516 



Messrs. Carnelley and Haldane. 



Frora the first two observations it appears that micro-organisms 

 are undoubtedly disseminated in sewer air by splashing ; bnt whether 

 they are carried far in the air cannot be decided from the above 

 experiments. The point is one of great practical importance, as the 

 micro-organisms in question are those on which most suspicion 

 of properties injurious to health naturally falls. Hence we thought 

 it desirable to make some laboratory experiments with a view to 

 elucidating the matter. 



In connexion with the effects of splashing we also investigated the 

 effects of the bursting of bubbles. Professor Frankland (' Roy. Soc. 

 Proc.,' vol. 25,. p. 542) has already made experiments on this point by 

 means of lithia solutions. He found that lithia was disseminated in 

 the air and carried to a considerable distance, when a solution of 

 lithia was made to effervesce. Hence the presumption is that micro- 

 organisms might be disseminated in a similar way. 



Our experiments were made with the artificial drain-pipe arrange- 

 ment described above (pp. 513 — 514). Control determinations of the 

 air in the box were first made after the draught had been established 

 some little time. A putrefying solution was then poured from a height 

 into a vessel placed at about 6 inches below the end of the glass 

 tube, so as to imitate the splashing in a sewer; or effervescence 

 was brought about in the same solution, placed at the mouth of the 

 long glass tube by adding sodium carbonate and hydrochloric acid, 

 or by blowing small and numerous jets of air through the putrid fluid 

 by means of a fine rose from an ordinary garden hose pipe. 



water from a dye works was discharged into this sewer, accompanied by a distinct 

 smell of chlorine at the time of our experiment. These conditions possibly 

 exerted a disinfecting action. 



