2j% On the different Kinds of Cadmia, and 



and, at times, alio a final! portion of copper. In blende tlic 

 fulphur is combined with iron, and the particles of zinc 

 are fcattercd through the mixture. The fo called hirnace 

 calamine is obtained by the fulion of fome kinds of lead ore 

 when the particles of zinc arc fublimatcd by ftrong heat 

 to a cooler place of the furnace called the z.inc Jlool, where 

 they adhere in the form of a grey or yellowifh ftonc. In 

 preparing brafs, and other operations of the like kind, 

 the fublimatcd zinc calx is collected under the name of 

 toh'tle n'lcht ; but what adheres lower down, and becomes a 

 hard mafs, is called grrji tut'ia; and this fubftance, as fomc 

 fulphurcous vapour fcems to adhere to it the longer it lies 

 expol'ed near the fmelting houfcs, becomes, by the effcAs of 

 the atmofpherc, always more proper for life. Befides the 

 above, we have zinc calx, zinc fpar, tutanego ore, the lad 

 of which was firft difcovcred in China; but I am convinced, 

 by experiments, that a like ore, which is natural flowers of 

 zinc, is found in Germany in the Thomas-flollcn at Blei- 

 berf. We have alio zeolite-formed calamine, zinc blende, 

 fluttering blende, black blende, reddifli brown, phofphorifed, 

 frrecnifh -yellow, white, and vellow blende. Such kinds are 

 found in England, Sibcri;-., China, Sweden, Silelia, Saxony, 



&.C. 



In examining thefc fubftanccs various chemids have ren- 

 dered great fervice to mineralogy, particularly Brand and 

 Schwab, counfellors of the mines in Sweden; and thcfe 

 were followed by Julli, Pott, Henkel, and, above all, War- 

 graaf, who employed great care and accuracy in fuling and 

 examining them : but Bergmaun, to w hom Icicnce is fo 

 much indebted, has given nioft excellent models for the 

 decompofition of thefe ores. Whether there be native zinc 

 or not, has never yet been fully afcerlained ; and we mu(t 

 ftill remain in doubt until the account of its being found iu 

 the illand of Naxos, iu the Archipelago, be belter con- 

 firmed. The zinc ore of Goflar, that found in Cornwall, 

 and a little of the Swedlfli, can be rendered ulcful and pro- 



6 duCtive. 



