Abstract :
The first commerical metal-filament lamp was the osmium lamp, the filaments of which were made of osmium. They had a good commercial life at 1.5 watts per c-p., and were used in considerable quantity in Vienna and Berlin where they were made. They were not shipped to distant points, as the filaments were very fragile, and the metal osmium was so valuable that it was desirable to recover all the lamps after they had burned out.
