48 Mr. W. H. Preece. Effects of Temperature on [Feb. 22, 



average of the eight determinations in which sulphurous acid was not 

 employed as the reducing agent is 55*038, oxygen being taken as 16 

 and silver as Stas's value 107'93. 



Thus another element is added to the list of those whose atomic 

 weights have been found on revision to be exceedingly near whole 

 numbers. 



Further details and discussion must be reserved for another co m- 

 munication. 



February 22, 1883. 



THE PRESIDENT in the Chair. 1 



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

 for them. 



The following Papers were read : — 



I. " The Effects of Temperature on the Electromotive Force 

 and Resistance of Batteries." By William Henry Preece.' 

 F.R.S., Received February 8, 1883. 



It is well known that heat influences the conditions of galvanic 

 elements so as to vary the strength of the currents generated by them 

 in those parts of the circuits connecting their poles. 



In 1840 De la Rive* found that the action of a galvanic pair was 

 accelerated when it was put into hot fluid instead of cold fluid, and he 

 attributed the result to increased chemical affinity. 



Faradayt repeated De la Rive's experiment, but he, on the other 

 hand, attributed the result to improved conductivity in the liquid, 

 and he showed that the effect was not due either to motion, to 

 chemical action, or to thermo-electric action, or indeed to any 

 increase in the electromotive force. 



Daniell,^ also, found an increased current due to increased tempera- 

 ture. According to him, one of his elements was nearly trebled in 

 strength when raised to 212° F. He attributed the effect to the 

 increased energy of the affinity. Said he, " Changes of temperature 

 «ven have a marked influence upon the working of the voltaic battery, 

 and must not be neglected in nice comparative experiments." 



J. B. Cooke§ made careful observations on the chemical affinity in a 



* <£ Ann. Chern.," 1828, xxxvii, p. 242. 



f "Researches," 17th Series, §§ 1925-26. 



£ " Chemical Philosophy," p. 506. 



§ " Phil. Mag.," 1861, p. 95. 



