56. For this colour I shall give three formulas, all of which I have
found good, notwithstanding the universally acknowledged difficulty of
obtaining a real green colour. This difficulty has arisen, I believe,
solely from the imperfections and impurities in the nitrate of baryta
which finds its way into the market. This salt should be prepared from
the sulphate of baryta, _and not from the carbonate_; and I think I am
right in stating that it is far more generally prepared from the
carbonate than from the sulphate. When this is the case you either get a
very decent _yellow_ colour from the sample, or you get a salt which
burns about as green as a very bad specimen of nitre will burn. My
readers will readily understand that nitre ought not to be so green as
to admit of this.
And now, before giving the formulas, it only remains for me to say that
if you have but a really good sample of _dry_ nitrate of baryta _in fine
powder_, you ought to be able to make from the following receipts a
green fire which will answer any purpose:—
GREEN FIRE.
No. 6.
Nitrate of baryta 45 parts.
Chlorate of potash 10 „
Sulphur 10 „
Antimony (sulphide) 1 part.
The above formula gives a pure but pale green. It has a most intense
illuminating power, and for this cause is very valuable. The addition of
a little nitrate of baryta will render the composition more intense in
colour, but will detract from its rapidity of combustion, and therefore
from its illuminative power.
No. 7.
Nitrate of baryta 77 parts.
Chlorate of potash 5 „
Sulphur 12 „
Charcoal 2 „
Orpiment or realgar 2 „
Shellac 2 „
Composition No. 7 is a very old one, slightly altered to make it burn
more freely. It gives a more intensely green colour than No. 6, but has
not the same advantage with regard to its illuminative properties. It
is, however, a very serviceable and inexpensive receipt to employ.
We now come to the best of all the formulas for green fire that I have
been able to meet with, and one which has thoroughly satisfied me. It is
almost the same as that recommended by Chertier, the difference
consisting in a slight decrease in the quantity of calomel, which
enables the composition to burn rather more freely and adds to its
reflective power. I have seen a real emerald green produced by this
composition when good nitrate of baryta has been used, but in this, as
in the case of all other green fires, if you do not succeed you may
generally fasten your suspicions upon the nitrate of baryta.
No. 8.
Nitrate of baryta 40 parts.
Chlorate of potash 4 „
Sulphur 8 „
Calomel 8 „
Charcoal (fine) 2 „
Shellac 1 part.
I do not think that any better formula than this can be needed. It
carries with it a better combination of intensity of colour with
intensity of illuminating power than any coloured fire composition that
I am acquainted with.