High pressure mercury vapor lamp with zirconium getter

Claim 1

A HIGH PRESSURE MERCURY VAPOR DISCHARGE LAMP COMPRISING A QUATZ ARC TUBE ENVELOPE EXHIBITING SOME PERVIOUSNESS TO HYDROGEN AT ELEVATED TEMPERATURES AND DEFINING A DISCHARGE SPACE CONTAINING AN IONIZABLE MEDIUM INCLUDING MERCURY AND HAVING SEALED THEREIN A PAIR OF DISCHARGE SUPPORTING ELECTRODES, A SEALED GLASS OUTER JACKET ENCLOSING THE ARC TUBE, MEANS SUPPORTING THE ARC TUBE WITHIN THE JACKET AND PROVIDING ELECTRICAL CONNECTIONS TO SAID ELECTRODES, SAID LAMP BEING SUBJECT TO GRADUAL LIBERATION OF HYDROGEN IN THE INTER-ENVELOPE SPACE IN AMOUNTS SUFFICIENT TO BUILD UP A PRESSURE AT LEAST OF THE ORDER OF A MILLIMETER AFTER SEVERAL THOUSAND HOURS OPERATION AND BEING DELETERIOUSLY AFFECTED BY DIFFUSION OF SUCH HYDROGEN INTO THE ARC TUBE FROM THE INTER-ENVELOPE SPACE, AND A GETTER CONSISTING OF ZIRCONIUM METAL MOUNTED IN THE INTER-ENVELOPE SPACE AND IN HEAT RECEIVING RELATIONSHIP TO SAID ARC TUBE TO ABSORB HYDROGEN EVOLVED IN THE INTER-ENVELOPE SPACE PRIOR TO DIFFUSION INTO THE ARC TUBE AND THEREBY MAINTAIN THE DISCHARGE SPACE WITHIN THE ARC TUBE SUBSTANTIALLY FREE OF HYDROGEN.