340 Transactions. —Chemistry. 
8. That itis also thus affected by being placed in contact for a very 
short time with an aqueous solution of caustic or carbonated 
alkali or ammonia, at their boiling points respectively, or for a 
somewhat longer time when the solution used is at a common 
temperature. 
4, That gold is also passed to this condition when ignited with a weak 
solution of sodic carbonate. 
5. That when put into this condition as to its surface, it becomes 
readily amalgamable by a short contact with either weak acetic 
or hydrochloric acid ; also by ignition, except in the case where 
ignition has been resorted to, to produce this particular condi- 
tion of such surfaces. 
These facts prove, I think, that gold is chemically acted upon when im 
contact with water or neutral saline solutions charged with oxygen and 
nitrogen gases, and that this action is facilitated by the presence of alkaline 
substances and especially when these are used hot in place of being used 
cold. It seems to me there can be little doubt entertained, but that gold 
thus acted upon has been oxidized, and this either to a sub-oxide, or to the 
purple oxide of gold. 
The gold used in these experiments was prepared as pure as possible. 
Some I twice precipitated by oxalic acid, from very dilute solutions of its 
chloride. 
Other gold I electro-deposited on platinum from its cyanide. Both 
samples gave similar results, but that obtained by deposition, yielded them 
quicker, owing perhaps, to the fact of its being coupled with platinum. 
There are two circumstances connected with this subject I should relate, 
which puzzled me a great deal, as they hardly seem to tally with certain 
reactions of this metal as now known. They are—first, that proto-sulphate 
of iron in contact with gold which has been acted upon by alkaline solu- 
tions or both does not render it amalgamable; secondly, that sunlight, even 
direct, does not appear to exercise any influence in the reaction I have 
described. Possibly, though, the purple oxide of gold may prove on ex- 
amination to be invulnerable in these respects. 
I may further relate that gold in either argentic-nitrate or mercuric- 
chloride rapidly becomes non-amalgamable, but it is recovered to its 
former condition by acetic acid, I question whether either of these salts are 
decomposed here. I further find that pure gold, fused with borax and bi- 
sulphate of potash, though very bright, will not amalgamate ; the solution 
of flux was acid. In weak sulphuric acid also, gold passes to this non- 
amalgamable condition. 
These results, however, and the question they raise demand investigation 
