418	BOOK IX.
	If the tin is so impure that it cracks when struck with the hammer, it is not immediately made into lattice-like bars, but into the cakes which I have spoken of before, and these are refined by melting again on a hearth. This hearth consists of sandstones, which slope toward the centre and a little toward a dipping-pot ; at their joints they are covered with lute. Dry logs are arranged on each side, alternately upright and lengthwise, and more closely in the middle ; on this wood are placed five or six cakes of tin which all together weigh about six centumpondia ; the wood having been kindled,
	the tin drips down and flows continuously into the dipping-pot which is on the floor. The impure tin sinks to the bottom of this dipping-pot and the pure tin floats on the top ; then both are ladled out by the master, who first takes out the pure tin, and by pouring it over thick plates of copper makes lattice-hke bars. Afterward he takes out the impure tin from which he makes cakes ; he discriminates between them, when he ladles and pours, by the ease or difficulty of the flow. One centumpondium of the lattice-hke bare sells for more than a centumpondium of cakes, for the price of the former