Another process for making candles, in which sal ammoniac is used, is mentioned in the Annales des Arts et Manufactures, Nos. 142 and 146. Eight pounds of suet are melted, and a pint of water is added. The tallow is again submitted to heat, and the same quantity of water, holding in solution half an ounce of saltpetre, half an ounce of sal ammoniac, and one ounce of alum, is added. It is then suffered to stand, and when used is re-melted. The wick is first dipped in a mixture of camphor and wax. Care must be taken, before the tallow is used, to evaporate the water. Equal parts of beef and mutton tallow are recommended.
Sect. XXXIV. Of Corrosive Sublimate.
Corrosive sublimate, known in chemistry by the names of corrosive muriate, and perchloride of mercury, is made use of in some preparations of fire-works, and particularly in the composition of stars, in which it is mixed with a variety of substances, such as steel filings and antimony, in order to vary the appearance of the flame, and to communicate to it particular colours. Corrosive sublimate is formed by various processes, among which we may enumerate the following: Take five parts of sulphuric acid, four parts of mercury, four parts of muriate of soda, and one part of black oxide of manganese. Boil the mercury in the sulphuric acid, until it forms a dry sulphate, which is to be reduced to five parts. Mix the sulphate thus formed, with the muriate of soda, previously dried, and the oxide of manganese, and sublime the mixture. By this process the sulphuric acid of the sulphate unites with the soda, and forms sulphate of soda; while the muriatic acid of the muriate of soda combines with the oxide of mercury, (which receives an addition of oxygen from the oxide of manganese,) and forms the perchloride, called by Thenard the deutochloride of mercury. The same process is used without the addition of manganese. By exposure to heat, the sublimate sublimes, and the sulphate of soda forms the residuum. The same salt, if re-sublimed with an addition of crude mercury, will be changed into the protochloride of mercury, or calomel. Or, if the sulphate of mercury and muriate of soda be mixed with crude mercury, and sublimed, calomel will be formed at one operation. It is sufficient to observe, that corrosive sublimate is one of the most virulent of poisons when swallowed; and therefore should be used with caution.
It is soluble in water, and capable of crystallizing. It is also soluble in alcohol, to the flame of which it communicates a yellow colour, and in sulphuric, nitric, and muriatic acids. It is decomposed by alkalies, forming with ammonia a triple salt, (Sal Alembroth,) by the alkaline earths, and the metals or their sulphurets; and, when distilled with arsenic, bismuth, antimony, or tin, the mercury is separated.
The proper antidote for corrosive sublimate, is the white of egg or albumen, which converts it into calomel. Sulphuretted hydrogen water may also be employed along with emetics. The effect of albumen, in this way, may be relied on.
Sect. XXXV. Of Orpiment.
Orpiment, or the yellow sulphuret of arsenic, which is either native or artificial, is principally used in fire-works for the composition of stars. Orpiment is divided by some into two kinds; viz. the red, called realgar, and the yellow, called yellow arsenic.
Arsenic combines readily with sulphur. When they are mixed together, and put into a crucible and fused, the product will be a red vitreous mass. This red sulphuret may also be formed, by melting sulphur with arsenious, or arsenic acid. Sulphurous acid gas will be evolved, evidently showing that a portion of the sulphur unites with the oxygen of acid employed.
When arsenious acid, known in commerce by the name of white arsenic, and called by some oxide of arsenic, is dissolved in muriatic acid, and a solution of sulphuretted hydrogen in water is added, a yellow precipitate will be obtained which is orpiment. The hydrogen, in this case, unites with the oxygen of the arsenious acid, by which the metal is reduced, and the sulphur then combines with it. A mixture of sulphur and arsenic, exposed to a heat not sufficient to melt them, will sublime into a yellow sulphuret.
Both the yellow and red sulphurets are employed in fire-works. They are not, however, required, except in particular cases. In the composition of Bengal lights, given in the Bombardier or Pocket Gunner, by R. W. Adye, orpiment is used. According to the same author, it is also used in Chinese white lights. Both the yellow and red sulphuret of arsenic will detonate with chlorate of potassa.