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NITRIC ACID                                                        4S1

colour of blood contained in the vomited matter is yellowisli-brown. Owing
to the development of a larger quantity of gas by the direct action of the
acid on organic matter in the stomach the abdomen is more distended and
lender than in poisoning by sulphuric acid. GasejOLUS^^uctations^are also
more frequent and distressing with this acid. Lockjaw and insensibility are \
known to have occurred as special symptoms.

Inhalation of the fumes of nitric acid produces irritation of the eyes,
lachrymation, burning in the throat, cough, feeling of constriction in the
chest and dyspnoea -and may cause death immediately from suffocation, or
later from pulmonary oedema or pneumonia.

Fatal Dose. — The smallest quantity on record is two drachms which
killed a boy, aged 13 years ; a similar dose killed an adult woman in 14 days.
But a smaller quantity — even a drachm — would suffice to kill a child, and
in certain conditions, an adult ; foftne fatal result depends on the extent of
the mischief produced by its corrosive action on the throat, windpipe and
stomach. Recovery has taken place after half an ounce or more.

Fatal Period. — The average fatal period is from twelve to twenty-four
hours. A Hindu silversmith took one ounce of the pure acid and died in
ten hours.6 A goldsmith's wife drank the concentrated acid with the inten-
tion of committing suicide, and died after twenty days.7 The shortest
recorded period in an adult is one hour and forty-five minutes and a few
minutes in an infant.

Post-mortem Appearances. — The skin and the mucous membranes are
corroded and yellow in colour, but the colour of the mucous membrane of
the stomach is greenish, if bile is present. The stomach wall is soft, friable
and ulcerated, but perforation is not so common as in sulphuric acid poison-
ing. There may be corrosion of the duodenum. In his annual report for the
year 1929, the Chemical Analyser to the Government of Bombay reports a
case of death by nitric acid poisoning, in which post-mortem examination
showed that the lips and fingers were stained yellow and corroded. The
alimentary canal from the lips to the duodenum was stained yellow and there
was necrosis of the coats of the stomach with perforation.

In death from inhalation of the nitric acid fumes the larynx, trachea and
bronchial tubes are usually congested, and the lungs are sometime§_£edema-
tous or show effusion of blood. Inflammatory changes in the lining
membrane of the right auricle of the heart may be found in some cases.8

Chemical Tests. — 1. If strong ferrous sulphate solution and sulphuric
acid are added to a solution containing nitric acid, a brown ring is formed
at the junction, of the two fluids. r

2.   Nitric acid forms a blood-red* colour with a 1 per cent solution of
brucine in strong sulphuric acid and a rich orange colour with morphine.

3.   llflien heated with strong sulphuric acid and copper foil, reddisk-
"brown Itimes of nitric oxide are given off, and the solution, become^ green.
If only a trace of nitric aeid is present, the reddish-brown* fumes may not Be
visible, but will be easily detected by starch-iodide paper which inrns blue,

4.    Diphenylamine Test — A solution of diphenylamine is prepared by
dissolving 1 gnx of the substance in S cc. of iQ per cent sulpiniric acid apf
1(H) cc. of water.   A few drops of this solution are added to ihe

liquid and the mixture is layered over some concentrated stri||%i^
a test tube.   A latt^ colour is visibk at the junction of tfee tWt>
nitric acid is preset/  This test is mot specific for nitric acid

6,   JN& Med. Gw^ fee 1W p. 2M,                               ,   -   -

7.   Madras Chemical E&awier*s Agaffal Report, 192% pt- 3L'1-
&  Holland, Med. Chem. <md Toocic*, ®i V,, p. 173. r       "