112 PATHOLOGY. 



developed bacteria have as yet been found to sumve after long 

 exposure to 60° C. when in the moist state, and but few resist a 

 temperature 50° C. = 112° F. 



The spores of bacteria, however, can resist a much higher 

 temperature than that which destroys the adult organism, and all 

 agree that the boiling-point of water is the lowest which can be 

 relied upon to destroy spores ; but in the dried state they are 

 much less readily destroyed, requiring three hours' exposure to 

 a temperature of 140° C. = 284° Y. 



Again, intense motion and sunlight checks bacterial life, but 

 electricity seems to have no effect upon them. 



Of the chemical influences which destroy or retard bacterial 

 life the most powerful is corrosive sublimate, its action being 

 instantaneous even in a dilution of one part to five thousand. 

 Next to the bichloride are placed bromine, iodine, and chlorine ; 

 but carbolic acid is not so reliable, as nothing less than a three per 

 cent, solution destroys spores, and requiring at least seven days, 

 and a five per cent, solution requiring from twenty-four to forty - 

 eight hours. When dissolved in oil, Koch says it is harmless 

 both to spores and developed bacteria. When immersed in it in 

 the dried state and dissolved in alcohol, it is also inert. 



The only other agents which can be depended upon to destroy 

 microbic life in less than twenty-four hours are permanganate of 

 potash in five per cent., and osmic acid one per cent, solution. A 

 five per cent, solution of chloride of iron destroys within six days, 

 l)ut neither sulphate of copper nor chloride of zinc seem to 

 have any effect. 



