The Refiner's Test is pointed out to us;--a sort of shovel, with a spout, lined throughout with a material of burnt bones, the only substance which can endure unchanged the heat necessary for testing the metals. Of this material are made the little crucibles that we see in the furnaces, which our conductor admits to be "rather warm." There they are, ranged in rows, so obscured by the mere heat, which confounds every thing in one glow, that their circular rims are only seen by being looked for. Yet, one little orifice, at the back of this furnace, shows that even this heat can be exceeded. That orifice is a point of white heat, revealed from behind. We do not see the metal in the crucibles; but we know that it is simmering there. One more oven is opened for us--the assay furnace, which is at a white heat. As the smallest quantities of metal serve for the assay, the crucibles are here on the scale of dolls' tea-things. The whole concern of that smallest furnace looks like a pretty toy; but it is a very serious matter--the work it does, and the values it determines. The metals, which run down to the bottom, in the melting furnaces, are separated (the gold and silver by aquafortis), and cast in moulds, coming out as ingots; or, in fragments, of any shape they may have pleased to run into. Some of the gold fragments are of the cleanest and brightest yellow. Other, no less pure, are dark and brownish. They are for gilding porcelain. Lastly, we see a pretty curiosity. In the counting-house, a little glass chamber is erected upon a counter, with an apparatus of great beauty--a pair of scales, thin and small to the last degree, fastened by spider-like threads to a delicate beam, which is connected with an index, sensitive enough to show the variation of the hundredth part of a grain. The glass walls exclude atmospheric disturbance. Behind the rusty-looking doors were the white glowing crucibles; within the drawers was the yellow gold; and, hidden in its glass house, was the fairy balance. Now, we will follow some of the gold and silver to a place where skilled hands are ready to work it curiously.