62 



Dr. A. Bansome and Mr. A. G. R Foulerton. 



a large number of colonies of different bacteria ; and it was apparent 

 that the exposure to ozone had resulted in the destruction of a large 

 majority of these, although complete sterilisation was not obtained as 

 in the case of flasks 1, 2, and 5. 



At the end of the experiment, the milk in flasks 1, 2, 3, and 4, 

 although not changed in appearance, had acquired an extremely dis- 

 agreeable taste and smell, which was in all probability at least partly 

 due to the development of fatty acids. It seemed therefore possible 

 that in the case of these milks, not only might the ozone have had a 

 directly injurious action on the bacteria, but it might also have affected 

 them indirectly by producing from the natural milk various bodies 

 which might themselves also have to be considered as factors in the 

 experiment. 



The milk in flask 5 was in a late stage of decomposition and pos- 

 sessed of a most offensive odour ; it was noticed that the offensiveness 

 of this milk was considerably reduced after the passage of the ozone. 



Experiment V. — Our next experiment was made in order to ascertain 

 whether ozone had any influence on the virulence as apart from the mere 

 vitality of B. tuberculosis, and was carried out in the following way : — 

 Sputum rich in the specific bacillus was smeared over strips of filter-paper. 

 These strips were then dried, and afterwards exposed for varying periods 

 to the action of highly-ozonised air. The exposure was ensured by 

 pinning out the strips on a board, which was hung about 6 feet from 

 the same ozonising apparatus as that used in Experiment I, and in the 

 same room. The apparatus was set at work two hours before the 

 exposure of the sputum was commenced, and was continued without 

 intermission throughout the experiment. When the exposure was 

 commenced the air of the room was so highly charged with ozone as to 

 be extremely unpleasant, and not respirable by anyone for more than a 

 few minutes at a time. After undergoing exposures of the several 

 durations given in the table below, the strips of infected paper were 

 moistened, stretched out on glass, and the surface which had been 

 smeared with the sputum was scraped off lightly with the edge of a 

 knife. The scraping from each strip was collected in a cubic centi- 

 metre of sterilised normal saline solution, and doses of 0*2 c.c. of the 

 emulsions thus obtained were injected under the skin of the inguinal 

 fold in guinea-pigs. As controls, other guinea-pigs were similarly 

 inoculated with some of the crude sputum, and also with the scrapings 

 from an infected strip of paper which had not been previously 

 ozonised. Fourteen animals in all were inoculated; the following 

 table gives their weights and the nature of the emulsion used for 

 each : — 



