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aqua sortis is added, and heated more considerably thanbefore, to extract what silver may still be left in it ; thismay be repeated a second or a third time ; aster whichsome water is poured on, and renewed two or three times,to wasli off the saline matter. The parting glass beingthen full of water, a small gold vessel (s silver one willdo) is applied closely on its top ; and both being nimblyinverted, and the parting glass carefully raised a little atone side, the golden plate is washed down into the lowervessel : if this last is insufficient for receiving all the water,,the glass is to be listed up a little, so as that the thumb ora piece of stiff paper can be applied to its orifice under thewater, after which it may be removed without disturbingthe liquor, or damaging the brittle plate. The water be-ing poured off, the plate is dried, and gradually heated tillthe gold resumes its proper colour, which happens soonafter its becoming red hot. Some make use of an earthencrucible; but in this cafe, small particles of the earth areapt to adhere imperceptibly to the gold, whence the assaybecomes less certain.

If the gold, after having passed through these opera-tions, is found to be of the same weight as at first, it isreputed nearly fine, but not entirely so : for the aqua sortisleaves always in the gold a small portion of the silver,amounting commonly to above a three hundredth, andsometimes to a hundredth part of its weight; whence, ifthe gold was at first fine, it will in this process receive anincrease. If it is required to determine exactly the pro-portion of this increase, it may be done by submitting tothe same operation an equal quantity of gold known to befine, mixed with the same proportion of silver. The dif-ferences in the quantity of silver, thus left in the gold,are supposed to proceed from unheeded differences in thequality of the aqua sortis, particularly in its strength ; so

that