Report on the Bacteriology of Water. 411 



Porcelain-filtered Thames Water. 



3 flasks incubator. 3 flasks incubator. 



3 refrigerator. 3 refrigerator. 



Steamed Thames Water. 



3 flasks incubator. 3 flasks incubator. 



3 refrigerator. 3 refrigerator. 



UNINFECTED CONTROL WATERS. 



2 flasks incubator. 

 2 refrigerator. 



N.B. The convention is adopted throughout the text of the 

 Report of designating the flasks 1 1, 21, 31, and IE, 2E, 3 B, ac- 

 cording as they have been kept in the incubator or refrigerator 

 respectively, and in this manner the individual flasks are readily 

 identified. 



In order to ascertain whether the infection of the water had com- 

 municated any large amount of organic matter to the water, some of 

 the infected waters were submitted to a partial chemical analysis. 

 This is a matter which has, unfortunately, been almost entirely 

 neglected in previous observations on the vitality of pathogenic 

 bacteria in potable waters, and it is obvious that if such investiga- 

 tions are to have anything but a negative value, the waters, after 

 infection, must not differ materially in their chemical composition 

 from that which they possess in their natural state. 



These chemical analyses yielded the following results : 



Results of Analysis expressed in Parts per 100,000. 



Unfiltered TJnfiltered 



Unfiltered Thames water Thames water 



Thames water* infected infected 



uninfected. with typhoid. with _B. coli. 



Ammonia (free) 0-013 0'013 O'OIS 



(albuminoid) 0'016 0'020 0"028 



Oxygen consumed .... 0'102 O'lOl 



Chlorine T65 170 170 



Thus the infection, especially in the case of the typhoid bacillus, 

 had caused but very little increase in these ingredients. 



The examination of the several flasks was conducted on the fol- 

 lowing principles : 



1. The unfiltered infected Thames water was examined by plate- 

 cultivation from time to time in order to ascertain the changes in the 



* The full analysis of this water is given on p. 4O9. 

 TOL. LVI. 2 F 



