[ I 5° ]

to such a height, as not to hinder the operator fromobserving how the dissolution goes on : some quicklime,slaked with beer, and mixed with whites of eggs, is spreadon a linen cloth, which being wrapped round the glass,a composition of clay and hair is applied over it. He givesalso a contrivance of his own, which he seems to haveintroduced into the works of the lower Hartz, for pre-serving the dissolved silver, as well as the gold, when theglasses happen to break, or the liquor to run over. Hisparting glasses are fifteen inches high, ten or twelve incheswide at the bottom, and at the top about as wide as themouth of a common bottle : for each of these he has acopper pan, twelve inches wide at bottom, fifteen at top,and ten in height, which stands on a trevet, with somecharcoal under it : some water is put into the pan, andtwo pieces of wood placed crosswise in its bottom, as asupport for the glass, to prevent it from hitting against thecopper. Into one of these glasses he puts about eightyounces of gold-ho!ding silver, with twice as much aquafortis, without danger of any loss though the glass shouldbreak : the heat may likewise be speedily diminished, ifthe acid should act too impetuously, by pouring cold waterinto the pan. Great care must be taken in the additionof the cold water : it should be poured against the sides ofthe pan, and stirred with the rest, that it may be equallymixed before it reaches the glass.

The silver is recovered from its solution by means ofcopper. The solution, diluted with water, being putinto a copper vessel, or into a glass one along with copperplates (the refiners use commonly a wooden bowl-dishlined with copper) the silver begins immediately to sepa-rate from the liquor in form of fine grey scales or powder;a part of the copper being dissolved in its place, so as totinge the fluid more and more of a blue colour. The

plates