712 Transactions. — Chemistry. 



So soon as the electric connection is made through the gal- 

 vanometer G, a current of electricity is produced, the direction 

 of which shows that the gold in the vessel A (cyanide solution) 

 is the positive pole of the voltaic pair, and in a short time the 

 gold in that vessel w'ill have dissolved away from its support, 

 \vhile that in the vessel C is not at all affected. 



Now, here there can be no electromotive action at the upper 

 surfaces of any of the liquids ; and there is no electrical effect 

 produced except that which goes to form the electromotive 

 power that is given out at the surface of the gold that is in 

 the cyanide solution A. Clearly, then, the gold in this case 

 is not dissolved by electrolytic action, and consequently in 

 Mr. Maclaurin's experiment (see his Fig. 3''') the gold A at the 

 bottom was not dissolved by electrolytic action as he con- 

 tends. In my experiment, for the potash in vessel C may be 

 substituted any of the acids, even nitric acid, with the same 

 results. With the metal silver the results are of the same 

 kind — that is, the silver is rapidly dissolved by the cyanide, 

 and this even when the silver in the nitric acid is being rapidly 

 dissolved, thus showing the great affinity of silver for cya- 

 nogen. 



These results certainly appear to prove that Mr. Mac- 

 laurin has been all along upon this particular matter mistak- 

 ing, as I have said, the effect for the cause. 



In case these results may not be deemed sufficient proof 

 of the incorrectness of this theory of the author's, I give the 

 details of another experiment, with its results. 



A and B are slips of gold leaf in electrical 

 connection with the galvanometer G by in- 

 sulated wires E, E. A is in a concentrated 

 D solution of potassic cyanide C, C, C, C, while 

 the gold B is in a weak cyanide solution, or 

 in potash solution C, C, D, D, partly sepiirated 

 from the strong cyanide by a diaphragm H. 

 By this apparatus a strong electric current 

 is generated, and the gold plate A is shown 

 Pi 2 to be positive to the plate B, and very soon 



" dissolves in the liquid. 



Here we get entirely rid of all chemical action at the 

 surface of a liquid (D) in contact with the atmosphere, conse- 

 quently of all electrolytic action that could possibly be pro- 

 duced there ; and yet the dissolution of the gold in a concen- 

 trated solution of the cyanide goes on as rapidly as it did in 

 Mr. Maclaurin's experiments. 



Now, just setting aside galvanometric indications alto- 

 gether, Mr. Maclaurin may contend here that, by allowing, as I 



* Above, p. 703. 



