50. We may now go on to deal with another branch of this part of our
subject—viz., that which concerns the manufacture of coloured lights for
illuminating wheels, or set-pieces, or any larger kind of firework. This
species of colour is perhaps more useful in exhibition work than any
single firework that can be named, for there are few set-pieces, or
wheels, or designs of any pretensions to which these coloured lights
cannot be adapted, and adapted, too, with a very enhancing effect.
Their preparation is exceedingly simple. They are generally made in two
sizes only; these are the two-ounce and the one-ounce sizes. The cases
are made of cartridge or foolscap paper and are about two inches long
for the two-ounce size and one inch and three-quarters for the one-ounce
size. Used-up copy-books furnish excellent paper for making these
coloured light cases. Three or four rounds of the paper will give you
ample thickness for the case. The paper should be pasted _all the way
along the strips_. When the cases are thoroughly dry, ram into the
bottom of them some dry powdered clay; this will make a close end, and
will also furnish an incombustible part by which the case may be tied or
fastened to its place. The clay is often rammed so as to fill the case
nearly half-way up; but, of course, the space left for the composition
will depend upon the length of time that you wish the colour to burn.
There is some exactness and nicety, besides a certain amount of actual
experience, required for the proper adjustment of these colours to the
cases in combination with which they are to burn. The coloured light
should be under control, so that it makes its appearance and introduces
its intended effect at the right time, and lasts only as long as it is
required to last. I will now give a few formulæ for these larger
coloured lights. These, if made up with ordinary care and their
ingredients thoroughly mixed will produce magnificent colours, both as
regards depth of tint and brilliancy of reflective power. The
compositions given above for lances are for the most part of too rapid
combustion to answer well in these larger and more open cases, but the
following will be found to succeed admirably if the chemicals used be
only pure and dry, and properly incorporated:—
WHITE LIGHTS FOR DECORATION.
No. 19.
Nitre 4 parts.
Sulphur 1 part.
Sulphide of antimony 1 „
Or,
No. 20.
Nitre 4 parts.
Sulphur 1 part.
Meal-powder 1 „
These will give the ordinary bluish-white light, and compositions made
from them will remain good for any length of time.
The yellow lights may be made from the formulæ given under the head of
Lances.