_To dissolve Silver in_ Aqua Fortis, _and thereby separate it from every other metalline substance. The Purification of_ Aqua Fortis. _Silver precipitated by Copper._ The Silver you intend to dissolve being beaten into thin plates, put it into a glass cucurbit; pour on it twice its weight of good precipitated _aqua fortis_; cover the cucurbit with a piece of paper, and set it on a sand-bath moderately heated. The _aqua fortis_ will begin to dissolve the Silver as soon as it comes to be a little warm. Red vapours will rise; and from the upper surfaces of the Silver there will seem to issue streams of little bubbles, ascending to the top of the liquor, between which and the Silver they will form, as it were, a number of fine chains: this is a sign that the dissolution proceeds duly, and that the degree of heat is such as it ought to be. If the liquor appear to boil and be agitated, a great many red vapours rising at the same time, it is a sign that the heat is too great, and should be lessened till it be reduced to the proper degree indicated above: having obtained that, keep it equally up till no more bubbles or red vapours appear. If your Silver be alloyed with Gold, the Gold will be found, when the dissolution is finished, at the bottom of the vessel in the form of a powder. This solution must now be decanted while it is yet warm; on the powder pour half as much fresh _aqua fortis_ as before, and make it boil; again decant this second _aqua fortis_, and repeat the same a third time; then with fair water wash the remaining powder well: it will be of a brown colour inclining to red. In the observations we shall show how the Silver is to be separated from the _aqua fortis_. _OBSERVATIONS._ All the processes on Silver already delivered, whether for extracting it from its ores, or for refining it, either by the Cupel or by Nitre, are applicable to Gold also. And if Silver be alloyed with Gold before it undergo those several operations, it will still remain alloyed therewith after them, in the same manner, and in the same quantity; because both metals bear them equally. All therefore that can be expected from those several assays, is the separation of every thing that is neither Silver nor Gold from these two metals. But in order to separate these two from each other, recourse must be had either to the process laid down under the head of Gold, or to that here described, which is the most commodious, the most usual, and known by the names of _Quartation_ and the _Parting Assay_.