IW M. R. Clausius on the Moving Force of Heat, 



rous experiments. He has constructed curves in which the 

 abscissae represent the temperature, and the ordinates the pres- 

 sure jo, taken at different intei-vals from —33° to 230°. From 

 100° to 230° he has drawn another curve, the ordinates of which 

 represent, not;? itself, but the logarithms of;?. From this dia- 

 gram the following values are obtained ; these ought to be re- 

 garded as the most immediate results of his observations, while 

 the other and more complete tables which the memoir contains 

 are calculated from formulae, the choice and determination of 

 which depend in the first place upon these values. 



Table II. 



To carry out the intended calculations fi'om these data, I have 



first obtained from the table the values of - • ^ for the tempe- 



p at ^ 



ratures —15°, —5°, 5°, 15°, &c. in the following manner. As 



the quantity — • -^ decreases but slowly with the increase of 



temperature, I have regarded the said decrease for intervals of 

 10°, that is, from -20° to - 10°, from - 10° to 0°, &c. as uniform, 

 so that the value due to 25° might be considered as a mean 



between that of 20° and that of 30°. As - • ^ = ^^2^', I was 



p at at 



by this means enabled to use the following formula : 



\p ' dt/^iP ' 10 ' 



* This column contains, instead of the logarithms derived immediately 

 from the curve and given by Regnault, the corresponding numbers, so that 

 they may be more readily compared with the values in the column preceding. 



