68 SEPARATING GOLD FROM ARGENTIC CHLORIDE. 



in tLe Colony, wliere acids are very expensive, not be foimd 

 remunerative, especially as silver bullion containing 5 grains of 

 gold per lb. troy, can be more advantageously sold in London. 

 "When the auriferous argentic chloride is merely fused iu a 

 boraxed clay pot without any addition of silver or anything 

 else, about 60 per cent, of the gold therein is separated, v^hile 

 about 40 per cent, remains in combination with the argentic 

 chloride. 



In the use of metallic silver, which was employed in strips 

 about i" thick, the silver thus added acts decomposing upon the 

 gold compounds, forming chloride of silver, at the expense of the 

 chlorine formerly in combination with the gold. The silver bad 

 to be in contact with every part of the molten chloride, which 

 was, as much as possible, achieved by stirring the same with the 

 silver strips employed. Was the heat of the furnace a little too 

 great and thus allowed the silver strips to melt too rapidly, the 

 silver sank to the bottom of the pot with only a portion of the 

 gold, producing a silvery gold button, while more or less gold was 

 left in the liquid cliloride. This no doubt was the chief cause of 

 irregularity in the results obtained by employing silver strips. 

 But even had this not been so frequently the case, a considerable 

 objection to its use would always have been the fact that a large 

 amount of metallic silver would annually have been converted 

 into argentic chloride, and back again into metallic silver. 



To avoid this addition of metallic silver, and to substitute other 

 reducing agentsi, a series of experiments was instituted ; fusion, 

 with addition of argol and of resin, as well as reduction by means 

 of hydrogen gas, and also coal gas, were successively tried ; the 

 results have, however, not been found sufficiently practicable. 



The addition of carbonate of soda promised more success. 

 Indeed, during the experiments carried on in the Sydney Mint, in 

 1868-9, conjointly with Mr. Miller, by Mr. Hunt and" myself, to 

 test the applicability of the refining process on a large scale, the 

 employment of soda for freeing the argentic chloride from gold 

 was suggested by me ; but only one trial was made, and not 

 having been carried out with the precaution Avhich I now found 

 to be required, a considerable loss in the operation caused its re- 

 jection in favour of the before-mentioned metallic silver strips. 

 When soda is added in powder to fused chloride of silver, the 

 action ensuing is very violent, and this causes a spitting and throw- 

 ing up of metallic silver, thereby causing great loss ; but when the 

 fused chloride. is covered with, a layer of borax one-eighth to one- 

 quarter inch in thickness, and the soda is gradually introduced on 

 the top of this layer of borax, the action is found to be very 

 gentle, and can easily be regulated. The quantity of soda required 

 may vary from 16 to 20 ounces per 230 ounces of chloride fused 



