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Articles from Aids To Forensic Medicine And Toxicology

Evidence Of Poisoning

Aconite

Signs Of Death

Sulphuric Acid

Duty Of Practitioner In Supposed Case Of Poisoning

Action Of Poisons; Classification Of Poisons

Death By Strangulation

Definition Of A Poison

Hydrochloric Acid

Petroleum And Paraffin-oil


Action Of Poisons; Classification Of Poisons





=Action of Poisons.=--They may act either locally or only after
absorption into the system.

1. Local Action, as seen in (a) corrosive poisons; (b) irritant
poisons, causing congestion and inflammation of the mucous
membranes--e.g., metallic and vegetable irritants; (c) stimulants or
sedatives to the nerve endings, as aconite, conium, cocaine.

2. Remote Action.--This may be of reflex character, as seen in the
shock produced by the pain caused by corrosive poisons, or the poison
may exert a special action on certain structures, as belladonna on the
cells of the brain, strychnine on the motor nerve cells of the spinal
cord.

3. In Both Ways.--Certain poisons, as carbolic or oxalic acids, act in
this way.

Age, idiosyncrasy, tolerance, and disease, all exert modifying
influences on the action of a poison. The form in which the poison is
swallowed and the quantity also determine its action. In the gaseous
form, poisons act most rapidly and fatally. When in solution and
injected hypodermically, they also act very rapidly. In the solid form
they act as a rule slowly, and may even set up vomiting, and so may be
entirely ejected by vomiting. Poisons act most energetically when the
stomach is empty. If taken when the stomach already contains food,
solution and absorption may be greatly delayed.

Some poisons are cumulative in their action, and thus, even if
infinitesimal doses be swallowed each day, there is a certain amount of
storage in the tissues (though a certain percentage of the poison is
being constantly eliminated), and at last symptoms of poisoning show
themselves.

=Classification of Poisons.=--As an aid to memory, the following
classification is perhaps the best:


I. Inorganic.

1. Corrosive acids and alkalies, and caustic salts (carbolic and
oxalic acids also).
2. Irritant--practically all the metals and the metalloids (I. Cl.
Br. P.).

II. Organic.

{ Animal--venomous bites, food poisoning, cantharides.
1. Irritant { Vegetable--all strong purgatives, hellebores, savin,
{ yew, ergot, hemlock, laburnum, bryony, etc.

2. Neuronic.

(a) Somniferous--opium and its alkaloids.
(b) Deliriant--belladonna, hyoscyamus, stramonium, cannabis,
cocaine, cocculus, camphor, fungi.
(c) Inebriants--alcohol, ether, chloral, carbolic acid (weak),
benzol, aniline, nitro-glycerine.

3. Sedative or depressant.

(a) Neural--conium, lobelia, tobacco, physostigma.
(b) Cerebral--hydrocyanic acid.
(c) Cardiac--aconite, digitalis, colchicum, veratrum.

4. Excito-motory or convulsives--nux vomica, strychnine.

5. Vulnerants--powdered glass.


III. Asphyxiants.

Poisonous and irrespirable gases.





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