706 Transactions. — Chemistry. 



4 only in having a platinum wire ia 5, and a strip of pla- 

 tinum in 6, resting as shown in the figure, and projecting 

 above the surface of the liquid. In half an houi* 1, 2, 3, 

 and 4 were appai-ently unaltered, whilst 5 and 6 were 

 almost completely dissolved. After twenty-four hours 1, 2, 

 3, and 4 showed no appreciable alteration. I now suspended 

 a platinum wire so that one end rested on No. 1 strip, the 

 other projecting above the surface of the liquid. In the same 

 way a platinum strip (varnished at the surface of the liquid) 

 was suspended so as to touch No. 2 strip. In forty minutes 

 No. 1 was almost entirely dissolved, whilst No. 2 showed no 

 alteration. 



These results are very similar to those obtained with gold 

 strips partly immersed, and show clearly that, as in the 

 former case, solution of the gold is due to an electric current 

 generated at the surface of the liquid. 



The follovving experiments were made in order to deter- 

 mine what influence oxygen in solution has on the electrical 

 solution of gold. Two circular plates of gold of the same 

 diameter were marked 1 and 2 respectively ; a narrow slit 

 was cut in each near the margin, and the plates weighed. 

 Through one of these slits one end of a long strip of gold about 

 ■|in. wide was passed and bent back on itself, being tapped 

 with a small hammer to insure close contact with the plate ; 

 the other end of the strip of gold was bent round a glass 

 rod, resting across the top of a Nessler glass containing 

 50cc. of cyanide solution. By this means the plate was sus- 

 pended in the cyanide solution at about |in. from the bottom 

 of the vessel. The gold strip was varnished from within -i^in. 

 of the plate to within ^in. of the surface of the liquid. 

 The second plate was suspended by cottoii at the same 

 depth in the second Nessler glass, which also contained 

 50cc. of the same cyanide solution. In other words, the 

 conditions were the same for the two plates, except that 

 one was suspended by gold and the other by cotton. After 

 being exposed to the action of the cyanide solutions for one 

 hour the plates were removed and reweighed. The strip of 

 gold was now attached to No. 2 plate, No. 1 being suspended 

 by cotton, and the experiment repeated, still keeping No. 2 

 plate in No. 2 Nessler glass. These four determinations 

 were made first in a solution containing little air, and then 

 in the same solution saturated with air. The results are 

 shown in the following table, the means only being given. 

 The weights shown are in terms of assay weights : 1,000 = 0*5 

 gram : — 



