S12 Prof. Schcenbein on the Current Electricity 



stance, to zinc, cadmium, tin, iron, copper, mercury, silver 

 on the one side, and water on the other. By associating any 

 one of the metals named with platina, and putting such a 

 combination into water entirely deprived of air and che- 

 mically pure in every other respect, I always obtained a cur- 

 rent which passed from the oxidable metal through the fluid 

 to the platina, and the strength of which seemed, generally 

 speaking, to be proportional to the degree of affinity of that 

 metal for oxygen. Th^ deviation of the needle caused by 

 zinc, for instance, was greater than that occasioned {cceteris 

 jJaribus) by copper. But even the strongest of the said cur- 

 rents proved to be so weak as to require the most delicate 

 galvanometer in order to be made perceptible. 



The instrument with which I made my experiments is pro- 

 vided with 2000 coils. To ascertain whether a current ex- 

 cited by chemical tendencies is possessed of any electroly- 

 sing power, I constructed a pile of substances which, being 

 in contact, do not cause any sensible chemical action, but 

 which have a strong tendency to unite chemically with one 

 another. In my last letter to Prof. Faraday I stated the fact, 

 that inactive iron voltaically associated with platina excites a 

 continuous current when put into nitric acid, and that this 

 current is apparently quite independent of any chemical com- 

 bination or decomposition, the inactive iron retaining its me- 

 tallic lustre, and the nitric acid containing no perceptible 

 quantity of nitrate of iron, however long the voltaic pair may 

 have been immersed in the acid fluid. On account of this re- 

 markable property of iron I formed the voltaic arrangement 

 in question, of this metal, platina, and nitric acid of 1*35 sp. 

 gr. Nothing, indeed, can be easier than the construction of 

 such a pile. Having joined one of the ends of a common iron 

 wire to one of the ends of a platina wire, prepared the num- 

 ber desired of such associations, and filled a corresponding 

 set of cups with nitric acid of the above-mentioned strength, 

 I first put the free end of the platina wire of one pair into 

 the exciting fluid, and afterwards immersed in the latter the 

 free end of the iron wire belonging to the same pair. Accord- 

 ing to my now well-known experiments, iron turns inactive 

 in the circumstances here mentioned. The iron wires of all the 

 pairs being rendered chemically neutral after the manner in- 

 dicated, and arranged into a " couronne des tasses" the pile 

 is ready for use. The one I employed in my experiments 

 consisted of a dozen of pairs. If the extremities of such a pile 

 are connected by the ends of the wire of a very delicate gal- 

 vanometer, the needle is affected so as to indicate a continuous 

 current passing from iron to platina. Acidulated water being 



