certain Specific Heats at High Temperatures. 301 



published numbers can be clearly traced to an error of 

 copying, which, however, has had no effect on the original 

 calculations, so that the values of the specific heat at different 

 temperatures have been found correctly. 



The actual rates of cooling at different temperatures 

 were obtained from Hirn's data by dividing change of tem- 

 perature by time elapsed during change and taking this as the 

 rate of cooling at the mean of the extreme temperatures. The 

 actual rates thus found were plotted and a curve drawn 

 amongst the points. From the curve were then taken for use 

 in the formula the values of v for 140°, 120°, 100°, and 80°. 

 As the curves lay very steadily amongst the points down to 

 80° and not so well below that, it seemed advisable not to use 

 Hirn's results below that temperature, but to adopt Regnault's 

 data at lower temperatures. 



The following table contains in the first row for each sub- 

 stance the actual rates of cooling; in the second the rates due 

 to radiation only in degrees per minute ; and in the third the 

 specific heats. 



Substance. 



140°. 



120°. 



100°. 



80°. 



Water < 



•775 



•703 



1-023 



•575 



•535 



1-018 



•410 



•391 



1013 



•270 



•264 



1-009 



Ether \ 





1-275 



1-008 

 •803 



•892 

 •765 

 •736 



•580 

 •528 

 •690 



Alcohol ...\ 



1-22 

 •959 

 •987 



•92 



•781 

 •909 



•70 



•626 



•797 



•495 

 •459 

 •712 



•761 

 •715 



•260 



cs 2 | 



2-225 



1-86 



•284 



1-625 



1-424 



•276 



1-15 

 105 



•268 



cci 4 I 



2-12 

 1-756 

 •243 



1-57 

 1-361 

 •233 



1-11 

 •998 

 •228 



■74 



•685 



•219 



To obtain the most accurate values of the specific heats of 

 these liquids at 0°, I applied the method of least squares to 

 Regnault's experiments by the ordinary calorimeter method, 

 and combined the results with the above to obtain the follow- 

 ing values of the constants in the formula (Iq/cW = a + b6 + c6 2 , 

 where 6 represents temperature C. 



