Medicines which are capable of preventing the ill effects of a poison;
or, of counteracting its fatal virulence.
There is perhaps no subject upon which the credulity of mankind has been
so extravagantly exercised as on that of POISONS; nor is there,
certainly, any class of remedies whose history has suffered so many
vicissitudes from the caprice of hypothesis, as that of ANTIDOTES.[212]
It is not my intention, on the present occasion,[213] to enumerate the
many extraordinary virtues[214] which credulity has, at different times,
assigned to such medicines; nor shall I consume the time of the reader
by attempting to expose the absurdity of those fearful powers with which
ignorance, terror, and imposture, have invested certain poisons,—a
subtlety so extreme as to defeat the most skilful caution, and a
virulence so manageable as to be capable of the most accurate
graduation; so that while the former attribute was believed to ensure
their deadly operation, although exerted through the most secret and
least suspicious medium, as that of gloves,[215] tapers, or letters, the
latter was said to enable the accomplished assassin to measure the
allotted moments of his victim with the nicest precision, and to
occasion his death at any period that might best answer the objects of
the assassination.[216]
The abandonment of such notions may be considered as one among the many
advantages which have arisen to medicine, from the cultivation of
physiology.
Without farther introduction, I shall proceed to the main object of this
work, and inquire how far a _chemical agent_ may be capable of
neutralizing, or of decomposing, a poisonous substance in the human
body; and endeavour to ascertain the degree of confidence to which it
may in each particular case be entitled; equally important is it to
learn, whether certain _vital_ agents may not be serviceable in cases of
poisoning, either by promoting the elimination of the poison, or by
producing a state of the system best calculated to resist its
deleterious operation.
It may be safely asserted that we possess very few true antidotes; for
although several of the mineral poisons may be neutralized or decomposed
by various reagents, yet their destructive action is generally so rapid,
that the mischief is effected before any chemical changes can avail;
and, in other cases, the substances resulting from the chemical action,
are as poisonous as the original ingredients, as in the case of the
decomposition of _Corrosive Sublimate_, by the alkalies and earths, when
the precipitated oxide is as virulent as the original salt; while, under
certain circumstances, I suspect that the vital powers of the stomach
are in direct opposition to those changes and decompositions which so
readily, and so uniformly, take place in our laboratories. To _vital
agents_ then, the practitioner must principally look for succour; but
before we can establish any general rules for the treatment of
poisoning, it is essential to distinguish between the different modes in
which poisonous substances produce their effects, or at least to
determine the parts of the living system through which they act; for it
will be found, that each poison has its own _modus operandi_, from which
alone can be derived the particular indications of cure.
The hypotheses devised by the ancient physicians, to account for the
destructive powers of these substances, were principally derived from
mechanical notions respecting the supposed form of their particles,
which they imagined capable of lacerating and disuniting the animal
fibres by the sharpness of their spiculæ;[217] it is however, now
satisfactorily established that the action of a poison in the human
stomach is very rarely, if ever, _mechanical_; sometimes _chemical_; but
for the most part _vital_ in its operation.
Each of the three kingdoms of Nature furnishes a number of poisons, the
investigation of whose chemical properties and physiological actions,
and that of the symptoms to which their administration gives rise, the
lesions of structure which they occasion, and of the medical treatment
which they require, constitutes an elaborate branch of science
designated by the term TOXICOLOGY, and of which I have more fully
treated in my work on Medical Jurisprudence.
Poisons differ materially from each other, not only with respect to the
modes in which they produce their effects in relation to the several
vital organs, but with respect to their application; some of those, for
instance, which, if introduced into a wound, are speedily fatal, may be
taken into the stomach with complete impunity, as in the instance of the
venom of the viper and other snakes, which appears to exert no influence
on the stomach; others, on the contrary, display their deleterious
action on the stomach alone, such as caustic acids, and alkalies,
corrosive sublimate, and some chemical poisons; while others, again, are
equally destructive whether applied to the inner surface of the stomach,
or to the lower intestines, in the form of clyster, or even to the
mucous membrane of the mouth or nose; to the eye; to the vagina and
orifice of the uterus, or to an abraded portion of the skin. There is,
moreover, a class of substances which may be termed _Aerial_ poisons,
for they may exist in the state of gas, or be held dissolved in the
atmosphere, and be received by respiration, or by the mucous membranes
of the nose and throat; the saliva may also thus become the medium for
transferring various subtile poisons from the atmosphere to the animal
body; this is well illustrated by the fact of the transfer of metallic
influence, as related in the case of a gentleman in perfect health who
became salivated in consequence of sitting for one hour by the side of a
person who was in a state of mercurial ptyalism, in order to give him a
lesson in botany.
It also deserves notice, that a poison acts with different degrees of
force and celerity in different parts of the same tissue; its
absorption, for instance, would appear to be energetic in proportion to
the number of veins,[218] although several apparent exceptions to this
law might be adduced, and it is evident that the plethoric state of the
part with respect to its blood-vessels has a considerable share in
modifying the effects; this observation, however, has no relation to
those poisons which operate on the system through the sympathetic
communication of the nerves; Mr. Brodie, for instance, found that the
poison of bitter almonds acted more speedily when applied to the tongue
than when injected into the intestine, though the latter presents a much
better absorbing surface.
_Foderé_, in the fourth volume of his _Medicine Legale_, arranges
poisons according to their action on the living system, and which, with
a slight alteration in the order of the classes, has been adopted by
_Orfila_, and most other writers on Toxicology. Poisons are thus reduced
into six classes: viz. 1. CORROSIVE or ESCHAROTIC, as the _Preparations
of Mercury_, _Arsenic_, _Antimony_, _Copper_, _Tin_, _Zinc_, _Silver_,
_Gold_, and _Bismuth_; the _concentrated Acids_, and _caustic Alkalies_,
and _Earths_; _Cantharides_; _glass and enamel powder_; _diamond
dust_.[219] 2. ASTRINGENT POISONS, of which the _preparations of Lead_
constitute the only species. 3. ACRID or RUBEFACIENT POISONS, which,
with a few exceptions, are furnished by the vegetable kingdom, as
certain _drastic purgatives_, _Hellebore_, _Euphorbium_, &c. 4. NARCOTIC
POISONS, _Opium_, _Henbane_, the _Cherry-laurel_, _Stramonium_, &c. 5.
NARCOTICO-ACRID, embracing such articles as produce the united effects
of the two former, and which constitute some of the most deadly poisons,
as the _Ticunas_, _Nux-vomica_, _Belladonna_, _Tobacco_, _Hemlock_,
_Digitalis_, &c. 6. SEPTIC POISONS, _contagious miasmata_, _putrid
exhalations from animal matter_, _Sulphuretted Hydrogen_, the _venom of
the viper_, &c.
The value of this classification has been very justly stated to consist
in its combining to a certain degree, the advantages of a pathological
arrangement with those of one founded on the basis of Natural History;
for, while it is strictly pathological, it at the same time distributes
the different poisons, with some few and unimportant exceptions, in an
order corresponding with that of their natural history. The First two
classes, for instance, present us with substances of a mineral origin;
the Third and Fourth, with those which are chiefly of a vegetable
nature; and the Sixth, with objects principally belonging to the animal
kingdom. The importance of acknowledging a division, which has a
reference to the organic and inorganic kingdoms of Nature, is
considerable in a chemical point of view; for in enumerating the various
experiments to be instituted for the detection of poisons, we are thus
enabled to bring together a connected series of processes, nearly allied
to, intimately connected with, and in some respects mutually dependent
upon, each other. At the same time it must be acknowledged, that this
classification has many defects and some fallacies. In the first place,
it has little or no reference to the enlarged views of the modern
physiologist, respecting the “_modus operandi_” of Poisons; nor indeed
is its construction susceptible of such modifications and improvements,
as can ever render its degree of perfection progressive with the
advancement of science. In the next place, the classes are in many
particulars ill defined, and indistinctly, if not erroneously, divided.
How questionable, for instance, are the boundaries which separate
_Corrosive_ from _Acrid_ poisons? the respective species, even, of each
class are, in many cases, less allied to each other, than are the great
divisions to which they are subordinate. As an exemplification of this
fact we have only to compare the physiological actions of _Arsenic_ and
_Corrosive Sublimate_, both of which are arranged under the class of
Corrosive Poisons. The former of these substances undoubtedly occasions
death by being absorbed, and thus acting as a vital agent; the latter,
by its local action, as a caustic on the textures with which it
immediately comes into contact. In the same manner, if we examine the
individual actions of the different species composing the class of
“_Acrid_ Poisons,” we shall discover the same want of uniformity; thus,
the _Spurge Flax_, and the _Iatropa Curcas_, act by occasioning a local
inflammation, while the _Hellebore_, being rapidly absorbed, exerts a
fatal action on the nervous system, and produces only a very slight
inflammation. The class of Narcotic Poisons is certainly more absolute
in its definition, and more uniform in its physiological affinities, and
therefore less objectionable than the divisions to which we have just
alluded; but the propriety of the class “_Narcotico-Acrid_” is by no
means equally unexceptionable; indeed Orfila himself questions it,
“because the narcotic or sedative effects only follow the previous
excitement.” Some of the poisons of this division also are rapidly
absorbed, and act, through the medium of the circulation, on the nervous
system, without producing any local inflammation; while others, on the
contrary, merely act upon the extremities of the nerves, with which they
come in contact, and, without being absorbed, occasion death by a
species of sympathetic action.
These few objections, and many more might be urged, are sufficient to
demonstrate the imperfection of the classification under consideration,
and which must render it wholly unavailable to the physician in the
treatment of cases of poisoning, who must derive his plan of cure from
the physiological action of the substance against which he has to
contend; thus, for instance, _Arsenic_ and _Corrosive Sublimate_ are
both corrosive poisons, but so materially do they differ from each other
in their physiological actions that, when swallowed, they will require
for the preservation of the individual, a very different system of
treatment.
For such reasons I have ventured to propose a new arrangement of
Poisons, which may furnish the practitioner with a general theorem for
the administration of Antidotes.