"A white flame is made by the addition of sulphide of antimony, sulphide of arsenic, camphor.
"Red by the mixture of lampblack, coal, bone ash, mineral oxide of iron, nitrate of strontia, pumice stone, mica, oxide of cobalt.
"Blue with ivory, bismuth, alum, zinc, copper sulphate purified of its sea water (sic).
"Yellow by amber, carbonate of soda, sulphate of soda, cinnabar.
"It is necessary in order to make the colours come out well to animate the combustion by adding chlorate of potash."
These formulæ, if somewhat incoherent, and clearly showing a want of experimental verification, indicate a real advance in pyrotechnic chemistry, not only by the addition of chlorate of potash, but by the multiplication of the number of metal salts used.
At the same time it is evident that the old alchemistic ideas were not entirely extinct by the use of such ingredients as ivory, mica, and pumice stone.
However, there can be no doubt that from the third decade of the nineteenth century dates the modern era of the pyrotechnic art. From this date onward chemical ingredients, metals and their salts as they were provided by the commercial chemist were eagerly taken and tested by the pyrotechnist, and adopted or rejected on their merits. And from this date begins the rapid elimination of useless additions.
Of those compositions given above the following salts are at present in use: nitrate of baryta, sulphide of antimony, sulphide of arsenic, nitrate of strontia, copper sulphate, carbonate of soda, and chlorate of potash.
Zinc, alum, lampblack, and oxide of iron are also used, but not for the purpose indicated.
Nitrate of copper and sulphate of soda would both be
