Heat of Granite and Basalt at High Temperatu 



res. 



73 



The potentiometer was set at the commencement of a set of 

 observations and the accuracy of the setting checked at the 

 end. The variation was always negligible. The small 

 potentiometer error before mentioned was measured before 

 and after each series (there being no time to do so between 

 the readings) and corrected for, any small variation in it 

 being distributed according to the time. This correction 

 was generally quite unimportant. 



It will be noticed that each value of C is obtained from 

 the difference between a pair of successive values of E 2 , so 

 that any error in taking a reading of E 2 at, the right instant 

 will affect two successive values of (J with errors of opposite 

 sign. Theoretically it might be preferable to plot E 2 against 

 time and smooth out any irregularities in doing so, but in 

 practice the above method was found more convenient. The 

 irregularities occurring in individual values of C can be 

 removed by taking means as there are a very large number 

 of results available. 







T 



\ble IV. (Granite). 









1 



e . 



E 2 . 



-£E 2i 



E 3 . 



E 4 . 



C 

 K' 



0. 



K. 





4611 



18-9 -2-5 



4833-5 























252 



248 



250-5 



1520 



330 



3-97 



•230 



4358 



19-0 



4581-5 























240-5 



236 



238-5 



151-4 



314 



400 



•230 



4117-5 



19-0 



4341 



















-20 





233 



219 



221 



144-9 



298 



4-03 



•222 



3884 



19-1 



4108 























214 



201 



203 



144-9 



284-5 



4-05 



•223 



3669 



19-2 



3894 























198 



186 



188 



144-9 



271 



4-08 



•225 



3469 



19-3 



3696 













- 











187 



170-5 



172-5 



1410 



258-5 



4-10 



•220 



3282 



19 3 



3509 























170 



159-5 



161-5 



145-1 



247 



4-13 



•226 



3111 



19-4 



3339 























173 



147 



149 



131-6 



236 



4-15 



•208 



2938 



19-4 



3166 



















-1-5 





160 



138 



139-5 



133-2 



225 



4-17 



•212 



2778-5 



194 



3006 























150 



128 



129-5 



132-0 



215-5 



419 



•211 



2627-5 



19-5 



2856 















A few figures from one cooling determination are given 



in Table IV. The values of K used to find the specific heat 



S were calculated from the formula K=(4'60— 0*001920) 



xl0~ 3 . The density of the rock was 2'625. The other 



symbols have the same signification as in Table II. 



