In Janus Lacinius' A Form and Method of Perfecting Base Metals (published together with his abridged versions of Petrus Bonus' New Pearl of Great Price and several other alchemical texts) he describes the action of the secret solvent ("Our Water") on gold:

http://www.levity.com/alchemy/new_pearl.html

Mix one part of gold (X) with twelve parts of Our Water; pound them small; place them in a moderately deep jar; set over it an alembic in the ordinary way; stop up the jar and the apertures of the alembic, up to the beak, with clay; let it dry thoroughly; place it on the oven (not immediately over the coals, but on the iron) in such a way that the whole jar shall be covered by it as far as the alembic, and let the aperture between jar and furnace be also sealed with clay. Then light the fire, and there will come oil into the alembic, together with the water, and will float on the water with an orange colour. Continue the fire till all the water is distilled; let it cool; remove the recipient; separate the oil from the water, and open the jar: you will find a hard, brittle, and pulverizable body. If you like, repeat the whole process, pouring the same or other water over the body; distil as before. The water that comes out will not be so much as at first, and if you repeat the process a third time, there will be hardly any water at all. The body that remains will be a blackish powder...

Notice well how the secret solvent after exerting its action on the metallic matter distills both partly in the form of a "water" and partly in the form of an "oil" that floats on top. Notice also that after repeating the same operation several times, there is less and less of the "water", while the body of the metal remains behind as a darkish powder. Ordinary solvents cannot do any of this. Anyone who has tried to volatilize gold by means of common corrosive solvents, like aqua regia, will know this (see, for example, Lawrence Principe's experiments regarding this subject in his attempts at replicating what the commentators of Basil Valentine's 12 Keys explain regarding one part of the process where gold is partly volatilized.)

One question that pops to mind from the above English translation is: was Lacinius using a solid form of the secret solvent? Notice that it says "pound THEM small" (i.e. the gold and the solvent), which would suggest that he was in fact using a solid form of the solvent (a liquid obviously cannot be "pounded/ground small"!!!) However, I checked the original Latin edition of 1546 and he just says "and grind finely/subtly" ("et tere subtiliter"), he does not specify that both have to be finely pounded/ground:

https://books.google.com/books?id=2e...issimo&f=false

So, the "them" is an assumption by the English translator. For all we know, Lacinius was working with a liquid form of the secret solvent, and what he is directing to pound/grind small is the gold, not the solvent, since a liquid obviously cannot be "pounded/ground".

Another thing: the English translator says that the color of the "oil" floating on the "water" is orange, but Lacinius actually says "yellow/golden" ("stabit supra aquam in colore citrino")