468 MEDICAL JURISPRUDENCE them in water. There i# yet a third method by which the organic mixture is evaporated and extracted with alcohol acidified with a little hydrochloric acid. The alcoholic solution is then evaporated to dryness, and the residue is dissolved in water to apply the tests for oxalic acid. Tests.—1. A solution of barium nitrate gives a white precipitate of barium oxalate, soluble in hydrochloric acid or nitric acid without effervescence. 2. A solution of silver nitrate gives a copious white precipitate of silver oxalate, soluble in ammonia and nitric acid. 3. Calcium chloride or sulphate gives a white precipitate, insoluble in acetic acid, but soluble in strong hydrochloric acid. 4. Lead acetate gives a white precipitate, soluble in nitric acid, but insoluble in acetic acid. 5. Potassium permanganate in an acid solution is decolourised and is reduced to the colourless manganese salt. 6. About 5 cc. of oxalic acid are mixed with 1 cc. of sulphuric acid (1 : 2) and 2 drops of 10 per cent copper sulphate solution; about 1 g. of granulated zinc is then put into the mixture so as to form a zinc-copper couple. After three minutes 2 cc. of concentrated sulphuric acid and 0.1 cc. of a 2 per cent aqueous solution of resorcinol are added to the mixture. A pale blue colour develops, which deepens on warming. Medico-Legal Points.—In the form of oxalate of ammonium, sodium, potassium or calcium, oxalic acid exists as a natural constituent of several plants and vegetables, such as sorrel, rhubarb, cabbages, lichens and guano. Hence it may gain access to the body through food and drugs of vegetable origin. It often occurs as a constituent of the human urine, 0.02 gramme (0.3 grain) being excreted in 24 hours. Oxalic acid is largely used in calico printing, in the manufacture of straw hats, and in cleaning brass and copper articles, and wooden surfaces. It is used for removing writing and signatures from paper and parchment documents. It is a common household remedy for removing ink stains and iron moulds from linen. Cases of accidental poisoning by oxalic acid have sometimes occurred from it having been swallowed in mistake for a saline purgative of magne- sium sulphate. A young woman took 2 drachms of oxalic acid by mistake for magnesium sulphate at about 8 ajn. on the 29th October 1930. Immediately she complained of burning sensation in the mouth, throat and abdomen, and induced vomiting by tickling her fauces. She vomited many times and two hours later she brought up a good quantity of blood. She was removed to the King George's Hospital, Lucknow, where she was found restless with a rapid pulse (132 per minute) and hurried respirations (52 per minute). She complained of very severe epigastric pain. She had no difficulty in swallowing, but experienced burning pain in the abdomen after swallowing liquids. Excoriations were present on the tongue and the post-pharyngeal wall, but not on the lips and gums. She vomited occasionally, and brought up a few streaks of blood with the detached pieces of the mucous membrane. She was given lime water and morphine hypodermically. She was discharged cured on the third day. A case25 occurred at Amritsar where 30 grains of oxalic acid were used instead of 40 grains of tartaric acid in the manufacture of " Darling Seidlitz powders ". Due to the prompt action of the Police Department, all the tins containing these powders were confiscated from different areas in the Punjab, and no accidents occurred. During recent years cases of suicide by oxalic acid poisoning, although very few, have occurred in India due to its increased use as a remover of stains on clothes and the ease with which it can be obtained at a druggist's shop. Owing to its taste, it is rarely used for homicidal purposes'. In his 25. Punjab Chemical Examinees Annual Eeport, 1929, p. 10.