DISINFECTANTS 293 



ointments, with the exception of those in which ' lanolin ' 

 forms the base, reduce the disinfectant action of most 

 substances which may be conveyed in them. 



For certain purposes disinfection has been attempted by 

 the use of solid substances possessing very slight solubility, 

 or by inert solids steeped in disinfectant solution and dried. 

 It is obviously a condition of disinfectant action that the 

 substances should come in contact with every organism ; 

 and when the size of the organipm is considered, it will be 

 seen that the difficulties of disinfection are considerably 

 increased by dispensing with the liquid form. In practice 

 it is safe to say that nothing more than deodorant and 

 mildly antiseptic effect can be obtained from such 

 substances. 



Many vapours have a well-marked disinfectant action. 

 It may, however, be stated broadly that, until some means 

 of obtaining an equal diffusion of a vapour in atmospheric 

 air can be provided, the use of disinfectant in the form of 

 vapour or gas must be largely illusory. A considerable" 

 number of experiments have been made demonstrating the 

 action of vapours in glass bells and under laboratory con- 

 ditions; but such observations avoid the dif&culty of 

 diffusion of vapours and gases in general into air to a much 

 larger extent than is possible in practice. 



