Chap. 27.] Making of Brafs, Pinch&eck, &c. 155 



enough to melt the copper, but fufficient lo reduce 

 the zinc, and convert it into vapours. Thefe vapoury 

 penetrate the copper in proportion to the furface ex- 

 pofed to th,eir action, changing its colour from red to 

 yellow, and augmenting its weight in a great propor- 

 tion. When they make brafs, which is to be caft 

 into plates, from which pans and kettles are to be 

 formed, and wire is to be drawn, they ufe calamine of 

 the fineft fort, and in greater proportion than in the 

 compofition of common brafs. 



Tutty is the flowers of zinc taken from the furnaces 

 in which the ores containing this metal are wrought, 

 It varies in colour and confidence according as the 

 calx is more or lefs perfecl:, and is mixed with more or 

 }efs of an argillaceous fubftance. Newman fays, that 

 the lapis tutias is compofed of clay beaten up with a 

 fmall quantity of lapis calaminaris. 



Zinc and copper, when melted together in different 

 proportions, conftitute what are called pinchbeck, &c. 

 of different fhades of yellow. Margraff melted pure 

 zinc and pure copper together in a great variety of 

 proportions, and he found that eleven, or even twelve 

 parts of copper, being melted with one of zinc, gave 

 a mod beautify! an,d very malleable tombac or pinch- 



