Part 12 (1/2)

_General Reactions for Alkaloids._--(1) Wagner's reagent (iodine dissolved in a solution of pota.s.sium iodide) yields a reddish-brown precipitate; (2) Mayer's reagent (pota.s.sio-mercuric iodide) gives a yellowish-white precipitate; (3) phospho-molybdic acid gives a yellow precipitate; (4) platinic chloride, a brown precipitate; (5) tannic acid, etc.

In order to isolate an inorganic substance from organic matter, Fresenius's method is adopted. Boil the finely divided substance with about one-eighth its bulk of pure hydrochloric acid; add from time to time pota.s.sic chlorate until the solids are reduced to a straw-yellow fluid. Treat this with excess of bisulphate of sodium, then saturate with sulphuretted hydrogen until metals are thrown down as sulphides.

These may be collected and tested. From the acid solution, hydrogen sulphide precipitates copper, lead, and mercury, _dark_; a.r.s.enic, antimony, and tin, _yellowish_. If no precipitate, add ammonia and ammonium sulphide, iron, _black_, zinc, _white_, chromium, _green_, manganese, _pink_. The residue of the material after digestion with hydrochloric acid and pota.s.sium chlorate may have to be examined for silver, lead, and barium.

For the detection of minute quant.i.ties, the microscope must be used, and Guy's and Helwig's method of sublimation will be found advantageous.

Crystalline poisons may be recognized by their characteristic forms.

IX.--THE MINERAL ACIDS

These are sulphuric, nitric, and hydrochloric acids.

_Symptoms of Poisoning by the Mineral Acids._--Acid taste in the mouth, with violent burning pain extending into the oesophagus and stomach, and commencing immediately on the poison being swallowed; eructations, constant retching, and vomiting of brown, black, or yellow matter containing blood, coagulated mucus, epithelium, or portions of the lining membrane of the gullet and stomach. The vomited matters are strongly acid in reaction, and stain articles of clothing on which they may fall. There is intense thirst and constipation, with scanty or suppressed urine, tenesmus, and small and frequent pulse; the lips, tongue, and inside of the mouth, are shrivelled and corroded. Exhaustion succeeds, and the patient dies either collapsed, convulsed, or suffocated, the intellect remaining clear to the last. After recovering from the acute form of poisoning, the patient may ultimately die from starvation, due to stricture of the oesophagus, stomach, etc.

_Post-Mortem Appearances Common to the Mineral Acids._--Stains and corrosions about the mouth, chin, and fingers, or wherever the acid has come in contact. The inside of the mouth, fauces, and oesophagus, is white and corroded, yellow or dark brown, and shrivelled. Epiglottis contracted or swollen. Stomach filled with brown, yellow, or black glutinous liquid; its lining membrane is charred or inflamed, and the vessels are injected. Pylorus contracted. Perforation, when it takes place, is on the posterior aspect; the apertures are circular, and surrounded by inflammation and black extravasation. The blood in the large vessels may be coagulated.

Avoid mistaking gastric or duodenal ulcer, with or without perforation, for the effects of a corrosive poison.

_Treatment._--Calcined magnesia or the carbonate or bicarbonate of sodium, mixed with milk or some mucilaginous liquid, are the best antidotes. In the absence of these, chalk, whiting, milk, oil, soap-suds, etc., will be found of service. The stomach-pump should not be used. If the breathing is impeded, tracheotomy may be necessary.

Injuries of external parts by the acid must be treated as burns.

X.--SULPHURIC ACID

=Sulphuric Acid=, or oil of vitriol, may be concentrated or diluted. It is frequently thrown over the person to disfigure the features or destroy the clothes. Parts of the body touched by it are stained, first white, and then dark brown or black. The presence of corrosion of the mouth is as important as the chemical tests. Black woollen cloths are turned to a dirty brown, the edges of the spots becoming red in a few days, due to the dilution of the acid from the absorption of moisture; the stains remain damp for long, owing to the hygroscopic property of the acid.

_Method of Extraction from the Stomach._--The contents of the stomach or vomited matter should, if necessary, be diluted with pure distilled water and filtered. The stomach should be cut up into small pieces and boiled for some time in water. The solution, filtered and concentrated, is now ready for testing. Blood, milk, etc., may be separated by dialysis, and the fluid so obtained tested. A sulphate may be present.

Take a portion of the liquid, evaporate to dryness, and incinerate; a sulphate, if present, will be obtained, and may be tested.

_Caution._--Sulphuric acid may not be found even after large doses, due to treatment, vomiting, or survival for several days. In all cases every organ should be examined. Vomited matters and contents of stomach should not be mixed, but each _separately_ examined. This rule holds good for all poisons. On _cloth_ the stain may be cut out, boiled in water, the solution filtered, and tested with blue litmus and other tests.

_Post-Mortem Appearances._--Where the acid has come in contact with the mucous membranes there are dark brown or black patches. The stomach is greatly contracted, the summits of the mucous membrane ridges being charred and the furrows greatly inflamed; the contents are black or brown.

_Tests._--Concentrated acid chars organic matter; evolves heat when added to water, and sulphurous fumes when boiled with chips of wood, copper cuttings, or mercury. Dilute acid chars paper when the paper is heated; gives a white precipitate with nitrate or chloride of barium, and is entirely volatilized by heat. Dilute solutions give a white precipitate with barium nitrate, insoluble in hydrochloric acid even on boiling.

_Fatal Dose._--In an adult, 1 drachm.

_Fatal Period._--Shortest, three-quarters of an hour; average period from onset of primary effects, eighteen to twenty-four hours.

XI.--NITRIC ACID