ome circumstances a large voltaic battery competent to produce
electro-deposition of metals, and that the order of the deposit of these
mineral lodes will be found to bear a definite relation to the order
in which the sulphides rank in the table of their electro-motive power.
These researches may lead to some clearer comprehension of the law which
regulates the distribution of auriferous veins, and may explain why in
some cases the metal should be nearly pure, while in others it is so
largely alloyed with silver.

The following extract was lately clipped from a mining paper. If true,
the experiment is interesting:--

"An American scientist has just concluded a very interesting and
suggestive experiment. He took a crushed sample of rich ore from Cripple
Creek, which carried 1100 ozs. of gold per ton, and digested it in a
very weak solution of sodium chloride and sulphate of iron, making
the solution correspond as near as practicable to the waters found in
Nature. The ore was kept in a place having a temperature little less
than boiling water for six weeks, when all the gold, except one ounce
per ton, was found to have gone into solution. A few small crystals of
pyrite were then placed in the bottle of solution, and the gold began
immediately to precipitate on them. It was noticeable, however, that the
pyrite crystals which were free from zinc, galena, or other extraneous
matter received no gold precipitate. Those which had such foreign
associations were beautifully covered with fine gold crystals."

Experimenting in a somewhat similar direction abut twelve months since,
I found that the West Australian mine water, with the addition of an
acid, was a solvent of gold. The idea of boiling it did not occur to me,
as the action was rapid in cold water.

Assuming, then, that gold originally existed as a mineral salt, when and
how did it take metallic form? Doubtless, just in the same manner as
we now (by means of well-known reagents which are common in nature)
precipitate it in the laboratory. With regard to that found in quartz
lodes finely disseminated through the gangue, the change was brought
about by the same agency which caused the silicic acid to solidify and
take the form in which we now see it in the quartz veins. Silica is
soluble in solutions of alkaline carbonates, as shown in New Zealand
geysers; the solvent action being increased by heat and pressure, so
also would be the silicate or sulphide of gold. When, ho