"M. Geoffroy, having put his Sedative Salt made by crystallization to all the same trials with that made by sublimation, satisfied himself that there is no other difference between the two. If the Sedative Salt made by crystallizations happens to calcine in the sun; that is, if its lustre tarnishes, and its surface grows mealy, it is a sign that it still contains either a little Borax or some Glauber's Salt: for these two Salts are apt to calcine in this manner, and pure Sedative Salt should not be subject to this inconvenience. In order to purify it, and free it entirely from those Salts, it must be dissolved once more in boiling water. As soon as the water cools, the Sedative Salt reappears in light, shining, crystalline plates, swimming in the liquor. After standing four and twenty hours, the liquor must be decanted, and the salt washed with fresh water; by which means it will be very pure and beautiful." Glauber's Salt and Borax dissolve in water with vastly more ease than the Sedative Salt, and consequently do not crystallize so readily by much: so that the small portion of those salts which may have been left on the surface of the Sedative Salt, being diffused through a large quantity of water, continues in a state of solution, while the Sedative Salt crystallizes; which being also washed afterwards with fair water, it is impossible that the smallest particle of those other Salts should remain adhering to it; and consequently this must be deemed an excellent way of purifying it. SECTION II. _Of Operations on_ METALS. CHAP. I. _Of_ GOLD. PROCESS I. _To separate Gold, by Amalgamation with Mercury, from the Earth and Stones with which it is found mixed._ Pulverize the earths and stones containing Gold. Put the powder into a little wooden tray; dip this tray in water, gently shaking it and its contents. The water will grow muddy, by taking up the earthy parts of the ore. Continue washing it in this manner till the water cease to appear turbid. Upon the ore thus washed pour strong vinegar, having first dissolved therein, by the help of heat, about a tenth part of its weight of alum. The powder must be quite drenched and covered with this liquor, and so left to stand for twice twenty-four hours. Decant the vinegar, and wash your powder with warm water, till the last that comes off hath no taste: then dry it, and put it into an iron mortar, with four times its weight of Quick-silver: triturate the whole with a heavy wooden pestle, till all the powder be of a blackish colour: then pour in a little water, and continue rubbing for some time longer. More earthy and heterogeneous particles will be separated from the metalline parts by means of this water, which will look dirty: it must then be decanted, and more fair water added. Repeat this several times; then dry what remains in the mortar with a sponge, and by the help of a gentle heat: you will find it an Amalgam of the Mercury with the Gold.