Low pressure mercury vapor discharge lamp containing an amalgam

In a low pressure mercury vapor discharge lamp of the type having an amalgam for absorbing mercury vapor by contacting an exposed surface portion of the amalgam, a sealed glass envelope having disposed therein ingredients comprising mercury for forming an electric arc sustaining gas within the interior of the glass envelope, a pair of electrodes mounted in sealing relationship with said glass envelope, a tubulation positioned at a location spaced from said electrodes, said tubulation having one end in communication with said arc sustaining gas and the other end being closed, and a container confined within said tubulation and adapted for retention of liquified amalgam within said tubulation wherein mercury vapor from said electric arc sustaining gas is in communication with said amalgam for absorption, wherein the improvement comprises a restriction at the other end of said tubulation wherein said container holds the amalgam confined within the tubulation when said lamp is mounted with said electrodes in an upward position.