SPECIAL EXAMINATIONS 383 



process is carried on ; (3) The kind of water used for 

 dilution hard water, soft water, or sea water ; (4) The 

 type of micro-organism that has to be dealt with ; (5) The 

 nature of the substance to be disinfected and the character 

 of its surface ; (6) The time to be allowed for the process. 

 That only when the influence of such factors can be 

 calculated will it be possible to modify any standard co- 

 efficient figure, and thus to obtain data for the preparation 

 of effective and economical dilutions for the practical 

 problem of disinfection. 



The inquiry has shown that, so far as emulsions are 

 concerned, those which contain the highest quantity of 

 phenoloids in the finest state of division and having the 

 least tendency to combine with albumins, lime, or other 

 foreign substances in solution (and remain combined), will 

 be found to be the most efficient disinfectants. 



The remarkable parallelism between the results of this 

 inquiry (as shown in the figures for the coefficient) and the 

 results of the independent chemical one, is very striking. 

 The chemical commissioners discovered that if they 

 subtracted the carbolic acid equivalent of the bromine 

 absorbed by the percentage of phenoloids present, from 

 the percentage of phenoloids present, and divided the 

 difference by 3, the figures obtained in many instances 

 are the same (or very nearly so) as those assigned as the 

 carbolic acid co-efficient for the same substance by the 

 bacteriological commissioners. In the exceptions the dis- 

 infecting fluids did not form an emulsion with water, nor 

 show Brownian movements. (See p. 142.) 



*= = c.c. 



3 



Tables showing the results of the examination (on these 

 principles) of the disinfectants in common use, are given 

 in the Lancet for 1909, vol. ii. 



