IRRITANT POISONS The more important irritant poisons will he considered under this heading (vide list above) but it must be remembered that many of the general poisons, e.g., savin, cantharides, etc., have an irritant action on the stomach and intestines in addition to their special action on important organs and nerve centres.
Oxalic Acid occurs in colourless crystals resembling Epsom salts ; it is very soluble in water. Salts of Sorrel or Salts of Lemon is the quadrioxalate of potash ; it is a white powder very soluble in water. Both of these substances are commonly used for do mestic purposes, e.g., for cleaning straw hats, removing ink stains, cleaning brasses, etc. They are frequently the cause of accidental and of suicidal poisoning.
As regards symptoms, when swallowed in solution the typical symptoms of irritant poisoning are set up, but in addition the poison when absorbed into the system has a profound depressing action on the heart and nervous system. Thus an acrid burning taste is experienced and pain occurs which is referred from the throat, oesophagus, stomach and later possibly the intestines. Vomiting is common, the vomit being very acid, and giving the tests for oxalic acid. It often contains blood. Unless immediate treatment is adopted collapse speedily occurs, the patient being cold, pale and faint with a rapid feeble pulse and at this stage death from syncope may occur. In some cases nervous symptoms such as tinglings and numbness, muscular spasms, convulsions, delirium and coma occur, but these symptoms are uncommon. Owing to the rapid absorption of the poison death is likely to occur rapidly, e.g., within an hour, but it may be delayed.
As respects treatment, fresh lime water, or better the sac charated lime water which is 15 times as strong, should be given in large quantities and it should be mixed with calcium carbonate in the form of chalk or whiting. Since oxalic acid has only slight corrosive action the stomach should be washed out im mediately if no antidote is at hand. It is best to give the anti dote freely if immediately available and after a few minutes to wash out the stomach thoroughly with a soft stomach tube and funnel, and then finally introduce a pint of lime water made into a thin cream with an ounce of chalk, leaving this mixture in the stomach.
Arsenic.—This is the most important of the irritant poisons and owing to the tasteless property of many of its compounds and preparations it is the commonest poison used for homicidal purposes.
The most important and commonest compound is arsenious anhydride or white arsenic. It occurs in the form of a white powder or in lumps of a white porcelain-like appearance. The powdered form resembles powdered sugar or flour and when mixed with food is almost tasteless. It is sparingly soluble in cold water. When mixed with alkaline substances white arsenic becomes freely soluble.
Commercial preparations containing white arsenic mixed with alkalies such as sodium hydrate or carbonate are weed killers, sheep dip and wood preservatives which may contain from 20% to 4o% of white arsenic. Copper arsenite (Scheele's Green), lead arsenate and other arsenical preparations are used as insecticides for the spraying of fruit trees. Rat poisons may contain arsenic as the active ingredient. Wallpapers which formerly often con tained green pigment (Scheele's Green) or the yellow sulphides of arsenic are now coloured with arsenic-free pigments, arsenic being prohibited from use. White arsenic, if sold except for medicinal purposes, must be coloured with soot or indigo.
Arsenic in Food.—Accidental contamination of food with ar senic has occurred in the past. Thus in 19oo a beer poisoning epi demic occurred as the result of the use of commercial glucose which contained arsenic in the preparation of beer. (See ADUL TERATION.) Acute Arsenical Poisoning.—When arsenic is taken by the mouth in poisonous quantities symptoms of acute gastrointestinal irritation such as vomiting, diarrhoea and abdominal pain occur within a few hours and death may result within a few days. Two grains of arsenic have caused death though larger quantities have been taken without fatal result. In acute arsenical poison ing the heart, kidneys and other organs are seriously affected so that the poison has a systemic action in addition to its irritant properties to the stomach and intestines.