TEMPERATURE-TIME RELATIONS IN CANNED GOODS 43 

 DETERMINATION OF k. 



All of the constants except k have been determined ; this must 

 be determined experimentally. A sufficiently accurate value of 

 k may be found by using the experimental curve shown in Figure 

 1 in connection with Equation (8) and the constants given in 

 Table 1. Since sterilization begins at about 60° C, the important 

 part of the curve will be that extending upward from 60° C. We 

 may find the value of k corresponding to the average tempera- 

 ture of this part of the curve which is about 80°C. Figure 1 shows 



120 



Fig. 3. 



eo too 120 



MINUTES 



WO no 



that 52 minutes were required for this temperature to be at- 

 tained. Making appropriate substitutions in Equation (8) we 

 have 



80=98-1.602X1 .272X8. 05e 

 from which k = .105. 



-{9) 



GLASS CANS. 



Extensive experimentation has not been done with glass cans 

 but it seems that the effect of the glass is negligible, and that the 

 rate of heat flow is about the same as in tin. From theoretical 

 considerations this is to be expected because glass is at least as 

 good a conductor as the contents of the can in the cases here 

 cited, and being very thin as compared to the radius of the can 

 very little effect is to be expected. 



