Maclaurin. — Action of Potassimn-Cyanide upon Gold. 705 



necessary to show chat the ratio of the potash formed above 

 the cork to that formed below it is greater than the ratio of 

 the gold dissolved above to that dissolved below. The follow- 

 ing results show that this is the case : — 



KHO from 5cc. 



Gold 



(1-) (2.) 



Gram. Gram. 



top of test-tube 0155 0-0171 



bottom „ 00075 0-0088 



top ., 00333 003195 



bottom „ 0-02674 00232 



KHO above cork 



KHO below cork 



Gold above cork 

 Gold below cork 



a0155 0-0171 

 0-0075 0-0088 



2-06 



1-94 



0-0333 0-03195 



0-02674 00232 



1-24 



1-37 



The titration of the solutions in No. 3 test-tube showed 

 that, although the decomposition in the top solution was 

 rather greater than that in the solution below the cork, the 

 difference was so slight as not to affect the above results. 



These experiments clearly show, that the solution of a gold 

 plate partially exposed to the air is largely due to electric 

 currents acting in the manner above described. 



In regard to Mr. Skey's second experiment, in which he 

 coupled gold lying at the bottom of a cyanide solution with 

 platinum, I have repeated it several times, but have failed to 

 get his results. This may be due to the fact that he does not 

 enter into detail sufficiently to insure any one repeating the 

 experiment under exactly the same conditions. The following 

 are some of my experiments in regard to this matter : — 



\2\ ^5^ 



Surface of Liquid 



In Fig. 5, 1 and 2 are small strips of gold foil (gummed 

 on paper) lying at the bottom of a saturated solution of potas- 

 sium cyanide. 3 and 4 are like the last, and in addition they 

 have lying across them narrow strips of platinum attached 

 with gum to one edge of the gold. 5 and 6 differ from 3 and 



45 



