334 M. R. Bornstein on the Influence of 



each consisting of a pair of dissimilar metals, were employed. 

 The different samples of the same combination were so arranged 

 thatj as far as possible, each of any two particular metals 

 should sometimes be the upper and sometimes the lower one 

 at the surface of contact ; but the results of the experiments 

 gave no indication of this producing any difference. The 

 silver and the platinum, on account of their adherence to the 

 glass, could only form the lower layer in any combination. 

 The tenth possible combination, viz. platinum and silver, 

 could not be prepared. 



On warming the junctions, the thermoelectric series of the 

 metals under examination was found to be as follows : — 



+ Silver, 

 Platinum, 

 Copper, 

 Gold, 

 Aluminium. 



In this list the relative positions of the first two metals is 

 assumed from the results obtained by several other observers. 

 It was impossible to determine directly the relative behaviour 

 of silver and platinum. 



Under the influence of luminous radiation these metals 

 arrano-ed themselves in the reverse order, viz. : — 



■fc)' 



+ Aluminium, 

 Gold, 

 Copper, 

 Platinum, 



Silver. 



Here, again, the relative behaviour of platinum and silver 

 could only be determined by analogy. 



Some experiments were then made with plates consisting 

 of one metal only, the construction of these plates being, in 

 other respects, exactly like that of the previous ones. In one 

 such single plate of gold a current was produced on illumina- 

 tion, and a current in the opposite direction on slightly warm- 

 ing it. In this case we may fairly assume, just as in the 

 experiments of Adams and Day with partially illuminated 

 pieces of selenium, that the substance was not homogeneous, 

 and therefore behaved like a combination of different metals. 

 Other plates, which consisted of silver only, or of aluminium 

 only, showed no electromotive force under the action of light. 

 When, instead of using the magnesium-light, the unrefracted 

 solar rays were allowed to fall upon the plates composed of 



