Philips Air cooled fixed anode, hot cathode line focus tube, 12” (30 cms) long, made in England, dated 1935. An identical tube is still in the housing, and was in a good working condition when the set-up was dismantled in 1965. ( I used it !)

            The cooling is by forced air: the suction fan (quite noisy!) is in the black section on the left of the housing, and the air input is through the perforations on the right end.  This tube could easily be run up to 100 kV and 100 mA.

            The particularity of this tube is the metal waistline jacket (looks like copper or bronze) under the black bakelite protective fixings, and to which the name "Metalix" probably refers.

Picture of the “Philips METALIX Junior - 1928 ” as  seen  in “Mit Röntgen begann die Zukunft” 1981,  by  Werner  Fehr  of  “CHF Müller-Philips - Hamburg”, p.62.