24. If a deeper blue is required, use the following, which I shall
dignify by the name of
PURPLE STARS.
No. 9.
Chlorate of potash 16 parts.
Chertier’s copper 12 „
Calomel 8 „
Stearine 2 „
Sulphur 2 „
Shellac 1 part.
This gives the most intense blue that I have seen used in pyrotechny,
and, with crimson or yellow stars, forms a truly magnificent contrast.
Chertier’s copper is a preparation discovered by a Frenchman of that
name, and particularly adapted to the requirements of the pyrotechnist.
It is made as follows:—Take any quantity of common sulphate of copper
(blue vitriol) and dissolve it in as little water as possible; then take
an _equal_ quantity by weight of chlorate of potash and dissolve it also
in as little water as will hold it in solution. Mix these two solutions,
and boil them _gently_ over a clear fire until the moisture is nearly
evaporated; then dry the green precipitate that remains _by a gentle
heat_. _When dry_ treat it with strong liquor ammoniæ till it changes to
a _deep blue_ colour; then let it dry very gradually in a warm place. If
this operation be properly performed you will have a fine, very light
blue powder, which is in reality a _chlorate of potash with copper and
ammonia_. This is what I designate as Chertier’s copper. Messrs. Bolton
and Co. will no doubt prepare it for you if you please.
The stearine employed in the above composition must be in fine powder.
It is easily reduced to this state by being treated in the same way as
camphor or spermaceti. If a few drops of spirits of wine are used with
it, it can be powdered in a mortar.
Compositions Nos. 7, 8, and 9, must be moistened, NOT _with the solution
of shellac, but with the gum-water_ which have recommended to be used in
making up the _brilliant_ stars. Care, however, should be taken that for
this purpose the gum-water has not become acid by long standing. A very
little of the fluid will make the composition bind well, and will enable
you to form from it stars of great tenacity and hardness.
I think now that want of variety is a thing that you can hardly complain
of; but I must beg you to bear in mind the following particulars:—
The stars of which I have at present spoken are only _for rocket
purposes_; they are not to be used for Roman candles. Another plan is
adopted with reference to these, and their preparation will be described
in its proper place.
When these rocket stars are to be used some of the powder recommended
before must be strewed among them; you can make that mixture weaker if
you please, using one proportion of fine charcoal to _five_ or even
_four_ of meal-powder.
The projecting ends of quick-match render these stars much more certain
of ignition than the ordinary cubic stars.
It is advisable not to prepare your coloured stars until you are ready
to use them, because, unless protected from damp in the most careful
manner, they will lose some of their beauty, and you will thereby not be
making the most of them. They may appear to you expensive things to
prepare, but you must bear in mind that _two or three rockets containing
them_ are quite sufficient for any one exhibition such as I suppose you
will be likely to give.
Remember that the red, green, and blue or purple stars may be used
_mixed_ with a very beautiful effect. The purple and golden, or purple
and crimson, or rose, will also form excellent contrasts.