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reduction effected by the addition of otliei" strong deoxydizing agents, such as 

 tannic oi^ gallic acid, to these various solutions of the auriferous sulphide. 



All this tends to show, I think, that in the instance where Mr. Newberry 

 obtained the reduction of gold upon iron pyrites, from the solution of its 

 sulphide in bicarbonate of soda mixed with organic matter, the gold had, prior 

 to the act of reduction, become in some manner divested of its sulphur, and 

 in exchange for this had combined with oxygen, thus passing to an oxy-salt, 

 readily reducible by deoxydizing agents. 



During the period of time which had to be allowed by Mr. Newberry for 

 this experiment, the oxygen of the air might perhaps have oxydized the sul- 

 phur of the atiriferous sulphide, as it does that of several other sulphides, and 

 so reduced the gold amenable to the deoxydizing power of such substances as 

 the metallic sulphides ; any way, it is inconceivable how organic matter and 

 metallic sulphides, singly or conjointly, can desulj)hurize such a svilphide as 

 this. The effects of oi-ganic matter in a state of decay is rather to generate 

 siilphides than to decompose them, thus retarding, in the place of promoting, 

 the redviction of gold from such compounds. 



It is hard to suppose that there could have been any chemical interchange 

 effected by the mere addition of bicarbonate of soda to the gold sulphide, — 

 gold having far more affinity for sulphur than for oxygen, it could hardly pass 

 to an oxy-salt therefore in this manner ; besides, if it could, then reduction 

 should have proceeded as well with this kind of solution as with the gold 

 oxide in solution of bicarbonate of soda, which, as stated above, I found was 

 not the case. 



Further experiments in this direction are however absolutely necessitated, 

 from the importance of ascertaining positively, whether there is any solution of 

 gold (likely to occur naturally), able to resist the reducing effects of either 

 metallic sulphides or organic matter, at common temperatures. 



The several results arrived at in these investigations are now stated ; it 

 only remains therefore to point out, or rather to refer to, the very obvious 

 relations they appear to sustain to the manner in which certain of our native 

 metals are frequently associated. 



The great deoxydizing power of sulphides generally upon most gold, silver, 

 or platina salts, as manifested by the experiments just described, renders them 

 so absorbent as it were of these metals, when presented to them as chlorides 

 or oxy-salts (the forms usually contemplated for them when in solution), that 

 any such solutions traversing even a very thin vein or reef of the common 

 metallic sulphides, would in all probability be completely divested of these 

 metals. 



Solutions of silver however would be little, if anything, affected in traversing 

 a reef of common iron pyrites or stibnite, alone, but if the solution contained gold 

 in addition, it would be very probable that a certain portion of the silver 



