3. An ordinary bat's-wing gas-burner mounted at the far corner of the table top is invaluable in the preparation of tubular apparatus with sharp curves, and for coating newly-made glass apparatus with a layer of soot to prevent too rapid cooling, and its usually associated result--cracking. [Illustration: FIG. 12.--Glass blower's table with Enfer's foot bellows.] 6. ~Sedimentation tubes 5×0.5~ cm., for sedimentation reactions, etc., and for containing small quantities of fluid to be centrifugalised in the hæmatocrit. These are made by taking 14-cm. lengths of stout glass tubing of the requisite diameter and heating the centre in the Bunsen or blowpipe flame. When the central portion is quite soft draw the ends quickly apart and then round off the pointed ends of the two test-tubes thus formed. With the glass-cutting knife cut off whatever may be necessary from the open ends to make the tubes the required length. A rectangular block of "plasticine" (modelling clay) into which the conical ends can be thrust makes a very convenient stand for these small tubes. ~Capillary Pipettes or Pasteur's Pipettes~ (Fig. 13 a).--These little instruments are invaluable, and a goodly supply should be kept on hand. They are prepared from soft-glass tubing of various-sized calibre (the most generally useful size being 8 mm. diameter) in the following manner: Hold a 10 cm. length of glass tube by each end, and whilst rotating it heat the central portion in the Bunsen flame or the blowpipe blast-flame until the glass is red hot and soft. Now remove it from the flame and steadily pull the ends apart, so drawing the heated portion out into a roomy capillary tube; break the capillary portion at its centre, seal the broken ends in the flame, and round off the edges of the open end of each pipette. A loose plug of cotton-wool in the open mouth completes the capillary pipette. After a number have been prepared, they are sterilised and stored in batches, either in metal cases similar to those used for the graduated pipettes or in large-sized test-tubes--sealed ends downward and plugged ends toward the mouth of the case. [Illustration: FIG. 13.--Capillary pipettes. a, b, c.] The filling and emptying of the capillary pipette is most satisfactorily accomplished by slipping a small rubber teat (similar to that on a baby's feeding bottle but _not perforated_) on the upper end, after cutting or snapping off the sealed point of the capillary portion. If pressure is now exerted upon the elastic bulb by a finger and thumb whilst the capillary end is below the surface of the fluid to be taken up, some of the contained air will be driven out, and subsequent relaxation of that pressure (resulting in the formation of a partial vacuum) will cause the fluid to ascend the capillary tube. Subsequent compression of the bulb will naturally result in the complete expulsion of the fluid from the pipette (Fig. 14). [Illustration: FIG. 14.--Filling the capillary teat-pipette.]