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easily separated by chloride of calcium. (Lipowitz.) 5. Oil containing
alcohol takes up small quantities of water without turbidity when
agitated with that liquid. (Herzog, N. Br. Arch. 28, 16.) 6. Potassium
oxidizes in the oil, with evolution of gas, the more quickly, as the
quantity of alcohol present is greater. A piece of potassium as large as
the Semen Psyllii should remain unaltered for five minutes in a drop of
pure oil; with -^ of alcohol, it disappears in less than five minutes;
with , in less than a minute; in which case it runs about like a
shining fused metallic globule till it is oxidized. (Beral, J. chim. intd.

3, 381; also Berl. Jahrb. 29, 2, 185.) By this method, | alcohol may be


162 TYPES.

detected with certainty, -^ with less certainty, -$ but uncertainly; if the
alcohol amounts to y^ or less, the potassium does not fuse into a globule, but
still produces a stronger evolution of gas than in pure oil. The oxidation
of the potassium may likewise proceed from water instead of alcohol in
the oil. (Pleischl, Zeitschr. Phys. v. W. 2, 308; Lipowitz.) Doubtless
also, the difference of rapidity with which the potassium is oxidized,
varies with the nature of the oil, the oxidation being more rapid when
the oil contains oxygen. 7. A pure volatile oil agitated with an equal
volume of olive-oil, yields a clear mixture; whereas that which contains
alcohol forms a turbid mixture, the alcohol being separated. (Righini,
J. cldm. mcd. 20, 351.)

III. Adulterations of expensive Oils with Oil 'of Turpentine. 1. The
presence of this adulteration may be detected by the smell, especially on
rubbing the oil between the hands, or after setting it on fire and then
blowing it out. 2. Since oil of turpentine is less soluble in hydrated
alcohol than many other oils, the suspected oil may be agitated with its
own bulk of 80 per cent, alcohol; if oil of turpentine, anise, or fennel, be
present, the solution is incomplete. 3. Oil of turpentine mixes much less
easily with fixed oils, than the oils of marjoram, lavender, valerian, sage,
peppermint, or wormwood. If, therefore, 3 grammes of the suspected oil
be agitated with 3 grammes of poppy-oil, and the mixture remains
turbid, we may conclude that the oil is not mixed with turpentine; for
even a small quantity of the latter would render the mixture clear. This
method is not applicable to the oils of thyme and rosemary. (Mero,
J. chim. med. 21, 93.) 4. Many volatile oils dissolve the colouring
matter of sandal-wood, but oil of turpentine does not; the presence of the
latter will, therefore, diminish the solvent power of the other oil. (Voget,
Ann. Pharm. 6, 42.) 5. Oil of turpentine becomes strongly heated, and
detonates by contact with iodine; many other oils do not; but if the
latter are mixed with only a small quantity of oil of turpentine, they
likewise detonate by contact with iodine. (Tuchen.)

Those volatile oils which are free from oxygen are specifically the
lightest; their density ranges from 0*627 (the most volatile oil of oil-
gas) to 0*921 (heveene); the specific gravity of non-oxygenated cam-
phors varies from 0'870 (paraffin) to 1'048 (naphthalin). Oxygenated
volatile oils and camphors vary in density from O'SOO to I'lOO. The
solidifying point of volatile oils in general is in some cases below 0,
sometimes being very low and therefore unknown, such oils being the
volatile oils properly so called ; in other cases, that is to say, in the
camphors or stearoptenes, it is above 0, and among these, phenene melts
at + 6 , chryscne not till heated to 240. In the solid state, volatile oils
(taking the term in its more general sense) are crystalline: in the liquid
state, they have a thin oily consistence. They are colourless; any yel-
lowish or brownish tint that they may exhibit being due to admixture of
resin. The oils of certain Composite are, however, coloured blue or green,
probably from admixture of a volatile blue colouring matter. Volatile
oils have great refracting power. The boiling points of non-oxygenated
volatile oils are given in the table on pages 154, 155, whence it appears
that they vary between 10 (the most volatile oil of oil-gas) and 260
(oil of copaiba), and in camphors, between 86 (phenene) and 380 (paraf-
fin). The boiling points of oxygenated oils are comparatively higher, as
may be seen by some examples in the table just cited. Most volatile oils,
properly so called, boil between 150 and 200; oil of copaiba at 260,


and several camphors between 300 and 400. At these temperatures,
provided the air be excluded (which might otherwise convert part of the
oil into resin), the non-oxygenated oils distil over unchanged; those
which contain oxygen, having higher boiling points, are liable to partial
decomposition when distilled at those temperatures.

The volatile compounds belonging to this class are distinguished by a
powerful odour, sometimes pleasant, sometimes repulsive, and form the
odoriferous principles of many parts of plants and some parts of animals.
Some volatile oils are tasteless; others have a fiery aromatic flavour;
others, again, an acrid taste, and these latter have likewise an acrid action
on the animal body.

According to Liebig (Chim. org. 2, 308), volatile oils appear to emit a
stronger odour in proportion as they oxidize more quickly in the air.
When volatile oils free from oxygen, such as the oils of turpentine, elder,
and lemon, are distilled over freshly burnt lime in an apparatus exhausted
of air or filled with carbonic acid gas, they can scarcely be distinguished
by their odour; but by exposing them for a while to the air, and more
especially by saturating paper with them, the characteristic odours are

Volatile oils appear to be incapable of emitting any odour, except in
presence of moisture. Paper moistened with a volatile oil, and then per-
fectly dried, no longer emits any odour; but the odour becomes apparent
on exposing the paper to the air, or more quickly by moistening it with
a few drops of water. Flores Rosarum, Sambuci, or Verbasci, likewise
completely lose their odour when thoroughly dried, but recover it on
exposure to damp air. (J. A. Buchner, Repert. 15, 57.) When violets are
dried under a bell jar containing chloride of calcium, they retain their
blue colour, but completely lose their smell, which, however, is entirely
restored by moistening them with water. (Hiinefeld, J. pr. Chem. 7,

The cold infusion of roses, orange-blossom, lime-blossom, or elder-
blossom, acquires a much stronger odour on addition of sulphuric acid;
this acid likewise imparts characteristic odours to the inodorous decoction
of gall-nuts, horse-chestnuts, barley, and yellow and red sandal-wood.
A much more strongly smelling water is also obtained by distilling roses
(as was long ago recommended by Albertus Magnus), elder-blossom, lime-
blossom, or pinks, with a mixture of water and sulphuric acid, than by
distilling them with water alone. Volatile oils may be completely
deprived of their odour and fiery taste, by proper treatment with caustic
alkalis and by other means. They may, therefore, be regarded as com-
pounds of inodorous oils with acids, to which the odour and burning
taste of the entire oil are properly due. Many volatile oils yield two
acids, one liquid and the other crystalline. (Couerbe, J. Pharm. 15, 598;
19, 542; the latter also in Pogg. 31, 525.) Couerbe has not hitherto
fulfilled his promise of confirming this view by more exact observations,
and thereby removing the doubts which attach to it.

The more important Decompositions or Reactions of Volatile Oils are
as follows:

1. Those oils which have a high boiling point are partly decomposed
by distillation, per se, and leave a residue of charcoal; but when distilled
with water or gently heated in the air, they may be volatilized without
decomposition. But even the more volatile oils, when mixed with earthy

M 2

164 TYPES.

substances, such as clay, chalk, sand, &c., which mechanically prevent
their volatilization, are partially decomposed by distillation, combustible
gases being evolved, and charcoal left behind; if they contain oxygen,
they may likewise yield carbonic oxide, acetic acid, &c. When the
vapour of a volatile oil is passed through a red-hot tube, it is resolved
into combustible gases arid charcoal, which is sometimes finely divided,
sometimes shining, dense, and difficult to burn; the portion of the oil
which has passed over undecomposed, is often found to be altered in its
properties, as, for example, in its boiling point. 2. Volatile oils are very
inflammable, and burn with a clear flame which deposits a large quantity
of soot. If the vapour of a volatile oil be made to issue from a fine jet,
under a pressure of 1 6 centimetres of mercury, it does not take fire till
it has reached a distance of some centimetres from the jet; that is to say,
till it has become mixed with 4 or 5 times its volume of air; it then
burns with a bright flame, which no longer smokes, and may be used for
illumination. (Busson-Dumaurier & Ronn, Compt. rend. 16, 1164.)
Volatile oils may be used like alcohol to feed the lamp without flame.
(Karmarsch, Gill). 75, 83.) The oils of amber, anise, juniper, savine,
rosemary, peppermint, wild marjoram, nutmeg, cinnamon, and cloves,
emit acid vapours when burnt in this manner. (Miller, Ann. Phil. 28,
21.) A piece of red-hot spongy platinum, laid upon common camphor,
continues to glow, and sinks deeply into the camphor. (Gm.). 3. Vola-
tile oils proper, when placed in vessels not perfectly closed, and at the
medium temperature of the air, absorb oxygen-gas; acquire the power
of reddening litmus strongly, from formation of benzoic, cinnamic, acetic,
and other organic acids; and are then partially converted into resins,
becoming viscid and less odoriferous, and passing from the colourless
state to yellow or red-brown, or from blue to brown. Oils thus altered
are resolved by distillation into pure oil and a residue of resin. The
absorption of oxygen takes place with different degrees of rapidity in
different oils. For the first few days it goes on slowly, then increases in
rapidity up to a certain limit, beyond which it again diminishes, and after
several months becomes imperceptible. During this change, and espe-
cially towards the end, the oil exhales a small quantity of carbonic acid,
and a still smaller quantity of hydrogen. At the same time, a small
quantity of very acid water is produced, which is loosely attached to the
resinized oil, but may be separated from it either by the application of
heat or by exposure to the sun. Rock-oil absorbs scarcely any oxygen,
and therefore forms neither acids nor resin. (Th. Saussure.) The forma-
tion of acid and water was observed by Fourcroy. The oils of Valeriana
off., Artemisia Absinthium, Carum Carvi, Juniperus communis, Citrus
Aurantium and medica, Melissa off.^ Dracocephalum Moldavica, Mentha
piperita and crispa, Origanum vulgare and Major ana, Salma off. and
Laurus Cinnamomum, Cassia, and Sassafras, are neutral when fresh, but
after exposure to the air in thin layers, for intervals varying from a few
days to several months, acquire an acid reaction, in consequence of
the formation of a crystalline acid, the oil still remaining fluid. They
then thicken in consequence of the formation of resin and acetic acid,
which latter is given off with a pungent odour, and if the oil be enclosed
in a confined portion of air over hydrate of potash, converts that alkali
into an acetate, carbonate of potash being at the same time produced from
carbonic acid given off by the oil. The oils of camomile, anise, fennel,
roses, and turpentine, on the other hand, acquire no acid reaction at first,
not indeed till they begin to assume the resinous condition, and acetic

acid bes


acid begins to form. (Bizio.) The crystalline acid often formed in
abundance from volatile oils at the commencement of the oxidation,
varies according to the nature of the oil; in some cases, it has been found
to be benzoic acid; in others, cinnamic. When oxygen gas is passed
through a volatile oil, a formation of acid likewise takes place at first,
most quickly when the oil is suspended in water; the aqueous solutions
of the oils likewise turn sour on exposure to the air. According to
Unverdorben (Pogg. 8, 483), volatile oils, when they thicken in the air,
are converted: (1) into a difficultly volatile oil having but little odour;
(2) into a resin soluble in potash; (3) into a resin insoluble in potash;
(4) into an oily acid, insoluble in water, lighter than water, and having
a sweet, pungent taste. The same products are obtained, but in larger
quantity, by passing volatile oils through a red-hot tube. The thickening
takes place with various degrees of rapidity, according to the nature of
the oil. 4. A similar decomposition to that which takes place in the
air, is likewise produced, by placing the oil in contact with nitrous gas,
which it rapidly absorbs (Priestley); also by boiling the oil with oxide
of copper or peroxide of lead, water being then formed (A. Vogel); or
by digesting it with mercuric nitrate or corrosive sublimate, these bodies
being thereby converted into mercurous nitrate and calomel respectively.
(Margueron.) Volatile oils are likewise resinized by bichloride of tin
and pentachloride of antimony, the latter often yielding reduced metal.
Oils which easily resinize in the air are likewise immediately thickened
by agitation with a warm concentrated solution of tersulphate of ferric
oxide. (Berzelius.) 5. Volatile oils absorb chlorine gas, with evolution
of heat, and are converted into viscid substances. (Thenard.) Hydro-
chloric acid is frequently formed in this reaction, a substitution of chlorine
for hydrogen likewise taking place. Bromine exhibits similar reactions.
(Laurent.) 6. Many volatile oils proper give up their hydrogen to
iodine so rapidly, and with so great a development of heat, that an
explosion takes place accompanied with evolution of violet and yellow-
vapours. This is the case with the oils of turpentine, juniper, savine,
lemon, rosemary, and lavender. The residue is a thickened oil or a
brown acid resin. These oils lose by age the property of deflagrating
with iodine. Other oils dissolve iodine quickly with or without evolution
of heat, forming therewith a brown, thickish oil, or a soft or hard resin,
with separation of a brown liquid, containing hydriodic acid. Such is
the case with Oleum Oinnamomi, Sassafras, Caryophyllorum, Rutas,
Tanaceti, Carvi, Foeniculi, Mentkce piperitce and crispce, and the Oleum
animate Dippelii. (Tuchen, Walcker, Flashoff, Zeller, Winckler)
H When oil of anise or fennel is dropped into a cold saturated solution
of iodine in aqueous iodide of potassium, a gelatinous magma is formed,
which, on addition of six or eight times its volume of alcohol, deposits a
pulverulent substance, becoming dazzling white after washing with
alcohol. This body is free from iodine, and appears to be composed of
C^H^O 4 . It may be supposed to be formed by the addition of 1 At.
to 3 At. of anise or fennel-camphor:

3C 10 H 6 O + O =

The oils of cumin, wormwood, camomile, tansey, rue, cloves, and
peppermint, do not yield any similar product when thus treated. (Will,
Ann. Pharm. 65, 230.) IT 7. Fuming nitric acid decomposes volatile oils
proper, mostly with great rapidity, the action being attended with evolution
of gas, and with development of heat often amounting to the most vivid

166 TYPES.

inflammation; those volatile oils which are not set on fire by fuming nitric
acid, generally burst into flame when treated with nitric acid to which
half its bulk of sulphuric acid has been added. After the combustion, a
residue of charcoal is left. If, however, the oil does not take fire, there
remains a soft, bitter resin, which retains hyponitric acid, even after long
washing with water, and a yellow or brown acid liquid from which water still
separates a resinous substance. Camphors are not so rapidly decomposed j
several of them and of other volatile oils are converted by heating with
dilute nitric acid, partly into peculiar acids (benzole and anisic acids),
partly into oxalic acid. Many oils turn yellow when mixed with ^
concentrated nitric acid; others first turn pale red, then bright red, and
after 24 hours, brown; others, again, acquire a beautiful violet colour.
(Bonastre, J. Pharm. 15, 663.) Oil of vitriol mixes with most volatile
oils proper, causing rise of temperature and evolution of sulphurous acid,
together with a volatile oil (probably eupione) which smells of straw-
berries; the product is a thick brown liquid, from which water, in many
cases, separates an isomeric compound (e. </., anisoin from anise-oil); in
other cases, a brown acid substance, which behaves, sometimes like arti-
ficial tannin, sometimes like an acid resin, dissolves in alcohol and alkalis,
and, to a certain extent, also in water; heating the sulphuric acid solution
causes the mass to carbonize. Camphors, which usually dissolve without
decomposition in cold oil of vitriol, likewise become charred when heated
with it. Certain non-oxygenated volatile oils, such as eupione and
paraffin, do not mix with cold oil of vitriol, or undergo any alteration
by contact with it. Respecting the peculiar colouring of different oils
by cold oil of vitriol, vid. Gaultier de Claubry. (J. Phys. 81, 69.)
9. Oils consisting wholly of carbon and hydrogen are not acted upon in
any way by potassium or potash.

Combinations. A. Volatile oils proper and many camphors are
slightly soluble in water to the extent of about 1 pt. in 1000; those
which contain oxygen dissolve more freely than those which do not.
The solution is sometimes obtained by agitating the volatile oil with
water, but more frequently by distilling the water with substances which
contain the volatile oil. The products are called Distilled Waters (Aquas
distillatoe). They are transparent and colourless, unless the oil is in
excess, in which case it remains for a long time suspended in the liquid
and renders it turbid; they possess the taste and smell of the volatile oils
which they contain. Agitation with a fixed oil (Davies, J. Pharm. 9, 16),
or with ether, withdraws the volatile oil from the water, and on evapo-
rating the ethereal solution, the greater part of the oil is left behind.
(Soubeiran, J. Pharm. 17, 620; 19, 50.) Agitating the water with
common salt, separates a considerable portion of the oil; such is the
cass with Aqua Foeniculi, Menthce piperitce, and Cinnamomi, and with
water containing primrose-camphor. (Hiinefeld, J. pr. Chem. 9, 24.)

To determine the quantity of volatile oil contained in a distilled
water, half an ounce of the liquid is to be mixed with a small quantity
of gelatinous starch, and a solution of 1 grain of iodine in 500 grains
of alcohol and 1500 grains of water added, with agitation, till the
oil ceases to give up hydrogen to the iodine, and consequently the iodine
begins to impart a blue colour to the starch. It must, however, be
observed, that different oils destroy the blueing properties of different
quantities of iodine; thus, the same quantity of iodine is required to im-
part an incipient blueness to 24 ounces of water mixed with starch paste,


when the water contains 0'5 grain of oil of roses, 2'6 gr. fennel-oil; 3-6
gr. oil of Mentha crispa, 5'3 gr. peppermint-oil, or 20 gr. oil of cinnamon.
Hence oil of roses gives up nearly 40 times as much hydrogen to the
iodine as an equal quantity of oil of cinnamon. (Gruner, Jahrb. prakt.
Pharm. 7, 304.)

The oil contained in the water gradually changes into acid and resin,
when exposed to the air, especially in a warm place; it is also imme-
diately precipitated as a resinous matter by chlorine. A distilled water
may be kept unaltered for a long time in a cellar at a temperature of 10
or 12; but at 25 or 30 it turns acid in a week, especially if exposed
to the sun; by this change, however, the water loses little or nothing of
its peculiar odour. The water which acidifies most quickly and strongly
of all is Aqua Melissce, then come Aqua Rosarum, Sambuci and Chamo-
millce, while Aqua Hyssopi and Menthce crispce and piperitce remain un-
altered. (Flashoff, N. Tr.11, 1, 294; Br. Arch. 21, 222.) If the distilled
water contains a small quantity of alcohol, a considerable quantity of
acetic acid is quickly formed in it. (Warington, Phil. Mag. J. 26, 574.)

Many distilled waters, when kept in well closed bottles, become
slimy, lose their proper odour, and acquire an offensive smell, whereas,
if kept in loosely covered vessels, they remain unaltered. This change
appears to arise from the action of mucous and albuminous particles
carried over in the distillation, which, when they putrefy, rob the volatile
oil of a portion of its oxygen, or give up to it a portion of their own
hydrogen, thereby depriving it of its peculiar odour; hence such waters
recover their odour on exposure to the air. The same raspberry- water
spoils in four weeks if kept in a bottle of colourless glass, but may be
kept unaltered for a year in a bottle of orange-coloured glass: a proof of
the influence of light. (Hanle, Repert. 67, 392.) The white flakes
deposited from distilled waters consist of plants. (Simoriin.) The white
or brown mucus thus separated does not dissolve either in alcohol or in
boiling potash, and, when examined with a lens, appears like an agglome-
ration of fine confervoidal fibres resembling mother of vinegar. (Gruner.)
According to Buchner (Br. Arch. 7, 284), Aqua Rosarum, Menthce pipe-
ritce, Cinnamomi, keep best in close vessels; Aqua Chamomillce, Fosniculi,
Naphce, Menthce crispce, Hyssopi, Cerasorum, less perfectly ; and Aqua
Valeriance, Rutce, ISambuci, Tilice, Riibi Idcei, Petroselini, Melissce,
Sal vice, worst of all; but if such waters be once distilled as long as water
containing oil passes over, a distillate is obtained which may be kept
without alteration in close vessels for four years or more. A good mode
of preservation is to leave the distilled water for several days in contact
with the oil which has passed over, agitating frequently ; then filter it
into medicine-glasses containing from half a pound to a pound, bind the
glasses round with moist bladder, introduce them, according to Appert's
method (p. 100), into water heated to ebullition in a boiler, and bind
round the bladders, after cooling, with paper. Even raspberry- water
thus treated may be kept unaltered for 8 years. (Wend, Jahrb. prakt.
Pharm. 1, 35.)

Certain hydrocarbons, oil of turpentine for example, when kept over
water, take up the elements of water, and are converted into camphors.

B. Liquid volatile oils absorb small quantities of carbonic oxide,
carbonic acid, and nitrous oxide gas, and larger quantities of sulphurous
acid, hydrosulphuric acid, or fluoride of silicium.

With the aid of heat, they dissolve a tolerably large quantity of

168 TYPES.

phosphorus, forming a liquid which shines in the dark, and deposits tho
greater part of the phosphorus on cooling.

They also, when heated, dissolve a small quantity of sulphur, which
crystallizes out again on cooling; when boiled for some time with sulphur,
they unite in the decomposed state, with considerable quantities of that
substance, forming a brown, greasy, stinking mass, called Volatile Balsam
of Sulphur, which, if heated for a longer time, quickly evolves a large
quantity of sulphuretted hydrogen gas. Most camphors may also be
made to unite with sulphur and phosphorus by fusion.

Bisulphide of Carbon mixes in all proportions with liquid oils, and
dissolves camphors.

C. Many volatile oils and camphors absorb large quantities of hydro-
chloric acid gas, producing great rise of temperature, and forming some-
times oily, sometimes camphoroidal compounds, in which the chlorine
cannot be detected by nitrate of silver. With hydrobromic acid gas they
behave in a similar manner. Many of them combine with chloride of
phosphorus and chloride of sulphur, the combination being attended with
evolution of heat.

D. Only a few oils, which contain oxygen, and have a slightly acid
character, viz., creosote, oil of cloves, and oil of pimento, absorb ammo-
niacal gas in abundance, dissolve in aqueous alkalis, and form with these
and other bases, saline compounds, in which the odour of the oil is
destroyed .

Volatile oils dissolve oxide of copper at ordinary temperatures, but

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