48 METALLURGY. 



there was not obtained above a few ounces of lead ; though a ton 

 of unadulterated lead ore yields in Derbyshire, at an average, 

 fourteen or fifteen hundred weight of lead. 



Calainiue is found in most parts of Europe ; we have great 

 plenty of it in Somersetshire, Flintshire, Derbyshire, and in many 

 other parts of England. It is scarcely to be distinguished by its 

 appearance from some sorts of lime-stone; for it has none of the 

 metallic lustre usually appertaining to ores : it differs, however, 

 by its weight from every sort of stone; it being, bulk for bulk, 

 near twice as heavy as either flint or limestone. Before the reign 

 of Elizabeth, this mineral was held in very little estimation in 

 Great Britain ; and even at so late a period as towards the end of 

 the 17th century, it was commonly carried out of the kingdom as 

 ballast by the ships which traded to foreign parts, especially to 

 Holland.* It use is now as perfectly understood in England, as 

 in any part of the world ; and as we have greater plenty of cula- 

 minu, and that of a better sort, than most other nations have, 

 there is no fear of our losing the advantages in this article of trade 

 which we are now possessed of. 



Great quantities of caiauiin^ nave of late years been dug in Der- 

 byshire, on a spot callfd liousale Moor, in the neighbourhood of 

 Alatlock. A bed of iron stone, about four fett in thickness lies 

 over ti.e calamine ; and the calumine is much mixed not only with 

 this iron stone, but with cawk, lead ore, and limestone. The 

 calamiue miners never wibh to meet with lead ore; they say that 

 it eats up the calamine: and tli<> lead miners in return never wish 

 to meet with calamine in a rich vein of lead ore, since they are 

 persuaded that it injures the quality of the ore. It would In- too 

 much to infer, from these observations of the miners, that one of 

 these substances arises from the natural decomposition of the other. 

 Juxtaposition of substances in the bowels of the earth, is no cer- 

 tain proof of their being derived from each other : for no one 

 will contend that chert is derived from the limestone in which it is 

 bedded, or flint and pyrites from the chalk in which they are found ; 

 yet when a great variety of substances are found mixed together 

 in the same little lump, the mind cannot help conjecturing that a 

 more improved state of mineralogy will shew some connection in 

 their origin. I have often seen calamine, and blackjack, and lead 



Essay on Metal: Wordi by Sir J. Petty, and Phil. Trans, for 1694. 



