710 Transactions. — Chemistry. 



And now in regard to the theory the author of that paper 

 advances to explain the singular fact that I published as to 

 the rapid dissolution of gold in concentrated solutions of the 

 cyanide when the gold plate used is but loartly submerged. 

 This theory is that the dissolution of the submerged gold in 

 these cases is due to electrolytic action produced at the surface 

 of the cyanide next to the atmosphere ; and in support of this 

 statement he shows, and by incontrovertible evidence, that 

 electric currents are produced under these circumstances. 



Now, I am very glad to have all this evidence from 

 Mr. Maclaurin, as it goes to sustain a statement of mine to 

 the same effect, and which was in page form in the Govern- 

 ment Printing Office for the Laboratory Report cited, page 44,"^' 

 on the 8th of February, consequently before I saw his paper. 

 There I stated, in effect, that an electric current is produced 

 when gold is partly submerged in potassic cyanide. On this- 

 point, then, we agree ; but when I go over his statements in 

 regard to the direction of this current, and its relations to, or its 

 bearings upon, the dissolution of gold, I am quite unable to 

 agree with him, nor can 1 agree with him in regard to his 

 statement that potassium is set free in any of his experiments. 

 These three points I will take consecutively. 



First, then, as to the direction of the current — that is, as 

 to the particular part of the apparatus where this electro- 

 motive power is generated : Mr. Maclaurin states that it is 

 generated at the surface of the liquid, and that the current 

 will flow down to the submerged end of the gold. But I state, 

 in the report referred to, that it is the loioer part of the sub- 

 merged gold where this electromotive power is generated — 

 that is, in my own words, " the lower end being the positive 

 pole " ; and I show that the electromotive power generated by 

 the lower end (the more deeply submerged end of the gold 

 strip) is sufficiently strong to electro-deposit copper from its 

 sulphate. I have now also tested the direction of the current 

 in the apparatus figured 3 in Mr. Maclaurin' s paper, and, as I 

 expected, find that the lower end of the submerged gold strip 

 certainly is the positive pole in this apparatus too. 



Second, as to the relation of the electric current, or this 

 electrolytic action, as it is termed, to the dissolution of gold 

 in the potassic cyanide. Mr. Maclaurin assumes that it is 

 this current — this action — which causes the solution of the 

 gold in the cyanide. Now, I must contend here that it is 

 just vice versa ; that, in fact, Mr. Maclaurin has got the cart 

 before the horse — the effect for the cause. I contend that the 

 current (or the electromotive power) is produced by chemical 

 action alone — that is, by the dissolution of the lower sub- 



The Government Printer also certifies to this by letter. 



