1903.] On the Resistance to Heat of B. antlinicLs. 493 



" rreliiuinary Note on the liesistauce to Heat of B. anthraris." By 

 A. MALLOCK, F.E.S., and Lieut.-Col. A. M. DAVIES, E.A.M.C., 

 Eeceived November 30, Head December 10, 190:3. 



Very discrapant statements have been made by various authorities 

 as to the degree of temperature and duration of heating requisite to 

 destroy the spores of various species of bacteria. The great impor- 

 tance of the subject, especially as regards the rapid and effective 

 sterilisation of water for troops in the field, made us think it worth 

 while to undertake the experiments here recorded. 



Our object was to determine a curve whose ordinates should repre- 

 sent the time necessary for sterilisation in terms of the temperature to 

 which the infected water was heated. Since many of the authorities 

 give very long times as necessary (ranging from 10 minutes to some 

 hours) even at temperatures considerably above 100 C., we expected 

 to find that the slope of the curve would be a comparatively gentle 

 one, and would meet the temperature axis at a finite but acute angle. 

 This expectation, however, was not fulfilled, and we rarely found any 

 survival of living matter in fluid which had been raised to a tempera- 

 ture of 100 C. even for as short a time as 20 30 seconds. 



In our earlier experiments (Nos. 1 85) we used B. anihracis, B.m. 

 r uber, Staph. p. aureus, Slaph. p. dtreus and B. whtilis, but subsequently 

 we confined our attention to anthrax, and the results here recorded 

 refer only to this latter, which may be considered as a typically 

 resistant germ. 



The experiments consisted in exposing infected water in sealed glass 

 tubes to heat in steam, at various temperatures, and for various times, 

 the contents of the tubes being afterwards incubated in broth. 



The method and procedure employed is described in some detail, so 

 that there may be no doubt about the conditions under which the 

 results were obtained. 



The heat was applied in a small closed chamber (A) (fig. 1), which 

 by means of a two-way cock (B) could be placed in communication 

 either with a steam boiler, or with the outer air. 



The chamber had an easily removable steam-tight cover, to which 

 was attached a light brass holder (C) fitted to receive six of the culture 



tubes. 



Through the centre of the cover a thermometer was introduced into 

 the chamber, its stem passing through a steam-tight packing, arid its 

 bulb dipping into water contained in the glass tube (D), of the same 

 size as the culture tubes. The stem of the thermometer outside the 

 chamber could be viewed through a lens attached to a movable pointer 

 (E). This pointer was carried on the vertical rod (1), which could be 

 moved up and down by the milled head (G), and a pen (K)^connected 



VOL. LXXII. 



