CHAPTER II.

Classification of Poisons - Irritant Poisons

Poisoning by Mineral Acids, by Alkalies and their Salts, Noxious Gases-Poisoning by Phosphorus, Arsenic, Antimony, Mercury, Lead, Copper, etc.—Poisoning by Oxalic Acid, Carbolic Acid, etc.—Poisoning by Decomposed Food, Ptomaïnes, Neurotic Poisons-Poisoning by Opium, Alcohol, Ether, Chloroform, Chloral, Nux Vomica, Strychnia, Belladonna, Stramonium, Tobacco, Lobelia, Hydrocyanic Acid.

SYSTEMATIC Writers upon the subject of Toxicology vary very much in the manner in which they classify poisons. In this manual, however, poisons will be regarded as consisting of only two kinds: IRRITANTS and NEUROTICS.1

Irritant poisons include substances which, when swal

lowed, give rise to an acrid, burning taste, followed by nausea, vomiting, cramps in stomach, purging, the matters Taylor: op. cit., p. 78.

vomited and purged being often mixed with blood, these symptoms being due to inflammation of the mucous membrane of the alimentary canal, terminating not unfrequently in ulcer, perforation, and gangrene. They may possess simple irritant properties or specific ones, and are derived from the mineral, vegetable, and animal kingdoms. The simple irritant poisons include such substances as the mineral acids and alkalies. Among those possessing specific properties may be mentioned phosphorus, arsenic, antimony, mercury, oxalic and carbolic acids, cantharides, poisoned meat, fish, etc.

Neurotic poisons include such substances as have a specific action upon the brain and spinal cord, causing headache, giddiness, drowsiness, stupor, delirium, coma, convulsions, paralysis. They are derived from the vegetable kingdom and include substances like opium, chloral, strychnia, atropia, Calabar bean, prussic acid, etc.

IRRITANT POISONS.-Poisoning by Mineral Acids.-As a general rule, most cases of poisoning due to mineral acids are accidental in character, suicide being only occasionally committed by such means, and homicides but rarely. As the symptoms, post-mortem appearances, general treatment, in poisoning by the different mineral acids, are very much the same, they may be conveniently considered together. The symptoms in cases of poisoning of this kind, which depend more on the degree of concentration than on mere quantity, are a burning sensation in the mouth, followed by violent pain in the stomach, vomiting of darkcolored coffee-grounds-like matters containing blood, and occasionally portions of mucous membrane. In all cases of poisoning by mineral acids, magnesia, chalk, plaster off the walls (if nothing better), soap-suds, oil, milk, mucilaginous drinks, flaxseed tea, or barley-water may be adminis

tered. If undiluted acid has been swallowed, however, there is but little hope that the remedies just mentioned or any others will do much good. The smallest recorded quantity of sulphuric acid known to have destroyed life was one drachm, the shortest known period at which death has taken place being within two hours.1

On post-mortem examination stains and corrosions are found on all parts with which the acid has come in contact. The stomach is filled with black, yellow, or brown fluid, perhaps distended with gas, its mucous membrane charred or inflamed, perforation not being uncommon in cases of sulphuric acid poisoning. The skin is stained black or dark brown by sulphuric acid, yellow by nitric acid, white by hydrochloric acid. In cases of sulphuric acid poisoning the contents of the stomach should be filtered and then treated with any soluble salt of barium. The dense white precipitate produced, insoluble in acid and alkalies, with charcoal and blowpipe will yield barium sulphide, which in turn with a mineral acid gives sulphuretted hydrogen, recognizable by the black stain it gives to filtering paper dipped into a solution of lead salt.

The smallest quantity of nitric acid recorded as having destroyed life was two drachms, death having taken place within two hours."

In cases of poisoning by nitric acid, the matters obtained from the stomach should be first filtered. The clear acid liquid so obtained should then be heated and a weak solution of potassium carbonate added. Paper dipped into a concentrated solution of the latter will afterwards burn with deflagration. A few drops of the filtered solution evaporated to dryness on a glass slide will give 1 Christison: op. cit., p. 162.

2 Wharton and Stillé: op. cit., vol. ii. p. 179.

crystals of potassium nitrate. On making a solution of these crystals and adding a crystal of ferrous sulphate with a drop or two of strong sulphuric acid, the green color of the crystal will change to reddish-brown, due to the formation of ferric sulphate. Morphina and brucina will serve as tests for concentrated nitric acid, being turned red by the acid. Ruddy brown fumes are also given off when nitric acid is poured on copper. In order to extract hydrochloric acid from the stomach it is only necessary to add silver nitrate to the filtered contents, the white precipitate silver chloride formed being readily recognizable by being soluble in liquor ammoniæ and precipitable by nitric acid, blackening upon exposure to light and melting into a mass known as horn silver when heated. The fact that hydrochloric acid dissolves gold leaf in the presence of nitric acid affords a convenient test for the concentrated acid, as also the white fumes given off with vapor of ammonia. The smallest quantity of hydrochloric acid known to have destroyed life is half an ounce, the shortest period within which death took place being two hours.'

Poisoning by Alkalies.—The alkalies, potassa, soda, and ammonia, are rarely used for homicidal purposes. As potassa and soda are, however, extensively used in the arts, in the manufacture of glass and soap, under the name of pot- and pearl-ashes, soda ashes and soap lees, and ammonia in the form of aqua ammoniæ for various household purposes, illnesses and occasionally death have occurred as the result of taking them accidentally.

The symptoms of poisoning by the alkalies are an acrid, nauseating taste, followed by a burning heat in the throat and stomach, violent abdominal pains, vomiting and purging. Ammonia, being more irritating than potassa or soda, affects the respiratory organs especially, inducing a chok1 1 Taylor: op. cit., p. 102.

ing sensation. In cases of poisoning by any of the alkalies, vinegar and water, lime or orange juice, oil, which forms with alkali soap, should be given, opium being administered to relieve pain. The quantity of potassa or soda or ammonia that may prove fatal is variable, death having been caused by half an ounce of caustic potassa and by forty grains in solution and by two drachms of ammonia.1 Persons have, however, recovered after swallowing over an ounce of ammonia. Death may take place from poisoning by alkalies within a few hours or days, or may be protracted several months. In fatal cases, on post-mortem examination, the mucous membrane of the mouth, throat, and gullet will be found corroded, often blackened, and even completely destroyed, the larynx and bronchi being particularly inflamed and softened in cases of ammonia-poisoning.

In examining the contents of the stomach, as a general rule, the organic matters can be removed by evaporation and subsequent heating; the ash remaining being digested with distilled water and filtered, the potassa or soda will be found in solution as a carbonate. Potassium compounds give a violet color, sodium compounds a yellow color to the smokeless flame of spirit or gas. The presence of these alkalies can be readily recognized also by means of the spectroscope. Potassium can also be tested for by using tetrachloride of platinum, which throws down a yellow granular precipitate consisting of potassio-platino chloride. In making use of this test, the absence of ammonia must be insured. Soda may be recognized from the white precipitate thrown down by the addition of potassium antimoniate. Ammonia may be extracted from the stomach by distilling about one-fourth of the liquid, the vapor being carried through a bent tube into a well-cooled re1 Woodman and Tidy: op. cit., pp. 92, 105.