Report on the Bacteriology of Water. 



227 



It should be pointed out that neither the Loch Katrine nor the 

 Lintrathen waters are submitted to filtration before delivery, and that 

 these figures, therefore, indicate the bacterial life present in these 

 waters as they come from the loch, excepting in so far as chauges 

 may occur in their passage through the mains. 



The behaviour of these bacteria normally present in the Loch 

 Katrine water, when the latter is kept at winter and summer tem- 

 peratures respectively, was investigated, and the results are recorded 

 in Table XI. From this it will be seen that in four days a very con- 

 siderable multiplication had taken place, the increase in numbers 

 being much greater in the case of the incubator (19° C.) flask than in 

 that of the refrigerator (9° C). After three months, however, the 

 numbers in the incubator flask had fallen very much below those in 

 the refrigerator flask, showing that the higher temperature leads to 

 rapid multiplication followed by rapid decline, whilst at the lower 

 temperature the increase and decrease are of a more gradual character. 



As in the experiments on the behaviour of the anthrax bacilli in 

 Loch Katrine water, the latter was used both in the natural condition 

 and sterilised by filtration through porous porcelain ; the water was 

 also submitted to chemical analysis both in its natural state and after 

 passage through the porcelain filter, with the following results : — 



Results of Analysis expressed in Parts per 100,000. 





Loch Katrine 



Loch Katrine water 





water 



(filtered through 





(unfiltered). 



porcelain) . 





3-00 



3-00 





0-195 



0-220 





0-015 



0-030 









0-002 



,, (albuminoid) . . . 



0-003 



0-004 



Oxygen consumed by or- 







ganic matter, as measured 







by reduction of a solution 







of permanganate acting 







for three hours in the cold 



0-116 



0-140 



Nitrogen as nitrates and 









trace 



trace 



Total combined nitrogen . . 



0-015 



0-032 





0-6 



0-65 



Temporary hardness 











Permanent „ 



0-8 



0-8 



Total 



0-8 



0-8 





clear and palatable 



clear. 



These analyses show the Loch Katrine water experimented with 



