122 AXThSEPTICS 



If the antiseptic reaction is endothermic, an increase 

 in temperature should decrease the efficiency of the toxic 

 compound. This is contrary to all experience in disin- 

 fection, but at least one such case has been reported. 

 Cameron (1930) observed that thermophilic sporeform- 

 ers causing "flat sours" in canned vegetables required 

 10 ppm. of gentian violet at 55° C for complete inhibition, 

 while at 37°, 1 ppm. sufficed to inhibit growth. 



As a rule, however, a higher temperature makes an an- 

 tiseptic more efficient, which suggests that the antisep- 

 tic reaction is generally exothermic. More antiseptic 

 will then be needed at low temperatures than at high tem- 

 peratures to suppress microbial development. McCul- 

 loch (1936, p. 228) mentions that a certain glue was pro- 

 tected against molding by a phenol concentration which 

 was quite sufficient in summer, but which did not pre- 

 vent spoilage when the temperature dropped to about 

 10°C. 



As no rates can be measured in antisepsis, no temper- 

 ature coefficients can be computed. The only possibility 

 of expressing temperature relations is the recording of 

 the lowest inhibiting concentration for each tempera- 

 ture. 



But here, a considerable range of errors may be ex- 

 pected. Limiting values cannot be very precise when 

 the approach to the limit is asymptotic as in antisepsis. 

 For instance, Cruess and Eichert (1929) report that at 

 pH 3.0, Saccharomyces ellipsoideus was delayed by 0.02% 

 sodium benzoate, but began to grow after 12 days ; 0.06% 

 benzoate inhibited growth completely. The minimal in- 

 hibiting dose lies somewhere between these two values. 

 When the limiting concentrations at tw^o different tem- 

 peratures are determined, and when each value is sub- 

 ject to a considerable range of error, the ratio of these 

 two concentrations is no sound basis for an attempt at 

 explaining temperature effects. 



