Chap. 32.] QnCKSILTER. 113 



by the name of ''crudaria."^^ In ancient times, the excavations 

 used to be abandoned the moment alum^^ was met with, and no 

 further^* search was made. Of late, however, the discovery of 

 a vein of copper beneath alum, has withdrawn any such limits 

 to man's hopes. The exhalations from silver-mines are dan- 

 gerous to all animals, but to dogs more particularly. The 

 softer they are, the more beautiful gold and silver are con- 

 sidered. It is a matter of surprise with most persons, that lines 

 traced^^ with silver should be black. 



CHAP. 32.-^QnCKSILVEE. 



There is a mineral also found in these veins of silver, which 

 yields a humour that is always^^ liquid, and is known as 

 "quicksilver."" It acts as a poison^- upon everything, and 

 pierces vessels even, making its way through them by the 

 agency of its malignant properties. ^^ AH substances float upon 

 the surface of quicksilver, with the exception of gold,^ this 

 being the only substance that it attracts to itself.-^ Hence 

 it is, that it is such an excellent refiner of gold ; for, on being 

 briskly shaken in an earthen vessel with gold, it rejects all 

 the impurities that are mixed with it. When once it has thus 

 expelled these superfluities, there is nothing to do but to sepa- 

 rate it from the gold : to eflect which, it is poured out upon 

 skins that have been well tawed, and so, exuding through them 

 like a sort of perspiration, it leaves the gold in a state of 

 purity behind.^ 



^- Meaning " raw" silver, apparently. 



13 '• Alumen." See B. xxxv. c. -52. ' 



1* Kii-cher speaks of this being still the case in his time. 



13 See Chapter 19 of this Book. 



i'^ " Vomica liquoris aetemi." Mercury or quicksilver becomes solidified 

 and assumes a crystalline texture at 40^" below zero. It is found chiefly 

 in the state of sulphuret, which is decomposed by distUlation with iron or 

 lime. It is also found in a native state. 



i: «i Argentuni vivum," "living silver." 



1- Ajasson thinks that this is not to he understood literally, but that 

 Pliny's meaning is, that mercury is a universal dissolvent. 



1^ ''Permanans tabe dira." 



-'-' The specific gravity of mercury is 13.59S, that of hammered gold 

 19.361. Platinum is only a recent discovery. 



-1 '• Id unum ad se traliit." 



-- '• The first use of quicksilver is commonly reckoned a Spanish in- 

 vention, discovered about the middle of the sixteenth century ; but it 



VOL. VI. I 



