DISINFECTION AND DISINFECTANTS 251 



quickly poisonous to mammals and birds. As it may be 

 inhaled without the slightest indication of its presence 

 till the man falls senseless, its use is attended with serious 

 risk.) 



Some use has been made of crude sulphuric and hydro- 

 chloric acids in dilute solution for the disinfection of 

 fseces, and strong sulphuric acid has been used for the 

 disinfectant destruction of infected carcasses. 



Sulphur is used with some success in destroying Oidium 

 on vines, and other fungi parasitic for plants. Marcille 

 attributes the effect to the small amount of sulphuric 

 acid present in the preparations employed. 



Alkalies and Soaps. Efficiency here depends on the 

 character of the metal, but is also affected by the degree 

 of alkalinity. Faeces may be disinfected by caustic lime, 

 used generally as a 20 per cent, milk, but lumps must be 

 broken up. Kaiser's method consists in adding enough 

 hot water (50 to 65 C.) to cover the motion, and then 

 adding about one-fourth of the entire bulk of calcium 

 oxide, covering the receptacle, and allowing it to stand 

 for two hours. The hydration of the lime generates 

 sufficient heat to destroy typhoid. Lime is inefficient 

 against the more resistant organisms, and lime-whiting 

 is no sufficient precaution against them. Addition of 

 a suitable disinfectant renders the process efficient. 

 Ordinary size distemper has been shown by us to have no 

 action on the colon bacillus. Few disinfectants are 

 compatible with soap, binoxide of mercury and the best 

 coal-tar products being notable exceptions. Disinfectant 

 soap in the removal of grease, dirt, pus, etc., certainly 

 assists in eradicating bacteria, but the period of contact 

 of the soap in ordinary ablutions is insufficient to pro- 

 duce sterility. Nevertheless, as Rideal has pointed out, 

 organisms perhaps of an infective type left on the soap 

 by one person may remain long enough for the disinfectant 

 incorporated to act before another uses the soap. This 

 point is of importance in the prophylaxis of barber's 

 rash, for which purpose disinfectant shaving-soaps are 

 prepared. Commercial carbolic soaps are generally 

 worthless. 



Halogens. When dry, chlorine, bromine, and iodine 

 are poor disinfectants. Their use is practically confined 

 to solutions, and in practice they have to be used in an 



