ORIGIN OF GOLD NUGGETS. 305 
other pyrites. This specimen (No. 1) was kept in a dilute solution 
for about three weeks and is completely covered with a bright 
film of gold.” - 
He also used galena, copper, and arsenical pyrites, antimony 
(ce., antimonite ?), molybdenite, zinc blende and wolfram, with 
similar results. Brown iron ore only gave a deposit of gold powder. 
He found that when iron pyrites was tried with metallic copper, 
zine and iron, the gold was only deposited as a fine powder at the 
bottom of the vessel, and came to the conclusion that organic 
matter was necessary to form a coherent coating of gold on the 
nucleus, for without the presence of wood, or similar organic 
matter, he found that the six sulphides were unaltered. 
in his second experiment with iron pyrites, he found that the 
gold was deposited on it in a mammillary form, analogous to that 
presented by the surface of nuggets. 
To sum up Wilkinson’s paper, his points are 1° that gold is 
deposited upon sulphides in the presence of organic matter ; 2° 
that the organic matter is essential ; 3° that the coating is mam- 
millary in some cases ; 4° that gold is probably present in solution 
in mineral waters; 5° that nuggets are purer than vein gold and 
that this may be due to the nuggets having been deposited on situ 
from a solution of gold. 
The next to take up the subject was Mr. J. Cosmo Newbery 
in a paper On the introduction of Gold to, and the formation of 
Nuggets in, the Auriferous Drifts (Trans. Roy. Soc. of Victoria, 
1868, p. 52). In this he admits that some nuggets and alluvial 
gold may be derived from the denudation of reefs, but points out 
that the largest masses are sometimes found at great distances 
from the reefs and in the sand overlying the gravel, both of 
which are inexplicable when the very great specific gravity of 
gold is taken into account. He also states that the presence 
of gold in pyrites which has replaced the roots, branches and 
stems of recent trees, is a proof of the existence of gold in 
meteoric waters of the Tertiary Times. 
T—Sept. 6, 1893. 
