Chlorine as a Solvent of Gold. 49 



in 'a vessel so arranged that a current of chlorine can be passed 

 through it, by which the gold and iron are taken up and 

 afterwards separated from the residuum by the aid of a cer- 

 tain quantity of water, and the gold is afterwards precipi- 

 tated from this solution by sulphuretted hydrogen To 

 prevent the admixture of iron at this stage, a small dose of 

 hydrochloric acid is added to the solution before the sul- 

 phuretted hydrogen is introduced. The auriferous com- 

 pound having been separated from the liquor, is washed and 

 heated in an open porcelain crucible, to drive off the sulphur, 

 after which the gold is reduced to the metallic state by heat 

 in the usual manner. 



This simple and ingenious method, which has made it 

 worth while to reopen the "Richenstein mine, is equally 

 applicable to the vast quantity of refuse accumulated near 

 many other old works. In awarding the Council medal, the 

 jury have desired in this case to associate the name of Pro- 

 fessor Plattner, the inventor of the method with that of 

 M. Gualter, who has brought it into operation on a large 

 scale. 



Taking the above figures at their value as an experiment, 

 I think they are unusually favourable to the mercury pro- 

 cess, because the mixture was not subjected to so severe 

 an agitation as is usual on the gold-fields, and consequently 

 less would be floated away. 



I can refer to one instance, mentioned by my friend, Dr. 

 Otway, the owner of a Chilian mill at Steiglitz, of even 

 mercury having been carried away by the stream in a state of 

 very minute division, and having been found at a distance 

 from the mill, deposited, and after repeated additions agglo- 

 merated into visible globules. I dare say persons constantly 

 using those mills, if they observe the course of the water 

 after passing through the amalgamating machinery, will be 

 able to confirm this observation. I think no one doubts 

 that there is a very considerable loss of fine gold in any of 

 the present processes. 



The cost of Chilian mills, the rapid wear and tear of 

 machinery, and the expense of motive power, are very great. 

 The quantity of water required is also very great. I 

 regret that I have not been able to obtain full details of all 

 these matters from reliable sources. The loss of mercury is 

 variously estimated, but is always considerable. I think 

 these are some of the well-known and generally admitted 

 objections to the obtaining of gold by amalgamation. 



