In jacketing vessels, to prevent draughts, care must be taken
that the jackets do not cause currents of cold air to rise rapidly up
the sides of the vessel, and so cool it. If this is the case, the use of
a jacket, instead of being an economy, is a positive expense, and waste
of heat. Many processes, such as making oil and turpentine varnishes,
require a heat under instant control, and in these the use of gas is an
important matter, as the loss and risk of fire are very serious elements
of expense, more especially in small works where special and costly
preparations for contingencies cannot be afforded. I have here a burner
which, for its power, is, perhaps, the most compact and gives the
highest temperature of any burner yet known, and it is easily made in
almost any size; it has, I think, many special advantages. The use of
gauze, which is its only weak point, is more than compensated for by the
very high duties obtained in practice with it, owing to the compactness
and concentration of the heat obtained.
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