740 MEDICAL JURISPRUDENCE which retains its colour for several months. Normal blood forms a coagulum which is at first red, becomes brown in the course of one to two hours and then becomes grey in twenty-four to forty-eight hours. The blood saturated even with 10 per cent carbon monoxide responds to this test. 4. Katayama's Test.—Ten cubic centimetres of the suspected blood diluted with 50 parts of distilled water are mixed with four drops of orange- red ammonium sulphide solution and 4 to 6 drops of 30 per cent acetic acid. The mixture is filtered and the filtrate of carbon monoxide blood remains red, while normal blood becomes green or grey. Orange-red ammonium sulphide solution is made by adding 2 grammes of sulphur to 100 cc. of yellow ammonium sulphide. 5. Potassium Ferrocyanide Test.—If 15 cc. of blood are mixed with an equal amount of 20 per cent potassium ferrocyanide solution and 2 cc. of dilute acetic acid and shaken gently, a bright red coagulum will form, if the blood contains carbon monoxide, while a dark brown coagulum will form if. the blood is normal. The Reversion Spectroscope method designed by Professor Hartridge is very convenient for the quantitative -determination of carbon monoxide present in blood.8 Medico-Legal Points.—Poisoning by carbon monoxide is mostly acci- dental. Accidents may occur in connection with incomplete combustion of wood, charcoal or coal in ill-ventilated rooms, leaky gas pipes and taps in Dwellings, and motor car exhausts in small garages or even in narrow-streets where motor traffic is very dense. On the night of the 10th February 1924, a family consisting of a man, aged 35 years, his wife, aged 25 years, and a son, aged 10 years, went to sleep in a closed room, where coal was kept burning to ward off cold. Next morning the boy was found dead in bed, and the man and the woman were found in a state of unconsciousness. They were immediately removed to the King George's Hospital, Lucknow. On admission they were found in a comatose condition, and the limbs were rigid and the reflexes were exag- gerated. They gradually recovered in six or seven days. The blood of the three victims •showed the presence of carbon monoxide in the spectroscope. Sherman, Swindler and McEllroy9 describe three cases of collapse under the use of ethylene as an anaesthetic, of which two proyed fatal The .blood from the patients showed 50 to 60 per cent saturation with carbon monoxide. The cylinder of ethylene was found to contain carbon monoxide concentration of 0.7 per cent. Suicidal poisoning by carbon monoxide frequently occurs in England, and other Western countries. The victim generally shuts himself up in a •room after placing smouldering fire and after closing all the doors and win- dows. Sometimes, a suicide sleeps in a room where a gas tap is turned on or he may attach a rubber tube to the gas tap and then put it in his mouth. In India, suicide by carbon monoxide is rare. An Anglo-Indian, 65 years old, and resident of Lucknow, was found dead on a couch in a Small room of his house at about 4 p.m. on October 25, 1929. The room had been closed .from inside, all openings to allow ventilation had been closed and charcoal had been kept burning in an angeihi (stove). A case 10 also occurred in Bombay where a European committed suicide by sitting in a chair near a gas stove in his kitchen after opening the gas tap and then covering his head >and the gas stove with a rug and a sheet. The door and windows of the kitchen had also been shut. ,8. For details see Sydney Smith and Glaister, Recent Advances in Forensic Medicine, Ed. H, p. 201. 9. Jour. Amer. Med. Assoc., June S, 1926, p. 1765. 10. Times of India,, Dec. 13, 1934.