488 MEDICAL JURISPRUDENCE vapour of phosphorus gains access to the jaw (phossy jaw) through a carious tooth or an interspace caused by a missing tooth. Death occurs from debility, blood poisoning or pyogenic infection. Abortion usually occurs among pregnant women. Treatment.—Advise thorough cleanliness and ventilation by the use of extraction fans in the match factories. The air of the work rooms may be saturated with turpentine. The teeth of the workmen should be occasionally examined, and tKeteeth, if found carious, should be filled in or extracted. The workmen should also be persuaded to use systematically mouth washes of sodium bicarbonate. Chemical Analysis.—Phosphorus may be separated by distillation from organic mixtures, and may be detected by its smell and luminosity in the dark. Its phosphorescence is diminished by the presence of alcohol. Hence, in cases of suspected phosphorus poisoning a saturated solution of common salt should be used as a preservative instead of alcohol. It can also be separated by shaking the contents of the stomach, etc. with carbon bisul- phide, which dissolves phosphorus. Tests.—1, Scherer's Test.—The suspected material in a finally divided condition is placed in a conical flask with a capacity of about 500 cc. and covered with cold water. A few cubic centimetres of cadmium sulphate solution are added and the liquid is acidified with dilute sulphuric acid. The flask is closed with a cork having two slits from which are suspended two strips of filter paper, one soaked in 5 per cent silver nitrate solution and the other in a solution made by adding sodium hydroxide solution to 5 per cent lead acetate solution until the precipitate first formed is redissolved. The strips of filter paper must be so arranged as not to touch each other or the sides of the flask. The flask is then heated on a water bath in the dark to'40° or 50 °C. If the silver paper darkens from the fumes, while the lead paper does not change, phosphorus may be present. If the silver paper does not darken, phosphorus is not present. If both the papers darken, hydrogen sulphide is present, or both hydrogen sulphide and phosphorus may be present. 2. Mitscherlicli's Test.—If the mixture is acidulated with sulphuric acid and distilled, the luminous vapour of phosphorus will be seen in the cool condenser in the dark. Certain substances, such as alcohol, ether, chloro- form, phenol and turpentine, if present, will prevent the development of luminosity. This is a very delicate test, and will reveal one part of phos- phorus in 100,000 parts of the material. 3. Phosphine Test.—If hydrogen is passed through the warmed suspected fluid material, phosphoretted hydrogen is evolved, which will burn with a green flame. If the gas is passed into a solution of silver nitrate, a black precipitate is formed. The green flame, when examined with a spectroscope, shows one band in the orange and yellow between C and D, but very close to D, and several bands in the green. This test is also known as Dusart-Blondlot's test. 4. Heated with a few drops of strong nitric acid and some ammonium molybdate solution a concentrated acid solution of the suspected material gives a yellow, crystalline precipitate, if phosphorus is present. Medico-Legal Points.—The poisonous effects are more powerful if phos- phorus is dissolved or well triturated than when used in solid lumps. In Europe, phosphorus poisoning is usually suicidal. Pregnant women have often been accidentally poisoned by phosphorus as they take it to induce criminal abortion. It is seldom used for homicidal purposes. The odour and taste as also the luminosity in the dark reveal its presence.