58. We come now to the most telling colour of all—the red, or crimson as
it is usually called. In the preparation of the _green_ fires the
_purity_ of the nitrate of baryta is the most important consideration.
In that of the red fires the _dryness_ of the strontia is the main
point. This is most especially to be borne in mind, as success or
failure depends upon it. A really good red-coloured fire is often the
making of an exhibition or its redeeming point, but in any case it is a
most important feature, and on that account is worth the expenditure of
any trouble on its preparation.
I shall give several formulas for red fires, each having its own
characteristic properties. You will have but to determine the particular
description of fire that is necessary, and I think you will find all
that you need among the following compositions:—
RED FIRE.
No. 10.
Nitrate of strontia 20 parts.
Chlorate of potash 3 „
Sulphur 5 „
Antimony 2 „
Charcoal (fine) 1 part.
This formula gives rather a deep rose-coloured flame, and has a most
intense illuminating power. But the composition is one on which the
non-dryness of the nitrate of strontia has the most disastrous effects.
It is, when properly prepared, a very useful composition for
illuminating buildings, &c., &c.
The next is a slower composition, having decidedly more intensity of
colour. It is a remarkably good composition, having considerable depth
of tint, and a very fair amount of reflective power. Its proportions are
these:—
No. 11.
Nitrate of strontia 64 parts.
Chlorate of potash 4 „
Charcoal (fine) 5 „
Sulphur 24 „
The next formula is one of very slow combustion, but of the greatest
depth of colour. It has but a small illuminating power, and can
therefore be employed only for certain purposes.
No. 12.
Nitrate of strontia 48 parts.
Chlorate of potash 4 „
Sulphur 12 „
Calomel 8 „
Chertier’s copper 2 „
Charcoal (fine) 1 part.
This composition, burns so slowly that if it be very much compressed, or
its case be at all thick, much of its effect is lost. I should therefore
recommend that it be laid in a heap upon a tile in order to be fired.
Its beauty will then be seen to the greatest advantage.
The following composition for red fire is the one which I have always
found the most generally useful:—
No. 13.
Nitrate of strontia 70 parts.
Chlorate of potash 6 „
Sulphur 24 „
Charcoal (fine) 2 „
Shellac 2 „
This composition, when employed in a case 1¾ inch in diameter, produces
a magnificent effect, and is at the same time a very economical
composition to make up. Its combustion does not appear rapid, and yet
there seems to be no lack of illuminating power combined with intensity
of colour. It is, of all the compositions which I give, the one best
adapted for the use of young aspiring pyrotechnists, as very certain in
its results, very inexpensive, and very easy to prepare.
Thus we are brought to the close of our list of compositions for
Coloured Bengal Fires. I trust that this list will be found to contain
all that you require, and contain it, too, in variety and abundance.
But we have still to consider how these compositions are to be encased
and fired.
COLOURED FIRES (To Encase).
59. The cases, made as directed above, I will now suppose to be dry and
ready for use. Your drift, with which the composition is to be
compressed into the cases, is one-sixteenth of an inch smaller in
diameter than your former. It will therefore pass easily within the
cases which were made upon “the former.” Now cut some pieces of
newspaper, or thin brown paper, into squares or circles about 3 inches
in diameter. Place the flat end of your drift in the centre of these,
and turn down the papers round its sides in the same way that papers or
bladders are turned down over bottles or jars when these are to be
capped or covered. Then insert the drift with the paper cap over it into
one end of the coloured fire case and push it through to the other end.
Now withdraw the drift, and leave the paper cap in the end of the
coloured fire case. Next place the case upright upon your driving-block
with the end, thus filled up, downwards, and put into it as much
powdered clay as will, when driven, occupy about half-an-inch in the end
of the case. Drive this clay down firmly with a few blows of the mallet,
taking care, however, not to rupture the case by exerting too great a
force.
The case is now ready to be filled with composition. This operation is
to be done as follows:—First put in enough of the composition to occupy
about half-an-inch in the case, and ram this down with a few light blows
of the mallet. Then put in another quantity, and ram that down in the
same way; and so on till the case is filled. I strongly recommend you
not to put in more composition at a time than will ram down into the
space of half-an-inch. You will find it easy to compress the whole of
the composition equally and uniformly by attending to this simple piece
of advice; and you will soon discover, if you do not already know, the
advantage of uniform compression.
When you have charged the case as far as you can with the drift and
mallet, that is, to about a quarter of an inch from the top of the case,
press the mouth of the case into the composition (from which you were
filling it) until the case becomes full up to the brim. Over the flat
surface of composition thus left, paste a piece of touch-paper, or any
thin paper, taking care not to paste that part of the paper which lies
against the composition, but only that which is to stick to the sides of
the case.
COLOURED FIRES (To Fire).
60. Your coloured fire is now complete and ready for firing. This is the
usual and most convenient way of preparing colours for exhibitions. But
for your own experiments you may place a small quantity of the
composition to be tried upon a tile or brick, not spreading it about,
but piling it into a pyramidal heap, to be lighted at the top. Many
persons adopt this plan for exhibitions, but it is not good, because
several of the best compositions burn too rapidly when unconfined by a
case. I only beg that you will do me the justice to remember that the
formulas which I have given above are intended to furnish compositions
suitable for burning in such cases as I have described, and not, as a
general rule, adapted for open and loose burning. My plan all along has
been this—to find compositions of sufficient freedom of combustion to
enable them to consume their case, to give a powerful light, and not to
burn out too rapidly. I think I have succeeded in gaining the first two
of these qualities in the compositions themselves, and the third by
compressing them closely in cases.
It is very much better to put into each case two different sorts or
colours of fire, making the fire, for instance, change from white to
red, or from green to purple. But if this be done, and more than one
case is to be burning at a time, of course an especial regard must be
had to the contrast of colour. You should never burn a yellow with a red
fire, or a yellow with a white; green with red, yellow with purple,
white with red make the best contrasts.
But, for my own part, I never burn two Bengal fires of different colours
at once. If the fires have any illuminative power at all, they are
pretty certain to neutralise one another’s effect, and so give you a
very poor and unsatisfactory return for your outlay. It is very true
that red and green are _complementary_ colours, as they are called, and
look very well side by side, but the effect produced upon an object by
illuminating it with a red and green light is anything but complementary
to the object or to the coloured fires themselves. If you wish, however,
to try the effect of the contrast, use compositions possessing the
greatest depth of colour and the least reflective power; in this case
the fires themselves will be complementary one to another, and their
non-illuminative properties will effectually prevent any confusion of
reflection. That what I have said above is true any one may discover by
getting two pieces of stained glass, one of a rich red, the other of a
rich green colour. Let these colours be thoroughly _transparent_, and if
you place one before the other and attempt to look through them, you
will find that you have a medium through which very little can be seen
at all.
The cases of coloured fire, made as directed above, must not be placed
perpendicularly to be fired, but _horizontally_. The reason of this is
very simple. While they are burning a sort of boiling lava is formed,
which is the refuse of the combustion, and this will considerably clog
the flame and rob it of much of its light if allowed to remain at the
mouth of the case. Now if the cases be placed horizontally, this lava
will fall away as it forms, and leave the fire to burn without
impediment.
All that it is necessary to do to give the cases this horizontal
position is to drive two long, stout nails into a post horizontally,
about an inch and a-half apart, and lay the case on these. Coloured
fires should, as a general rule, be fired at a distance of about three
or four feet from the ground.
But as one cannot always find nails of the proper sort for these
purposes, especially when at a distance from one’s own stores, I have
sketched for you an iron which I always use, fig. 91, and which I am
sure you will find convenient. It is made in the shape of a tuning-fork,
with a screw at its handle; this screw is simply twisted into a
gimlet-hole in a post, and is easily put up or removed.
I must not omit to say a few words with regard to the placing of
coloured fires. This must depend mainly upon individual taste, but a few
hints may not be out of place. I cannot help thinking that the best and
most effective way of displaying coloured fires is _to conceal the fire
itself, and let only its illumination or reflection be seen_. Let any of
my readers keep his spectators at a distance of twenty or thirty yards
from the coloured fire, and hold up a tray or piece of board in front of
the fire, of such a size as will conceal only the fire itself. I think
it will be generally admitted that the beauty of the piece is much
enhanced by this simple contrivance, and if it be thought so, then it
becomes a consideration whether it would not be better to use the most
illuminative colours always out of sight, in such a position that their
effect only can be seen. For instance, if there be a large tree
conveniently at hand, place your colour on that side of it which is away
from the spectators, so that the trunk of the tree is between them and
the coloured fire. This plan I have always found to give a most charming
result.
But it must be remembered that anything but highly illuminative colours
cannot be employed in this manner. You will of course find objectors to
the plan mentioned above. There are many people who will tell you, “No,
I like to see the light itself,” as if gazing on the sun or moon, except
for astronomical purposes, could ever give half the pleasure that the
sight of a fine sunlit or moonlit landscape can impart.
What would a fairy scene in a pantomime be worth if you saw some of the
green-room myrmidons, with a pot of beer in one hand and a lucifer-match
in the other, lighting a heap of composition on a tile beside the stage,
and then saw the composition burst into a smoky flame, but were
prevented from seeing the effects of its colour?
This suggests to me another branch of my present subject, which some of
my readers may consider an important one.