PYROXANTHINE 685 



the composition (&s under) imbued with spirits and gum-water, small cylindric masses 

 are made, pierced with a hole in their centre. These bodies, when kindled and pro- 

 jected into the air, form the stars. There is first put into the cartridge a charge of 

 fine gunpowder of the size of the star; above this charge a star is placed; then a 

 charge of composition for the Roman candles. 



The stars, when less than f of an inch, consist of nitre, 16 ; sulphur, 7 ; gunpowder, 

 5. When larger, of nitre, 16; sulphur, 8; gunpowder, 8. 



Roman candles, nitre, 16 ; charcoal, 6 ; sulphur, 3. When above f of an inch, 

 nitre, 16 ; charcoal, 8 ; sulphur, 6. 



The girandes, or bouquets, are those beautiful pieces which usually conclude a fire- 

 work exhibition ; when a multitude of jets seem to enblazon the sky in every direc- 

 tion, and then fall in golden showers. This effect is produced by distributing a 

 number of cases open at top, each containing 140 sky-rockets, communicating with 

 one another by quick-match strings planted among them. The several cases com- 

 municate with each other by conduits, whereby they take fire simultaneously, and 

 produce a volcanic display. 



The water fire-works are prepared like the rest ; but they must be floated either by 

 wooden bowls, or by discs and hollow cartridges fitted to them. 



Blue fire for lances may be made with nitre, 16 ; antimony, 8 ; very fine zinc-filings, 

 4. Chinese paste for the stars of Roman candles, bombs, &c. : Sulphur, 16 ; nitre, 4; 

 gunpowder-meal, 12 ; camphor, 1 ; linseed oil, 1 ; the mixture being moistened with 

 spirits. 



The feu Gregeois of Ruggieri, the son : Nitre, 4; sulphur, 2 ; naphtha, 1 



The red-fire composition is made by mixing 40 parts of nitrate of strontia, 13 of 

 flowers of sulphur, 5 of chlorate of potash, and 4 of sulphuret of antimony. 



Green fire may be made by using nitrate of baryta, instead of nitrate of strontia. 

 Chloride of thallium also imparts a fine green colour to pyrotechnic mixtures. 



White fire is produced by igniting a mixture of 48 parts of nitre, 13 J sulphur, 7^ 

 sulphuret of antimony ; or, 24 nitre, 7 sulphur, 2 realgar ; or, 75 nitre, 24 sulphur, 

 1 charcoal ; or, finally, 100 of gunpowder-meal, and 25 of cast-iron fine borings. 



The blue-fire composition is, 4 parts of gunpowder-meal, 2 of nitre, sulphur and 

 zinc, each 3 parts, 



Picrate of ammonia is now used for the production of very brilliant coloured flames. 



Prof. Church has published the following very interesting process for the pro- 

 duction of coloured flames : Bibulous paper is soaked for ten minutes in a mixture 

 of 4 parts, by measure, of oil of vitriol with 5 parts of strong fuming nitric acid, and 

 when washed out thoroughly with warm distilled -water, is dried at a gentle heat. 

 The gun-paper thus prepared is then saturated with chlorate of strontium, with chlorate 

 of barium, or with nitrate of potassium, by immersion in a warm solution of these 

 salts ; a solution of chlorate of copper also may be used. If, after complete drying, 

 a small pellet of any of these papers be made, lighted at one point at a flame, and 

 then thrown into the air, a flash of intensely-coloured light is produced, while the 

 combustion is so perfect that there is no perceptible ash. The barium salt gives 

 a beautiful green light, the strontium salt a crimson, the potassium salt a violet, and 

 the copper salt a fine blue. The chlorate may be prepared sufficiently pure for these 

 experiments by mixing warm solutions of the chlorides of barium, strontium, or 

 copper, with an equivalent quantity of a warm solution of chlorate of potassium. 

 The clear liquid is to be poured off the precipitated chloride of potassium, and 

 employed for the saturation of different portions of the gun-paper. The foregoing 

 makes an admirable lecture-experiment, for illustrating the colours imparted to flamo 

 by barium, strontium, and other salts. 



PYROXAWTHITTE. A substance detected in pyroxylic spirit by Mr. Scanlan. 

 He thus describes this compound : 



If potash-water be added to raw wood-spirit (pyroligneous}, as long as it throws 

 down anything, a precipitate is produced, which is pi/roxanthine, mixed with tarry 

 matter. The precipitate is to be collected on a filter-cloth, and submitted to 

 a strong pressure between folds of blotting-paper ; it is next to be washed with cold 

 alcohol, spec. grav. 0'840, in order to free it from any adhering tarry matter ; when 

 the pyroxyline is left nearly pure. If it be dissolved in boiling alcohol, or hot oil 

 of turpentine, it crystallises regularly on cooling, in bright square prisms, of a fine 

 yellow colour, that look opaque to the naked eye, but when examined under the micro- 

 scope, have the transparency and colour of ferroprussiate of potash. Its turpentine- 

 solution affords crystals of a splendid orange-red colour, having the appearance of 

 minute plates, whose form is not discernible by the naked eye, but when examined 

 by the microscope, they are seen to be thin right rectangular prisms. The orange- 

 red colour is only the effect of aggregation; for when ground to powder, these 

 crystals become yellow; and under the microscope, the difference in colour between 



