HALOID ELEMENTS UPON BACTERIA. 169 



taining at least four volumes per cent of this gas in the presence of 

 moisture." 



Chlorine. The haloid elements are active germicidal agents, 

 especially chlorine on account of its affinity for hydrogen, and the 

 consequent release of nascent oxygen when it comes in contact with 

 microorganisms in a moist condition. And for the same reason this 

 agent is a much more active germicide in the presence of moisture 

 than in a dry condition. The experiments of Fischer and Proskauer 

 showed that when dried anthrax spores were exposed for an hour in 

 an atmosphere containing 44. 7 per cent of dry chlorine they were not 

 destroyed ; but if the spores were previously moistened and were ex- 

 posed in a moist atmosphere for the same time, four per cent was 

 effective, and when the time was extended to three hours one per 

 cent destroyed their vitality. The anthrax bacillus, in the absence of 

 spores, was killed by exposure in a moist atmosphere containing 1 

 part to 2,500, the time of exposure being twenty-four hours, and the 

 same amount was effective for Micrococcus tetragenus ; the strepto- 

 coccus of erysipelas and the micrococcus of fowl cholera were killed in 

 three hours by 1 : 2,500, and in twenty-four hours by 1: 25,000. The 

 bacillus of mouse septicaemia and the tubercle bacillus were killed in 

 one hour by 1 : 200. 



In the writer's experiments (1880) four children were vaccinated 

 with virus from ivory points which had been exposed for six hours in 

 an atmosphere containing one-half per cent of chlorine ; also with 

 four points, from the same lot, not disinfected. Vaccination was un- 

 successful in every case with the disinfected points, and successful 

 with those not disinfected. Koch found that anthrax spores failed 

 to grow after twenty-four hours' exposure in chlorine water. In 

 the experiments of De la Croix to determine the antiseptic power of 

 this agent, it was found that when present in unboiled beef infusion 

 in the proportion of 1 : 15,000 no development of bacteria occurred. 

 Miquel gives the antiseptic value of chlorine as 1 : 4,000. 



Chloroform. Immersion for one hundred days in chloroform 

 does not destroy the vitality of anthrax spores (Koch). This agent 

 is without effect on the virus of symptomatic anthrax (Arloing, 

 Cornevin, and Thomas). Salkowski found that the anthrax bacillus 

 in the absence of spores, and the cholera spirillum, were killed by 

 being immersed in chloroform water for half an hour. Kirchner 

 reports still more favorable results. In his experiments a one-per- 

 cent solution killed the cholera spirillum in less than a minute, and 

 a one-quarter-per-cent solution in an hour. But the typhoid bacillus 

 required at least one-half per cent acting for an hour. 



Iodine. In the writer's experiments (1880) iodine in aqueous 

 solution with potassium iodide was found to be fatal to Micrococcus 



