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For many years no advance was made upon these forms of burner, but
when, ten years ago, it was recognized that anything which cools the
flame reduces its value, while anything which increases its
temperature raises its illuminating power, then a change took place in
the forms of burner in use, and the regenerative burners, introduced
by such men as Siemens, Grimston, and Bower, commenced what was really
a revolution in gas lighting.

By utilizing the heat contained in the escaping products of combustion
to raise the temperature of the gas and air which are to enter into
combination in the flame, an enormous increase in the temperature of
the solid particles of carbon in the flame is obtained, and a far
greater and whiter light is the result.

The Bower lamp, in which (at any rate in the later forms) the flame
burns between a downward and an upward current of air, was one of the
first produced, and so well has it been kept up to date that it still
holds its own; while as types of the "inverted cone" regenerative
burner, we may also take the Cromarty and Wenham lights, which have
been followed by a host of imitators, and so closely are the original
types adhered to that one begins seriously to wonder what the use of
the Patent Office really is.

The Schulke, and the last form of Siemens regenerative burner,
however, stand apart from all the others by dealing with flat and not
conical flames, and in both regeneration is carried on to a high
degree. The only drawback to the regenerative burner is that it is by
far the best form of gas stove as well as burner, and that the amount
of heat thrown out by the radiant solid matter in the flame is, under
some circumstances, an annoyance. But, on the other hand, we must not
forget that this is the form best adapted for overhead burners, and
that nearly every form of regenerative lamp can be adapted as a
ventilating agent, and that with the withdrawal of the products of
combustion from the air of the room, the great and only serious
objection to gas as an illuminant disappears.

When coal gas is burned, the hydrogen is supposed to be entirely
converted into water vapor, and the carbon to finally escape into the
air as carbon dioxide; and if this were so, every cubic foot of gas
consumed would produce approximately 0.52 cubic foot of carbon dioxide
and 1.34 cubic feet of water vapor, while the illuminating power
yielded by the cubic foot of gas will