Akd^ihe Laws regarding tlie Nature of Heat :^^^ tfr 

 of (30.) the equation - <t is :?^r^^x<> 

 ''=0-623.-:^, (31.) 



— ne^' 



From this we should derive for 0^ the specific weight 0*643( 

 instead of 0*622, and the other numbers of the above table would 

 have to be increased proportionately. But we are not yet jus- 

 tified in making so wide an application of the formula (26.), as 

 it has been merely derived empirically from the values contained 

 in Table III.; and among these, the values belonging to the 

 lowest temperatures are insecure. We must therefore for the 



present regard the limit of A (^—cr) — -- as unknown, and con- 

 tent ourselves with an approximation similar to that furnished 

 by the numbers in the foregoing table ; so much however we may 

 conclude, that these numbers are rather too small than too large. 

 By combining (Ya.) with the equation (III.), which was im- 

 mediately derived frOm the original maxim, we can eliminate 



at a-\-t ^ ' 



By means of this equation, the quantity A, described above as 



negative, can be more nearly determined. For c and r let the 



expressions in (23Z>.) and (24.) be substituted, and for a the 



number 273 ; we then obtain 



I n ons. 606-5-0-695/-0-0000/2-0-0000003^^ ,^^ , 

 A=0-305 ^^3-p^ ; (33.) 



and from this we derive among others the following values for h : 



Table VI. 



50°. 



-1-9161 -1-465 



1 



lOQO. 



I- 133 



150°. 200°. 



•0-879 -0-676 



In a manner similar to that already pursued in the case of ■ 

 water-vapour, the equation (V«.) might be applied to the vapours 

 of other fluids, and the results thus obtained compared with each 

 other, as is done in Table I., with the numbers calculated by Cla- 

 peyron. We will not, however, enter further upon this application, * 



We must now endeavour to determine, at least approximately, 

 the numerical value of the constant A, or, what is more useful, 



the value of the fraction -r- : in other words, to determine the 



A ^ -'.'"'* 



equivalent of work for the unit of heat. [mufirin 



Pursuing the same course as that of Meyer and Holtzmann, we 

 can in the first place make use of equation {\0a.) developed for 



Phil Mag, S. 4. Vol. 2. No. 9. Aug, 1851. K 



