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KiNLOCH (J. P.)- An Investigation of the Best Methods of Destroying 

 Lice and other Body Vermin. — Brit. Med. Jl, London, no. 2842, 

 June 1915, pp. 1040-1041. 



As the result of a very large number of experiments, the author 

 concludes that dry heat is more effective than moist heat in destroying 

 lice and their eggs. Though lice can be revived after immersion for 

 one minute in water at 100° C, exposure to a dry heat at the same 

 temperature and for the same time, appears to kill both adults and 

 eggs. The paraffin bodies are actively insecticidal, and of these, 

 petrol is the most effective. Lice and their eggs are destroyed by 

 immersion in petrol for one minute, and they may be killed by exposure 

 to the vapour of petrol for half an hour. Powerful fatty solvents other 

 than the paraffins, are also actively insecticidal. Benzene, toluene, 

 and acetone are as toxic to lice as petrol. Certain chlorine derivatives 

 of methane, ethane and ethylene are more lethal to lice than any other 

 substances, and have the important merit of being non-inflammable. 

 Immersion in the chlorine derivatives of ethane and ethylene imme- 

 diately destroys all lice and their eggs, while exposure to the vapour 

 of these substances for five minutes is equally destructive to them. 

 Even soap solutions containing 2 per cent, of trichlorethylene or 10 

 per cent, of tetrachlorethane are capable of killing both adults and 

 eggs in half an hour at ordinary temperatures. A 25 per cent, solution 

 of dichlorethylene or trichlorethylene in vaseline when applied to the 

 human body has been found capable of exerting its insecticidal action 

 for hours. The action of a 25 per cent, solution of petrol in vaseline is 

 of shorter duration, but is also effective for some hours. The common 

 phenol disinfectants in their usual degrees of dilution for disinfectant 

 purposes and at ordinary temperature fail to kill lice or their eggs, 

 even after steeping for half an hour, but become efficient as insecticides 

 if the temperature of the steeping tank is maintained at 65° C. The 

 volatile oils have no direct insecticidal effect. In a moist vapour of 

 oil of wintergreen, oil of cloves, oil of caraway, oil of turpentine, oil of 

 eucalyptus, oil of thyme, etc., lice live for many hours at body tempera- 

 ture, and can be revived after immersion in these oils. When in 

 contact with solid substances, such as iodoform, camphor and paraform, 

 or in contact with garments impregnated with sulphur, borax, black 

 hellebore, alum, etc., lice appear to remain practically imaffected. 

 Lice, when himgry, feed on the human body even if previously anointed 

 with sulphur ointment, balsam of Peru, mercury oleate ointment, 

 chrysarobin ointment, stavesacre ointment, and hellebore ointment. 

 It still however remains to be determined whether some of these bodies 

 which have been shown not to be actively insecticidal, may not have, 

 when rubbed on the body or placed in the clothing, a useful repellent 

 effect on the body vermin. For practical purposes it has been found 

 that destruction of lice and their eggs is best secured by immersion of 

 verminous garments and bedclothes in a petrol or benzene bath. 

 Danger from fire and waste of petrol are avoided by using such a bath 

 and extractor as are employed in a dry-cleaning apparatus. In such 

 an apparatus, 90 per cent, of the petrol or benzene is recovered for 

 future use. A petrol or benzene bath is necessary, especially for 

 uniforms and woollen garments generally. Where the clothing is 

 such that it is not injured by immersion in water, steeping the garments 



