This substance is what is generally termed a _gum-resin_; that is, a
compound consisting of gum, resin, and volatile oil: late researches
however seem to shew that these bodies are compounds of a peculiar
character, consisting of a volatile substance, something between
essential oil and a constituent which possesses the properties of
extractive rather than those of gum.
True Elemi has a fragrant aromatic odour, not unlike that of
fennel-seeds, but more potent. _Sp. gr._ 1·0182. When powdered it mixes
with any unguent; it also combines with balsams and oils, and by the aid
of heat, with turpentine. USES. It is only employed for forming the
_mild digestive ointment_ which bears its name, viz. _Unguent: Elemi_
_comp:_ L.D.
EMPLASTRA. L.E.D. Plasters.
The principles upon which this form of preparation is to be constructed
are fully detailed at p. 207.
EMPLASTRUM AMMONIACI. L. _Ammoniacum_ reduced to a suitable consistence
by distilled vinegar. It adheres to the skin without irritating it, and
without being attended with any unpleasant smell.[494] There is a
peculiar disease of the knee, to which servant maids, who scour floors
upon their knees, are liable, and for which this plaster is a specific.
I have also found it particularly eligible in cases of delicate women
with irritable skins.
EMPLASTRUM AMMONIACI CUM HYDRARGYRO. L.D. The mercury in this plaster is
in the state of oxidation _ad minimum_. It is discutient and resolvent,
and is applicable to indurated glands, and venereal nodes, and for
removing indurations of the periosteum, remaining after a course of
mercury; the addition of the ammoniacum increases the stimulating and
discutient powers of the mercury, which gives this plaster a superiority
over the _Emplastrum Hydrargyri_. It is also powerfully adhesive.
EMPLASTRUM ASSAFŒTIDÆ. E. Emplast. Plumbi and Assafœtida, of each _two
parts_, galbanum and yellow wax, of each _one part_. I have seen it
useful in flatulent cholic, when applied over the umbilical region.
EMPLASTRUM CANTHARIDIS. L. _Emplast: Cantharidis vesicatoriæ._ E.D. A
variety of substances has in different times been employed for producing
vesication, but no one has been found to answer with so much certainty
and mildness as the _Lyttæ_. All the others are apt to leave ill
conditioned ulcers: true it is, that the emplastrum lyttæ will
occasionally fail, but this is generally attributable to some
inattention, or want of caution on the part of the person who prepares
it; in spreading it, the spatula should never be heated beyond the
degree of boiling water; the plaster also should be sufficiently secured
on the part by slips of adhesive plaster, but it ought not to be bound
on too tight; where the cuticle is thick, the application of a poultice
for an hour, previous to that of the blister, will be useful, or the
part may be washed with vinegar. In consequence of the absorption of the
active principle of the _Lyttæ_, blisters are apt to occasion strangury
and bloody urine; it has been a problem therefore of some importance to
discover a plan by which such an absorption may be obviated, for this
purpose, camphor has been recommended to be mixed with the blistering
composition, and a piece of thin gauze has been interposed between the
plaster and the skin; but it has been lately found, that ebullition in
water deprives the _Cantharides_ of all power of thus acting on the
kidneys, without in the least diminishing their vesicatory properties:
the ordinary time required for the full action of a blister is ten or
twelve hours, but if it be applied to the head, double that period will
be necessary. Children, owing to delicacy of skin, are more speedily
blistered, the epispastic may therefore be removed earlier. In some
cases the blistered parts, instead of healing kindly, become a spreading
sore; whenever this occurs, poultices are the best applications; it may
arise from a peculiar irritability of the constitution, although I
apprehend that it not unfrequently depends upon the sophistication of
the plaster with euphorbium. In cases where it is desirable to keep up
the local irritation, it is still a question with some practitioners
whether it be more advisable to encourage a discharge from the vesicated
part by some appropriate stimulant, or to renew the vesication at short
intervals by repeated blisters; the latter mode is perhaps to be
preferred, as being more effectual, and certainly less troublesome to
the patient: it has moreover been stated,[495] that by a repeated
application of this nature, the influence excited appears to extend much
deeper, so as to derive a greater quantity of blood from the immediate
neighbourhood of the vessels, or from the vessels themselves which are
in a state of disease, than the influence excited by an application less
stimulating upon the surface of a part already abraded. The character of
the discharge would likewise appear essentially different; it being in
the latter cast a purulent secretion from the superficial exhalants of
the surface only; in the former, a copious effusion of serum, mixed with
a large portion of lymph, produced from a deeper order of vessels.
EMPLASTRUM CERÆ. L. _Emplast: Simplex_. E. This is the _Emplast: Ceræ_
of P.L. 1787, the _Emplast: Attrahens_ of 1745, so called because it was
formerly employed to keep up a discharge from a blistered surface, and
the _Emplastrum de melilolo simplex of_ 1720.
EMPLASTRUM CUMINI. L. A valuable combination of warm and stimulant
ingredients.
EMPLASTRUM GALBANI COMPOSITUM. L.D. _Emplast: Gummos_. E. More powerful
than the preceding plaster. In indolent glandular enlargements of a
strumous character, in fixed and long continued pains in the
neighbourhood of the joints, or in anomalous or arthritic pains of the
ligaments, this plaster is said to be frequently beneficial.
EMPLASTRUM HYDRARGYRI. L.E. The mercury in this plaster is in the state
of oxidation _ad minimum_; each drachm containing about fifteen grains
of mercury, (_sixteen grains_, _Edinb._) It is alterative, discutient,
and sometimes sialogogue; but it is inferior to the _Emplast: Ammoniac:
cum Hydrargyro_.
EMPLASTRUM OPII. L.E. This plaster is supposed to be anodyne, but it is
very doubtful whether the opium _can_, in such a state, produce any
specific effect. See _Form: 5_.
EMPLASTRUM PICIS COMPOSITUM. L. _Emplast: Picis burgundicæ_, P.L. 1787.
It is stimulant and rubefacient, and is often employed as an application
to the chest, in pulmonary complaints; the serous exudation however
which it produces, frequently occasions so much irritation that we are
compelled to remove it.
EMPLASTRUM PLUMBI. L. _Emplast: Oxydi Plumbi semi-vitrei._ E. _Emplast:
Lythargyri._ P.L. 1787. _Emplast: commune_, 1745. _Diachylon_[496]
_Simplex_, P.L. 1720. This is a very important plaster, since it forms
the basis of a great many others; under the name of _Diachylon_ it has
long been known, and employed as a common application to excoriations,
and for retaining the edges of fresh cut wounds in a state of
apposition, and at the same time for defending them from the action of
the air; when long kept it changes its colour, and loses its adhesive
properties, and by high temperature the oxyd of lead is revived.[497]
EMPLASTRUM RESINÆ. L. Olim, _Emplast: commune adhæsivum_, P.L. 1745.
_Emplast: Resinosum_. E. _Emplast: Lithargyri cum Resina._ D. It is
defensive, adhesive, and stimulant.[498]
EMPLASTRUM SAPONIS. L.D. _Emplastrum Saponaceum._ E. The Soap Plaster is
said to be a mild discutient application.