ch
they are made, 82-83

CHAPTER VII.

VITREOUS SILICA

Introductory--Properties of Vitreous Silica--Preparing
non-splintering Silica from Brazil Pebble--Apparatus--The
Method of Making Silica Tubes--Precautions--Making Larger
Tubes and other Apparatus of Silica--Quartz Fibres, 84-95

INDEX, 97

CHAPTER I.

_GLASS-BLOWER'S APPARATUS._

=Introductory.=--I shall endeavour to give such an account of the
operations required in constructing glass apparatus as will be useful to
chemical and other students; and as this book probably will come into
the hands of beginners who are not in a position to secure any further
assistance, I shall include descriptions even of the simple operations
which are usually learned during the first few hours of practical work
in a chemical or physical laboratory. I shall not give any particular
account of the manufacture of such apparatus as thermometers, taps,
etc., because, being in large demand, they can be bought so cheaply that
time is not profitably spent in making them. But it will be found that
what is included will enable any one, who will devote sufficient time to
acquiring the necessary manipulative dexterity, to prepare such
apparatus as test-tubes, distillation flasks, apparatus for washing
gases, ozone generating tubes, etc., when they are required, as they
often are, without delay or for special purposes. The amateur probably
will not succeed in turning out apparatus so finished in appearance as
that of the professional glass-blower until after long practice, but
after a little daily practice for the space of a few weeks, any one who
is fairly skilful in ordinary manipulation, and who perseveres in the
face of failure at first, will find himself able to make almost all the
apparatus he needs for lecture or other experiments, with a considerable
saving in laboratory expenses, and, which very often is more important,
without the delay that occurs when one depends upon the professional
glass-worker. In the case of those who, like myself, work in the
provinces, this latter advantage is a very weighty one.

After the description of the instruments used in glass-blowing, which
immediately follows, the following arrangement of the subject has been
adopted. In the first place, an account of the two chief kinds of glass
is given, and of