SCIENCE AIDS POLICE

Thames Star, Volume LXVI, Issue 20197, 23 December 1937, Page 4

SCIENCE AIDS POLICE

CHEMICAL ANALYSIS WORK OF DOMINION LABORATORY Remarkable instances of the value ol chemical analyses in carrying out investigations for the Police Department are given in the annual report of the Dominion Laboratory. In one investigation in Auckland numbers which had been filed off several stolen bicycles were made visible by using a solution of copper chloride in hydrochloric acid containing 5 per cent, glycerine, the solution being kept saturated by a freezing mixture until application. A small reservoir of dental sheet was made round the number and the solution applied for several short periods. Minute green patches on two overcoat buttons of a person killed in a "hit and run" case, and a dull streak on the mudguard of the accused's motor-truck were submitted for examination in Wellington. It was shown that the green patches on the buttons corresponded with the green paint on a bent bar of the truck. Scrapings from a number of the dull streaks on the mudguard all gave the characteristic smell of burning rubber when carefully heated over a small flame. No similar smell was observed with scrapings from any other part of the mudguard. Smears were then made on the mudguard with the rubber grip of deceased's motor-cycle handle, and scrapings from these. all gave the smell of burning rubber when heated. It was found, however, that after a period of three weeks no such smell could be obtained from these on the original smear. This was probably due to oxidation changes in very thin deposits of rubber. It was therefore concluded that the original smear could not have been more than three weeks old when first examined. Four cases of animal poisoning were investigated in Christchurch. The most important of these investigations related to the death of two hundred sheep. It was thought that they had been poisoned with strychnine, but an examination of two sheep negatived this. It was found that the feed had not been digested and had formed into hard lumps, causing an impacted condition of the bowels. This resulted from the dry condition of the pastures in use. When removed to green pasture, other sheep similarly affected' rapidly recovered. Friar's balsam was found to have been used in a case of attempted suicide in Christchurch. Glauber's salts, or sodium sulphate, a definitely mineral salt, was the main constituent of a "herbalist's" remedy. Seven samples of liquor were examined, ale (1), hop beer (1), and cider (5). The cider, which contained 14 per cent, to 20 per cent, of proof spirit, was on open sale in single bottles in various unlicensed premises in Christchurch. A preparation sold as aluminium solder in Wellington was found to be a mixture of 8 per cent, aluminium powder with melted sulphur, and quite useless for the purpose of soldering aluminium. With a forged pakapoo ticket it was found possible from an examination of the ink and paper to discover the method used by the accused. In the case of a forged receipt which was said to have been through the washtub, it was possible to show by means of absorption of eosin from ether by the paper fibres that as little as 30 seconds' immersion in water would have removed the sizing of the paper. Several cases of malicious poisoning of horses with strychnine have been investigated in Dunedin in recent years. During last year the strychnine in one case was associated with red dye, as required by the Poisons Act, 1934. This would indicate that the poisoning was not accidental. In a case of suspected incendiarism in Auckland, several samples of fabric were found to have been soaked with kerosene. The laboratory in Christchurch examined a total of 2635 samples during the year, 2444 being received from the Health Department, 147 from, the Justice and Police Departments, 23 from other Government departments, and 22 from local bodies and miscellaneous sources.