Part 7 (1/2)

CORROSIVE SUBLIMATE (_Oxymuriate of Mercury_, _Chloride of Mercury_, _b.i.+.c.hloride of Mercury_).-This preparation of Mercury, which, more strictly speaking, belongs, like the chlorides of zinc and antimony, to the cla.s.s Corrosives, is usually met with in the form of imperfect crystalline ma.s.ses, or as a white powder. It has an acrid, coppery taste, so powerful that but little could be swallowed without the individual becoming aware of it. It is very soluble in water. Three grains is the smallest quant.i.ty that has been known to prove fatal; and from this to five grains may probably be stated as the average dose necessary to destroy life. Recovery has taken place after as much as eighty grains had been swallowed. Death has occurred in less than half an hour; while, in some instances, life has been maintained until the sixth day, and in one instance (where between three and four scruples had been swallowed) until the twelfth day. It is probable that the average duration of fatal cases is from twenty-four to thirty-six hours.

_Symptoms._-In the majority of cases the symptoms commence immediately, with an acrid metallic taste, often described as coppery, and a sense of constriction and burning heat in the throat and stomach. The burning pain gradually extends over the abdomen, and is much increased by pressure. There is nausea, with vomiting of the contents of the stomach.

These matters are sometimes mixed with blood and stringy ma.s.ses of mucus. The sickness is accompanied by diarrha or dysentery, swelling of the abdomen, and increased pain. The countenance becomes flushed and often swollen, though it is occasionally pallid and anxious; the lips and tongue get white and shrivelled; there is frequently some dyspna, while the pulse is small, or wiry and frequent; and death is preceded by faintness, cramps, insensibility, or convulsions.

Should these effects not prove rapidly fatal, the pain will gradually become lessened, though attacks of colic and nausea may come on at intervals for several days. Often the secretion of urine is almost, or even quite, suppressed. After a time there are symptoms of hectic fever, with much depression. The gums and salivary glands also become swollen, there is a coppery taste in the mouth, the breath is very ftid, and there is severe ptyalism or salivation. This latter effect is the most prominent feature in the _chronic_ form of poisoning, where small and frequently-repeated doses have been given: it often proceeds to such an extent as to cause death, when the patient would otherwise probably recover.

It must not be forgotten that salivation sometimes arises where no mercurial of any kind has been given. Thus a.r.s.enic, bis.m.u.th, lead, iodide of pota.s.sium, opium, &c., may induce it in some very peculiar const.i.tutions. Small medicinal doses (as a few grains of calomel) may also excite it in certain susceptible individuals; and especially in persons suffering from renal disease. It may also occur spontaneously, as in stomat.i.tis or inflammation of the mouth; and very troublesome examples of it may occur in pregnant women.

It is strange that neither in acute nor chronic mercurial poisoning do we observe any marked loss of muscular power. Yet workers in quicksilver (owing to the absorption of the fumes of mercury during respiration) are very apt to suffer from a peculiar kind of paralysis; which commences with inability to direct the hands and arms, and goes on to a shaking or trembling of all parts of the body.

_Post-mortem Appearances._-The appearances produced by corrosive sublimate are confined chiefly to the digestive ca.n.a.l. The mucous membrane of the mouth, fauces, and sophagus is softened and of a whitish or bluish-grey color. The stomach also presents marks of violent inflammation; beneath the mucous membrane numerous patches of extravasated blood are seen, and frequently corrosion or ulceration has been found. The large and small intestines, the peritoneum, and especially the urinary organs, often appear inflamed. In many instances the bladder has been much contracted.

_Treatment._-This must consist in the removal of the poison and the administration of antidotes. Vomiting is best promoted by administering copious draughts of fluids containing alb.u.men: but if necessary ipecacuan may be given. The white and the yolk of raw eggs with milk should be abundantly administered. Gluten has been much recommended, and may readily be prepared by was.h.i.+ng flour in a muslin bag under a stream of water; but on an emergency it will be best to exhibit the flour at once, made into a paste with milk or water. The free use of demulcent drinks, milk, and ice will be very grateful to the patient's feelings.

Gargles of alum or borax do some good. Opiates may be given in small doses, if there be much pain, and we should allow only a milk or farinaceous diet. Sucking chlorate of potash has been recommended to check the salivation. The most useful remedy, however, is the iodide of pota.s.sium; for this salt destroys the compounds formed by the union of mercury with certain of the tissues, and eliminates the poison through the kidneys.

_Tests._-Corrosive sublimate is completely volatilized by heat.

1. Liquor pota.s.sae added to its solution gives a yellow precipitate. This precipitate, if washed, dried, and heated in a test tube, gives a ring of metallic mercury in the form of globules in the cool part of the tube. In like fas.h.i.+on corrosive sublimate itself may be reduced and volatilized if heated with black flux.

2. On adding a solution of iodide of pota.s.sium to a small quant.i.ty of the solution, a bright scarlet precipitate, soluble in excess of iodide of pota.s.sium, is produced.

3. If a drop or two of a solution of corrosive sublimate, slightly acidulated with hydrochloric acid, be placed on a sovereign, and the solution and the gold be touched with a piece of zinc or an iron key, the mercury will be deposited as a bright silvery stain on the gold.

CALOMEL (_Subchloride_ or _Chloride of Mercury_) is a heavy white powder, which is usually regarded as a safe medicine. Yet, in some peculiar const.i.tutions, it has caused excessive salivation and death, even though only a few grains have been given. In large doses it may be regarded as an irritant poison. It is distinguished from corrosive sublimate by forming a black precipitate with caustic potash and by its insolubility in water.

AMMONIO CHLORIDE OF MERCURY (_White Precipitate_).-This substance is a chalky looking powder, containing about eighty per cent. of mercury. It produces vomiting, purging, great pain in the stomach, cramps, and convulsions. Out of fourteen cases, collected by Dr. Taylor, in which from a few to forty grains were taken, only two proved fatal.

The remaining preparations of mercury, which in rare instances have been used as poisons, are the _Red Oxide of Mercury_ (red precipitate); the _Red Sulphuret of Mercury_ (cinnabar or vermilion); the _Cyanide of Mercury_; the _Nitrates of Mercury_; and _Turpeth Mineral_.

Mercury may be separated from organic admixture by Reinsch's method.

CHAPTER XVIII.

PREPARATIONS OF LEAD.

Lead, in its metallic state, is not injurious. It is, however, really acted on by acids, exposure to the atmosphere, &c., and converted into carbonate of lead. The chief compounds of this metal which have been found to produce poisonous effects are the acetate, subacetate, and the carbonate.

ACETATE OF LEAD (_Sugar of Lead_).-This is sold as a glistening white powder, or in the form of crystalline ma.s.ses resembling loaf sugar. It is more frequently used as a poison than either of the other compounds.

It is very soluble in water and has a sweetish metallic taste. Three or four instances are recorded in which recovery has taken place after an ounce of this substance has been taken in solution.

Mr. Bancks, of Stourbridge, has reported the particulars of a series of cases of poisoning by the acetate of lead (_Lancet_, 5th May, 1849). It appears that thirty pounds of this substance were accidentally mixed at the miller's with eighty sacks of flour. This was made into bread, from eating which 500 persons suffered severely. The chief symptoms were a sense of constriction in the throat and at the pit of the stomach, crampy pains round the navel, stiffness of the abdominal muscles, paralysis of the lower extremities, constipation, scanty urine, and the formation of a deep blue line round the gums. Although in many cases there was great prostration with other alarming symptoms, yet under the use of purgatives all recovered. It was noticed that after a temporary convalescence many of the symptoms returned in an aggravated form without any apparent cause. Sometimes there has been vomiting and purging, and there is great prostration, with cramps and convulsions.

_Post-mortem Appearances._-They are not usually very distinct. The stomach and intestines have been found inflamed, and the surface of the former softened and, in the case of animals, corroded. There may be no characteristic signs in chronic poisoning.

SUBACETATE OF LEAD (_Goulard's Extract_).-This substance is known to have proved fatal in three or four instances, after having caused great agony. It is a more powerful poison than the acetate. It is found in the shops as a whitish-colored liquid.

CARBONATE OF LEAD (_White Lead_, _Ceruse_, _&c._).-This is sold in heavy white ma.s.ses, looking like chalk. It is readily acted on by acids, but is very insoluble in water.