'i8o Of the Arsenic 



and lying a- top the tapped black- copper, and from 

 white inclining a fmall matter to a copper reddifh 

 caft. Both are of a whitifh metallic appearance, 

 texture, and weight, but brittle •, moreover, tole- 

 rably hard, according as they are more or lefs in- 

 corporated with metallic earth •, both contain from 

 a third to a half of arfenic, and, as I have expe- 

 rienced myfelf, may alfo hold a good deal more, 

 but feldom lefs -, and that from incidental circum- 

 ftances, which, in the bufinefs of fmelting, both 

 in regard to the method of working, and to the 

 matters themfelves, may be endlefsly variable. 



Speife is a term ufed alfo among workers in brafs, 

 but with the addition glocken, thus denoting bell- 

 metal ; a matter appearing pretty pale, though 

 inclining more to a yellowiih caft, as it muft, on 

 account of its principal ingredient, the brafs : as 

 to the reft, it is harder, and more metallic than, 

 and therefore not to be confounded with, our hut- 

 fpeife. AfTayers alfo have their fpeife, but which 

 they might more properly call an iron-regulus ; as 

 yielded by thofe pyrites which contain no cop- 

 per, and remains further unexamined by them, 

 feeing they look for nothing elfe in pyrites, but 

 filver and copper, confequently is unknown to, 

 and thrown away by them, under an appella- 

 tion borrowed from fome colour or other, and 

 which, in fome meafure, ferves as a fcreen for their 

 ignorance. Now, 'tis true, there are ibme pyrites, 

 whofe iron-earth is arfenicaled, as the white, en- 

 tirely •, many of the yellowiih, confiderably ; and 

 thus, in affaying, there arife fuch reguli, as affay- 

 ers may, on the fame foot with fmelters, q?l\\ fpeife; 

 but as fome of .them afford only a very fmall mat- 

 ter of, or no arfenic at all, 'tis wrong to bring 

 them under one common appellation, fpeife. 



In 



