In order to make the mixture of the sulphur with the iron more intimate, the latter may be wetted occasionally with spirit of wine, which should contain no water, as water would tend to rust the metal, and injure its effect. The sulphur would then mix with more freedom, and the composition be more perfect. The spirit of wine, acting merely as a vehicle, afterwards evaporates; and, as it has no chemical action on either the sulphur or the metal, they would remain unaltered.
By proceeding in this manner; namely, first mixing the other substances by themselves, and afterwards the iron and sulphur, and then the whole, we form an intimate mixture throughout.
The composition, prepared in this way, makes the fire more brilliant; giving it a greater lustre than by proceeding in a contrary manner.
We are informed, that spontaneous combustion has frequently taken place, by suffering the iron and alcohol, or spirit of wine, to remain in contact; and, although this appears an anomaly, which we will not attempt to explain, yet that it is a fact, and that it has occurred at Paris, we have the authority of M. Morel.
When the cast-iron is reduced to powder, or sand, it is divided into several sorts, which are proportioned to the caliber employed. These sorts are marked or numbered, and are used as follows: For calibers under 7/12ths of an inch in diameter, No. 1; for those of 7/12ths to 10/12ths, No. 2; and for larger calibers, No. 3.
In charging with the composition, care must be taken to turn it over repeatedly at every other ladle full; because the iron, which is the heaviest substance, is liable to fall to the bottom. If the composition be not equally diffused, the fire would be irregular, and go out by puffs. This is a defect which ought to be guarded against.
The mixture of the composition for Jessamine is made in the same manner.
Chinese fire, in cases, is commonly employed in garnishing, as it is called, the circumference of a decoration, or in forming pyramids, galleries, yew trees, cascades, palm trees, or in short, in producing a variety of figures, according to taste and fancy. They are often employed in turning pieces for their last fire, in consequence of the brilliancy of their effect.
We are told, that nothing is more elegant than Chinese fire; and that it forms, in its descent, flowers of variegated beauty, which, being scattered about by the rotation of the piece, resemble the hydraulic girandole in the rays of the sun.
Chinese fire, however, has little force; and hence, when it is used, it is accompanied with other fire, as two or more jets of white fire. The latter is only employed, when the Chinese fire is to be exhibited on wheels, or turning pieces. When it is on fixed pieces, there is no occasion for them. Cases of Chinese fire, when burnt alone, will not turn a wheel.