200 VETERINARY HYGIENE 



disinfectant, it is a valuable " cleanser." The combined action of 

 fresh air and sunlight is by no means to be regarded as negligible. 



Heat is one of the most valuable disinfectants we have. 



Electricity is used to some extent for the sterilisation of milk, 

 and also sometimes for the purification of water. With these pos- 

 sible exceptions its use is limited, so far as concerns veterinary 

 practice. 



DISINFECTION BY HEAT. 



Heat is used in two forms, dry and moist. 



DRY HEAT. Most vegetative forms of bacteria and those 

 which do not sporulate are killed off if exposed to a temperature of 

 150F. for about ten minutes. Dry heat might therefore be of 

 value if one could be certain that the more resistant forms of 

 bacteria are not present, and if one could be sure that all the organ- 

 isms in an article to be disinfected would be exposed to this heat. 

 Unfortunately one has to deal with highly resistant spores, and the 

 penetrating power of dry heat is very poor, so that though bacteria 

 on the surface of goods may be destroyed this is not the case with 

 those that are buried in the depths of closely woven articles or in 

 between layers of rugs. It has, furthermore, been found that as 

 high a temperature as 212 F. for a period of an hour fails to destroy 

 even non-sporing forms, if these are in a dry state when exposed. 

 Dry heat, therefore, is of no practical value for the disinfection of 

 such articles as horse rugs and the like, as these would be scorched 

 if the heat is great enough and the period of exposure long enough 

 for all the pathogenic organisms to be made harmless. 



Dry heat in the form of a live flame is, however, a most valu- 

 able agent for the disinfection of things that would not be damaged 

 by its use. The cremation of dangerous bedding and excreta, of 

 soiled halters, sponges, rags, and such things of no great monetary 

 value is the surest way of disposing of them. A painter's or brazier's 

 lamp is the most useful " disinfectant " at the disposal of the veteri- 

 nary hygienist, and here he possesses a great advantage over his 

 medical confrere. The flame can be applied to almost any part of 

 a stable or byre without doing injury. 



A splash of anthrax blood on the travise in a cow byre can in a 

 few moments be made harmless -with certainty if burned with the 

 flame, whereas there is always a possible element of doubt when 

 chemical disinfectants are used. 



Shovels and forks used in the cleaning up following anthrax or 

 other dangerous disease can be treated in the same way. Curry 

 combs used on mangey horses are made safe beyond any question of 



