llow of a
cork carrying a bit of glass tube for the same purpose to be inserted.
This tube should not be less than half an inch in inside diameter.
Never use a new bottle before it has been heated sufficiently to get
rid of grease and carbonaceous dirt. A convenient oxygen-making
apparatus is shown in Fig. 4, which is drawn from "life."

Sec. 16. For large blow-pipe work with lead glass I recommend a system
of four simple blow-pipes, in accordance with the sketch annexed. I
first saw this system in operation in the lamp factory of the
Westinghouse Electric Company at Pittsburg in 1889, and since then I
have seen it used by an exceedingly clever "trick" glass-worker at a
show. After trying both this arrangement and the "brush flame"
recommended by Mr. Shenstone, I consider the former the more
convenient; however, I daresay that either can be made to work in
competent hands, but I shall here describe only my own choice.
[Footnote: A brush flame is one which issues from the blow-pipe nozzle
shaped like a brush, i.e. it expands on leaving the jet. It is
produced by using a cylindrical air jet or a conical jet with a large
aperture, say one-eighth of an inch. See Fig. 25.]

As will be seen, the blow-pipe really consists of four simple brass
tube blow-pipes about three-eighths of an inch internal diameter and 3
inches long, each with its gas and air tap and appropriate nozzle.
Each blowpipe can turn about its support (the gas-entry pipe) to some
extent, and this possibility of adjustment is of importance, The air
jets are merely bits of very even three-sixteenths inch glass tubing,
drawn down to conical points, the jets themselves being about 0.035
inch diameter.

Fig. 5.

The flames produced are the long narrow blow-pipe flames used in
blow-pipe analysis, and arranged so as to consist mostly of oxidising
flame. The air-supply does not require to be large, nor the pressure
high--5 to 10 inches of water will do--but it must be very regular.
The "trick" glass-blower I referred to employed a foot bellows in
connection with a small weighted gasometer, the Westinghouse Company
used their ordinary air-blast, and I have generally used a large
gas-holder with which I am provided, which is supplied by a Roots
blower worked by an engine.

I have also used a "velocity pump" blower, which may be purchased
amongst others from Gerhardt of Bonn. The arrangement acts both as a
sucking and blowing apparatus, and is furnish