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LEAD. 
THE only coloured preparation of leady is that 
produced by calcination in the furnace. The firft 
of the primary colours produced by this procefs is 
yellow, the calx paffing from that colour through 
orange into red. 
It is remarkable, that, though in the calcination 
previous to the reverberatory heat in which thefe 
colours are produced, the lead is diminiJJjed in 
weight j yet in the reverberatory fire it gains con- 
fiderably, and in proportion to that increafe of 
gravity, it paffes from the more refrangible to the 
lefs r frangible colours ; fo that while the calx re- 
mains of a lefs weight than that of the lead originally,^ 
it’s colour is yellow, with the next mcreafe of 
weight it paifes to orange, which is the colour of 
dlnem ; unde et non tantum tin£lum ipfum eft, fed et tin£luram 
ruhedlnis confert abundante'm. 
Dum c'ltrinum dicitur, externus vultus qualis eft poft excodti- 
onem refpicitur : ilia tamen citrinitas igne caementi et in opere 
philofophico fumma rubedtne permutatur, Itaquehinc eft philo- 
Ibpliorum axioma, quod in dtrinitate lateat rubedo excellemiftinia,_ 
qualis eft rubedini gemmae. 
V oces occultum, manifeftum, non ita pueriliter funt accipiendae, 
quafi in fuperficie fit flavum, in centro rubrum: fed progrefliones 
colorum in perfedlione artiliciali notantur, quod naturali pro- 
cfivitate et difpofuione poft citrinitatem abolitam, alTuinat 
rubedinern. 
Leo ruber non folet vocari, ante quam ab arte eleboratum, et 
aftrale, ut aiunt, fadtum. Potentia tamen etiam fimplcx et natu- 
rale aurum ita vdcare non eft abfurdum, cujus tindiura appella, 
tur ejus fanguis, quo vocabulo et fcrnienturn denotatur. 
glaft 
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