Table VII gives the melting points of several metals which are highly refractory and those already mentioned are not the only ones which have been successfully used in incandescent lamps. Titanium, zirconium, iridium, etc., have been successfully employed, but the tantalum and tungsten lamps are the only ones which are used to any extent in the United States.

Table VII. Melting Point Of Some Metals

Metal

Approximate Melting Point in Degrees C.

Tungsten

3080-3200

Titanium

3000

Tantalum

2900

Osmium

2500

Platinum

1775

Zirconium

1500

Silicon

1200

Carbon (not a metal)

3000