BOOK XXXIV. xxxvi. 134-XXXV111. 137 



copper spirts out. The floor on which it is received 

 ought to be strewn with charcoal-dust. 



XXXVII. Distinguished from ' smegma ' is ihe other impu- 

 substance in the same forges called by the Greeks "'***' 

 diphryx, from its being twice roasted. It comes 



from three diiferent sources. It is said to be ob- 

 tained from a mineral pyrites which is heated in 

 furnaces till it is smelted into a red earth. It is also 

 made in Cyprus from mud obtained from a certain 

 cavern, which is first dried and then gradually has 

 burning brushwood put round it. A third way of 

 producing it is from the residue that falls to the 

 bottom in copper furnaces ; the ditference is that 

 the copper itself runs down into crucibles and the 

 slag forms outside the furnace and the flower floats on 

 the top, but the supphes of diphryx remain behind. 

 Some people say that certain globules of stone that 

 is being smelted in the furnaces become soldered 

 together and round this the copper gets red hot, 

 but the stone itself is not fused unless it is transferred 

 into other furnaces, and that it is a sort of kernel 

 of the substance, and that what is called diphryx 

 i>^ the residue left from the smelting. Its use in 

 medicine is similar to that of the substances already 

 described ; to dry up moisture and remove excrescent 

 growths and act as a detergent. It can be tested 

 by the tongue — contact with it ought immediately 

 to have a parching effect and impart a flavour of 

 copper. 



XXXVIII. We will not omit one further remark- 

 able thing about copper. The Servilian family, 

 famous in our annals, possesses a bronze J as piece 

 which it feeds with gold and silver and which con- 

 sumes them both. Its origin and nature are un- 



227 



