18 Starkweather — Begnaulfs Calorie and Our 



Two of the constants were determined so as to make c 16 equal 

 to unity and <? _ 100 equal to 1-00358, while the remaining con- 

 stant was adjusted to give a good value to c %0 ; the mimimum 

 value is reached at 35°. A better agreement might be obtained 

 by the method of least squares, but since <? _ ]00 is not too well 

 known and the remaining data all lie below 40° such nicety 

 would not be justified. Moreover the only use made of the 

 formula is to obtain latent heats from total heats, and also the 

 entropy of dry saturated steam, and the term given by this 

 formula is very small in comparison with the quantities with 

 which it is combined. 



The formulae adopted for the heat of the liquid give us the 

 following for the entropy of water : 



Vw =z a \og 10 T-bT + cT 2 -d. 



Below 100°. Above 100°. 



log a. 3-173436 3-015698 



log b 0-156626 1-2501U 



log c 3065024 4-229792 



d 3328-0 2490-9 



This gives the entropy in kilogram meters (at Paris) per degree, 

 the zero of entropy being that of water at 0° C. T is the 

 temperature absolute, absolute zero being taken as — 2T3°-7 C. 

 ftegnault's ninth memoir, Memoirs of the Institute of France, 

 vol. xxi, furnishes us with the greater part of our knowledge 

 concerning the total and latent heat of steam. Other experi- 

 ments have been made bv Andrews,* Favre and Silbermann,f 

 Berthelot4Schall,§Dieterici, || Hartog and Harker,! Griffiths,** 

 G. Fuchs,ff A. Svensson,^ W. Kamsay and D. Marshall,§§ and 

 Harker.ll All excepting those by Dieterici, Griffiths and 

 Svensson are at, or in the close vicinity of, 100°. Those by 

 Hartog and Harker and by Harker alone are admitted by the 

 authors themselves to be inaccurate. In all the remainder 

 there is doubt as to what unit the results are expressed in, and 

 they are few in number. Taken at their face value they all 

 give a remarkable confirmation of Regnault's determination at 

 100°. The following table, taken partly from Griffiths' paper 

 on latent heats, shows this : 



* Chem. Soc. Journal, 1849. f Ann. de Chimie et de Phys., xxxvii, 1853. 



% Comptes Rendus, Ixxxv, 1877. § Berichte d. Chem. Gesell., xvii, 1884. 

 I Wied. Ann., xxxvii, p. 494, 1889. 

 TfProc. Manchester Phil. Soc, 1893-4. 

 ** Phil. Trans., clxxxvi A, p. 261, 1895. 



ft Inaug. Dissertation, Erlangen, 1894, and Beiblaetter zu Wied. Ann., xix, 

 p. 559, 1895. 



XX Beiblaetter zu Wied. Ann., xx, p. 559, 1895. 



§§ Rep. British Ass., 1895, p. 628. 



HI Mem. and Proc. Manchester Lit. and Phil. Soc. (4), x, p. 38, 1896. 



