Prof. Majocchi on the Origin of the Voltaic Current. 101 



metallic circuit in one part of which a chemical action is by 

 any matter produced, there ought to arise, in the same cir- 

 cumstances of the wire above described, an electric current. 

 Before entering on experiments on this point, I foresaw that 

 no current would be caused in that entirely metallic circuit, 

 notwithstanding that from one side of the place where the 

 chemical action would be exerted, an obstacle should be inter- 

 posed by any heterogeneity in the conductor forming the cir- 

 cuit. 



First experiment. — A strip of copper of the length of 1*30 

 metre, and 2 centimetres wide, is united by its extremities 

 to the terminals of a long wire-galvanometer ; afterwards 

 with those of another with a short wire, and successively 

 with my universal galvanometer disposed as a duplicator. By 

 means of nitric, sulphuric, or hydrochloric acid, solutions of 

 potass, soda or of ammonia, a chemical action was succes- 

 sively exerted in one part of this metallic band ; but no in- 

 dication of current appeared in the needle of these instruments. 

 Tlie experiment was made in a like manner with a similar 

 strip of iron, zinc, and any other metal, and no current ap- 

 peared svhich caused the needle to deviate on either of the 

 galvanometers. In this experiment therefore the circuit was 

 quite homogeneous, proving that the thermo-electric current 

 originated from the different conditions of the wire. 



Second experiment. — The metallic strip is compressed by 

 means of a clamp in one place, then it bends again upon itself 

 in many folds, being held by a clamp ; then it is subjected in 

 that place again to tempering, and then it is also ham- 

 mered in a cold state : in each of these cases, operating in 

 the same manner, a chemical action was exerted with one of 

 the above-named materials in a portion of the strip without 

 obtaining any indication of current on the needleof one of the 

 galvanometers. The strip was divided into two parts, which 

 were joined, bending back upon one another, and held fast 

 together by the clamp : exciting afterwards a chemical ac- 

 tion with one of the acids or the alkalies above-mentioned, 

 there resulted no current perceptible by the galvanometer. 



Third c.iperiment. —The preceding copper strip is connected 

 by means of the clamp with a similar one of zinc. These two 

 strips thus united, by one of their extremities placed beneath, 

 formed a continuous and wholly metallic circuit with the wire 

 of the galvanometer. On causing a chemical action upon one 

 of the strips, no current was manifested. The effect was null 

 upon producing a chemical action on one of the metallic lists 

 with an acid and on the other with an alkali, and also upon 

 alternating this double action. 



