The manufacture of tube and cane glass for various purposes forms a large and extensive portion of the glass trade. Considerable quantities of tube and cane glass in various sizes are used by lamp workers in the manufacture of certain forms of chemical apparatus and filling electric light bulbs. By re-heating glass tube and working before a blow-pipe flame, the various forms of test tubes, pipettes, burettes, soda-lime U-tubes, and condensers are made. Generally, for chemical apparatus two classes of tube are made, one a soft soda tube, and the other hard combustion tubing. Particular care has to be devoted to the grading and sorting of the various sizes. The bore of the tube, the thickness of the walls, and the outside width have all to be checked and the lengths classed accordingly. In the manufacture of tubing, unless the glass is of large size or great thickness, it is not annealed, and shows a case-hardened condition which materially increases the strength of the tube to resist internal pressure, as is the case with boiler gauge tubing. In the manufacture of apparatus from tube and cane, care must be taken that the various pieces used in welding together the different portions of the apparatus should be of the same temper and composition, and supplied from one source, so that they may join and work perfectly together. The lamp worker or glass blower should take care to get his supplies from a reliable source, so that the glass pieces will be adapted to work together. Trouble occurs when odd tubings from various makers are worked together. The same applies to fancy glass working, where various coloured canes are worked into ornaments. Reputable firms can always supply from stock such colours and tubing properly adapted for their specific purposes, and they take every precaution to see that the various colours join and work together. Supplies of glass rod can be had that will join on to platinum, nickel, iron, or copper wire with sound joints.