Let P (fig. 2) be the particle and PB a normal to the surface.
Blue and purple unite to form purple-blue (PB), popularly called violet.
Lead is not a compound, but an element whose chemical symbol is PB, taken from the Latin name for lead.
Now, similarly, at PB the sector B has come around and begins to pass behind P.
The symbol for the element lead2.
The symbol for lead.
A soft, ductile, heavy, bluish-gray metallic element that is extracted chiefly from galena. It is very durable and resistant to corrosion and is a poor conductor of electricity. Lead is used to make radiation shielding and containers for corrosive substances. It was once commonly used in pipes, solder, roofing, paint, and antiknock compounds in gasoline, but its use in these products has been curtailed because of its toxicity. Atomic number 82; atomic weight 207.2; melting point 327.5°C; boiling point 1,744°C; specific gravity 11.35; valence 2, 4. See Periodic Table. See Note at element.