106 BIOLOGY AND TECHNIQUE 



a few, however, are of sufficient bactericidal strength to be of prac- 

 tical importance. 



Oxygen, especially in the nascent state, may exert distinct bac- 

 tericidal action upon some bacteria. That strictly anaerobic strains 

 are inhibited by its presence has already been mentioned. 



Ozone was shoAvn by Ransome and Fullerton 63 to exert consider- 

 able germicidal power when passed through a liquid medium in 

 which bacteria were suspended, but was absolutely without activity 

 when employed in the dry state. 



Chlorine because of its powerful germicidal action was once 

 looked upon with favor, but has been found quite inadequate from 

 a practical point of view because of its injurious action upon ma- 

 terials, and its irregularity of action. Chlorine, too, is but weakly 

 efficient unless in the presence of moisture. 64 



Sulphur dioxide or sulphurous anhydrid (S0 2 ), formerly much 

 used for room disinfection, is no longer regarded as uniformly effi- 

 cient for general use. The gas is produced by burning ordinary roll 

 sulphur, conveniently in a Dutch oven. To be at all effective, water 

 should be vaporized at the same time, since the disinfectant action 

 is dependent upon the formation of sulphurous acid. The concen- 

 tration of the gas should be at least 8 per cent of the volume of 

 air in the room. For this purpose about three pounds of sulphur 

 should be burned for every thousand cubic feet of space. It should 

 be allowed to act for not less than twenty-four hours. The researches 

 both of Wolff hugel 65 and of Koch 66 have 'shown that the gas is not 

 sufficient for the destruction of spores. Park 67 believes that sulphur 

 dioxid used in quantities of four pounds of sulphur to 1,000 cubic 

 feet is of practical value for fumigating purposes in cases of diph- 

 theria and the exanthemata. Sulphur dioxid fumigation is more 

 effective than formaldehyd for the destruction of insects fleas, lice 

 and bedbugs a matter of importance in epidemics of typhus fever, 

 relapsing fever, plague, etc. 



Of all known gaseous disinfectants by far the most reliable is 

 formaldehyd. In all cases where formaldehyd fumigation is in- 



* 3 Bansome and Fullerton, Eep. Public Health, July, 1901. 



"Fischer and Proskauer, Mitt. a. d. kais. Gesundheitsamt, x, 11, 1882. 



65 Wol/fhugel, Mitt. a. d. kais. Gesundheitsamt, i, 1881. 



66 Koch, Mitt. a. d. kais. Gesundheitsamt, i, 1881. 



67 Park, "Pathogen. Bact.," N. Y., 1908. 



