What is the fine-grained topic of the following text: Argon is extensively used in filling incandescent and fluorescent lamps and electronic tubes; as an inert gas shield for arc welding and cutting; as a blanket in the production of titanium, zirconium and other reactive metals; to flush molten metals to eliminate porosity in castings; and to provide a protective shield for growin silicon and germanium crystals. Only return the topic.
Uses of Argon