Why was the initial arc tube of Hewitt's invention necessarily constructed of quartz?

Answer

Glass would absorb too much of the ultraviolet radiation produced.

The quartz tube was required because standard glass material would absorb an excessive amount of the ultraviolet radiation generated by the mercury plasma.

Why was the initial arc tube of Hewitt's invention necessarily constructed of quartz?

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The Mercury Vapor Lamp 1901 - YouTube

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