Chap. 32.] QUICKSILVER. 113 



by the name of "crudaria." 12 In ancient times, the excavations 

 used to be abandoned the moment alum 13 was met with, and no 

 further 14 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 a vein of copper beneath alum, has withdrawn any such limits 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 23 with silver should be black. 



CHAP. 32. QUICKSILVER. 



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

 yields a humour that- is always 10 liquid, and is known as 

 " quicksilver." 17 It acts as a poison 1 '' upon everything, and 

 pierces vessels even, making its way through them by the 

 tigeiicy of its malignant properties. 15 * All substances lloat Upon 

 the surface of quicksilver, witli -the exception of gold, 20 this 

 being the only substance that it attracts to itself.- 1 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 effect 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 oi 

 purity behind. 22 



12 Meaning " raw" silver, apparently. 



13 " Alumen." Sec ]{. xx\v. c. 52. 



n.Kirchcr speaks of this hi-ing still the case in his time. 



15 See Chapter 1'J of this Hook. 



16 " Vomica liquori* a-terni." Mercury or quicksilver becomes solidified 

 anil assumes a crystalline texture at 40' below zero. It is found chiefly 

 in the state of UipUuret, which is decomposed by distillation with iron or 

 lime. It is also (mind in a native state. 



l ~ " Argeiitum viviiTii," " living silver." 



^ Aj.iSMm thinks that this is not to be understood literally, but that 

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



\v < Ptrmanaus tab- diru." 



2 " The specific gravity of nn-rcury is 13.508, that of hammered gold 

 19. .SGI. Plat ilium is only a recent'di.seoviry. 



21 " Id uniim ad se trahit." 



" The lirst use of ({uieksilver is commonly reckoned a Spanish in- 

 vention, discovered about the middle of the tixtceuth ct-ntury ; but it 

 VOL. VI. 1 



