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4. A bright steel needle or piece of iron wire, if introduced into a
solution of a copper salt acidulated with a few drops of hydrochloric acid,
becomes covered with a red coating of metallic copper after some time.
5. Feigl's Test.—A few drops of dilute zinc nitrate solution and 1 or 2
cc. of Feigl's reagent added to a neutral or faintly acid solution give a pink,
purple or deep violet precipitate, if copper is present.
Feigl's reagent is prepared by dissolving 8 grammes of mercuric chloride
and 9 grammes of ammonium thiocyanate in 100 cc. of distilled water.
Medico-Legal Points.—1. Copper as a metal is not poisonous. Copper
coins, when swallowed, may remain in the stomach or in the intestines for
days without producing any poisonous symptoms. However, when alloyed
with other metals and reduced to a fine powdery state, copper may act as a
poison. All the copper salts are poisonous.
2, The blue or green colour and the strong metallic taste of copper salts
prevent their use for homicidal purposes, though in India copper sulphate is
known to have been used homicidally mixed with powdered glass, sweetmeat
or some other article of food. In his annual report for the year 1935, the
Chemical Examiner, Madras, records a case in which a woman of immoral
character put copper sulphate in the food intended for her husband. The
husband tasted the food and noticed a peculiar burning sensation in the
mouth as well as the peculiar colour of the food. The matter was reported
to the police, and the woman was prosecuted and sentenced to undergo eight
months7 rigorous imprisonment. A case S3 is also recorded where a boy, aged
about 7 years, died from poisoning by copper sulphate given to him in peras
by the man who wanted to marry his widowed mother. The widow had
refused to marry the man saying that she would remain a widow for the rest
of her life for the sake of her only son.
Copper sulphate has been used, though rarely, as a cattle poison. In
his annual report for the year 1907, the Chemical Examiner of the United
Provinces of Agra and Oudh mentions a case in which copper sulphate was
found in a piece of rag stated to have been inserted into the rectum of a
buffalo. In his annual report for the year 1919, the Chemical Analyser of
Bombay also mentions some cases of cattle poisoning by copper sulphate.
Suicidal cases are occasionally met with. Sometimes, copper sulphate
and copper subacetate are taken internally with a view to procuring abortion.
Accidental cases occur from swallowing copper sulphate by mistake or
from contamination of food due to the formation of verdigris resulting from
the action of vegetable acids on copper cooking vessels which are dirty and
have not been properly tinned.
The author has seen two cases of accidental poisoning. In one case a
child playfully swallowed a big crystal of copper sulphate. In the other case
an adult woman took it by mistake for a condiment. Both recovered after
having suffered from pain in the stomach, vomiting and purging. In his
annual report for the year 1940, the Chemical Examiner, Madras, records
three cases of accidental poisoning by copper sulphate. In one case a young
man found a blue lump on the floor of a latrine and ate it thinking it to be
candy. In the second case a man found a packet containing cashew nut
kernels mixed with blue stone pieces in front of a cinema and devoured the
lot in spite of the disagreeable taste. In the third case a person found a
packet of blue stone lying on the road and ate the contents. Vomiting ensued
in each of these individuals, and recovery occurred after their removal to
hospital. In his annual report for the year 1949, the Chemical Examiner,
Bengal, quotes a case in which a village quack administered copper sulphate
83. U.P. and C.P. Chenu Exam. Annual Rep., 1940, p. 5.