ORIGIN OF GOLD NUGGETS. ond 
precipitants, and none came down as 4 loose powder nor upon the 
sides of the glass vessel. The miners at Ballaarat and other places. 
attach a good deal of importance to the graphite casing of veins, 
and speak of it as the “indicator.” It usually contains iron 
pyrites; the carbon and the pyrites together reduce the gold 
very quickly. 
Plates of pure gold, cleaned by ignition and boiling potash, were 
also placed in photographer’s gold solution with the following 
non-metallic substances ; they were shaken daily and refilled with 
fresh gold and sodium chloride solution as often as the solution 
became colourless. 
" Experiment 34, with graphite, Ceylon.—Decolourised several 
charges of solution. The gold plate was frosted (moiré métallique) 
on one side, and had increased -0001 g. in fifty-nine days. 
Experiment 35, with charcoal.—Decolourised many successive 
two ounce charges of gold solution, and the charcoal became 
thickly coated with dull brown gold, under microscope this was 
seen to be mammillated. The plate increased ‘00005 g. only in 
fifty-nine days. 
Experiment 36, with coal powder.—The gold plate was still 
bright when removed, on the 31st May 1893, i.e., after thirty-five 
days, and had lost (0019 g. On burning off the coal spongy 
brown gold was left mixed with the coal ash. 
Haperiment 37, with white sandstone, Sydney.— The gold plate 
gradually acquired a frosted appearance and became stained of a 
dull brown colour. Under the microscope the frosting was seen 
to be due to the gold having crystallised in the same way that 
zine crystallises on galvanized iron and tin in the moiré-métallique; 
the crystals on the gold plate were nearly all square or rectangular 
in outline and about 1 mm. across. From April 26 to May 31, 
1893, the plate increased ‘0007 gramme in weight. 
Laperiment 38, with reddish coloured sandstone, Sydney.— Foil 
became very dull and acquired a rough incrustation of gold. The 
foil increased -0060 g. in weight in fifty-nine days. 
