708 Transactions. — Chemistry. 



As iny experiments have fully answered the points raised 

 by Mr. Skey, it is hardly necessary to consider the above 

 hypothesis except to point out that there is nothing to base it 

 upon. I have already shown that in potassium-cyanide solu- 

 tions the rate of solution of gold is due to the same causes as 

 that of silver. Now, it is well known that silver cyanide is 

 more rapidly soluble in concentrated than in dilute solutions 

 of potassium cyanide, and why Mr. Skey should assume that 

 the reverse is the case with the gold compound is inexplicable. 



In conclusion, I wish to point out that nothing has been 

 adduced by Mr. Skey to weaken the theories stated by me in 

 regard to the solution of gold in potassium-cyanide solutions. 

 These theories were advanced to explain the action of pure 

 potassium-cyanide solutions on pure gold wholly immersed 

 therein, and of course were never intended to include the cases 

 of partial immersion, or those of contact with other sub- 

 stances, both of which require special consideration of the 

 kind described in the latter part of this paper. 



Akt. LXXIV. — Notes on Mr. J. S. Maclaurin's Paper on 

 the Action of Potassium-Cyanide Solutions ui^on Gold. 



By William Skey, Government Analyst. 

 {Read before the Wellington Philosophical Society, 26th February, 1896.] 

 This paper is a reply to a part of a communication of mine 

 that appeared in the Annual Eeport of the Mines Department 

 for 1895, and, in justice both to Mr. Maclaurin and to myself, 

 I make these few notes thereon. 



In regard to the publications of his that he cites showing 

 the great insolubility of oxygen in strong or concentrated 

 solutions of potassium cyanide, all I wish to say is that at the 

 time I wrote my contribution for the Mines Department my 

 acquaintance with the facts that he has given and his theory 

 respecting these was entirely gathered from short notices of 

 his paper as scattered in other works, and I regret my know- 

 ledge of his labours in this matter being then so slight as it 

 was. However, Mr. Maclaurin will find that in a part of my 

 anncial Laboratory Eeport that was in page form on the 8th 

 February,* and is now just about ready for issue, I had 

 acknowledged both the accm-acy and the great value of his 

 discovery that potassic- cyanide solutions are absorptive of 

 oxygen to a degree that is approximately the inverse of their 

 strengths ; and as I (in common with most chemists) have 

 always held that free oxygen is required for the cyanide pro- 



* This fact is certified to by a letter I have trom the Government 

 Printer. 



