THE MULTIPLICATION OF MICRO-ORGANISMS 245 



peroxide of hydrogen was found to depend upon the 

 number and variety of the microbes present. Thus a 

 water containing 19,600 microbes per c.c. was sterilised 

 within a day by the addition of 1 : 50,000, whilst a 

 water containing originally 34,850 organisms per c.c. 

 required an addition of 1 : 10,000 parts of the water. 



Water purposely infected with cholera organisms 

 was rendered sterile in 5 minutes by the addition of 

 1 : 10,000, whilst in similar experiments with the 

 typhoid bacillus, the latter required a whole day's 

 exposure to an addition of 1 : 5000 before they were 

 destroyed. 



Altehoefer : examined the action of the peroxide on 

 Eostock water obtained (1) from a well containing 560 

 bacteria per c.c., (2) from Eostock tap- water containing 

 180 per c.c. A sample of river-water was also employed 

 containing 1,800 organisms per c.c. An addition 

 of 1 : 5,000 sufficed, after being undisturbed for 24 

 hours, to sterilise all these waters kept at ordinary 

 temperatures during the first 4 days, whilst all those 

 samples to which an addition of 1 : 10,000 had been 

 made exhibited organisms, although only a small num- 

 ber. On the 6th day, however, growths were obtained 

 from the samples treated with 1 : 5,000, whilst in 

 the second series very active multiplication of the 

 bacteria present had taken place. Similar negative re- 

 sults were also obtained by this author when ordinary 

 tap-water infected with drain- water (98 c.c. tap-water 

 and 2 c.c. drain-water, and 199 c.c. tap-water and 1 c.c. 

 drain-water) was treated in the proportion of 1 : 5,000 

 and 1 : 2,500. In order to further test the action of 

 peroxide of hydrogen on water bacteria, an addition 

 of 1 : 1.000 parts of the water was made. (Altehoefer 



1 ' Ueber die Desinfectionskraft von Wasserstoffsuperoxycl auf Wasser,' 

 Centralblattf. Bakteriologie, vol. viii., 1890, p. 129. 



