Melting of the Arsenic metal under pressure.

Arsenic is a one of two elements which does not melt at normal pressure (another one is carbon). But in sealed ampule it's possible to melt it at the temperature 817C and pressure 35 bar. You can clearly see yellow Arsenic vapors (consists of As4 molecules).
After beginning of the cooling down, As start to boil and re condense on the walls of ampule. Then quickly crystallize.
This video recorded with the light but you can also see similar movie without external light.

[everettduncan]

At 1:30 you can see the arsenic reaching its triple point

[КотикЛаваш-сс]

какой замечательный канал, подпишусь)

[lajoswinkler]

Arsenic is not a metal, it's semimetal.