Experiments on the Latent Heat of Steam. 37 



Preliminary Experiments on the Latent Heat of Steam 

 at ioo°C. By P. J. Hartog, B.Sc. (Lond. and Vict.) 

 Assistant Lecturer and late Berkeley Fellow in the 

 Owens College, and J. A. Harker, D.Sc. (Tubingen) 

 Berkeley Fellow in the Owens College. Com- 

 municated by Professor Arthur Schuster, Ph.D., 

 F.RS. 



{Received December 12th, i8gj) 



The latent heat o f steam at ioo°C. has been determined 

 since the time of Black by a number of observers, Rumford 

 (1), Ure (2), Watt (3), Despretz (4), Brix (5), Regnault (6) 

 Favre and Silbermann (7), Andrews (8), Berthelot (9), and 

 Schall (10). 



We quote in the following table the results obtained by 

 Regnault and subsequent observers: — 



Observer. 



No. of 

 Experiments. 



Extreme Values of L. 



Mean 

 Value of L. 



Regnault 



Favre and Silber- 

 mann 



Andrews 



Berthelot 



Schall 



44 



3 



8 



3 



no details. 



533*3— 538'4(ii) 



53 2 '59— 54177 



530-8 —543"4 



535*2 —537*2 



no details. 



536-67 



536-2 



532 



(1) Complete Works (Boston, 1875), Vol. If., p. 417. 



(2) Phil. Trans., 1818, Part II., p. 385. 



(3) Robison's Mechanical Philosophy, ed. Brewster, Vol. II., p. 5 (1822). 



(4) Ann. chim. et phys. [1] 24, p. 323 (1823), and Traite elementaire de 

 physique, p. 94, et seq. (1825). 



(5) Pogg. Ann., Vol. LV., p. 341 (1842). 



(6) Memoir es de VAcademie des Sciences, Vol. XXL (1847). 



(7) Comptes Rendus, Vol. XXIII., p. 411 (1846). A few details are 

 added in Ann. chim. et phys. [3] Vol. XXXVII., p. 464 (1853). 



(8) Q.J. Chem. Soc, Vol. I., p. 27 (1849). 



(9) Mecanique Chimique, Vol. I., p. 296 (1879). 



(10) Ber. der deutschen chem. Gesellschaft, Vol. XVII., p. 2199 (1884). 



(11) If we exclude the first six experiments, which Regnault regarded as 

 preliminary, the lower limit is 535 "6. These experiments are, however, 

 included in the calculation of the mean by the author. It should be added that 

 Regnault gives the ' total heat ' and not the latent heat. His actual figures 

 exceed, therefore, by 100 units the numbers given here. 



C 



