ORIGIN OF GOLD NUGGETS. 307 
present when Daintree discovered the enlarged piece of gold, says 
that the original piece was a small fragment which remained 
undissolved after making some chloride and the bottle was closed 
with a cork, when again observed the solution was colourless and 
the fragment of gold of such a size that it could not be removed 
from the bottle through the narrow neck.” 
Newbery, like Skey, found that hammered pieces of gold did 
not increase in size, but he had little doubt of others with a rough 
or natural surface doing so. 
Mr. Newbery was followed by Mr. W. Skey, F.c.s., Analyst to 
the Geological Survey of New Zealand, ina paper On the Reduction 
of Certain Metals from their Solutions by Metallic Sulphides, and 
the relation of this to the.occurrence of such Metals in a Native State. 
' (Trans. N. Z. Inst., 1870,. p. 225), Mr. Skey also repeated 
Wilkinson’s experiments and obtained the deposits of gold on 
various sulphides and arsenides, and further found that the pres- 
ence of organic matter is quite unnecessary for bringing about the 
deposition of gold upon the above minerals. He also found that 
silver nitrate and acetate, and the salts of one or more of the 
platinum group of metals, are reduced by the metallic sulphides 
and arsenides. He points out that the metallic sulphides possess 
much greater reducing power than organic matter, and that a 
single grain of iron pyrites will reduce 8% grains of gold. And 
that although organic matter may have had a share in the reduction 
_of gold, he is of opinion that the greater portion of the deposits— 
especially the deep seated ones—have been due to the deoxidising 
effects of pyritous minerals. 
In a succeeding paper, On the Electro-motive Power of Metallic 
Sulphides (Trans. N. Z. Inst., Nov. 12, 1870, p. 232), Mr. Skey 
describes experiments which he made to show that when such 
sulphides as pyrites and galena are placed in dilute acids or saline 
solutions and connected by a platinum wire, the current generated 
is sufficient to throw down gold in separate vessel from its chloride. 
He points out from these experiments and Mr. Fox’s statements 
