. Report of the fifty-fourth meeting of the British Association for the Advancement of Science [microform] : held at Montreal in August and September 1884. Congresses and conventions; Science; Congrès et conférences; Sciences. by platinum, wliicli barely pulls at all until it is coated and alloyed with bydrotren. This answci" cannot be considered as complete, and in order to complete it consider a more precise experiment. ArranfjfC a series of common dilute acid voltameters witb their plates respectively, zinc zinc, zinc-iron, zinc-copper, and zinc-platinum. Pass one curieufc through the
. Report of the fifty-fourth meeting of the British Association for the Advancement of Science [microform] : held at Montreal in August and September 1884. Congresses and conventions; Science; Congrès et conférences; Sciences. by platinum, wliicli barely pulls at all until it is coated and alloyed with bydrotren. This answci" cannot be considered as complete, and in order to complete it consider a more precise experiment. ArranfjfC a series of common dilute acid voltameters witb their plates respectively, zinc zinc, zinc-iron, zinc-copper, and zinc-platinum. Pass one curieufc through the series from zinc to the other metal, and measure the diO'erences of potential between the plates in eti,ch cell. Now the same chemical action is going on in each. In each, zinc is dissolved at one side and hydrogen evolved at the other—the only dilference being that it is liberated from surfaces of znic, iron, copper, platinum, in the four cases. What is to prevent the , between the terminals of each volta- meter from being the same P But it is not the same (2} Prof. Exner); the zinc-zinc cell shows the greatest difference of potential between its terminals, the zinc-iron less; and the zinc-platinum may easily show a reverse difference because it helps the current on instead of hinder- ing it. It will bo understood that the fvcclso behaviour of the cells is determined \v the intensity of the current ( current per area)—if it is weak, even rhe zinc-iron cell may help it on, but the zinc-platinum will help it on most; if it is very strong, even the zinc-platinum will retard it, but the others will retard it more, and the zinc-zinc most. Now why is all this ? Take the difl'crenco between the heats of formation of Zn, SO.) and of H^, SO4, at the comma, and you will li;ne the total energy assimilated by tlie current in each cell. This energy is the same in all the cells, but not in all does it take the same form. In the zinc-platinum cell it mainly results in driv
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1885
