288 LEAD. 



Werner ; Plomb chromate, llauij \ Prismatic Lead-Spar, or Red 

 Lead-Spar, Jameson. — Its colour is hyacinth-red. It seldom 

 occurs massive, generally in flakes ; and crystalized in many 

 varieties of form, of which the primitive is an oblique four-sided 

 prism, fig. i. The lateral planes of the crystals are longitudinally 

 streaked, the other planes smooth, shining, or splendent, and the 

 lustre adamantine. The structure is distinctly lamellar ; the frac- 

 ture is small-grained, uneven. It is more or less translucent, and 

 gives a pale orange-yellow streak. It is almost sectile, and easily 

 frangible. The specific gravity is 5*7 to 6. Before the blow-pipe 

 it tinges borax green, and on charcoal it is reduced to the metallic 

 state. It does not effervesce with acids. It consists of, oxide of 

 lead 63-96, chromic acid 36*40. — Vauqnelin. Chromate of lead 

 is found in veins, in gneiss, at Beresofsk, in Siberia. In Russia, a 

 pigment is prepared from it of a very beautiful orange-yellow 

 colour. 



Sp. 7. Sulphate of Lead. — Vitrol Bleirz, Werner; Plomb 

 Sulphate, Hauy. — The colours are yellowish and greyish-white. 

 It occurs massive, disseminated, and crystalized, in oblique four- 

 sided prisms, and broad rectangular four- sided pyramids. The 

 crystals are small \ externally splendent ; internally shining, and 

 the lustre adamantine. The cross fracture is conchoidal ■ it 

 varies from transparent to translucent ; it is brittle, and yields to 

 the nail. Before the blow-pipe it melts, and is soon reduced to 

 the metallic state. It consists of 70-50 oxide of lead, 2575 sul- 

 phuric acid, 2-25 water.— Klaproth. Sulphate of lead is found at 

 Pary's mine in Anglesey, and Penzance, in Cornwall ; at Wan- 

 lockhead and Lead-hills, in Scotland. 



The physical characters of lead in its metallic state are univer- 

 sally known. It has a blueish-white colour, and, when recently 

 melted or cut, exhibits considerable lustre, which it looses when 

 exposed for some time to the air. It is nearly insipid, and, like 

 copper, emits, when rubbed, a peculiar unpleasant odour. It 

 stains the fingers, and paper, of a blueish colour, and its specific 

 gravity is 11 35. It is very soft and flexible, and, though it has 

 little tenacity, it is very malleable, and may be beaten into thin 

 leaves and drawn into wire. It melts at about 610° of Fahrenheit, 



