438 METALLURGY. 



Near twenty years ago, I saw th.- operation of procuring zinc 

 from ralamine performed at Mr. Champion's copper works near 

 13ri>fol ; it was then a great secret, and though it be now b<ttei 

 known, yet I am not certain whether then- are any works of the 

 kind lished in any other part of either England or Europe, 



except that before mentioned at Henham. In a circular kind of 

 oven, like a glass-house furnace, there were placed six pots about 

 four feet each in height, much resembling large oil jars in shape; 

 into the bottom of each pot was inserted an iron tube, which passed 

 through the floor of the furnace into a vessel of water. The poti 

 were tilled with a mixture of calamine and charcoal, and the mouth 

 of each was then close stopped with clay. The fire being properly 

 applied, the metallic vapour of the calamine issued through the 

 iron tube, there being no other place through which it could es- 

 cape, and the air being excluded, it did not take fire, but was 

 condensed into very small particles in the water, and being re. 

 melted was formed into ingots, and sent to Birmingham under the 

 name of zinc or spelter*. The reader will understand that this 

 zinc wtil be more or less pure, according as the calamine is free 

 from or mixed with iron, lead, copper, or other metallic sab. 

 stances. At Goslar in Germany, they smelt an ore which contains 

 lead, and silver, and copper, and iron, and zinc in the same mass; 

 the ore is smelted for the purpose of procuring the lead and silver, 

 and by a particular contrivance in the fuin.ice, which is well de- 

 scribed by Cramert, they obtain a portion of zinc in substance ; 

 another portion ot it is inflamed, and the ashes of the zinc which 

 is thus consumed, and which it has been observed before are called 

 philosophic wool, <Sa-. stick to the top and sides of the furnace, and 

 are denominated by the smelters cadmia fornacum^ or furnace 

 fragment: these ashes are used as calamine is for the making of 

 brass. We know nothing of the method of fluxing the zinc which 

 is brought from India. According to Musschenbroeck, a cubic 

 foot of Indian /.inc weighs 7240 ounces ; the same bulk of 0< 

 zinc, taking the medium of three specimens, gave 7210 ounces} ; 

 the Goslar zinc, which I examined, gave only 6593 ounces to a 

 cubic foot ; a cubic foot of English zinc, from Bristol, weighs 



* There is another substance \\liirh i denominated spelter < spelter voider 

 bv i : ; it is composed of two parts of zinc and one of bi>s. 



t Ai, D.M-im. Vol. I. |'.': 

 t IntroU.adPhil. Nat. Vol. 11. 



