[ <53 J

the bottom, which the acid had before retained, andwhich the long boiling has disengaged. Stone ware cu-curbits, coated with lute, are charged with the liquor toabout two thirds of their height : the French have akind of ware spots de graisj which is said to answer ex-tremely well for this use : such of our common stonewares as I have formerly tried, frequently failed. Fiveor six of these vessels are let into one furnace, up tothe height of the liquor, and the bottoms made to reston iron bars : the furnace is long and narrow, with adoor at one end for putting in the fuel, and the chim-ney at the other. On each jar is luted a stone warehead with two spouts and receivers. The fire is raisedto such a degree as to make the distillation go onwith sufficient dispatch, with care only not to increaseit so far, as to endanger the matter swelling up intothe head. When about three fourths have come over,the fire is suffered to decay, and the vessels to cool, thatthe heads may be unluted, and more of the copper so-lution poured in. This is repeated three or four times,till it is judged that the calx of copper in each jar risesto about a fourth of its height, after which the fire isstrongly urged, till the bottoms of the jars become redhot, and nothing more will distil. This troublesome pro-cess might be improved by substituting to the cucurbitsthe copper pan in which the evaporation is performed ;which may be converted into a distilling vessel, by fittingto it a stone-ware breast and head, in the fame manner asthe copper breast and head are fitted to the still in the firstplate: there is no occasion for two spouts, as one, of aproper width, will supply the place of the two : the cop-per pan should be let into the furnace almost to itsupper edge; and the breast should enter the pan nearlyto the surface of the liquor. The aqua fortis thus ob-

X tained