BOOK XXXIII. XXIX. 93-xxxi. 95 



made of Cyprian copper in mortars of the same 

 metal, and the Latin name for the mixture is 

 santerna. It is in this way used in soldering the 

 gold called silvery-gold ; a sign of its having been 

 so treated is if the appHcation of borax gives it 

 brilliance. On the other hand ' coppery ' gold 

 shrinks in size and becomes dull, and is difficult to 

 solder ; for this purpose a solder is made by adding 

 some gold and one seventh as much silver to the 

 materials above specified, and grinding them up 

 together. 



XXX. While speaking of this it wili be well to 

 annex the remaining particulars, so as to occasion 

 all-round admiration for Nature. The proper solder 

 for gold is the one described ; for iron, potter's clay ; 

 for copper in masses, cadmea "■ ; for copper in sheets, 

 alum ; for lead and marble, resin. Black lead how- 

 ever is joined by means of white lead,'' and white 

 lead to white lead by using oil ; stagnum ^ likewise 

 with copper fiHngs, and silver with stagnum. For 

 smelting copper and iron pine-wood makes the best 

 fuel, though Egyptian papyrus can also be used; 

 gold is best smelted with a fire made of chaff. Water 

 puts heat into quicklime and Thracian stone,*^ and 

 oHve-oil puts it out; fire however is most readily 

 quenched by vinegar, mistletoe and eggs. Earth it 

 is quite impossible to ignite, but charcoal gives a 

 more powerful heat if it is burned till it goes out and 

 then catches fire again. 



XXXI. After these details let us speak about the sUvcr. 

 varieties of silver ore, the next madness of mankind. 

 Silver is only found in deep shafts, and raises no 

 hopes of its existence by any signs, giving off no 

 shining sparkles such as are seen in the case of gold. 



73 



