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Full text of "Medical Jurisprudence And Toxicology"

PICRIC  ACID                                                          475

30 grains as an anthelmintic. It is a powerful antiseptic, but it is chiefly used in the
treatment of ankylostomiasis.

In large doses thymol acts as a poison and produces a burning sensation in the
stomach, nausea, vomiting, diarrhoea, tinnitus, headache, giddiness, collapse and death
from respiratory failure. It may cause abortion in a pregnant woman and may colour
urine green. Forty grains of thymol killed a woman, 34 years old, in 3 hours and 30
grains taken in two doses of 20 and 10 grains proved fatal to a woman, aged 40 years,
on the 9th day,35 while a dose of 300 grains caused only diarrhoea.36

The washing out of the stomach and the administration of the symptomatic treat-
ment are the chief remedial measures to be adopted in poisoning by thymol. Avoid
alcohol and fats or oils.

The post-mortem appearances are irritation of the stomach and intestines, fatty
degeneration of the hver and congestion of the lungs.

Chemical Tests.—A solution of thymol in chloroform, when warmed with a small
piece of caustic potash, assumes a dark-red colour. Thymol dissolved in glacial acetic acid
and warmed with an equal amount of strong sulphuric acid yields a violet-red colour,

PICRIC ACID   (CARBAZOTIC ACID,  TRINITROPHENOL,  TRINITROPHEN),

CoH2(NO2)3OH

This is obtained by the action of nitric and sulphuric acids on phenol. It exists
as yellow crystalline prisms or plates, and explodes under the action of heat or percus-
sion. It is soluble in 90 parts of water, and in about 12 parts of alcohol. It Has no odour,
but has an intensely bitter taste, and consequently has been used as a substitute for
hops in beer.

Picric acid precipitates albumin, and causes local necrosis. It decomposes the red
blood corpuscles, and produces methcemoglobin. It also irritates the central nervous
system, causing convulsions.

Symptoms.—Pain in the stomach ; severe vomiting of yellow matter ; diarrhoea with
yellow stools; the conjunctivas and the skin assume a bright yellow colour, which is
known as " picric jaundice " ; the pupils are dilated; there may be itching and eczema ;
the urine is at first dark yellow in colour, and later becomes ruby red, owing to the
formation of picramic acid, but it does not contain bile or albumin; there may be anuria
and strangury; rapid pulse; muscular cramps; convulsions; drowsiness; delirium;
stupor and collapse.

Fatal Dose and Fatal Period.—The fatal dose and fatal period are uncertain.
Poisoning has followed thirty grains, but recovery has ensued after swallowing about
300 grains. In his annual report for the year 1943, the Chemical Examiner, Bengal,
mentions a case in which death occurred on the 4th day after the ingestion of picric acid.

Treatment.—Wash out the stomach. Give diuretics and purgatives. Administer
morphine to relieve pain. The antidotes are proteins as found in raw eggs and milk.
The administration of large doses of dextrose has been recommended as this substance
is believed to aid the reduction of picric acid to the less poisonous picramic acid.

Post-mortem Appearances.—All the viscera are stained yellow and are congested.
The stomach and the upper part of the intestine show signs of irritation.

Chronic Poisoning.—Men who handle picric acid in munition plants and get dusted
over with it suffer from dermatitis which may be extremely irritating. Workmen engaged
in the manufacture of the explosive, melinite, which chiefly consists of picric acid, suffer
from a form of chronic poisoning, the chief symptoms being abdominal cramps, vomit-
ing, diarrhoea, loss of appetite and loss of weight.

A case37 is recorded in which a youth, aged 17, was unpacking "Explosive D",
ammonium picrate, which covered his face and hands and got into his eyes. He suffered
from conjunctivitis and tubular nephritis with heavy albumin and casts in urine.

Chemical Tests.—An aqueous solution is intensely yellow, is acid to litmus and
dyes wool and silk yellow. Ammonio-sulphate of copper produces a green precipitate.

When an aqueous solution of picric acid is warmed with potassium cyanide, a blood-
red colouration is produced owing to the formation of potassium isopurpurate.

Medico-Legal Points.—Picric acid is used as a yellow dye for silk and wool, and is
also used in the manufacture of explosives and fireworks. It has produced toxic effects
when swallowed in the form of a solution, when applied externally and also when
inhaled in the form of dust or fumes. Picric acid is now largely used as a dressing for
burns, and one death 3S has been recorded from the poisonous effects thus produced,

35.   Barnes, Jour. Amer. Med. Assoc., Sep. 16, 1922, p. 954.

36.   Jour. Amer. Med. Assoc^ 1912, Vol. 57, p. 1744.

37.   Jour. Amer. Med. Assoc^* Oct. 19, 1929, p. 1243.

38.   Alexander, Med. Press and Cir^ 1912, p. 112.