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these vessels are of the fame width at the mouth, so that thesame breast fits them both, and either may be used as astill equally with the other : either of them serves also, onother occasions, as an evaporating pan, a boiler, forexperiments in dying, and other like purposes. All theparts are made of thin copper plate, and well tinned onthe inside with pure tin : in consequence of their thin-ness, they admit of some alteration of their figure aboutthe edges, so that, though they should not be perfectlyround, they are readily accommodated to one another,and fit close : the juncture is easily made perfectly tight byapplying round it narrow flips of moistened bladder;which are more convenient than luting, as being readilystript oss when the operation is finished. A short pewterpipe, with a pewter stopper fitted to it, for returning thedistilled liquor, or pouring fresh liquor occasionally intothe still, without the trouble of unluting and separatingthe vessels, is soldered into the top of the head ; which,in these kinds of instruments, is the most convenientplace for it. For separating, by distillation, spirituousfrom watery liquors, or the rectification of spirit of wine,the head is raised, by inserting, between it and the breast,a thin copper pipe about two feet long. A worm andrefrigeratory are necessary, as for the common still : anda glass head is requisite for some uses, particularly for thedistillation of vinegar, and such other liquors, as wouldcorrode a copper one, and impregnate themselves withthe metal; in which cafe, the use of the metalline wormalso is to be avoided, and the glass or stone-ware receiverjoined to the pipe of the head.

The above apparatus is as commodious, as can bewished, for distillation in the way of experiment. Con-trivances for expediting and accelerating the process donot belong to the present design : but as this is an affair

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