324 Mr. J. Dewar on the Physical 



whence, by the substitution of J for m, we obtain 



7T 



2 



2~T + - 3 2 w 



+ 2+| 5« 



+ 2 + . # 



which takes us back to Brounker and the infancy of continued 

 fractions. 



The University, Glasgow, 

 March 28, 1874. 



P.S. — Since the above was written I have read part of an en- 

 cyclopaedic paper by Stern in Crelle's Journal, vols. x. and xi. 

 (1832-33), entitled "Theorie der Kettenbriiche uud ihre An- 

 wendung," and have to-day arrived with surprise at the third 

 chapter, the first division of which has the same title as Mr. 

 Glaisher's paper above referred to, viz. " Verwandlung der un- 

 endlichen Producte in Kettenbriiche." In this Stern establishes 

 a general formula of transformation, and then proceeds to give 

 examples illustrative of it. Among these are five forms of con- 



7T 



tinued fraction for — , and first of the five the very fraction we 

 2 



have been speaking of as Sylvester's. Stranger still, in a foot- 

 note Stern adds, "Diesen Ausdruckhat schonEuler auf anderem 

 Wege gefunden"" {Com. Ac. Petr. vol. xi. p. 48); so that the 

 expression derived so ingeniously in 1869 must at that time have 

 been over a century old. Professor Sylvester and Mr. Glaisher 

 will, I am sure, rejoice with other workers to see justice done to 

 their predecessors Euler and Stern. 



The University, Glasgow, 

 April 10, 1874. 



XLI. On the Physical Constants of Hydrogenium. 

 By James Dewar*. 



IN March 1869 I communicated to the Society a paper en- 

 titled " Motion of a Palladium Plate during the Formation 

 of Graham's Hydrogenium," which appears in the Proceedings 

 for Session 1868-69 1- When engaged with this subject, many 

 points of interest regarding the behaviour of palladium contain- 

 ing occluded hydrogen suggested themselves for investigation ; 

 and in concluding the paper I remarked that " careful determi- 

 nations must be made of the electromotive force, latent heat, &c. 



* From the Proceedings of the Royal Society of Edinburgh, Jan. 20, 

 1873. Communicated by the Author, 

 t Phil. Mag. June 1869, pp. 424-431. 



