“flouring,” is mainly due, in the process cited above; such ferric salts being able to either oxidize or chlorodize the surface of any mercury they may be in contact with, thus enfilming it with a compound, which being practically insoluble in water, or in water charged solely with the salts occuring in mineral workings, prevents that metallic contact taking place between detached mercurial globules, which is necessary to amalgamation.

In remedying or preventing flowing so occasioned, this salt, (Cyanide of Potassium) acts by decomposing these mercurial compounds and dissolving in part or wholly their constituent portions, while the surface of the mercury not thus floured, it keeps metallic, by preventing ferric salts acting in the manner stated; these salts being decomposed by this cyanide as they would by any other salt, having as it has, an alkaline reaction. ^*

In effecting these useful results it is thus seen that cyanide of potassium dissolves a portion of the mercury used; besides this there may be another portion of mercury, though a much smaller one dissolved away from the metal itself by the direct action of the cyanide upon it, aided by the free oxygen always present; this happens if no metal is dissolved in the mercury used, or is in contact with it, having a greater affinity for cyanogen than mercury has. Moreover, in thus contemplating the contingencies entailed or risked by the use of any alkaline cyanide in such milling operations, it must be remembered that both gold and silver are not absolutely insoluble in these cyanides.

Now, the loss of mercury in this way may not be serious, but if gold or even silver be thus lost (that is by its solution) even in much less quantity than mercury well could be, the loss then may be serious.

Now whether the loss of metal certain to be entailed by the use of cyanide of potassium, falls upon the mercury or upon the gold or silver of these blankettings, conjointly or separately, depends entirely upon this relative affinity of these metals for this salt, or in other words, it depends upon their electro-motive order therein.

According to our present knowledge in regard to this subject, mercury is positive both to gold and silver, under these circumstances, the loss of metal would therefore fall upon the mercury, which is of course desirable: thus we have it distinctly affirmed that “neither gold, silver, or platinum, directly percipitate mercury from its solutions,” But feeling the importance of this subject, and moreover having for various reasons grave doubts as to the correctness of these opinions, I investigated this matter for myself, and soon found that in reality mercury is not positive to either gold or