Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/17/84; site aluxe.UUCP Path: utzoo!watmath!clyde!cbosgd!cbdkc1!desoto!cord!bentley!hoxna!houxm!mhuxj!aluxe!2141smh From: 2141smh@aluxe.UUCP (S. M. Henning,) Newsgroups: net.consumers Subject: Re: Lifetime Lightbulbs Message-ID: <700@aluxe.UUCP> Date: Thu, 7-Feb-85 16:06:24 EST Article-I.D.: aluxe.700 Posted: Thu Feb 7 16:06:24 1985 Date-Received: Sat, 9-Feb-85 09:32:03 EST References: <1516@hplabs.UUCP> <517@houxu.UUCP> <8054@brl-tgr.ARPA> Organization: AT&T Bell Laboratories, Allentown, PA Lines: 8 > Also, the tungsten actually boils off. If we fill the bulbs with > a halogen we can get the tungsten deposited back on the filiment. > I used to be able to explain how this works, but I've forgotten. > The tungsten forms a tungsten-halide at lower intermediate temperatures. The tungsten-halide is a gas and carries the gas back to the filament where the heat decomposes the tungsten halide into tungsten which is deposited on the filament and halogen gas which free to do it again as needed.