Gold in British Guiana. 279 
to the deposition of gold by thermo-electric earth-cur- 
rents from aqueous solution. This hypothesis is sup- 
ported by abundance of evidence which need not be 
repeated here. It was a common belief with old miners 
that gold grew like a plant, and that many placers admitted 
of being worked again and again, a sufficient interval 
being allowed between the operations for the gold to 
accumulate. 
Prof. EGLISTON of the New York School of Mines who 
investigated this subje6l remarks, "the same conditions 
which cause the solution of gold in certain cases cause 
also the solution of silica. This explains the phenome- 
non of mammillary and apparently waterworn nug- 
gets encased in quartz, while both the gold and quartz 
have been formed posterior to the blue gravel. Many 
of the causes which produce the precipitation of the 
gold would also produce the reduction of soluble 
sulphates to insoluble sulphides, the gold being re- 
tained in the mass. This would account for the almost 
constant presence of gold in pyrites, or the occurrence 
of some of the copper-ores of Texas in the form of trees, 
the ore containing both gold and silver; also for the 
constant presence of gold in the iron-ores of Brazil, the 
so-called jacutinga, and for the presence of trees trans- 
formed into iron-ore carrying gold in some of our Wes- 
tern States." 
It is not uncommon in the colony when a large 
tree is overturned in the course of working to find 
a number of small nuggets adhering to its roots, a posi- 
tion which points clearly to their having been deposited 
from solution. The composition of the large nugget refer- 
red to as having been sold for more than £1,000, and the 
MM 2 
