ham wire gauge--does
not do, for it gets burned through, and perhaps allows the work
to fall apart at a critical moment.

The work being securely fastened, the next step is to cover the
cleaned parts with flux in order to prevent oxidation. For this
purpose "glass borax" is employed. "Glass" borax is simply ordinary
borax which has been fused for the purpose of getting rid of water of
crystallisation. The glass borax is reduced to powder in an iron
mortar, for it is very hard, and is then made up into a cream with a
little water. This cream is painted on to the parts of the work which
are destined to receive the solder.

The next step is to prepare the spelter, and this is easily done by
mixing it with the cream, taking care to stir thoroughly with a
flattened iron wire till each particle of spelter is perfectly covered
with the borax. The mixture should not be too wet to behave as a
granular mass, and may then be lifted on to the work by means of the
iron spatula.

Care must be taken to place the spelter on those parts only which are
intended to receive it, and when this is done, the joint may be
lightly powdered over with the dry borax, and will then be ready for
heating.

If the object is of considerable size it is most conveniently heated
on the forge; if small the blowpipe is more convenient. In the
latter case, place the work on a firebrick, and arrange two other
bricks on edge about it, so that it lies more or less in a corner. A
few bits of coke may also be placed on and about the work to increase
the temperature by their combustion, and to concentrate the flame and
prevent radiation. The temperature is gradually raised to a bright
red heat, when the spelter will be observed to fuse or "run," as it is
technically said to do.

If the cleaning and distribution of flux has been successful, the
spelter will "run" along the joint very freely, and the work should be
tapped gently to make sure that the spelter has really run into the
joint. The heating may be interrupted when the spelter is observed to
have melted into a continuous mass. As soon as the work has fallen
below a red heat it may be plunged into water, a process which has the
effect of cracking off the glass-like layer of borax.

There is, however, some risk of causing the work to buckle by this
violent treatment, which must of course be modified so as to suit the
circumstances of the case. If the joint is in such a position that
the bor