PRACTICAL DIRECTIONS FOR DISINFECTION. 217 



failed to kill typhoid bacilli ; but when suspended in water in the proportion 

 of 1 : 40 by weight this bacillus was killed at the end of two hours. Anthrax 

 spores were not killed in the same time by a lime wash containing twenty 

 per cent by weight of pure calcium oxide. According to Kitasato, the 

 typhoid bacillus and the cholera spirillum in bouillon cultures are destroyed 

 by the addition of one-tenth per cent of calcium oxide. Pfuhl experimented 

 upon sterilized faeces to which pure cultures of the typhoid bacillus or 

 cholera spirillum were added. The liquid discharges of patients with typhoid 

 fever or diarrhoea were used for the purpose. He found that sterilization 

 was effected at the end of two hours by adding fragments of calcium hydrate 

 in the proportion of six per cent, and that three per cent was effective in six 

 hours. When a milk of lime was used which could be thoroughly mixed 

 with the dejecta the result was still more favorable. A standard preparation 

 of milk of lime containing twenty per cent of calcium hydrate killed the 

 typhoid bacillus and the cholera spirillum in one hour when added to liquid 

 faeces in the proportion of two per cent. 



The experiments with this agent show that time is an important factor, 

 and that much longer exposures, as well as stronger solutions, are required 

 to destroy pathogenic bacteria than is the case with chloride of lime. For 

 this reason we still give the last-named agent the preference for the disinfec- 

 tion of excreta in the sick-room. But in latrines the time required to accom- 

 plish disinfection is of less importance, and we are disposed to give recently 

 burned quicklime the first place for the disinfection of excreta in privy 

 vaults or on the surface of the ground. It may be applied in the form of 

 milk of lime, prepared by adding gradually eight parts, by weight, of water 

 to one part of calcium hydrate. This must be freshly prepared, or protected 

 from the air to prevent the formation of the inactive carbonate of lime. 



According to Behring, lime has about the same germicidal value as the 

 other caustic alkalies, and destroys the cholera spirillum and the bacillus of 

 typhoid fever, of diphtheria, and of glanders after several hours' exposure, 

 in the proportion of fifty cubic centimetres normal-lauge per litre. Wood 

 ashes or lye of the same alkaline strength may therefore be substituted for 

 quicklime. 



Finally, it must not be forgotten that we have a ready means of disinfect- 

 ing excreta in the sick-room or its vicinity by the application of heat. 

 Exact experiments, made by the writer and others, show that the thermal 

 death-point of the following pathogenic bacteria, and of the kinds of virus 

 mentioned is below 60 C. (140 F.): Spirillum of cholera, bacillus of an- 

 thrax, bacillus of typhoid fever, bacillus of diphtheria, bacillus of glanders, 

 diplococcus of pneumonia (Micrococcus Pasteuri), streptococcus of erysipelas, 

 staphylococci of pus, micrococcus of gonorrhoea, vaccine virus, sheep pox 

 virus, hydrophobia virus. Ten minutes' exposure to the temperature men- 

 tioned may be relied upon for the disinfection of material containing any of 

 these pathogenic organisms, except the anthrax bacillus when in the stage 

 of spore formation. The use, therefore, of boiling water in the proportion 

 of three or four parts to one part of the material to be disinfected may be 

 safely recommended for such material. Or, better still, a ten-per-cent solu- 

 tion of sulphate of iron or of chloride of zinc at the boiling point may be 

 used in the same way (three parts to one). This will have a higher boiling 

 point than water, and will serve at the same time as a deodorant. During 

 an epidemic of cholera or typhoid fever such a solution might be kept boil- 

 ing in a proper receptacle in the vicinity of hospital wards containing 

 patients, and would serve to conveniently, promptly, and cheaply disinfect 

 all excreta. 



For the disinfection of fseces in privy vaults, etc., Vincent (1895) 

 gives the first place to sulphate of copper, which should be used in the 

 proportion of eight to ten grammes per litre of contents, together 

 with an equal part, by weight, of sulphuric acid. 



