MET.AI.LMIGY. 



calamine, not being volatile, will remain in the clay, and (he brass 

 when the whole is nieltnl will not be mixed with them, but 

 pure on the surface of the clay. Mr. John Champion, brother to 

 hint who first established the manufactory of zinc at Bristol, is a 

 very minimus metallurgist, and he has lately obtained a patent for 

 brass by combining zinc in vapour with heated copper 

 and the brass is said to be very fine; whether the process 

 he uses has any correspondence with this mentioned by Cramer, or 

 not, his brass will certainly be free from the mixture of lead, 

 &c. But the care to purify brass from such metallic mixtures as 

 may be accidentally contained in the calamine, is, or is not neces- 

 sary, according to the purposes to which brass is applied. These 

 mixtures may probably injure the malleability of the brass, but 

 they may at the same time increase its hardness, or render it sus- 

 ceptible of a better polish, or give it a particularity of colour, or 

 some other quality by which it mriy be more useful in certain ma- 

 nufactories, than if it was quite free from them, and consisted of 

 nothing but the purest metallic part of the calamine, united to the 

 purest copper. This may be illustrated from what is observable in 

 other mtals. The red iron ore from Furncss, in Lancashire, pro- 

 duces an iron which is as tough as Spanish iron ; it makes very fine 

 wire; but when converted into bars, it is not esteemed so good as 

 that which is made in the forest of Dean, and other places. There 

 are but few sorts of iron which, though useful in other respects, 

 are fit for being converted into steel: some sorts of iron will ad- 

 mit a high polish, as may be seen in many expensive grates which 

 are sold as grates of polished steel, though they are nothing but 

 iron; whilst others take but a very indilli r< nf polish; the Swe- 

 dish, Russian, and Knglish irons, and even the irons made at dif- 

 ferent furnaces in the same country, are respectively fit for some 

 purposes, and unfit for other : he who should attempt to use the 

 same iron for the making of wire, and for coach and waggon 

 wheel*, would betray great ignorance in his business. In like 

 manner, a notable dill'erence may be observed in ditferent sorts of 

 copper, y< t all of them have their respective uses : the Swedish 

 copper is more malleable than the copper of Hungary ; the copper 

 of Anglesey ilillers from the copper of Cornwall and of Stafford, 

 shire. The br.i/.iers prefer that copper which they can work with 

 the greatest facility ; but the malleability of copper should not b 

 esteemed the only criterion of its goodness; for the copper whick 



