ired to attach an
ozone generator, of the form shown by Fig. 19, which previously had been
cemented into a heavy copper jacket, to a pressure-gauge rigidly fixed
to a support, and of considerable size. The employment of a flexible
spiral connection was prohibited by the fact that it was necessary that
the volume of the connecting-tube should be but a small fraction of that
of the ozone generator, a condition which compelled the use of a tube of
almost capillary bore, and of inconsiderable length. At the same time
the frailness of such a connection made it necessary to fix the
generator and pressure-gauge rigidly to their supports, in order to
avoid the possibility of breakage by slight accidental movements of
either of them, and it was obviously necessary to fix the pieces of
apparatus in their final positions before joining them, lest the fine
tube which connected them should be fractured during adjustment. The
possibility of a strain being caused by the contraction that would occur
during the cooling down of the joint last made had to be provided for
also. The desired object was effected as follows. In Fig. 29 _A_
represents a section of the ozone generator at the point where the tube
to connect it to the gauge was fixed. _B_ represents the top of the
gauge, with the side tube _C_, which was to be connected with that from
_A_, viz. _D_. The ends of _C_ and _D_ were expanded as shown at _D_ (by
melting them and blowing them out), so that one of them, made rather
smaller than the other, could be overlapped by the larger one. _A_ and
_B_ being rigidly fixed in their final positions, with _C_ and _D_ in
contact, as shown in the figure, all openings in the apparatus were
closed, except one, to which was attached an india-rubber blowing-bottle
by means of a tube of india-rubber long enough to be held in the hand of
the operator, and to allow him to observe the operation of joining the
tubes at _D_. When everything was in readiness, a very small-pointed
flame from a moveable blow-pipe held in the hand was directed upon the
glass at _D_ till it melted and the two tubes united. To prevent the
fine tube when melted from running into a solid mass of glass, and so
becoming closed, a slight excess of pressure was maintained inside the
apparatus during the operation by forcing air into it with the
india-rubber blower from the moment at which _C_ and _D_ united. A point
of charcoal was kept in readiness to support the softened glass a