VOL. XVri.] PHILOSOPHICAL TRANSACTIONS. 335 



intended by the author as a key to philosophy, discovering what may be known 

 by the light of nature, expounding the philosophical terms, and their various 

 acceptations according to the ancient and modern opinions. He explains words 

 relating to logic, natural and moral philosophy, especially such as cause the 

 greatest contests in the schools both of the ancients and moderns. Among 

 them are interspersed astronomical, optical, mechanical, chemical, and physico- 

 mathematical words, chiefly such as explain bodies and their several affections; 

 the whole is rendered the more intelligible by several schemes, contained in 

 30 folio plates, exhibiting to view the several hypotheses, with the structures 

 of many instruments and machines, as barometers, thermometers hygrometers, 

 telescopes and microscopes, made use of by the late inquisitive age, in searching 

 deeper into the nature of bodies. 



The Method, Manner, and Order of the Transmutation of Copper into Brass, 

 &c. By Thomas Povey, Esq. F. R. S. N° 200, p. 735. 



Calamine is dug out of several mines in the west of England, as about 

 Mendip, &c.* which lie about 20 feet deep. It is burnt or calcined in a kiln 

 or oven, made red-hot ; it is then ground to powder, and sifted into the fine- 

 ness of flour, and mixed with ground charcoal, because the calamine is apt to 

 be clammy, to clod, and not so apt to incorporate. They then put about 7 lb. 

 of calamine into a melting pot, of about a gallon content, and about 5 lb. of 

 the copper uppermost, the calamine must be mixed with as many coals as will 

 fill the pot. This is let down with tongs into a wind-furnace, 8 feet deep, 

 where it remains J 1 hours. They cast off not above twice in 24 hours, one 

 furnace holds 8 pots. After melting, it is cast into plates or lumps. 45 lb. of 

 raw calamine produces 30 lb, burnt or calcined. Brass shurff serves instead of 

 so much copper ; but this cannot always be procured in quantities, because it is 

 a collection of pieces of old brass, which is usually to be got only in small 

 parcels. The best guns are not made of malleable metal, nor can they be made 

 of pure copper or brass ; but it is necessary to put in coarser metals, to make it 

 run closer and sounder, as lead and pot-metal. Bell-metal is copper and tin, 

 pot-metal copper and lead. About 20 lb. of lead is usually put into 100 lb. of 

 pot-metal ; but about 61b. is sufficient to put into 100 lb. of gun-metal. 



The calamine stones were heretofore brought from Poland ; but since from 

 hence by the Dutch. The manufacture of brass was privately kept in Germany 

 for many centuries, wherein thousands were employed and well maintained, and 

 some raised themselves to great estates. 



* See N« 198 of these Transactions. 



