POIS′ON. Syn. Toxicum, Venenum, L. Any substance which, when swallowed or applied in any particular way to the living body, disturbs, suspends, or destroys one or more of the vital functions. In sufficient quantity, or in small doses long continued, the common result of the administration of deleterious substances is either impaired vitality or death.
Poisons are classified by Orfila under four heads:—
1. Irritant poisons, or such as inflame or corrode the parts with which they come in contact. Their chief effects are upon the alimentary canal, with, sometimes, ulceration of the tongue, fauces, and œsophagus. Nausea, vomiting, stomachic and intestinal pains, extreme
anxiety and anguish, quick and feeble pulse, cold and clammy skin, and mucous, bilious, or bloody diarrhœa, are among the common leading symptoms. Arsenic, blue vitriol, verdigris, strong acids and alkalies, drastic purgatives, and numerous other substances, belong to this class.
2. Narcotic or Stupefying poisons, or such as paralyse the functions of the nervous system, and produce headache, vertigo, confused vision, delirium, stupor, convulsions, coma, &c. It includes morphia, opium, henbane, oil of bitter almonds, prussic acid, &c.
3. Narcotico-acrid poisons, which produce at the same time narcotism and irritation of the parts which they touch. Alcohol, belladonna, cocculus indicus, colchicum, foxglove, hemlock, poisonous fungi, strychnine, tobacco, veratrine, &c., are of this kind.
4. Septic or Putrefiant poisons, including all those which alter, liquefy, or cause the putrescence of the fluids of the body; as sulphuretted hydrogen, the gas from sewers and cesspools, putrefying organic matter, miasmata, &c.
The treatment of cases of poisoning varies with the substance occasioning it; the proper antidotes will be found noticed under the names of the various substances that exert a deleterious action on the animal body. It may here, however, be useful to remark that, in almost all cases of poisoning, copious vomiting should be excited as soon as possible by the administration of a powerful emetic; its action being promoted by copious draughts of lukewarm water, tickling the throat with the finger, &c. Should this fail, but not otherwise, the stomach-pump should be had recourse to. The vomiting should be kept up and the stomach well washed out with bland albuminous or mucilaginous liquids, such as milk-and-water, barley water, sweetened water, flour-and-water, or any similar matters, as circumstances may afford. After the vomiting a brisk aperient draught, or clyster, may be administered, and nervous irritability or exhaustion allayed by means of ether, opium, wine, or warm spirit-and-water, as the case may require. Even in a suspected case of poisoning, when proper medical advice is not at hand, an emetic should be immediately administered. Vomiting may be, in general, produced very promptly by merely swallowing a cupful of warm water mixed with a teaspoonful of flour of mustard. If no dry mustard is at hand, a portion of the contents of a mustard-pot, put into the water, will answer nearly as well. As mustard may thus prove of so much use, it should never be wanting in any house; but even should there be no mustard at hand, warm water by itself, freely taken, forms a tolerably efficacious emetic.
POLARISA′TION (of Light). A change produced upon light by the action of certain media and surfaces, by which it ceases to present the ordinary phenomena of reflection and transmission.
Instruments or apparatus employed to effect this change are called ‘polariscopes.’ Although the polarisation of light is frequently employed as a means of chemical investigation, and is of the utmost interest to the philosophical inquirer, its consideration scarcely comes within the province of this work. See ‘Watt’s Dict. of Chemistry,’ ‘Ganot’s Physics,’ &c.