IV.—CHEMISTRY. 
Art. LI.—On the Mode of Producing Auriferous Alloys by Wet Processes. 
By W. Sxry, Analyst to the Geological Survey of New Zealand. 
[Read before the Wellington Philosophical Society, 23rd October, 1872. 
In former papers read before this Society* I showed that metallic sulphides 
generally reduced gold from both acid and alkaline solutions; that silver as 
nitrate was reduced by galena and sulphide of copper, but not by iron 
pyrites, while its ammoniated solutions were unaffected by any of the sulphides 
experimented with ; and from a consideration of these results I suggested 
that most of our iv deposits of noble metals have been formed by the 
agency of metallic sulphides, and not by that of organic matter as has hitherto 
been generally supposed. 
The question which naturally presented itself to me at the time as to the 
capability of processes of this nature producing alloys of such metals (as found 
in nature) was tacitly left over for consideration until the behaviour of these 
sulphides with metallic solutions should be more fully examined. 
. In pursuit of this question as to the possibility of obtaining mixed metallic 
deposits or alloys by the agency of metallic sulphides I have from time to 
time, as opportunity offered, studied the behaviour of different sulphides when 
in contact with various salts of gold and silver, and the principal results 
thus obtained I now beg to state. 
1. That solutions of chloride of silver in alkaline chlorides, rendered 
alkaline by addition of potash, soda, or lime, are readily decomposed by 
common iron pyrites. 
2. That this effect is not produced if such solution of silver is either acid 
or neutral. 
3. That when chloride of gold is added to an alkaline argentiferous 
solution of this nature, such mixed solution is capable of depositing the metals 
contained in it in the form of coherent alloys upon metallic sulphides generally 
when presented to them. 
4. That these alloys can also be formed from such solutions by voltaic 
action. 
As will be seen these results show that, by allowing an alkaline solution 
of gold and silver contact with iron pyrites (a mineral of most common 
*See Trans. N.Z. Inst., Vol. IIL, Arts. XL. and XLI. 
