41.—The points of difference between brilliant and Chinese fires are
these:—
1st.—The sparks produced in the combustion of brilliant fire by steel
filings are much whiter, but at the same time much smaller and
shorter-lived, than those produced by iron borings in Chinese fire.
2nd.—The steel sparks are not thrown to so great a distance, on account
of their superior weight and size; but they are much more numerous, and
afford a rich tale, or “brush,” as it is termed, of glowing
scintillations, rather than a gracefully-falling jet or fountain of
large sparks. This very fact, however, of their not being thrown so far
from the case out of which they are fired renders them capable of
producing an effect in combination of which Chinese fire is incapable.
The cases, when arranged in the position of the radii of a circle or
spokes of a wheel, will throw a _perfectly straight_ brush of brilliant
fire, which will, of course, much more closely represent rays of light
emanating from a centre than any fire the sparks of which have a
tendency to fall.
3rd.—Another point of difference between the composition containing iron
borings and that containing steel filings is that the former should
never be employed in the construction of pieces which have motion; for
the very motion of the piece, or rather the increased impetus with which
the particles of _iron_ are thrown out into the cold air, has the effect
of cooling them so rapidly that almost all their beauty is lost. But
this is not the case with _steel filings_: they seem almost unaffected
by the rapid motion of the piece in which they are employed; and for
this reason they possess an advantage which fully makes up for their
being so much less showy in their performance than the iron borings.
The cases into which the composition for brilliant fire is rammed need
not be so large as those employed for Chinese fire. I employ two
sizes—the 1-oz. size for cases that are intended to turn wheels or any
revolving pieces, and a smaller size still for those that are to remain
perfectly stationary during their combustion.
The fault into which the young pyrotechnist is most likely to fall is
that of using a power considerably in advance of his need. In order that
you may not do this (for there is always fear of failure when you do), I
recommend you _to use no cases for brilliant fire larger than the
one-ounce size_. This, you will find, will give you a moving power amply
sufficient for any wheels that I suppose you are likely to use, and
particularly if you bear in mind the rule, that _increase of power is
gained much more safely and much more effectively by an additional
number of cases burning at the same time than by any additional force
that you can get out of one case_.
The 1-oz. case, as you know by this time, is made round a former exactly
half-an-inch in exterior diameter and 12 inches long. The paper for
these cases may be cut precisely in the same manner as directed for
Chinese fire cases. The imperial board should be cut thus (fig. 52),
into twelve equal pieces. Take care that the _long_ side of the board is
divided into _three_, and the _short_ into four.
[Illustration:
Fig. 52.
]
If, however, you think a shorter case sufficient, cut your sheets of
paper into eight equal parts, thus (fig. 53), and your imperial board
into sixteen pieces—that is, half the length of the strips of paper;
this will give you cases about five and a-half inches in length. Both
these divisions of paper and board are for the 1-oz. cases.
[Illustration:
Fig. 53.
]
I will now speak of the smaller sizes, which are used only in fixed
pieces, and which are generally called on that account, for the sake of
distinction, _fixed cases_.
The former for these is a metal tube 12 inches long and seven-sixteenths
of an inch in exterior diameter. For cases of this size you may either
use paper and board cut as directed above for the longer 1-oz. cases, or
you may divide each sheet of paper into six strips thus (fig. 54), and
each sheet of board into twelve pieces half the length of the strips of
paper.
For filling either the 1-oz. or the fixed cases it will be evident that
you must have at least two drifts for each size that will pass _easily_
into their respective cases—one about 9 inches long in its straight
part, and the other from 2 to 3 inches in length.
[Illustration:
Fig. 54.
]
You must also have a nipple and point over which to ram each different
size of case. The exact size of these nipples you will see in the pages
of illustrations (figs. 45 and 46).
Use the same mallet and observe the same rules in filling these
brilliant fire cases as in filling the cases with Chinese fire.
We are now ready for the compositions. The first given is by far the
most beautiful, and most generally used; but being very rapid in its
combustion, it must be very carefully and uniformly compressed in the
case. No. 2 is of a much quieter character, and may be found useful for
some purposes.
BRILLIANT FIRE.
No. 1.
Meal-powder 4 parts.
Bright steel filings 1 part.
Or,
No. 2.
Meal-powder 16 parts.
Nitre 8 „
Sulphur 3 „
Fine Charcoal 3 „
Bright steel filings 10 „
Neither of these compositions should on any account be mixed before
their preparation is absolutely necessary, for their whole beauty
depends upon the brightness of the filings at the time of firing.