BOOK XXXIII. XL. 119-121 



another kind '^ of minium, found in almost all silver- 

 mines, and likewise lead-mines, which is made by 

 smelting a stone that has veins of metal running 

 through it, and not obtained from the stone the 

 round drops of which we have designated quick- § 09 

 siher — for that stone also if fired yields quicksilver — 

 but from other stones found at the same time. 

 These have no quicksilver and are detected only 

 by their leaden colour, and only when they turn red 

 in the furnaces, and after being thoroughly smelted 

 thev are puherized by hammering. This gives a 

 minium of second rate quality, which is known to 

 very few people, and is much inferior to the natural 

 sands we have mentioned. It is this then that is 

 used for adulterating real miiiium in the factories of 

 the company, but a cheaper kind is adulterated with 

 Syrian : the preparation of the latter will be des- xxxv. 40. 

 cribed in the proper place ; but the process of giving 

 cinnabar and red-lead a treatment of Syrian is 

 detected by calculation when the one is weighed 

 against the other. Cinnabar also, wath red-lead, 

 aifords an opportunity for pilfering by painters in 

 another way, if they wash out their brushes imme- 

 diately when full of paint ; the cinnabar or the 

 red-lead settles at the bottom of the water and stays 

 there for the pilferers. Pure cinnabar ought to 

 have the brilliant colour of the scarlet kermes- 

 insect, while the shine of that of the second quahty 

 when used on wall-paintings is affected by rust, 

 although this is itself a sort of metalHc rust. In 

 the cinnabar mines ^ of Almaden the vein of sand 

 is pure, without silver. It is melted like gold '^ ; it 

 is assayed by means of gokl made red hot, as if it 

 has been adulterated it turns black, but if genuine 



91 



