440

BOOK X.

three librae of alum, half a libra of brick dust, and three-quarters of a libraof spring water. The sixth consists of four librae of vitriol, three librae ofsaltpetre, one of alum, one libra likewise of stones which when thrown into afierce furnace are easily liquefied by fire of the third order, and one and ahalf librae of spring water. The seventh is made of two librae of vitriol, oneand a half librae of saltpetre, half a libra of alum, and one libra of stoneswhich when thrown into a glowing furnace are easily liquefied by fire of thethird order, and five-sixths of a libra of spring water. The eighth is made oftwo librae of vitriol, the same number of librae of saltpetre, one and ahalf librae of alum, one libra of the lees of the aqua which parts gold fromsilver ; and to each separate libra a sixth of urine is poured over it. Theninth 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 libraof spring water. Only the tenth lacks vitriol and alum, but it contains threelibrae of saltpetre, two librae of stones which when thrown into a hot furnaceare 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 6 , and one and one-sixthlibrae of spring water.

All the vitriol from which the aqua is usually made is first reduced topowder in the following way. It is thrown into an earthen crucible lined onthe inside with litharge, and heated until it melts ; then it is stirred with acopper wire, and after it has cooled it is pounded to powder. In the samemanner 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 fromimpurities, yet there are certain compositions which possess singular power.

4 Agricola, in the Interpretatio, gives the German equivalent for the Latin aerugo asSpanschgrun —“ because it was first brought to Germany from Spain ; foreigners call it“ viride aeris (copper green).” The English “ verdigris ” is a corruption of vert degrice. Both verdigris and white lead were very ancient products, and they naturally findmention together among the ancient authors. The earliest description of the method ofmaking 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 (vu, 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, salamanderhar). From Agricola’selaborate description in De Natura Fossilium (p. 252) there can be no doubt that he meansasbestos. 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 doubtthat Strabo (x, 1) 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 alsodescribed by Dioscorides (v, 113) and Pliny (xix, 4). Asbestos cloth has been found inPre-Augustinian Roman tombs.