7028 ; and hence if the lightness of zinc be a criterion of its pu- 

 rity, our English zinc is preferable to the Indian, ami nearly 

 equal to the German zinc. 



If the reader has never seen a piece of zinc, it will give him 

 some idea of it to be told, that in colour it is not unlike lead ; that 

 it is hard and sonorous, and malleable in a small degree; that it 

 does not melt so easily as tin or lead, but more easily than silver or 

 copper : that in a degree of heat just sufficient to melt it, it burns 

 away into a kind of grey ashes without being inflamed ; that in a 

 stronger heat it burns with a yellowish blue or green flame, resolr. 

 ing itself into a white earth, which is driven offby the violence of the 

 fire during the combustion, or remains surrounding the burning 

 zinc like a piece of cotton wool. This combustion of zinc is 

 as striking an experiment as any in chemistry, and it is in the 

 power of any person to make it, by sprinkling filings of zinc on a 

 pan of burning charcoal, or on a poker, or other piece of iron 

 heated to a white htat ; it is this property which renders fine filings 

 of zinc of great use in fire-works. Zinc is a very singular metal, 

 lie substance ; it not only burns when sufficiently heated with a 

 vivid flame, but it yields an inflammable air by solution in the 

 acids of vitriol and of sea salt, and even in some of its ores it ma. 

 nifests a phosphoric quality : 1 have seen a piece of black ja< k 

 from Freiburg, which being scratched in the dark with the nail of 

 a finger emitted a strong white light. The Chinese zinc is said to 

 contain about half a pound of lead in an hundred, and the German 

 zinc somewhat more*; and our English zinc is thought by some 

 to make the copper with which it is melted harsher and less mallea- 

 ble than when either of the o'ther sorts of zinc is used ; though 

 this opinion I suspect is rather founded in prejudice than in truth. 

 There is an easy meihod, when pure zinc is required, of obtaining 

 it : nothing more is required than to melt it with sulphur and some 

 fat substance to prevent its calcination, for the sulphur will unit* 

 itself to the lead, the copper, or the iron contained in the zinc, 

 and reduce them to a kind of scoria, which may be separated from 

 the melted zinc, but it has no action on the zim: itself +. The zinc 



Berj$. E. Vol. II. p. 318, note. 



t I am aware that Mr. Morvrau hat found out a method of combining tine 

 with sulphur ; but in this g'-ncral view, I purpocly pass over many tniofi w hied 

 are deservedly esteemed of great importance by persooi deeply skilled in cho- 

 o it try. 



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