72 Simple Preparations.

In this manner are to be preparedAmber,Antimony,Calamine,

vHALK)CoRAL,

Oister-shells, firft cleanfed fröm theirimpurities.

Tutty,

Crabs Claws, firil broken into fmall pie-ces, rauft be wafhed with boiling vvater beforethey are levigated.

Verdegris rauft be prepared in the famemanner.

i

R E M A R K.

Calamine is roafted, or calcined, in order that itmay be more eafily reducible to a very fine pow-der ; and, the fhops being ufually fupplied with itin this calcined ftate, the College have fo dirededit in the Materia Medica. See Zinc. Where Ca-lamine cannot be procured already calcined, thisore of Zinc is to be thrice heated to a ftrong redheat, and as often quenched wich water. Ed. D.1756.