408 Proceedings. 
One of the subjects of most general interest on which Mr. Skey has 
written disproves the view generally held that gold is unaffected by sulphur 
or sulphuretted hydrogen gas, and shows on the other hand that these 
elements combine with avidity, and that the gold thus treated resists amalga- 
mation with mercury, a most important fact, which, it will be remembered, 
was strikingly illustrated by experiment after one of our meetings. The author 
has also proved this act of absorption of sulphur by gold to be a chemical act, 
as he has shown that electricity is generated in sufficient quantity and 
intensity during the process to decompose metallic solutions. He thinks 
further that much native gold is thus sulphurized, and that this cireumstance 
is the greatest obstacle to its thorough amalgamation in ordinary quartz mills. 
Mr. Skey was led to this interesting observation while investigating the 
causes of the loss of gold experienced in the Thames district, and the object of 
his inquiry must be held to have been satisfactorily accomplished by the 
discovery of this important fact. 
He was aware that sulphur in certain forms has long been known to 
exercise a prejudical effect upon the amalgamation of gold, but this has always 
been attributed to the combination of the sulphur with the quicksilver used ; 
now, however, it is certain that the sulphurizing of the gold itself must be 
taken into account. So long as our chemical books described gold as being 
unaffected by sulphuretted hydrogen it appeared as if in the ordinary amalga- 
mating process we had nothing to fear from this gas, except its effect upon the 
mercury, but now that it is proved that gold itself is also readily attacked by 
this compound we must take the circumstance also into account that the 
particles of gold in the stone may be enveloped with a film of auriferous 
sulphide, by which they are protected from the solvent action of the mercury. 
The merit of this discovery, from an experimental point of view, is that 
the sulphurization of the gold gives no ocular manifestation by change of 
colour or perceptible increase of weight, as in the case of the formation of 
sulphides of silver, lead, and other metals, on account of the extremely 
superficial action of the sulphur, and hence probably the existence of the gold- 
sulphide hitherto escaped detection by chemists. 
Closely allied to this subject is the investigation of the mode in which 
certain metals are reduced from their solutions by metallic sulphides, or, in 
common language, the influence which the presence of such substances as mundic 
and galena may exercise in effecting the deposit of pure metals such as gold in 
mineral lodes. As this investigation has a very direct bearing on the discus- 
sions relative to the origin of large gold nuggets and the heavy masses of gold 
that are sometimes found in reefs formed by hydrothermiec agencies, I will 
take this opportunity of stating the position of the question. 
The close relation which the richness of gold veins bears to the prevalence 
