542 Profs. Percy Frankland and Marshall Ward. 



(a) In its natural unsterile state ; 



(&) Sterilised by steam ; 



(c) Sterilised by nitration through porous porcelain. 



In ea'ch case the effect of temperature was studied by pre- 

 serving the infected waters at winter and summer temperatures 

 respectively. 



'Description of experiments, see pp. 409 433, 451 465 ; summary 

 of conclusions, pp. 433, 434.) 



2. A perfectly similar series of experiments, carried on side by side 



with the above, in which the Bacillus coli communis was em- 

 ployed instead of the typhoid bacillus. 



(Description of experiments, see pp. 409 433 ; summary of conclu- 

 sions, pp. 433, 434.) 



3. A series. of experiments in which the effect of the addition of 



common salt in various proportions to unsterile Thames water 

 was studied, the unsterile Thames water being employed for 

 this purpose both uninfected and infected with the typhoid 

 bacillus. 



(Description of experiments, see pp. 434 450 ; summary of conclu- 

 sions, p. 450.) 



4. A series of experiments perfectly similar to No. 1 above, in 



which Loch Katrine water was employed instead of Thames 

 water. 



(Description of experiments, see pp. 465 et seq. ; summary of con- 

 clusions, pp. 476 486.) 



5. A further series of experiments made with the same sample of 



Loch Katrine water, only introducing a much larger number 

 of typhoid bacilli into a given volume of water ; in this series 

 of experiments only unsterilised Loch Katrine water was em- 

 ployed. 



(Description of experiments, see p. 486 ; summary of conclusions, 

 p. 492.) 



6. In order to compare the relative longevity of the typhoid bacillus 



in the more important types of potable water, a long series of 

 experiments was carried out in which typhoid bacilli from one 

 and the same cultivation, and in as far as possible equal num- 

 bers, were introduced into Thames water, Loch Katrine water, 

 and the deep well water of the Kent Company respectively. 

 Each of these waters was employed : 



(a) In its unsterile natural condition ; 



(5) Sterilised by steam ; 



(c) Sterilised by filtration through a porous cylinder of 

 infusorial earth. 



