cap of the transport vial to charge the loading chamber a capped vial 1 is inserted into the collar 17 and pushed home while swivelling back and forth if necessary until cap 4 engages the dowel pins dry gas is flushed through the chamber to remove contaminants that may have entered and also to vaporize and remove any adhering to the external surfaces of the vial before the cap is unscrewed the vial is then turned counterclockwise until the cap is released and is drawn up in the collar to provide enough clearance to allow the pellets to tumble out into the bottom of the loading chamber as shown at 22 a gentle flow of a dry nonreactive gas is maintained at all times through the loading chamber to protect the pellets from atmospheric contamination the inert gas argon is preferred for this purpose because it is also used as the fill starting gas in the metal halide discharge lamps for which the pellets are destined the argon is introduced through inlet fitting 23 shown in fig3 and a vent valve 24 has two positions determining a low or a high rate of flushing the high flush rate is maintained while vials are being exchanged and for an interval after the insertion of a fresh vial long enough to thoroughly dry its external surface and flush out any moisture or contaminants a vial is kept in the collar at all times while the argon flush is at the low rate and this maintains the loading chamber sealed off from the atmosphere prior to replacing a vial.