this purpose, the heat can scarcely be too great: driven snow is
not whiter than the burning coal in the centre of the furnace, when it
has reached its maximum of intensity.
If the Glass do not get fine by the usual
time allotted, and it should become coddled or gelatinous, it never
will recover, however urged by subsequent fusion. Such Glass must be
ladled into water, and considered only as cullet for re-fusion, with a
proportion of new materials.
The man who acts as tiseur has a
substitute allowed him every other Sunday. One man only is necessary to
attend the furnace while founding; but a boy, in addition, is desirable,
in case of accident by broken pots, that he may be sent to procure
assistance, should it be necessary; or that he may, in such cases,
suddenly ladle the remaining contents of a broken pot of Glass into water,
to prevent its running to waste through the bars, and checking the heat
of the furnace.
Formerly, scum, or sandiva, was
allowed to run off, or was taken off the surface of the pots when opened
for working, on Monday mornings; but the modern relative proportions
and purity of the chemical materials are so good, as seldom to render
this skimming necessary.
The blowing process commences on Monday
early, and ceases on Friday, in the morning, or towards noon, so that the
blowers have part of Friday and the whole of Saturday, for recreation:
still, it is not found that the average health or longevity of English
workmen is superior to the French, who work throughout the week. Both
French and English have two sets of workmen, day and night, relieving each
other usually every six hours; but in some parts of the Continent,