatile oils in general absorb six or eight times their bulk of

ammoniacal gas; but that of lavender absorbs 47 times.

The essential oils dissolve all the fat oils, the resins, and the animal

fats.

In commerce these oils are often adulterated with fat oils, resins, or

balsam of capivi dissolved in volatile oil. This fraud may be detected

by putting a drop of the oil on paper, and exposing it to heat. A pure

essential oil evaporates without leaving any residuum, whilst an oil

mixed with any of the above substances leaves a translucent stain upon

the paper. If fat oil be present, it will remain undissolved, on mixing

the adulterated essential oil with thrice its volume of spirit of wine

of specific gravity 0·840. Resinous matter mixed with volatile oil is

easily detected, being left in the alembic after distillation. Oil

diluted with spirit of wine, forms a milky emulsion on the addition of

water; the alcoholic part is absorbed by the water, and the oil

afterwards found on the surface, in a graduated glass tube will show by

its quantity the amount of the adulteration.

But it is more difficult to detect the presence of a cheap essential oil

in a dear one, which it resembles. Here the taste and smell are our

principal guides. A few drops of the suspected oil are to be poured upon

a bit of cloth, which is to be shaken in the air, and smelled to from

time to time. In this way we may succeed in distinguishing the odour of

the oil which exhales at the beginning, and that which exhales at the

end; a method which serves perfectly to detect oil of turpentine in the

finer essential oils. Moreover, when the debased oil is mixed with

spirits of wine at sp. gr. 0·840, the oil of turpentine remains in a

great measure undissolved. If an oil heavier than water, and an oil

lighter than water, be mixed, they may be separated by agitation for

some time with that liquid, and then leaving the mixture at rest.

Essential oils may also be distinguished by a careful examination of

their respective densities.

_Oil of bitter almonds_, is prepared by exposing the bitter almond cake,

from which the bland oil has been expressed, in a sieve to the vapour of

water rising within the still. The steam, as it passes up through the

bruised almond _parenchyma_, carries off its volatile oil, and condenses

along with it in the worm. The oil which first comes over, and which

falls to the bottom of the water, has so pungent and penetrating a

smell, that it is more like cyanogen gas than hydrocyanic or prussic

acid. This oil has a golden-yellow colour, it is heavier than water;

when much diluted, it has an agreeable smell, and a bitter burning

taste. When exposed to the air, it absorbs oxygen, and lets fall a heap

of crystals of benzoic acid. This oil consists of a mixture of two oils;

one of which is volatile, contains hydrocyanic acid, and is poisonous;

the other is less volatile, is not poisonous, absorbs oxygen, and

becomes benzoic acid. If we dissolve 100 parts of the oil of bitter

almonds in spirit of wine, mix with the solution an alcoholic solution

of potash, and then precipitate the oil with water, we shall obtain a

quantity of cyanide of potash, capable of producing 22-1/2 parts of

prussian blue. Oil of bitter almonds combines with the alkalis.

Perfumers employ a great quantity of this oil in scenting their soaps.

One manufacturer in Paris is said to prepare annually 3 cwt. of this

oil. A similar poisonous oil is obtained by distilling the following

substances with water:--the leaves of the peach (_amygdalus persica_),

the leaves of the bay-laurel (_prunus lauro-cerasus_), the bark of the

plum tree (_prunus padus_), and the bruised kernels of cherry and

plum-stones. All these oils contain hydrocyanic acid, which renders them

poisonous, and they also generate benzoic acid, by absorbing oxygen on

exposure to air.

_Oil of anise-seed_, is extracted by distillation from the seeds of the

_pimpinella anisum_. It is either colourless, or has merely a faint

yellow colour, with the smell and taste of the seed. It concretes in

lamellar crystals at the temperature of 50°, and does not melt again

till heated to 64° nearly. Its specific gravity at 61° is 0·9958, and at

77°, 0·9857. It is soluble in all proportions in alcohol of 0·806; but

only to the extent of 42 per cent. in alcohol of 0·84. When it becomes

resinous by long exposure to the air, it loses its congealing property.

It consists of two oils; a solid stearessence, and a liquid oleiessence,

which may be separated by compression of the cold concrete oil.

_Oil of bergamot_, is extracted by pressure from the rind of the ripe

fruit of the _citrus bergamium_ and _aurantium_. It is a limpid,

yellowish fluid, having a smell resembling that of oranges. Its specific

gravity varies from 0·888 to 0·885. It becomes concrete when cooled a

little below 32°.

_Oil of cajeput_, is prepared in the Moluccas, by distilling the dry

leaves of the _melaleuca leucadendron_. Cajeput is a native word,

signifying merely a white tree. This oil is green; it has a burning

taste, a strong smell of camphor, turpentine, and savine. It is very

fluid, and at 48° has a specific gravity of 0·948. The colour seems to

be derived from the copper vessels in which it is imported, so that it

is removed by distillation with water, which also separates the oil into

two sorts; the first which comes over having a density of 0·897, the

last of 0·920. This has a green colour.

_The oil of caraway_ is extracted from the seeds of the _carum carui_.

It has a pale yellow colour, and the smell and taste of the plant. Its

specific gravity is 0·960. The seeds of the _cuminum cyminum_ (cumin)

afford an oil similar to the preceding, but not so agreeable. Its

specific gravity is 0·975.

_The oil of cassia_, from the _laurus cassia_, is yellow passing into

brown, has a specific gravity of 1·071, and affords a crystalline

stearessence by keeping in a somewhat open vessel.

_The oil of chamomile_ is extracted by distillation from the flowers of

the _matricaria chamomilla_. It has a deep blue colour, is almost

opaque, and thick; and possesses the peculiar smell of the plant. In

the atmosphere it becomes brown and unctuous. If an ounce of oil of

lemons be added to 3 pounds of this oil, they make it separate more

readily from the adhering water.

Other blue oils, having much analogy with oil of chamomile, are obtained

by distilling the following plants: roman chamomile (_anthemis

nobilis_), the flowers of _arnica montana_, and those of milfoil

(_achillæa millefolia_). The last has a spec. grav. of 0·852.

_Oil of cinnamon_, is extracted by distillation from the bark of the

_laurus cinnamomum_. It is produced chiefly in Ceylon, from the pieces

of bark unfit for exportation. It is distilled over with difficulty, and

the process is promoted by the addition of salt water, and the use of a

low still. It has at first a pale yellow colour, but it becomes brown

with age. It possesses in a high degree both the sweet burning taste,

and the agreeable smell of cinnamon. It is heavier than water; its

specific gravity being 1·035. It concretes below 32° F., and does not

fuse again till heated to 41°. It is very sparingly soluble in water,

and when agitated with it readily separates by repose. It dissolves

abundantly in alcohol, and combines with ammonia into a viscid mass, not

decomposed on exposure to air.

When oil of cinnamon is kept for a long time, it deposits a stearessence

in large regular colourless or yellow crystals, which may be pulverized,

and which melt at a very gentle heat into a colourless liquid, which

crystallizes on cooling. It has an odour intermediate between that of

cinnamon and vanilla; and a taste at first greasy, but afterwards

burning and aromatic. It crackles between the teeth. It requires a high

temperature for distillation, and becomes then brown and empyreumatic.

It is very soluble in alcohol.

_The oil of cloves_, is extracted from the dried flower buds of the

_caryophyllus aromaticus_. It is colourless, or yellowish, has a strong

smell of the cloves, and a burning taste. Its specific gravity is 1·061.

It is one of the least volatile oils, and the most difficult to distil.

At the end of a certain time it deposits a crystalline concrete oil. A

similar _stearessence_ is obtained by boiling the bruised cloves in

alcohol, and letting the solution cool. The crystals thus formed are

brilliant, white, grouped in globules, without taste and smell. Oil of

cloves has remarkable chemical properties. It dissolves in alcohol,

ether, and acetic acid. It does not solidify at a temperature of 4°

under 0° F., even when exposed to that cold for several hours. It

absorbs chlorine gas, becomes green, then brown, and turns resinous.

Nitric acid makes it red, and if heated upon it, converts it into oxalic

acid. If mixed by slow degrees with one third of its weight of sulphuric

acid, an acid liquor is formed, at whose bottom a resin of a fine purple

colour is found. After being washed, this resin becomes hard and

brittle. Alcohol dissolves it, and takes a red colour; and water

precipitates it of a blood red hue. It dissolves also in ether. When we

agitate a mixture of strong caustic soda lye and oil of cloves in equal

parts, the mass thickens very soon, and forms delicate lamellar

crystals. If we then pour water upon it, and distil, there passes along

with the water, a small quantity of an oil which differs from oil of

cloves both in taste and chemical properties. During the cooling, the

liquor left in the retort lets fall a quantity of crystalline needles,

which being separated by expression from the alkaline liquid, are almost

inodorous, but possess an alkaline taste, joined to the burning taste of

the oil. These crystals require for solution from 10 to 12 parts of cold

water. Potash lye produces similar effects. Ammoniacal gas transmitted

through the oil is absorbed and makes it thick. The concrete combination

thus formed remains solid as long as the phial containing it is corked,

but when opened, the compound becomes liquid; and these phenomena may be

reproduced as many times as we please. Such combinations are decomposed

by acids, and the oil set at liberty has the same taste and smell as at

first, but it has a deep red colour. The alkalis enable us to detect the

presence of other oils, as that of turpentine or sassafras, in that of

cloves, because they fix the latter, while the former may be volatilized

with water by distilling the mixture. The oil of cloves found in

commerce is not pure, but contains a mixture of the tincture of pinks or

clove-gilly flowers, whose acrid resin is thereby introduced. It is

sometimes sophisticated with other oils.

_The oil of elder_, is extracted by distillation from the flowers of the

_sambucus nigra_. It has the consistence of butter. The watery solution

is used in medicine.

_Oil of fennel_, is extracted by distillation from the seeds of the

_anethum fœniculum_. It is either colourless or of a yellow tint, has

the smell of the plant, and a specific gravity of 0·997. When treated

with nitric acid, it affords benzoin. It congeals at the temperature of

14° F., and then yields by pressure a solid and a liquid oil; the former

appearing in crystalline plates. It is used in this country for scenting

soap.

_Oils of fermented liquors._ The substances usually fermented contain a

small quantity of essential oils, which become volatile along with the

alcoholic vapours in distillation, and progressively increase as the

spirits become weaker towards the end of the process. The vapours then

condense into a milky liquor. These oils adhere strongly to the alcohol,

and give it a peculiar acrid taste. They differ according to the vinous

wash from which they are obtained, and combine with greater or less

facility with caustic alkalis.

1. _Oil of grain spirits._ At the ordinary temperature it is partially a

white solid; when cooled lower it assumes the aspect of suet, and

therefore consists chiefly of stearessence. Its taste and smell are most

offensive; it swims upon the surface of water, and even of spirit

containing 30 per cent. of alcohol. It sometimes derives a green colour

from the copper worm of the still. When heated it fuses and turns

yellow. When it has become resinous by the agency of the atmosphere, it

gives a greasy stain to paper. It dissolves in 6 parts of anhydrous

alcohol, and in 2 of ether; and is said to crystallize when the spirit

solution has been saturated with it hot, and is allowed to cool. By

exposure to a freezing mixture, the whiskey which contains it lets it

fall. Caustic potash dissolves it very slowly, and forms a soap soluble

in 60 parts of water. It is absorbed by wood charcoal, and still better

by bone black; whereby it may be completely abstracted from bad whiskey.

According to Buchner, another oil may also be obtained from the residuum

of the second distillation of whiskey, if saturated with sea salt, and

again distilled. Thus we obtain a pale yellow fluid oil, which does not

concrete with cold, possessed of a disagreeable smell and acrid taste.

Its specific gravity is 0·835. It is soluble in alcohol and ether.

2. _The oil from potato spirits_, has properties quite different from

the preceding. It is obtained in considerable quantity by continuing the

distillation after most of the alcohol has come over, and it appears in

the form of a yellowish oil, mixed with water and spirits. After being

agitated first with water, then with a strong solution of muriate of

lime, and distilled afresh, it possesses the following properties: it is

colourless, limpid, has a peculiar smell, and a bitter hot taste of

considerable permanence. It leaves no greasy stain upon paper, remains

liquid at 0° F., but cooled below that point it crystallizes like oil of

anise-seed. When pure it boils at 257° F.; but at a lower degree, if it

contains alcohol. Its specific gravity is 0·821, or 0·823 when it

contains a little water. It burns with a clear flame without smoke, but

it easily goes out, if not burned with a wick. It dissolves in small

quantity in water, to which it imparts its taste and the properties of

forming a lather by agitation. It dissolves in all proportions in

alcohol. Chlorine renders it green. Concentrated sulphuric acid converts

it into a crimson solution, from which it is precipitated yellow by

water. It dissolves in all proportions in acetic acid. Concentrated

caustic lyes dissolve it, but give it up to water. It does not appear to

be poisonous, like the oil of corn spirits; because, when given by

spoonfuls to dogs, it produced no other effect but vomiting.

3. _The oil of brandy or grape spirits_, is obtained during the

distillation of the fermented residuum of expressed grapes; being

produced immediately after the spirituous liquor has passed over. It is

very fluid, limpid, of a penetrating odour, and an acrid disagreeable

taste. It grows soon yellow in the air. When this oil is distilled, the

first portions of it pass unchanged, but afterwards it is decomposed and

becomes empyreumatic. It dissolves in 1000 parts of water, and

communicates to it its peculiar taste and smell. One drop of it is

capable of giving a disagreeable flavour to ten old English gallons of

spirits. It combines with the caustic alkalis, and dissolves sulphur.

_Oil of Juniper_, is obtained by distilling juniper berries along with

water. These should be bruised, because their oil is contained in small

sacs or reservoirs, which must be laid open before the oil can escape.

It is limpid and colourless, or sometimes of a faint greenish yellow

colour. Its specific gravity is 0·911. It has the smell and taste of the

juniper. Water, or even alcohol, dissolves very little of it. Gin

contains a very minute quantity of this oil. Like oil of turpentine, it

imparts to the urine of persons who swallow it, the smell of violets.

Oil of juniper is frequently sophisticated with oil of turpentine

introduced into the still with the berries; a fraud easily detected by

the diminished density of the mixture.

_The oil of lavender_, is extracted from the flowering spike of the

_lavandula spica_. It is yellow, very fluid, has a strong odour of the

lavender, and a burning taste. The specific gravity of the oil found in

commerce is 0·898 at the temperature of 72° F., and of 0·877 when it has

been rectified. It is soluble in all proportions in alcohol of 0·830,

but alcohol of 0·887 dissolves only 42 per cent. of its weight. The

fresh oil detonates slightly when mixed with iodine, with the production

of a yellow cloud. There occurs in commerce a kind of oil of lavender

known under the name of oil of _aspic_ or oil of _spike_, extracted by

distillation from a wild variety of the _lavandula spica_, which has

large leaves, and is therefore called _latifolia_. This oil is

manufactured in the south of Europe. Its odour is less characteristic

than that of the lavender, resembling somewhat that of oil of

turpentine, with which it is indeed often adulterated. It is also so

cheap as to be sometimes used instead of the latter oil. Oil of lavender

deposits, when partially exposed to the air, a concrete oil, which

resembles camphor, to the amount of one fourth of its weight.

_Oil of lemons_, is extracted by pressure from the yellow peel of the

fruit of the lemon, or _citrus medica_. In this state it is a yellowish

fluid, having a specific gravity of 0·8517; but when distilled along

with water till three fifths of the oil have come over, it is obtained

in a colourless state, and of a specific gravity of 0·847 at 72° F. This

oil does not become concrete till cooled to 4° below 0° F.

The oil of lemons has a very agreeable smell of the fruit, which is

injured by distillation. It is soluble in all proportions in anhydrous

alcohol, but only 14 parts dissolve in 100 of spirits of wine of

specific gravity 0·837. This oil, especially when distilled, forms with

muriatic acid similar camphorated compounds with oil of turpentine,

absorbing no less than 280 volumes of the acid gas.

Oil of lemons kept long, in ill-corked bottles, generates a quantity of

stearessence, which when dissolved in alcohol, precipitated by water,

and evaporated, affords brilliant, colourless, transparent needles. Some

acetic acid is also generated in the old oil. According to Brandes, the

specific gravity of oil of lemons is 0·8786.

_The oil of mace_, lets fall, after a certain time, a concrete oil under

the form of a crystalline crust, called by John _myristicine_.

_The oil of nutmegs_, is extracted chiefly from mace, which is the inner

epidermis of these nuts. It is colourless, or yellowish, a little viscid

with a strong aromatic odour of nutmegs, an acrid taste, and a specific

gravity of 0·948. It consists of two oils, which may be easily separated

from each other by agitation with water; for one of them, which is more

volatile and aromatic comes to the surface, while the other, which is

denser, white, and of a buttery consistence, falls to the bottom. The

latter liquefies by the heat of the hand.

_The oil of orange flowers_, called _neroli_, is extracted from the

fresh flowers of the _citrus aurantium_. When recently prepared it is

yellow; but when exposed for two hours to the rays of the sun, or for a

longer time to diffuse daylight, it becomes of a yellowish-red. It is

very fluid, lighter than water, and has a most agreeable smell. The

aqueous solution known under the name of orange-flower water, is used as

a perfume. It is obtained either by dissolving the oil in water, or by

distilling with water the leaves either fresh or salted; the first being

the stronger, but the last being the more fragrant preparation.

Orange-flower water obtained by distillation, contains besides the oil,

a principle which comes over with it, of a nature hitherto unknown; it

possesses the property of imparting to water the faculty of becoming red

with a few drops of sulphuric acid. The water formed from the oil alone,

is destitute of this property. The intensity of the rose-colour is a

test in some measure of the richness of the water in oil.

_The oil of parsley_, is extracted from the _apium petroselinum_. It is

of a pale yellow colour, having the smell of the plant, and consists of

two oils separable by agitation in water. Its liquid part floats upon

the surface in a very fluid form; its stearessence, which falls to the

bottom, is butyraceous and crystallizes at a low temperature. This

concrete oil melts at 86° F.

_The oil of pepper_, is extracted from the _piper nigrum_. In the recent

state it is limpid and colourless, but by keeping it becomes yellow. It

swims upon the surface of water. In odour it resembles pepper, but is

devoid of its hot taste.

_The oil of peppermint_ is extracted from the _mentha piperita_. It is

yellowish, and endued with a very acrid burning taste. Its specific

gravity is 0·920. At 6° or 7° below 0° F., it deposits small capillary

crystals. After long keeping it affords a stearessence resembling

camphor, provided the oil had been obtained from the dry plant gathered

in flower, but not from distillation of the fresh plant. When

artificially cooled, it yields 6 per cent. of stearessence, which

crystallizes in prisms with three sides, has an acrid somewhat rank

taste, is soluble in ether and alcohol, and is thrown down from the

latter solution by water in the form of a white powder. Peppermint water

is characterized by the sensation of coolness which it diffuses in the

mouth.

_The oil of pimento_, is extracted from the envelopes of the fruits of

the _myrtus pimenta_, which afford 8 per cent. of it. It is yellowish,

almost colourless, of a smell analogous to that of cloves, an acrid

burning taste, and a specific gravity greater than water. Nitric acid

makes it first red, and after the effervescence, of a rusty brown hue.

It combines with the salifiable bases, like oil of cloves.

_The oil of rhodium_, is extracted from the wood of the _convolvolus

scoparius_. It is very fluid, and has a yellow colour, which in time

becomes red. It has somewhat of the rose odour, and is used to

adulterate the genuine _otto_. Its taste is bitter and aromatic, which

it imparts to the otto as well as its fluidity.

_The oil of roses_, called also the _attar_ or _otto_, is extracted by

distillation from the petals of the _rosa centifolia_ and

_sempervirens_. Our native roses furnish such small quantities of the

oil, that they are not worth distilling for the purpose. The best way of

operating is to return the distilled water repeatedly upon fresh petals,

and eventually to cool the saturated water with ice; whereby a little

butyraceous oil is deposited. But the oil thus obtained has not a very

agreeable odour, being injured by the action of the air in the repeated

distillations. In the East Indies, the attar is obtained by stratifying

rose leaves in earthen pans in alternate layers, with the oleiferous

seeds of a species of digitalis, called _gengeli_, for several days, in

a cool situation. The fat oil of the seed absorbs the essential oil of

the rose. By repeating this process with fresh leaves and the same seed,

this becomes eventually swollen, and being then expressed furnishes the

oil. The turbid liquid thus obtained is left at rest, in well-closed

vessels, where it gets clarified. The layer of oil that floats on the

top is then drawn off by a capillary cotton wick, and subjected to

distillation along with water, whereby the volatile otto is separated

from the fat seed-oil.

The oil of roses is colourless, and possesses the smell of roses, which

is not however agreeable, unless when diffused, for in its concentrated

state it is far from pleasant to the nostrils, and is apt to occasion

headaches. Its taste is bland and sweetish. It is lighter than water,

and at the temperature of 92°, its specific gravity compared to that of

water at 60° is 0·832. At lower temperatures it becomes concrete and

butyraceous; and afterwards fuses at 90°. It is but slightly soluble in

alcohol; 1000 parts of this liquid at 0·806 dissolving only 7-1/2 parts

at 58° F. This oil consists of two parts, the stearessence and

oleiessence; the latter being the more volatile odoriferous portion.

_The oil of rosemary_, is extracted from the _rosmarinus officinalis_.

It is as limpid as water, has the smell of the plant, and in other

respects resembles oil of turpentine. The oil found in commerce has a

specific gravity of 0·911, which becomes 0·8886 by rectification. It

boils at 320° F. (occasionally at 329°). It is soluble in all portions

in alcohol of 0·830. When kept in imperfectly closed vessels, it

deposits a stearessence to the amount of one tenth of its weight,

resembling camphor. It is sometimes adulterated with oil of turpentine,

a fraud easily detected by adding anhydrous alcohol, which dissolves

only the oil of rosemary.

_The oil of saffron_, is extracted from the _stigmata_ of the _crocus

sativus_. It is yellow, very fluid, falls to the bottom of water,

diffuses the penetrating odour of the plant, and has an acrid and bitter

taste. It is narcotic.

_The oil of sassafras_, is extracted from the woody root of the _laurus

sassafras_. It is colourless; but at the end of a certain time it

becomes yellow or red. It has a peculiar, sweetish, pretty agreeable,

but somewhat burning taste. Its specific gravity is 1·094. According to

Bonastre, this oil separates by agitation with water into an oil lighter

and an oil heavier than this fluid. When long kept, it deposits a

stearessence in transparent and colourless crystals, which have the

smell and taste of the liquid oil.

_The oil of savine_, is extracted from the leaves of the _juniperus

sabina_. It is limpid, and has the odour and taste of the plant, which

is one more productive of volatile oil than any other.

_The oil of tansy_ has a specific gravity of 0·946, the penetrating

odour of the _tanacetum vulgare_, with an acrid and bitter taste.

_Oil of turpentine_, commonly called essence of turpentine. It is

extracted from several species of turpentine, a semi-liquid resinous

substance which exudes from certain trees of the _pine_ tribe, and is

obtained by distilling the resin along with water. This oil is the

cheapest of all the volatile species, and, as commonly sold, contains a

little resin, from which it may be freed by re-distillation with water.

It is colourless, limpid, very fluid, and has a very peculiar smell. Its

specific gravity at 60° is 0·872; that of the spirit on sale in the

shops is 0·876. This oil always reddens litmus paper, because it

contains a little succinic acid.

100 parts of spirits of wine, of specific gravity 0·84, dissolve only

13-1/2 of oil of turpentine at 72° F. When agitated with alcohol at

0·830 the oil retains afterwards one fifth of its bulk of the spirit;

hence this proposed method for purifying oil of turpentine is defective.

The oil if left during four months in contact with air is capable of

absorbing 20 times its bulk of oxygen gas. One volume of rectified oil

of turpentine absorbs at the temperature of 72°, and under the common

atmospheric pressure, 163 times its volume of muriatic acid gas,

provided the vessel be kept cool with ice. This mixture being allowed to

repose for 24 hours, produces out of the oil from 26 to 47 per cent. of

a white crystalline substance, which subsides to the bottom of a brown,

smoking, translucent liquor. Others say that 100 parts of oil of

turpentine yield 110 of this crystalline matter, which was called by

Kind, its discoverer, artificial camphor, from its resemblance in smell

and appearance to this substance. Both the solid and the liquid are

combinations of muriatic acid and oil of turpentine; indicating the

existence of a stearine and an oleine in the latter substance. The

liquid compound is lighter than water, and is not decomposed by it, nor

does it furnish any more solid matter when more muriatic gas is passed

through it. The solid compound, after being washed first with water

containing a little carbonate of soda, then with pure water, and finally

purified by sublimation with some chalk, lime, ashes, or charcoal,

appears as a white, translucent, crystalline body, in the form of

flexible, tenacious needles. It swims upon the surface of water,

diffuses a faint smell of camphor, commonly mixed with that of oil of

turpentine, and has rather an aromatic than a camphorated taste. It does

not redden litmus paper. Water dissolves a very minute quantity; but

cold alcohol of 0·806 dissolves fully one third of its weight, and hot

much more, depositing, as it cools, this excess in the form of crystals.

The solution is not precipitated by nitrate of silver, which shows that

the nature of the muriatic acid is perfectly masked by the combination.

It is composed, in 100 parts, of 76·4 carbon, 9·6 hydrogen, and 14

muriatic acid. The muriatic acid, or chlorine may be separated by

distilling an alcoholic solution of the artificial camphor 12 or 14

times in succession with slaked lime.

Oil of turpentine is best preserved in casks enclosed within others,

with water between the two. Its principal use is for making varnishes,

and as a remedy for the tape-worm.

_The oil of thyme_, is extracted from the _thymus serpyllum_. It is

reddish yellow, has an agreeable smell, and, after being long kept, it

lets fall a crystalline stearessence. It is used merely as a perfume.

_The oil of wormwood_, is extracted from the _artemisia absinthium_. It

is yellow, or sometimes green, and possesses the odour of the plant. Its

taste resembles that of wormwood, but without its bitterness. Its

specific gravity is 0·9703 according to Brisson and 0·9725 according to

Brandes. It detonates with iodine when it is fresh. Treated with nitric

acid of 1·25 specific gravity, it becomes first blue, and after some

time brown.

OIL OF VITRIOL, is the old name of concentrated SULPHURIC ACID.

OLEATES, are saline compounds of oleic acid with the bases.

OLEFIANT GAS, is the name originally given to bi-carburetted hydrogen.

OLEIC ACID, is the acid produced by saponifying olive-oil, and then

separating the base by dilute sulphuric or muriatic acid. See FATS, and

STEARINE.

OLEINE, is the thin oily part of fats, naturally associated in them with

glycerine, margarine, and stearine.

OLIBANUM, is a gum-resin, used only as incense in Roman-catholic

churches.

OLIVE OIL. See OILS, UNCTUOUS.

ONYX, an ornamental stone of little value; a subspecies of quartz.

OOLITE, is a species of limestone composed of globules clustered

together, commonly without any visible cement or base. These vary in

size from that of small pin-heads to peas; they sometimes occur in

concentric layers, at others they are compact, or radiated from the

centre to the circumference; in which case, the oolite is called

_roogenstein_ by the German mineralogists. In geology the oolitic series

includes all the strata between the iron sand above and the red marl

below. It is the great repository of the best architectural materials

which the midland and eastern parts of England produce; it is divided

into three systems:--

1. _The upper oolite_, including the argillo-calcareous Purbeck strata,

which separate the iron and oolitic series; the oolitic strata of

Portland, Tisbury, and Aylesbury; the calcareous sand and concretions,

as of Shotover and Thame; and the argillo-calcareous formation of

Kimmeridge, the oak tree of Smith.

2. _The middle oolite_; the oolitic strata associated with the coral

rag; calcareous sand and grit; great Oxford clay, between the oolites of

this and the following system.

3. _The lower oolite_; which contains numerous oolitic strata,

occasionally subdivided by thin argillaceous beds; including the

cornbrash, forest marble, schistose oolite, and sand of Stonesfield and

Hinton, great oolite and inferior oolite; calcareo-siliceous sand

passing into the inferior oolite; great argillo-calcareous formation of

lias, and lias marl, constituting the base of the whole series.

These formations occupy a zone 30 miles broad in England.

OOST, or OAST; the trivial or provincial name of the stove in which the

picked hops are dried.

OPAL; an ornamental stone of moderate value. See LAPIDARY.

OPERAMETER, is the name given to an apparatus patented in February,

1829, by Samuel Walker, cloth manufacturer, in the parish of Leeds. It

consists of a train of toothed wheels and pinions enclosed in a box,

having indexes attached to the central arbor, like the hands of a clock,

and a dial plate; whereby the number of rotations of a shaft projecting

from the posterior part of the box is shown. If this shaft be connected

by any convenient means to the working parts of a gig mill, shearing

frame, or any other machinery of that kind for dressing cloths, the

number of rotations made by the operating machine will be exhibited by

the indexes upon the dial plate of this apparatus. In dressing cloths,

it is often found that too little or too much work has been expended

upon them, in consequence of the unskilfulness or inattention of the

workmen. By the use of the operameter, that evil will be avoided, as the

master may regulate and prescribe beforehand by the dial the number of

turns which the wheels should perform.

A similar clock-work mechanism, called a _counter_, has been for a great

many years employed in the cotton factories to indicate the number of

revolutions of the main shaft of the mill, and of course the quantity of

yarn that might or should be spun, or of cloth that might be woven in

the power looms. A common pendulum or spring clock is commonly set up

alongside of the counter; and sometimes the indexes of both are

regulated to go together, when the mill performs its average work.

OPIUM, is the juice which exudes from incisions made in the heads of

ripe poppies, (_papaver somniferum,_) rendered concrete by exposure to

the air and the sun. The best opium which is found in the European

markets comes from Asia Minor and Egypt; what is imported from India is

reckoned inferior in quality. This is the most valuable of all the

vegetable products of the gum-resin family: and very remarkable for the

complexity of its chemical composition. Though examined by many able

analysts, it still requires further elucidation.

Opium occurs in brown lumps of a rounded form, about the size of the

fist, and often larger; having their surface covered with the seeds and

leaves of a species of _rumex_, for the purpose of preventing the mutual

adhesion of the pieces in their semi-indurated state. These seeds are

sometimes introduced into the interior of the masses to increase their

weight; a fraud easily detected by cutting them across. Good opium is

hard in the cold, but becomes flexible and doughy when it is worked

between the hot hands. It has a characteristic smell, which by heat

becomes stronger, and very offensive to the nostrils of many persons. It

has a very bitter taste. Water first softens, and then reduces it to a

pasty magma. Proof spirit digested upon opium forms _laudanum_, being a

better solution of its active parts than can be obtained by either water

or strong alcohol alone. Water distilled from it acquires its peculiar

smell, but carries over no volatile oil.

Opium was analyzed by Bucholz and Braconnot, but at a period anterior to

the knowledge of the alkaline properties of morphia and opian

(narcotine). Bucholz found in 100 parts of it, 9·0 of resin; 30·4 of

gum; 35·6 of extractive matter; 4·8 of caoutchouc; 11·4 of gluten; 2·0

of ligneous matter, as seeds, leaves, &c.; 6·8 of water and loss. John,

who made his analysis more recently, obtained 2·0 parts of a rancid

nauseous fat; 12·0 of a brown hard resin; 10·0 of a soft resin; 2 of an

elastic substance; 12·0 of morphia and opian; 1·0 of a balsamic extract;

25·0 of extractive matter; 2·5 of the meconates of lime and magnesia;

18·5 of the epidermis of the heads of the poppy; 15 of water, salts, and

odorous matter.

In the Numbers of the Quarterly Journal of Science for January and June,

1830, I published two papers upon opium and its tests, containing the

results of researches made upon some porter which had been fatally dosed

with that drug; for which crime, a man and his wife had been capitally

punished, about a year before, in Scotland.[36] From the first of these

papers the following extract is made:--

[36] A country merchant travelling in a steam-boat upon the river

Clyde, who had incautiously displayed a good deal of money, was

poisoned with porter charged with laudanum. The contents of the dead

man’s stomach were sent to me for analysis.

“Did the anodyne and soporific virtue of opium reside in one definite

principle, chemical analysis might furnish a certain criterion of its

powers. It has been pretty generally supposed that this desideratum is

supplied by Sertürner’s discovery of morphia. Of this narcotic alkali

not more than 7 parts can be extracted by the most rigid analysis from

100 of the best Turkey opium; a quantity, indeed, somewhat above the

average result of many skilful chemists. Were morphia the real medicinal

essence of the poppy, it should display, when administered in its active

saline state of acetate, an operation on the living system commensurate

in energy with the fourteen-fold concentration which the opium has

undergone. But so far as may be judged from the most authentic recent

trials, morphia in the acetate seems to be little, if any, stronger as a

narcotic than the heterogeneous drug from which it has been eliminated.

Mr. John Murray’s experiments would, in fact, prove it to be greatly

weaker; for he gave 2 drachms of superacetate of morphia to a cat,

without causing any poisonous disorder. This is perhaps an extreme case,

and may seem to indicate either some defect in the preparation, or an

uncommon tenacity of life in the animal. To the same effect Lassaigne

found that a dog lived 12 hours after 36 grains of acetate of morphia in

watery solution had been injected into its jugular vein. The morphia

meanwhile was entirely decomposed by the vital forces, for none of it

could be detected in the blood drawn from the animal at the end of that

period. Now, from the effects produced by 5 grains of watery extract of

opium, injected by Orfila into the veins of a dog, we may conclude that

a quantity of it, equivalent to the above dose of the acetate of

morphia, would have proved speedily fatal.

“Neither can we ascribe the energy of opium to the white crystalline

substance called _narcotine_, or _opian_, extracted from it by the

solvent agency of sulphuric ether; for Orfila assures us that these

crystals may be swallowed in various forms by man, even to the amount of

2 drachms in the course of 12 hours, with impunity; and that a drachm of

it dissolved in muriatic or nitric acid may be administered in the food

of a dog without producing any inconvenience to the animal. It appears,

however, on the same authority, that 30 grains of it dissolved in

acetic or sulphuric acid caused dogs that had swallowed the dose to die

under convulsions in the space of 24 hours, while the head was thrown

backwards on the spine. Oil seems to be the most potent menstruum of

narcotine; for 3 grains dissolved in oil readily kill a dog, whether the

dose be introduced into the stomach or into the jugular vein.

“Since a bland oil thus seems to develop the peculiar force of

narcotine, and since opium affords to ether, and also to ammonia, an

unctuous or fatty matter, and a resin (the caoutchouc of Bucholz) to

absolute alcohol, we are entitled to infer that the activity of opium is

due to its state of composition, to the union of an oleate or margarate

of narcotine with morphia. The meconic acid associated with this

salifiable base has no narcotic power by itself, but may probably

promote the activity of the morphia.”

Opian or narcotine, and morphia, may be well prepared by the following

process. The watery infusion of opium being evaporated to the

consistence of an extract, every 3 parts are to be diluted with one and

a half parts in bulk of water, and then mixed in a retort with 20 parts

of ether. As soon as 5 parts of the ether have been distilled over, the

narcotic salt contained in the extract will be dissolved. The fluid

contents of the retort are to be poured hot into a vessel apart, and the

residuum being washed with 5 other parts of ether, they are to be added

to the former. Crystals of narcotine will be obtained as the solution

cools. The remaining extract is to be diluted in the retort with a

little water, and the mixture set aside in a cool place. After some

time, some narcotine will be found crystallized at the bottom. The

supernatant liquid thus freed from narcotine being decanted off, is to

be treated with caustic ammonia; and the precipitate thrown upon a

filter. This, when well washed and dried, is to be boiled with a

quantity of spirit of wine at 0·84, equal to thrice the weight of the

opium employed, containing 6 parts of animal charcoal for every hundred

parts of the drug. The alcoholic solution being filtered hot, affords,

on cooling, colourless crystals of morphia.

This alkali may be obtained by a more direct process, without alcohol or

ether. A solution of opium in vinegar, is to be precipitated by ammonia;

the washed precipitate is to be dissolved in dilute muriatic acid, the

solution is to be boiled along with powdered bone black, filtered, and

then precipitated by ammonia. This, when washed upon a filter and dried,

is white morphia, which may be dissolved in hot alcohol, if fine

crystals be wanted. See MORPHIA.

_Opium, quantity of,_

+-------+---------+------------+---------+

+-------+---------+------------+---------+

|1885. | 85,481 | 31,181 | 74,126 |

|1836. | 130,794 | 38,943 | 70,824 |

+-------+---------+------------+---------+

Duty, at present, 1_s._ per lb.

OPOBALSAM, is the balsam of Peru in a dry state.

OPOPONAX, is a gum-resin resembling gum ammoniac. It is occasionally

used in medicine.

ORANGE DYE, is given by a mixture of red and yellow dyes in various

proportions. Annotto alone dyes orange; but it is a fugitive colour.

ORCINE, is the name of the colouring principle of the _lichen

dealbatus_. The lichen dried and pulverized is to be exhausted by

boiling alcohol. The solution filtered hot, lets fall in the cooling,

crystalline flocks, which do not belong to the colouring matter. The

supernatant alcohol is to be distilled off, the residuum is to be

evaporated to the consistence of an extract, and triturated with water

till this liquid will dissolve no more. The aqueous solution reduced to

the consistence of syrup, and left to itself in a cool place, lets fall,

at the end of a few days, long brown brittle needles, which are to be

freed by pressure from the mother water, and dried. That water being

treated with animal charcoal, filtered and evaporated, will yield a

second crop of crystals. These are orcine. Its taste is sweet and

nauseous; it melts readily in a retort into a transparent liquid, and

distils without undergoing any change. It is soluble in water and

alcohol. Nitric acid colours it blood-red; which colour afterwards

disappears. Subacetate of lead precipitates it completely. Its

conversion into the archil red is effected by the action of an alkali,

in contact with the air. When dissolved, for example, in ammonia, and

exposed to the atmosphere, it takes a dirty brown red hue; but when the

orcine is exposed to air charged with vapours of ammonia, it assumes by

degrees a fine violet colour. To obtain this result, the orcine in

powder should be placed in a capsule, alongside of a saucer containing

water of ammonia; and both should be covered by a large bell glass;

whenever the orcine has acquired a dark brown cast, it must be

withdrawn from under the bell, and the excess of ammonia be allowed to

volatilize. As soon as the smell of ammonia is gone, the orcine is to be

dissolved in water; and then a few drops of ammonia being poured into

the brownish liquid, it assumes a magnificent reddish-violet colour.

Acetic acid precipitates the red lake of lichen.

ORES (_Mines_, Fr.; _Erze_, Germ.); are the mineral bodies which contain

so much metal as to be worth the smelting, or being reduced by fire to

the metallic state. The substances naturally combined with metals, which

mask their metallic characters, are chiefly oxygen, chlorine, sulphur,

phosphorus, selenium, arsenic, water, and several acids, of which the

carbonic is the most common. Some metals, as gold, silver, platinum,

often occur in the metallic state, either alone, or combined with other

metals, constituting what are called native alloys.

I have described in the article MINE, the general structure of the great

metallic repositories within the earth, as well as the most approved

methods of bringing them to the surface; and in the article METALLURGY,

the various mechanical and chemical operations requisite to reduce the

ores into pure metals. Under each particular metal, moreover, in its

alphabetical place, will be found a systematic account of its most

important ores.

Relatively to the theory of the smelting of ores, the following

observations may be made. It is probable that the coaly matter employed

in that process is not the _immediate_ agent of their reduction; but the

charcoal seems first of all to be transformed by the atmospherical

oxygen into the oxide of carbon; which gaseous product then surrounds

and penetrates the interior substance of the oxides, with the effect of

decomposing them, and carrying off their oxygen. That this is the true

mode of action, is evident from the well-known facts, that bars of iron,

stratified with pounded charcoal, in the steel cementation-chest, most

readily absorb the carbonaceous principle to their innermost centre,

while their surfaces get blistered by the expansion of carburetted gases

formed within; and that an intermixture of ores and charcoal is not

always necessary to reduction, but merely an interstratification of the

two, without intimate contact of the particles. In this case, the

carbonic acid which is generated at the lower surfaces of contact of the

strata, rising up through the first bed of ignited charcoal, becomes

converted into carbonic oxide; and this gaseous matter, passing up

through the next layer of ore, seizes its oxygen, reduces it to metal,

and is itself thereby transformed once more into carbonic acid; and so

on in continual alternation. It may be laid down, however, as a general

rule, that the reduction is the more rapid and complete, the more

intimate the mixture of the charcoal and the metallic oxide has been,

because the formation of both the carbonic acid and carbonic oxide

becomes thereby more easy and direct. Indeed the cementation of iron

bars, into steel will not succeed, unless the charcoal be so porous as

to contain, interspersed, enough of air to favour the commencement of

its conversion into the gaseous oxide; thus acting like a ferment in

brewing. Hence also finely pulverized charcoal does not answer well;

unless a quantity of ground iron cinder or oxide of manganese be blended

with it, to afford enough of oxygen to begin the generation of carbonic

oxide gas; whereby the successive transformations into acid, and oxide,

are put in train.

ORPIMENT (Eng. and Fr., _Yellow sulphuret of arsenic_; _Operment_,

_Rauschgelb_, Germ.); occurs in indistinct crystalline particles, and

sometimes in oblique rhomboidal prisms; but for the most part, in kidney

and other imitative forms; it has a scaly and granular aspect; texture

foliated, or radiated; fracture small granular, passing into conchoidal;

splintery, opaque, shining, with a weak diamond lustre; lemon, orange,

or honey yellow; sometimes green; specific gravity, 3·44 to 3·6. It is

found in floetz rocks, in marl, clay sand-stone, along with realgar,

lead-glance, pyrites, and blende, in many parts of the world. It

volatilizes at the blowpipe. It is used as a pigment.

The finest specimens come from Persia, in brilliant yellow masses, of a

lamellar texture, called golden orpiment.

Artificial orpiment is manufactured chiefly in Saxony, by subliming in

cast-iron cucurbits, surmounted by conical cast-iron capitals, a mixture

in due proportions of sulphur and arsenious acid (white arsenic). As

thus obtained, it is in yellow compact opaque masses, of a glassy

aspect; affording a powder of a pale yellow colour. Genuine orpiment is

often adulterated with an ill-made compound; which is sold in this

country by the preposterous name of king’s yellow. This fictitious

substance is frequently nothing else than white arsenic combined with a

little sulphur; and is quite soluble in water. It is therefore a deadly

poison, and has been administered with criminal intentions and fatal

effects. I had occasion, some years ago, to examine such a specimen of

king’s yellow, with which a woman had killed her child. A proper

insoluble sulphuret of arsenic, like the native or the Saxon, may be

prepared by transmitting sulphuretted hydrogen gas through any arsenical

solution. It consists of 38·09 sulphur, and 60·92 of metallic arsenic,

and is not remarkably poisonous. The finest kinds of native orpiment

are reserved for artists; the inferior are used for the indigo vat. They

are all soluble in alkaline lyes, and in water of ammonia.

ORYCTNOGNOSY, is the name given by Werner to the knowledge of minerals;

and is therefore synonymous with the English term Mineralogy.

OSTEOCOLLA, is the glue obtained from bones, by removing the earthy

phosphates with muriatic acid, and dissolving the cartilaginous residuum

in water at a temperature considerably above the boiling point, by means

of a digester. It is a very indifferent article.

OSMIUM, is a metal discovered by Mr. Tennant in 1803, among the grains

of native platinum. It occurs also associated with the ore of iridium.

As it has not been applied to any use in the arts, I shall reserve any

chemical observations that the subject may require for the article

PLATINUM.

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