SOME EXPERIMENTS WITH DISINFECTANTS II 



were made in sterile test glasses, and thereafter spread on the slips of 

 glass with a sterile ose, and allowed to dry in air. Control slips were 

 made, and also allowed to dry in air, and then put inside a sterile Petri 

 dish, and kept for the same time as those exposed to the disinfector. 

 The other slips were distributed in the house as in experiment i, viz., 

 (i) on floor behind the main door, (2) upon the shelf, 7 feet from the 

 floor, near to the lamp, (3) upon the mantelshelf above fireplace, (4) upon 

 the ledge above the window, and (5) on the floor of one of the smaller 

 rooms, in a corner remote from the door. They were then exposed to 

 the action of the Alformant lamps for 3J hours. The room, on being 

 opened at the end of the time, had a powerful odour of formaldehyde 

 gas. The different slips were then placed direct into bouillon tubes and 

 incubated for 7 days at 37'' C, the control slips being at the same time 

 placed in bouillon tubes. Within 24 hours, a copious growth was present 

 in all the control tubes, x^t the end of 7 days, the following results were 

 observed in the tubes containing the exposed slips : — 



In the 1st set (floor of main room) growths were observed in the 

 tubes inoculated with Anthrax, Staphylococcus, and B. coli, while the 

 B. typhosus tube remained sterile. 



In the 2nd set (shelf near to lamps) negative results were obtained in 

 all the tubes. 



In the 3rd set (mantelshelf above fireplace) growths were obtained in 

 the Anthrax and Staphylococcus tubes, while both the B. coli and 

 typhosus tubes remained sterile. 



In the 4th set (above window) growths were obtained in all the 

 four tubes. 



In the 5th set (floor of smaller room) growths were obtained in all the 

 four tubes. 



Conclusion. — This experiment shows that, where the gas is present in 

 sufficient quantity, as in the 2nd set of organisms, disinfection will be 

 obtained ; but it cannot generally be relied upon in ordinary conditions, 

 even where the proportion of paraform used, as in the foregoing experi- 

 ment, is considerably above that recommended by the makers of the 

 lamp. It also shows that B. typhosus is the most susceptible of the 

 exposed germs to the action of the gas, three out of the five samples of 

 the cultures of this bacillus being sterilized. 



(247) 



