le or preferably a
glass-worker's knife of hard Thuringian steel for cutting glass tubes
etc.; next a blowpipe flame, for although much can be done with the
ordinary Bunsen burner, a blowpipe flame makes for rapid work; and
lastly a bat's-wing burner.

[Illustration: FIG. 11.--Glass-cutting knife. a. handle. b. double
edged blade. c. shaft. d. locking nut. e. spanner for nut.]

1. The glass-cutting knife. This article is sold in two forms, a bench
knife (Fig. 11) and a pocket knife. The former is provided with a blade
some 8 cm. in length and having two cutting edges. The cutting edge when
examined in a strong light is seen to be composed of small closely set
teeth, similar to those in a saw. The knife should be kept sharp by
frequent stroppings on a sandstone hone. The pocket form, about 6-cm.
long over all, consists of a small spring blade with one cutting edge
mounted in scales like an ordinary pocket knife.

2. For real convenience of work the blowpipe should be mounted on a
special table connected up with cylindrical bellows operated by a pedal.
That figured (Fig. 12) is made by mounting a teak top 60 cm. square upon
the uprights of an enclosed double-action concertina bellows (Enfer's)
and provided with a Fletcher's Universal gas blowpipe.

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 5x0.5~ cm., for sedimentation reactions, etc., and
for containing small quantities of fluid to be centrifugalised in the
haematocrit. 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 goo