254* Professor Wartmann on the relations 



particularly when it is considered that one or two grains of 

 yttria have often been divided into nearly a hundred precipi- 

 tates, which have been individually examined ; but I live in 

 hopes that the knowledge already obtained will soon enable 

 me to publish a more complete account of my investigations. 



XXXI. Experiments on the mutual relations of Electricity, 

 Light, and Heat. By Elias Wartmann, Professor of 

 Physics in the Academy of Lausanne. 

 It On the relations which connect Light with Electricity, when 



one of the two fluids produces chemical action*. 

 T^HE experiments of Scheele, of Ritter, of Seebeck and of 

 Talbot on the chloride of silver, those of Wollastom on 

 gum guaiacum, of Sir J. Herschel on the precipitation of chlo- 

 ride of platinum by water, and lastly, the beautiful discoveries 

 of M. Daguerre, have placed beyond doubt the existence of a 

 particular influence of light which has been attributed, per- 

 haps without sufficient proofs, and by analogy, to a chemical 

 power supposed to reside in it. On the other hand, a nume- 

 rous train of electro-chemical labours from the beginning of 

 the present century have proved, that chemical and electrical 

 actions always accompany each other, and are, so to speak, 

 consolidated together and mutually answerable for each other. 

 Chemical action therefore forms a plain on which light and 

 electricity meet. What analogies and what dissimilarities do 

 they there present? Does one of the fluids act in the same 

 manner in the presence or in the absence of the other ? Does 

 light become electricity, or does it disengage it when it acts 

 chemically? Here are different questions which have hardly 

 been touched upon. Without pretending to reply to them in 

 a decisive manner, I have endeavoured to procure some data 

 at least with respect to them, and such has been the aim of 

 the following researches. 



I at first sought to discover what influence electricity already 

 produced might have on a chemical action operated simultane- 

 ously by light; for this purpose the Daguerreotype appeared 

 to me the most convenient and at the same time the most de- 

 licate instrument. A proof was obtained after an exposure for 



* [From the Archives de VElectric\t'e.~\ The lines which follow this title 

 form the second part of a memoir communicated to the Society of Physics 

 and Natural History of Geneva on the 1st of July, 1841. The title of this 

 memoir was, "Experimental Researches on the Imponderable Fluids." 

 The part which I now publish treats of matters in the order of the day, and 

 which are not without some connection with the fact mentioned at the end 

 of the preceding article. The same work had been communicated to the 

 Society of the Natural Sciences of the Vaudois (Vcrhandlungcn der Schweitz. 

 natur/orsck. Geselhchaft bei Hirer Versammlung in Zurich, 1841, p. 272).. 



