in Terms of the Mechanical Equivalent of Heat. 29 



intervening time. If t' and t" are the temperatures at the begin- 

 ning and end of an interval of T minutes, and r is the 



Batjdix 6165. Baudin 7320. 



g 



a 



it 



c 



■3 



c3 

 O 



Temperature 



on absolute 



scale from 0° C. 



1 

 a 



Sj) 



5 



o 



Is 



H 



Is 



p 



35 



o°-o 



320 



24° 



547 



50 



l°-368 



330 



25° 



365 



100 



5°-839 



340 



26° 



174 



150 



10°-183 



350 



26° 



981 



200 



14°-450 



360 



27° 



782 



250 



18°-709 



370 



28° 



584 



260 



19°-557 



380 



29° 



376 



270 



20°-401 



390 



30° 



170 



280 



21°-242 



400 



30° 



965 



290 



22°-076 



410 



31° 



786 



300 



22°-907 



420 



32°-581 



310 



23°-731 







bi 



.9 



Temperature 



on absolute 



scale from 0° C. 



bi 

 c 

 •5 



O 



Temperature 



on absolute 



scale from 0° C. 



0° 



0°'122 



23° 



23°-108 



5° 



5°-092 



24° 



24°-122 



10° 



io°-no 



25° 



25°-137 



15° 



l5°-090 



26° 



26°-152 



16° 



16°'093 



27° 



27°'166 



17° 



17°-094 



28° 



28°-l79 



18° 



18°-091 



29° 



29°-J92 



19° 



19°-086 



30° 



30°-205 



20° 



20°-081 



31° 



31°-217 



21° 



21°-085 



32° 



32°-230 



22° 



22°-095 







mean temperature of the jacket during the interval, then 

 i' — i"=cT[^(t' + t fr )— r], where c is the coefficient of radiation. 

 In the calculation of c, stem-corrections were applied and a 

 correction made for the heat generated by the stirrer. Hence 

 in the main experiment the temperature correction for an 

 interval T is J=cT / [i(* / +5 // )-r / ]+K, where s' and s" are 

 the observed temperatures corrected for stern-error, t' is the 

 mean temperature of the jacket and K is the stirrer-correction. 

 The sum of the corrections A from the beginning of the experi- 

 ment added to the stem-corrected observed temperature at any 

 point gives the temperature which would have been reached in 

 the absence of radiation. The difference between any two of 

 these theoretical temperatures multiplied by the heat capacity, 

 gives the heat generated in the interval. 



The coefficients of radiation were found to decrease with 

 decreasing difference of temperature between calorimeter and 

 jacket. When this decrease was regular the corresponding 

 value of c was used for each small interval of the main experi- 

 ment. When the decrease was small and irregular, the mean 

 value of c for that day was used throughout. In the revision 

 of the calculations, stem and stirrer corrections were neglected 

 in the calculation of both c and J, it being obvious that, both 

 being small and quite regular, they are eliminated in this way, 

 and the value of c corresponding to the difference between 

 calorimeter and jacket for each small interval of the main 

 experiment was used in all cases. The mean results of the 

 two methods differ about 1 part in 1,000, and the figures in 

 the table of results below are the means of both calculations 



