1885.] Studies of Disinfectants by New Methods. 2()5 



true disinfectant action takes place until the strength reaches 1 per 

 cent. 



Ferrous Sulphate and Potassic Permanganate. 



Days 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 



10. 



11. 



At 16° — 























Ferrous sulphate (saturated) 

















+ 







16'7 per cent. 























± errous sulphate 8 4 per cent 



— 



— 



— 



— 



+ 













Ferrous sulphate 5 per cent. . 



— 



— 



— 



— 



+ 













Ferrous sulphatel"6 per cent. 



— 



— 



— 



— 



+ 













At 35'5° — 























Ferrous sulphate 1*6 per cent. 













+ 











At 16°— 























Potassic permanganate O01 



- 



+ 



















per cent. 























Potassic permanganate 0'04 





+ 



















per cent. 























Potassic permanganate 1*0 























per cent. 























At 35-5°^ 























Potassic permanganate 0*04 















+ 









per cent. 























Potassic permanganate 0"4 

















+ 







per cent. 



























+ 



















Halogens. — Since minute quantities of the halogens have a very- 

 decided inhibitory action on growth, the thread method of investi- 

 gation was thought more suitable. Sterilised threads were, therefore, 

 infected with the bacterium, and submitted for twenty-four hours to 

 chlorine, bromine, and iodine water of known strength, the thread 

 being afterwards soaked in distilled water to free it from all traces 

 of the halogen, and then planted in gelatin. The results are not 

 essentially different from those obtained by other observers, and fully 

 confirm the great disinfecting power of the halogens, O01 per cent, 

 solution of any of the three being sufficient to destroy the bacterium. 

 Of the three, chlorine is the most active. 



i 



I 



