216 Mr. T. Andrews. Electromotive Force between [Mar. 26, 



March 26, 1885. 



THE TREASURER in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The Chairman announced that Mr. Walter White, after more than 

 forty years of faithful service, had retired from the office of Assistant 

 Secretary, and that Mr. Herbert Rix had been appointed to fill the 

 vacancy. 



The following Papers were read : — 



I. " Observations on Variations of the Electromotive Force 

 between Metals at High Temperatures in Fused Salts." 

 By Thomas Andrews, F.R.S.E., F.C.S. Communicated by 

 Sir Henry Roscoe, F.R.S. Received March 12, 1885. 



(Abstract.) 



Reversals of the electromotive force between platinum .and other 

 metals in fused salts appear to have been noticed by Andrews about 

 the year 1837, and in 1858 Hankel made some observations in this 

 direction (Hankel, " Poggendorff's Annalen," 103, p. 612, 1858). 

 Dr. Gladstone and Mr. Tribe (" Phil. Mag.," 1881) also found that a 

 strip of silver plunged in molten Agl or AgCl, gives rise to a 

 growth of silver crystals ; the cause of this separation is the dissimilar 

 temperature of different portions of the strip which produces thermo- 

 currents. The present communication is an attempt to obtain quan- 

 titative estimations of the E.M.P., and of the extensive deviations 

 from the normal electro- chemical positions of the metals (platinum 

 and copper and platinum and iron) in fused salts, and the conditions 

 of high temperature attending these reactions, which do not appear to 

 have been previously determined. The cell for fusing consisted of a 

 large platinum crucible (surrounded by known high temperatures) 

 forming one element, a thick bent copper or iron rod inserted in the 

 fused salt forming the other, or more frequently the copper plug of 

 the Siemens' water pyrometer (which had been used in taking the 

 time changes of temperature) was thus employed. A delicate gal- 

 vanometer of known constants was used for taking the E.M.F., which 

 was calculated from the observed deflections, in conjunction with the 



