440 BOOK X. 



three librae of alum, half a libra of brick dust, and three-quarters of a libra 

 of spring water. The sixth consists of four librae of vitriol, three librae of 

 saltpetre, one of alum, one libra likewise of stones which when thrown into a 

 fierce furnace are easily liquefied by fire of the third order, and one and a 

 half librae of spring water. The seventh is made of two librae of vitriol, one 

 and a half librae of saltpetre, half a libra of alum, and one libra of stones 

 which when thrown into a glowing furnace are easily liquefied by fire of the 

 third order, and five-sixths of a libra of spring water. The eighth is made of 

 two librae of vitriol, the same number of librae of saltpetre, one and a 

 half librae of alum, one libra of the lees of the aqua which parts gold from 

 silver ; and to each separate libra a sixth of urine is poured over it. The 

 ninth contains two librae of powder of baked bricks, one libra of vitriol, 

 likewise one libra of saltpetre, a handful of salt, and three-quarters of a libra 

 of spring water. Only the tenth lacks vitriol and alum, but it contains three 

 librae of saltpetre, two librae of stones which when thrown into a hot furnace 

 are easily liquefied by fire of the third order, half a libra each of verdigris 4 , 

 of stibium, of iron scales and filings, and of asbestos 5 , and one and one-sixth 

 librae of spring water. 



All the vitriol from which the aqua is usually made is first reduced to 

 powder in the following way. It is thrown into an earthen crucible lined on 

 the inside with litharge, and heated until it melts ; then it is stirred with a 

 copper wire, and after it has cooled it is pounded to powder. In the same 

 manner saltpetre melted by the fire is pounded to powder when it has cooled. 

 Some indeed place alum upon an iron plate, roast it, and make it into powder. 



Although all these aquae cleanse gold concentrates or dust from 

 impurities, yet there are certain compositions which possess singular power. 



*Agricola, in the Interpreiatio, gives the German equivalent for the Latin aerugo as 



Spanschgrun " because it was first brought to Germany from Spain ; foreigners call it 



" viride aeris (copper green)." The English " verdigris " is a corruption of vert de 



grice. Both verdigris and white lead were very ancient products, and they naturally find 



mention together among the ancient authors. The earliest description of the method of 



making is from the 3rd Century B.C., by Theophrastus, who says (101-2) : " But these are 



' works of art, as is also Ceruse (psimythion) to make which, lead is placed in earthen vessels 



' over sharp vinegar, and after it has acquired some thickness of a kind of rust, which it 



' commonly does in about ten days, they open the vessels and scrape off, as it were, a kind 



' of foulness ; they then place the lead over the vinegar again, repeating over and over 



' again the same method of scraping it till it is wholly dissolved ; what has been scraped off 



' they then beat to powder and boil for a long time ; and what at last subsides to the bottom of 



' the vessel is the white lead. . . . Also in a manner somewhat resembling this, verdigris 



' (ios) is made, for copper is placed over lees of wine (grape refuse ?), and the rust which it 



' acquires by this means is taken off for use. And it is by this means that the rust which 



' appears is produced." (Based on Hill's translation.) Vitruvius (vn, 12), Dioscorides (v, 51), 



and Pliny (xxxiv, 26 and 54), all describe the method of making somewhat more elaborately. 



6 Amiantus (Interpretatio gives federwis, pliant, salamander har). From Agricola's 



elaborate description in De Natura Fossilium (p. 252) there can be no doubt that he means 



asbestos. This mineral was well-known to the Ancients, and is probably earliest referred to 



(3rd Century B.C.) by Theophrastus in the following passage (29) : " There is also found in 



" the mines of Scaptesylae a stone, in its external appearance somewhat resembling wood, 



" on which, if oil be poured, it burns ; but when the oil is burnt away, the burning of the 



" stone ceases, as if it were in itself not liable to such accidents." There can be no doubt 



that Strabo (x, i) describes the mineral : " At Carystus there is found in the earth a stone, 



'" which is combed like wool, and woven, so that napkins are made of this substance, which, 



" when soiled, are thrown into the fire and cleaned, as in the washing of linen." It is also 



described by Dioscorides (v, 113) and Pliny (xix, 4). Asbestos cloth has been found in 



Pre-Augustinian Roman tombs. 



