204 plixy's natural history. [Book XXXIY. 



they have changed their colour, dried in the sun ; and the 

 foliage of the box, pseudo-cypirus/^ bramble, terebinth and 

 oenanthe.^^ The same virtues have also been found in the ashes 

 of bull-glue"*^ and of linen cloth. All these substances are 

 burnt in a pot of raw earth, which is heated in a furnace, 

 until the earthenware is thoroughly baked. 



CHAP. 36. SMEGMA. 



In the copper forges also smegma*^ is prepared. When the 

 metal is liquefied and thoroughly smelted, charcoal is added 

 to it and gradually kindled ; after which, upon it being sud- 

 denly acted upon by a powerful pair of bellows, a substance is 

 disengaged like a sort of copper chaif. The floor on which, 

 it is received ought to be prepared with a stratum of coal-dust. 



CHAP. 37. DIPHRYX. 



There is another product of these furnaces, which is easily 

 distinguished from smegma, and which the Greeks call '* di- 

 phryx,"^'^ from its being tAvice calcined. This substance is pre- 

 pared from three different sources. It is prepared, they say, 

 from a mineral pyrites, which is heated in the furnace until 

 it is converted by calcination into a red earth. It is also 

 made in Cyprus, from a slimy substance extracted from a cer- 

 tain cavern there, which is first dried and then gradually heated, 

 by a fire made of twigs. A third way of making it, is from 

 the residue in the copper-furnaces that falls to the bottom. 

 The difference between the component parts of the ore is this ; 

 the copper itself runs into the receivers, the scoriae make their 

 escape from the furnace, the flower becomes sublimated, and 

 the diphryx remains behind. 



Some say that there are certain globules in the ore, while 

 being smelted, which become soldered together ; and that the 

 rest of the metal is fused around it, the mass itself not becoming 

 liquefied, unless it is transferred to another furnace, and forming 

 a sort of knot, as it were, in the metal. That which remains 

 after the fusion, they say, is called ^'diphryx. " Its use in medi- 

 cine is similar to that of the substances mentioned above ;*^ it 



39 See B. xxi. c. 26, and B. xvi. c. 20. 39 See B. xxi. c. 95. 



*o See B. xi. c. 94. — B. ^^ " Detersive compositiou." 



^- From Ats (ppvyioOcn. — " being twice calcined." — B. 

 " The Scoriae, Cadmia, and Flos, which are described in Chapters 22, 

 23 and 24.— B. 



