complete the equipment of the city, are large sales palaces,
such as are to be found in European manufacturing centers,
for the display of glass and other manufactures, the whole
year round. Such modern methods of display would
attract buyers from all over the country and from foreign
countries.
MANUFACTURE OF GLASS
It has been said by an eminent authority on the subject,
that glass is a compound of various elements chemically
combined, and yet it is not a true chemical compound,
for the reason that it is not combined in definite proportions,
as are many other chemical compounds. We may say,
in short, that glass is but little more than vitrified sand.
If we could obtain a temperature sufficiently high, we
could make glass from sand alone. That this is not done
in practice is because of the difficulty of getting a temperature
sufficiently high to vitrify the sand, and also
for the reason that we could not get vessels that would
withstand the heat.
Nothing short of the intense heat of the electrical
furnace will melt sand alone. So to make glass commercially
we are obliged to use an alkali in connection
with the sand to be able to flux or vitrify it in an ordinary
temperature, or such as can be maintained with the ordinary
fuel at our command. In practice we use an alkali—
preferably, carbonate of soda or potash. In connection
with these two materials we have to add for a base, either
lime or the oxide of lead. We use the nitrate of soda
because it also has high fluxing properties, and has a tendency
to make the “batch,” as we term it, boil; or, in other
words, to set up a violent agitation which facilitates the
melting. So we can say that ordinary glass is a double
silicate of soda and lime; or, if we make the finer qualities,
in which we use potash and lead, in that case it is a double
silicate of potash and lead. So that sand, or, technically
speaking, silicic acid, with lime and nitrate of soda, are
the main constituents of ordinary glass; while sand and
potash, with the oxide of lead. are the main constituents
