ARSENIC 501 sleep. Ultimately collapse sets in, and results in death. In cases which end in recovery, chronic peripheral neuritis may persist, ending in paralysis from degeneration of the nerves extending upto the nerve centres. Unusual Symptoms.—These are convulsions, lock-jaw, delirium of a maniacal character, rise of temperature, salivation, loss of speech, ringing in the ears, and disordered vision with intolerance to light. Death occurs from asphyxia. Arseniuretted hydrogen, when inhaled in toxic amounts, acts as a direct poison to the haemoglobin of the red blood corpuscles, producing haemolysis, haemoglobinuria, jaundice, and sometimes anaemia. The other symptoms are faintness, giddiness, intense headache, nausea, vomiting, burning pain in the abdomen, pain in the loins, dark-red urine containing blood pigment and albumin, cyanosis and collapse. Coma or delirium may precede death, which occurs from oedema of the lungs or sudden failure of the heart. Fatal Dose.—Three grains of arserdous oxide is the average fatal dose. Two grains is the smallest amount known to have caused death. Recovery has taken place after much larger doses, varying from sixty grains to two ounces, but these are exceptional cases. The fatal dose of arseniuretted hydrogen is uncertain. It has been estimated that exposure to a concentration of 1 part of this gas in 20,000 parts of air for one hour is dangerous, while exposure to a concentration of 2.5 parts to 10,000 parts of air for half an hour is fatal to adults. Fatal Period.—The average fatal period is twelve to forty-eight hours, though death has frequently occurred within two to three hours. Hie shortest period is forty-five minutes.4 In this case it appears that death occurred from shock before the poison was absorbed into the system. In mild or sub-acute cases life may be prolonged for several weeks. In one case after a dose of 180 grains of white arsenic death did not occur until three months and seventeen days.5 In such cases the symptoms of gastro-intestinal irritation subside, and are usually followed by nervous affections. Diagnosis.—Acute arsenic poisoning has to be diagnosed from cholera, as the symptoms of both are similar in many respects, and it is possible that mistakes may be made in diagnosis. In order to avoid police investigations a case of acute poisoning by* arsenic is occasionally reported as that of cholera. It is, therefore, necessary for a medical practitioner to bear in mind the differentiating points between arsenic poisoning and cholera which are given below in a tabulated form : — Symptoms, Arsenic poisoning. Cholera. 1. Pain in the throat. 2. Purging. 3. Vomited matter. 4. Stools. 5. Voice. d. Conjunctivas. Before vomiting. Follows vomiting. Contains mucus, bile and streaks of blood. High coloured, bloody, fseculent, foetid, and discharged wjth straining and tenesmus. Very rarely '* rice-water *'. Not affected. Inflamed. Not so. Usually precedes vomiting. Is watery or like whey. ** Rice-water", liquid, whitish and discharged in an almost continuous and involuntary jet. Peculiar, rough and whistling. Not so. 4. Madras Chemical Examiner^ Annual Report, 1929, p, 2. 5. G. St. George, Brit. Med. Jonr^ Feb. 5, 1921, p. 192."