_Glass Spirals._--If a tube is heated by means of a long, flat-flame burner, the softened tube may be wound on to an iron mandrel which has previously been covered with asbestos. The mandrel should be made slightly conical in order to facilitate withdrawal. It is desirable to heat the surface of the asbestos almost to redness by means of a second burner, and thus avoid undue chilling of the glass and the consequent production of internal strain. [Illustration: Fig. 7] _A Thermo-Regulator for Gas._--Fig. 7, _a-e_, shows an easily constructed thermo-regulator. The mercury reservoir, _a_, and the upper part, _b_, are made by joining two larger pieces of tubing on to the capillary. The gas inlet passes through a rubber stopper, in order to allow of adjustment for depth of insertion, and the bye-pass branches, _d_ and _e_, are connected by a piece of rubber tubing which can be compressed by means of a screw clip, thus providing a means of regulating the bye-pass. _Use of Glass Rod._--Apart from its most common laboratory use for stirring; glass rod may be used in building up such articles as insulating feet for electrical apparatus or acid-resisting cages for chemical purposes. Such a cage is shown by _f_, _g_ and _h_, Fig. 7. Further, by an elaboration of the method of making an exhaustion branch, given on page 18, blown articles may also be constructed from rod. Note the added parts of _e_, Fig. 9. _A Simple Foot._--The form of foot shown by Fig. 7, _k_, is easy to make and has many uses. First join a glass rod to a length of glass tubing as shown (the joint should be expanded slightly by blowing), cut off the tube and heat the piece remaining on the rod until it can be turned out as shown by _i_. This should be done with the large turn-pin, and care should be taken not to heat the supporting rod too strongly, otherwise the piece of tube will become bent and distorted; it is better to commence by heating the edge of the piece of tube and turn out a lip, then extend the heating by degrees and turn out more and more until the foot looks like that shown by _i_.