_Chronic lead-poisoning_ is liable to occur in those who handle lead in any form--white-lead workers, paint manufacturers, plumbers, pottery workers, etc.

In chronic lead-poisoning the most prominent symptoms are a blue line on the gums, anaemia, emaciation, pallor, quick pulse, persistent constipation, colic, cramps in limbs, and paralysis of the extensor muscles, causing 'dropped hand.' May get _saturnine encephalopathies_, of which intense headache, optic neuritis, and epileptiform convulsions, are the most common. Alb.u.min in urine, tendency to gout, and in women to abortion.

_Post-Mortem Appearances._--Inflamed mucous membrane of stomach and intestines, with layers of white or whitish-yellow mucus, impregnated with the salt of lead.

_Treatment._--Sulphate of sodium or magnesium, or a mixture of dilute sulphuric acid, spirits of chloroform, and peppermint-water. Milk, or milk and eggs. As a prophylactic among workers in lead, a drink containing sulphuric acid flavoured with treacle should be given.

Lavatory accommodation should be provided, and scrupulous cleanliness should also be enjoined in the workshops. The dry grinding of lead salts should be prohibited. The ionization method of Sir Thomas Oliver is most useful both as regards cure and also prevention of chronic poisoning by lead.

_Fatal Dose and Fatal Period._--Uncertain.

_Method of Extraction from the Stomach._--Dry the contents of the stomach or portions of the liver, etc., and incinerate in a porcelain crucible. Treat the ash with nitric acid, dry, and dissolve in water.

The solution of nitrate of lead may now have the proper tests applied.

_Tests._--Sulphuretted hydrogen gives a black precipitate; liquor pota.s.sae, white precipitate; sulphuric acid, white precipitate, insoluble in nitric acid; iodide of pota.s.sium, a bright yellow precipitate. A delicate test for lead in water is to stir the water, concentrated or not, with a gla.s.s rod dipped in ammonium sulphide: a brown coloration is produced. One-tenth of a grain of lead in a gallon of water may be detected.

Chronic lead-poisoning is an 'industrial disease,' and, being an occupation risk, its victims are ent.i.tled to compensation at the hands of their employers. In case of death, compensation has been awarded even when at the autopsy the patient has been found to have suffered from acute tuberculosis of the lungs. The responsibility of apportioning the monetary value of disablement resulting from the action of the lead rests with a judge or jury, who are guided by the expert medical evidence available.

Diachylon, or lead-plaster, is largely used as an abortifacient.

XXV.--COPPER AND ITS PREPARATIONS

Poisoning with copper salts is rare. The most important are the sulphate, subacetate, and a.r.s.enite.

=Sulphate of Copper= (bluestone, blue vitriol) in half-ounce doses is a powerful irritant. Has been given to procure abortion.

=Subacetate of Copper= (verdegris) occurs in ma.s.ses, or as a greenish powder. Powerful, astringent, metallic taste. Half-ounce doses have proved fatal.

_Symptoms._--Epigastric pain, vomiting of bluish or greenish matter, diarrhoea. Dyspnoea, depression, cold extremities, headache, purple line round the gums. Jaundice is common. A _chronic_ form of poisoning may occur, with symptoms closely resembling those of lead.

_Post-Mortem Appearances._--Inflammation of stomach and intestines, which are bluish or green in colour.

_Treatment._--Encourage vomiting. Give alb.u.min or very dilute solution of ferrocyanide of pota.s.sium.

_Method of Extraction from the Stomach._--Boil the contents of the stomach in water, filter, pa.s.s hydrogen sulphide, filter, collect precipitate and boil in nitric acid, filter, dilute filtrate with water and apply tests. In the case of the solid organs, dry, incinerate, digest ash in hydrochloric acid, evaporate nearly to dryness, dilute with water, and test.

_Tests._--Polished steel put into a solution containing a copper salt receives a coating of metallic copper. Ammonia gives a whitish-blue precipitate, soluble in excess. Ferrocyanide of pota.s.sium gives a rich red-brown precipitate. Sulphuretted hydrogen gives a deep brown precipitate.

XXVI.--ZINC, SILVER, BIs.m.u.tH, AND CHROMIUM

The salts of zinc requiring notice are the sulphate and chloride.

=Sulphate of Zinc= has been taken in mistake for Epsom salts. In large doses it causes dryness of throat, thirst, vomiting, purging, and abdominal pain.

_Post-Mortem Appearances._--Those of inflammation of digestive tract.

_Treatment._--Tea, decoction of oak-bark, carbonate of pota.s.sium or sodium as antidote.

=Chloride of Zinc.=--A solution containing this substance (230 grains to the ounce) const.i.tutes 'Burnett's disinfecting fluid.' It is a corrosive poison.

The symptoms are burning sensation in the mouth, throat, stomach, and abdomen, followed by vomiting, diarrhoea, with tenesmus and distension of the abdomen. The vomited matter contains shreds of mucous membrane with blood. There is profound collapse, cold surface, clammy sweats, weak pulse, with great prostration. The _treatment_ is to wash out the stomach with large and weak solutions of carbonate of sodium.

Mucilaginous drinks may be given, and hypodermic injections of morphine are useful to allay the pain.

_Method of Extraction from the Stomach._--Dry and incinerate the tissues in a porcelain crucible, digest ash in water, apply tests.

_Tests._--Ammonia, a white precipitate soluble in excess, reprecipitated by sulphuretted hydrogen; ferrocyanide of pota.s.sium, a white precipitate; sulphuretted hydrogen, a white precipitate in pure and neutral solutions. Nitrate of baryta will show the presence of sulphuric acid, and nitrate of silver of hydrochloric acid.

=Silver.=--Nitrate of silver is a powerful irritant.

_Tests._--Black precipitate with sulphuretted hydrogen; white with hydrochloric acid.

_Treatment._--Common salt.

Chronic nitrate of silver poisoning is characterized by _argyria_. The gums show a blue line, which is darker than that produced by lead, and the skin presents a greyish hue, which is permanent.

=Bis.m.u.th.=--The bis.m.u.th salts are not poisonous, but may contain a.r.s.enic as an impurity, although this is far less common than it was some years ago.

=Chromic Acid, Chromate, Bichromate of Pota.s.sium.=--These act as corrosives when solid or in concentrated liquid forms. In dilute solutions they act as irritants. Used as dyes; have proved fatal more than once. Those engaged in their manufacture suffer from unhealthy ulcers on the nasal septum and hands. The former may to some extent be prevented by taking snuff. Lead chromate (chrome yellow) is a powerful irritant poison. Two drachms of the bichromate caused death in four hours.

_Tests._--Yellow precipitate with salts of lead, deep red with those of silver.

_Treatment._--Emetics, magnesia, and diluents. Washing out of the stomach with weak solution of nitrate of silver.

XXVII.--GASEOUS POISONS

=Carbon Dioxide.=--Carbon dioxide is a product of combustion and respiration, and is generated in many ways during fermentation. It is a const.i.tuent of _choke damp_ due to explosions in coal-mines, and is given off from lime-kilns, brick-kilns, and cement-works. It is often met with in dangerous quant.i.ties in wells and in brewers' vats. From 10 to 15 per cent. in the atmosphere would prove fatal, but even 2 per cent. inhaled for long would produce serious symptoms. The proportion usually present in air is 0.04 per cent.

_Symptoms._--Inhalation of the _pure_ gas causes spasm of the glottis, insensibility, and death from asphyxia, at once; _diluted_, causes sense of weight in forehead and back of head, giddiness, vomiting, somnolence, loss of muscular power. Insensibility, stertorous breathing, lividity of face and body, and death from asphyxia. Convulsions occasionally.

_Post-Mortem Appearances._--Face swollen and livid, or calm and pale; lividity is most marked in eyelids, lips, ears, etc.; limbs usually flaccid, abdomen distended; right side of heart, lungs, and large veins, gorged with dark-coloured blood. Brain and membranes congested.

_Treatment._--Pure air, cold affusion, stimulants, artificial respiration, galvanism, inhalation of oxygen, venesection, transfusion.

=Carbonic Oxide.=--This is one of the most poisonous of gases. It is evolved in the process of burning charcoal and c.o.ke in stoves or furnaces. Water-gas, obtained by pa.s.sing steam over heated c.o.ke, contains 40 per cent. of the substance, the remainder being chiefly hydrogen. It forms the chief part of the deadly 'choke damp' after an explosion in a mine. Two per cent. in the atmosphere is immediately fatal.

_Symptoms._--When in _large amount_, insensibility comes on at once; when in _very small amounts_, headache, giddiness, noises in the ears, nausea, and vomiting, with prostration, insensibility, and coma. There may be convulsions. Even in cases which recover, permanent impairment of the brain may result.