Lime, the last poison of the present group, is a substance of little interest to the toxicologist, as its activity is not great.
Its physical and chemical properties need not be minutely described. It is soluble, though sparingly, in water; and the solution turns the vegetable blues green, restores the purple of reddened litmus, gives a white precipitate with a stream of carbonic acid gas, and with oxalic acid a very insoluble precipitate, which is not redissolved by an excess of the test.
Its action is purely irritant. Orfila has found that a drachm and a half of unslaked lime, given to a little dog, caused vomiting and slight suffering for a day only, but that three drachms killed the same animal in five days, vomiting, languor, and whining being the only symptoms, and redness of the throat, gullet, and stomach, the only morbid appearances.[[465]]
Though a feeble poison, it has nevertheless proved fatal in the human subject. Gmelin takes notice of the case of a boy who swallowed some lime in an apple-pie, and died in nine days, affected with thirst, burning in the mouth, burning pain in the belly, and obstinate constipation.[[466]] A short account of a case of this kind of poisoning is also given by Balthazar Timæus. A young woman, afflicted with pica or depraved appetite, took to the eating of quicklime; and in consequence she was attacked with pain and gnawing in the belly, sore throat, dryness of the mouth, insatiable thirst, difficult breathing and cough; but she recovered.[[467]] It is well known that quicklime also inflames the skin or even destroys its texture, apparently by withdrawing the water which forms a component part of all soft animal tissues. When thrown into the eyes it causes acute and obstinate ophthalmia, which may end in loss of sight. On this account it will belong, I presume, to the poisons included in the Scottish act against disfiguring or maiming with corrosives.
CHAPTER XI.
OF POISONING WITH AMMONIA AND ITS SALTS.
The second group of the order of alkaline poisons, including ammonia with its salts, and the sulphuret of potass, have a double action on the system, analogous to that possessed by many metallic poisons. They are powerful irritants; but they produce besides, through the medium of the blood, a disorder of some part of the nervous system; and their remote is sometimes more dangerous than their local action. The nervous affection produced by ammonia and the sulphuret of potass closely resembles tetanus, and therefore depends probably on irritation of the spinal column.
Of the Chemical tests for the Ammoniacal Salts.—Ammonia is when pure a gaseous body; but as commonly seen, it exists in solution in water, which dissolves it in large quantity. The solution has the usual effects of alkalis on vegetable colours, with the difference, however,—that the changes of colour are not permanent under the action of heat. It forms a yellow precipitate, as potass does, with chloride of platinum. It may at once be distinguished from other fluids by its peculiar pungent odour, which is possessed by no other substance except its carbonate.
Various carbonates are known in chemistry, but the only one known in commerce or met with in the shops is the sesqui-carbonate (subcarbonate—smelling salt—volatile salt—hartshorn). It is solid, white, fibrous, and has the same odour as pure ammonia. Its solution differs little in physical properties from the pure liquid ammonia; but, unlike it, is precipitated by the salts of lime.
The hydrochlorate (muriate of ammonia—sal-ammoniac)—is known by its solid, white, crystalline appearance; its ductility; its volatility; and by the effect of caustic potass and nitrate of silver, the former of which disengages an ammoniacal odour, while the latter causes in a solution of the salt a white precipitate, the chloride of silver.
Of the action of the Ammoniacal Salts, and their effects on man.—To determine the action of ammonia on the animal system, Professor Orfila injected sixty grains of the pure solution into the jugular vein of a dog. Immediately the whole legs were spasmodically extended; at times convulsions occurred; and in ten minutes it died. The chest being laid open instantly, coagulated florid blood was seen in the left ventricle, and black fluid blood in the right ventricle of the heart. No unusual appearance was discernible any where else except complete exhaustion of muscular irritability.[[468]] The experiments of Mr. Blake also show that ammonia introduced in large doses into the veins acts by suddenly extinguishing the irritability of the heart. Small doses first lower arterial pressure from debility of the heart’s action, and then increase it by obstructing the systemic capillaries. When injected into the aorta from the axillary artery, it causes great increase of arterial pressure, owing to the latter cause; and then arrests the heart, while the respiration goes on. Four seconds are sufficient for the ammonia to pass from the jugular vein into the heart, so as to be discovered there by muriatic acid causing white fumes.[[469]] Half a drachm of a strong solution, introduced by Orfila into the stomach of a dog and secured by a ligature on the gullet, caused at first much agitation. But in five minutes the animal became still and soporose; after five hours it continued able to walk; in twenty hours it was found quite comatose; and death ensued in four hours more. The only morbid appearance was slight mottled redness of the villous coat of the stomach. A third dog, to which two drachms and a half of the common carbonate were given in fine powder, died in twelve minutes. First it vomited; next it became slightly convulsed; and the convulsions gradually increased in strength and frequency till the whole body was agitated by dreadful spasms; then the limbs became rigid, the body and head were bent backwards, and in this state it expired, apparently suffocated in a fit of tetanus.[[470]]