87 



the harmful influence dominâtes, during the following 

 hoiirs the favourable influence makes itself felt, vvhich 

 iiitluence causes no further altération of the presentation- 

 time when the preliminary waiming is extended over 12 hours. 



At 350 C. and still highcr températures the harmful 

 influence of the high température preponderates from the 

 first hour. This harmful influence gradually becomes less 

 during the successive hours of preliminary warming. A 

 favourable influence as time-function cannot hère be 

 distinguishcd. 



At 370 C. the behaviour of the presentation-time is the 

 same as at 35" C, only the harmful influence is more 

 powerful. At 38° C. the harmful influence is not exhausted 

 after some hours, at least after 24 hours' warming the 

 adverse influence does not yet show any diminution. At 

 390 C. and 40"^ C. this is even more strikingly the case. 



The optimum was not variable with the time of preli- 

 minary warming to the extent one would hâve expected 

 according to Blackman's theory. A slight displacement 

 from 25^' C. to 30'^ C. was ail that could be obtained. 

 This fact is doubtless connected with the favourable influ- 

 ence being a time-function. 



According to Blackman extrapolation from the curves 

 representing the intensity of the process after successive 

 hours of warming, should give the intensity of the process 

 after a time zéro, and the values thus obtained, should 

 harmonize with the values, calculated according to van 

 't Hoffs law, starting from the values found at low 

 températures. 



In the présent case this extrapolation afforded values, 

 differing widely from the theoretical ones. The explanation 

 of this discrepancy must be looked for in the fact, that 

 Blackman's theory does not take into account that the 

 favourable influence of high températures is also a time- 



