a1 From the Physiology Department, University College of South Wales and Monmouthshire, Cardiff, and the Bacteriological Laboratory, Imperial College of Science and Technology, London
1. The virtual sterilization time (v.s.t.) has been used as a measure of the rate of disinfection of Bact. coli cultures by phenol under carefully standardized conditions, and the relationship between this rate and temperature at five phenol concentrations has been examined.
2. The graphs of log (v.s.t.) against temperature reveal that the formula t×θT = A, as usually employed for the calculation of the temperature coefficient of the rate of disinfection, has only a limited applicability for these data. θ and Q10 increased with temperature especially at high concentrations, and at the lowest concentration there was a tendency for them to increase again as the temperature was reduced below a certain point.
3. The other general type of formula, t(T –α)b = a, used for the calculation of biological temperature coefficients, is also of very limited value when applied to these data since b increases with temperature at all concentrations.
4. The magnitude of these temperature coefficients and their manner of variation are considered in relation to previously published data by other authors and the way in which θ should theoretically vary with temperature is discussed.
(Received April 04 1945)