Camphor.
QUALITIES. _Form_, a white brittle substance, unctuous to the touch, but
possessing at the same time a degree of ductility which prevents its
being easily pulverised, unless a few drops of spirit be previously
added. It is capable of affecting a crystalline form.[438] _Odour_,
peculiar, fragrant, and penetrating. _Taste_, bitter, pungent, and
aromatic. _Specific gravity_, ·9887, it therefore swims on water; it is
so volatile that during warm weather a considerable proportion will
evaporate, especially if at the same time the atmosphere be rather
moist, for the reason stated in page 175. It is readily ignited, and
burns with a brilliant flame and much smoke; it melts at 288°, and boils
at 400. CHEMICAL COMPOSITION. It is a proximate vegetable principle,
resembling the essential oils in many of its habitudes, and probably
differs from them in composition only in containing a larger proportion
of carbon. SOLUBILITY. Water may be said to dissolve about a nine
hundredth part of its weight, or f℥j rather more than gr. ½, but its
solvent power is considerably increased by the addition of carbonic acid
gas; camphor is also rendered more soluble by trituration with magnesia;
it is soluble in an equal weight of alcohol, but it is again separated
by the addition of water; it is also dissolved by oils, both fixed and
volatile,[439] especially if their temperature be a little raised, and
by sulphuric and other æthers, but strong acetic acid may be said to be
its most powerful solvent. By repeatedly distilling it with nitric acid
it is converted into _Camphoric acid_, an acid distinguished by peculiar
properties, and composing, with alkalies and earths, a class of salts
called _Camphorates_, but which do not possess any medicinal value. The
alkalies do not produce any effect upon camphor. INCOMPATIBLE
SUBSTANCES. It is not affected by any substance with which we can
combine it. FORMS OF EXHIBITION. It is preferable in the form of
mixture, since it is very liable in the solid state to excite nausea,
and, from swimming on the contents of the stomach, to occasion pain at
its upper orifice. If a larger dose be required than that which water
can dissolve, an additional proportion may be suspended by means of
sugar, almonds, yelk of egg, or mucilage, for which purpose three times
its weight of gum arabic is required. If Camphor be first dissolved by
trituration in a very small portion of oil, it readily mixes with
mucilage of gum arabic, and may then be conveniently blended with
liquids. It has also the property of uniting with gum-resins, and of
converting them into permanently soft, and uniform masses; hence they
may sometimes be conveniently applied for diffusing it in water. It may
be formed into pill-masses by stiff mucilage, fœtid gums, or by a
confection. MEDICINAL USES. In moderate doses it exhilarates, without
raising the pulse, and gives a tendency to diaphoresis; and under
certain conditions of the body, when opium fails, it will frequently
promote sleep. As its effects are transient, its dose should be repeated
at short intervals. _Illustrative Formulæ_ 1, 6, 21, 125, 134, 164.
Camphor is said to correct the bad effects of opium, mezereon,
cantharides, and the drastic purgatives, and diuretics. DOSE, gr. ij to
℈j. In excessive doses it occasions anxiety, vomiting, syncope, and
delirium; these violent effects are best counteracted by opium.
OFFICINAL PREPARATIONS. _Mistura Camphoræ._ L.D. _Emulsio Camphorata._
E. _Spiritus Camphoræ_, L.E.D. _Tinctura Camphoræ comp:_ L.E.D. _Acidum
Acetosum Camphoratum._ E.D. _Linimentum Camphoræ._ L.E.D. _Liniment:
Camphoræ comp:_ L. _Liniment: Saponis_. (=G=) L.E.D. ADULTERATIONS. It
has been stated that pure camphor may be known by placing it upon hot
bread, when it will turn moist, whereas an adulterated specimen becomes
dry—but with what can it be adulterated?