Latent Heat of Evaporation of Benzene. 19 



At 20°, (^\ ='15941 at rate 5590, 



(?ii\ =-00127 at same rate. 

 Hence Q s (at rate 5-590) = -01171 ; 



but r 4 97fv6 



= a constant = 



Q 8 01174' 



hence Q s = -00949 at rate 5-300. 



A second determination gave '00951 at rate 5*300, 

 A third „ „ -00991 „ „ 5-300. 



In this last experiment, however, there is internal evidence 

 of some error in the time over the second interval. If we omit 

 this interval and calculate the value of Q s from the remaining 

 intervals of that experiment, we get -009 HI as the value. 



It is evident that "00950 is a sufficiently close approxi- 

 mation. 



We therefore assume 



Q s = -00950 + (/ - 789) x -0000120. 



Our experiments at 30° and 40° show that the values of 

 Q s at those temperatures as given in Paper W are correct. 

 The errors at 20° and 50° as given in that paper were due to 

 an arithmetical mistake, a difference having been added, 

 instead of subtracted, in each case. 



The following Table gives the expressions by which the 

 value of Q 3 can be obtained at any of the temperatures or 

 rates given in succeeding Tables : — 



Table IV. 



Temp. 



Value of Q s (in thermal gi*ms.). 



o 

 50 



40 



30 



20 



•00321 + (r x 4 -789) x -0000041 

 •00466 + (r x 4 - 789) X "0000059 

 •00665 + (r* - 789) x -0000084 

 •009504-(r l 4 -789) x -0000120 



C2 



