62 INFECTION AND IMMUNITY 



very poisonous nature of this salt must be constantly 

 kept in mind by those who make use of it for disinfect- 

 ing purposes. The solution is colourless, and a fatal 

 dose might easily be mistaken for water. To avoid 

 such accident it is customary to colour the solution 

 with indigo or an anilin dye. 



Sulphate of copper has been used to some extent, 

 especially in France, for the same purposes as the 

 salt last mentioned (corrosive sublimate). Its germ- 

 icidal value is considerably less, but in solutions con- 

 taining from two or five per cent, it is reliable for 

 the destruction of pathogenic bacteria not containing 

 spores. Like the bichloride of mercury its germicidal 

 action is neutralised to a considerable extent by the 

 presence of albuminous material. It is therefore not 

 to be selected for the disinfection of sputa and excreta. 



With reference to the various proprietary disinfect- 

 ants which are in the market and largely used, I 

 would say that many of them are deodorants of more 

 or less value and are entirely unreliable for the de- 

 struction of disease germs. Others contain germ- 

 icidal agents of value ; but, as a rule, they are not 

 economical in use, as compared with heat, carbolic 

 acid, formaldehyd, and other disinfectants of estab- 

 lished value referred to in the present volume. 



