The 68530 is a gas filled full wave rectifier for use in battery charging. Given the data sheet dates from 1960 it could only be for a few years that such a valve would be used before designs employing semiconductors would have taken over that market niche.
These Argon filled rectifiers with Tungsten filaments were branded Tungar and the original examples date to the 1920's or 1930s.
The special four pin base. The valve was designed to operate vertically.
The envelope is completely opaque. He we have the text printed on the glass.
The balloon envelope is 80 mm in diameter, and excluding the base pins is 129 mm tall.
Reference: Data-sheet. Type 68530 was first introduced in 1960. See also1960 adverts.