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554 MEDICAL JURISPRUDENCE
3. Water Test.—Hydrochloric acid gives a white precipitate, soluble in excess. To
the solution thus obtained if a large quantity of water is added, a white precipitate,
insoluble in tartaric acid is obtained. The same test is applicable in the case of anti-
mony, but the white precipitate is soluble in tartaric acid.
4. A piece of filter paper is soaked in a solution prepared by dissolving 1 g. Of
cinchonine in 100 cc. of water acidified with nitric acid, and adding 2 g. of potassium
iodide, when the solution is cold. A drop of bismuth solution free from acid placed on
the paper will show an orange-red coloured ring. In place of a bismuth salt a mercury
salt will form a white central ring, lead iodide will form a yellow ring and a cupric
salt will form an outermost brown ring due to the liberation of iodine.
Medico-Legal Points.—The salts of bismuth are ordinarily non-poisonous. Large
quantities (1 to 4 ounces), especially of the carbonate and subnitrate, mixed with gruel
of bread and milfc are used as a bismuth meal for the X-ray examination of the oeso-
phagus, stomach and intestine, as they obstruct the passage of the X-rays. These salts
are more readily absorbed by abraded surfaces, and poisonous cases have resulted from
the use of bismuth paste for the treatment of sinuses, abscess cavities and burns.
Taken internally, bismuth carbonate has produced poisoning in some instances
owing to its conversion into soluble chloride. Bismuth subnitrate has produced poisonous
symptoms possibly owing to the presence of the nitrite. It has produced fatal poisoning
in children from its reduction to nitrite by the action of putrefactive faecal bacteria in
the large intestine. The symptoms exhibited in such cases are cyanosis, diarrhoea,
methsemoglobinsemia, dyspncea, collapse and death from failure of respiration.
Bismuth subnitrate is more soluble in the stomach of a dyspeptic patient owing to
the presence of butyric and lactic acids. , It should, therefore, be prescribed with caution
in such cases, lest toxic effects be produced.
Bismuth is eliminated from the system in the fasces, urine and saliva. Like lead,
the greater portion of it passes out either unaltered from the bowels, or becomes con-
verted into bismuth sulphite imparting a black or dark-brown colour to the faeces.
The only salt that has any toxicological value is silver nitrate (AgNO«)t also known
as lunar caustic or lapis infernalis. It is administered internally in pill form in i to 1 grain
doses. It occurs as large, colourless, rhombic crystals. Mixed with potassium nitrate it
is moulded into white or greyish-white cylindrical rods or cones, and is known as
toughened caustic or argenti nitras induratus. It is freely soluble in distilled water.
Its solution has a styptic metallic taste and acid reaction.
Silver nitrate is used extremely as a styptic and as a destroyer of exuberant granu-
lations and warts. It is also used in photography, and constitutes the chief ingredient
of indelible ink and hair-dyes.
Argyrol (silver vitellin) and Protargol (silver protein), which are the organic
preparations of silver, are largely used in ophthalmic practice. Collargol (silver in a
colloid state) is opaque to the X-rays, and is, therefore, used in a 20 per cent solution
for injecting into the ureter and renal pelvis for the purposes of diagnosis,
Acute Poisoning.—Symptoms.—Severe pain in the throat and stomach and vomiting.
The vomited matter is at first flaky white, but becomes black on exposure to light, and
may contain blood. These are followed by frequent motions, the stools sometimes con-
taining blood. Cramps, convulsions and collapse precede death,
Fatal Dose and Fatal Period.—Uncertain. Thirty grains of silver nitrate have caused
the death of an adult. Death occurs in a few hours to a few days*
Treatment.—Wash out the stomach with 2 ounces of sodium chloride dissolved in
2 gallons of waier or give half an ounce of sodium chloride dissolved in a pint of milk
or water as an antidote to form insoluble silver chloride. Produce vomiting Toy adminis-
tering ipecacuanha powder, or hypodermic injection of apomorphine hydro chloride. Give
demulcent drinks, eggs and milk. Give morphine and stimulants.
Post-mortem Appearances.—The local action of the caustic will be evident by stains,
at first white, but becoming black on exposure to light. These stains are noticed on the
mouth and lips, on the mucous membrane of the alimentary canal touched by the poison,
as also on the white clothing. The mucous membrane of the stomach and duodenum
may be inflamed. The liver and kidneys may show slight parenchymatous changes*
Chronic Poisoning.—This results from the long continued use of an organic or
inorganic silver salt as a medicine or from its long applications to the granulations of
wounds and ulcers. It also affects those who constantly come in contact with silver salts
owing to their occupations.
Symptoms.—These are a black line on the gums and a general discoloration of -the
stan (argyria) due to the deposition of minute silver particles in the cutaneous tissues.
This discoloration is permanent, greyish-blue or dark-grey in colour and first sheets the