The Doctor touched a minute globule of it, in a platina spoon, resting on a table, with a fragment of phosphorus at the point of a pen-knife, and the blade was instantly shivered into fragments by the explosion.
Messrs. Porret, Wilson, and Kirk (Nicholson's Journal, Vol. XXXIV,) employed 125 different substances, by bringing them in contact; and out of that number the following caused it to explode:
Supersulphuretted hydrogen,
Phosphorus,
Phosphuret of lime,
Phosphuretted camphor,
Camphoretted oil,
Phosphuretted hydrogen gas,
Caoutchouc,
Myrrh,
Palm oil,
Ambergris,
Whale oil,
Linseed oil,
Aqueous ammonia,
Olive oil,
Sulphuretted oil,
Oil of Turpentine,
---- Tar,
---- Amber,
---- Petroleum,
---- Orange peel,
Naphtha,
Soap of silver,
---- Mercury,
---- Copper,
---- Lead,
---- Manganese,
Fused Potassa,
Nitrous gas.
According to Mr. Davy, chloride of azote contains
| 4 vols. of chlorine | = 10 + | or | 4 primes | = 18.0 + | ||
| 1 —— azote | = 0.9722 | 1 —— | = 1.75, | |||
| or very nearly 10 by weight of chlorine to 1 of azote. | ||||||
Pyrophorus is a black substance, which takes fire spontaneously, when brought into contact with air. It is the luft-zunder, or air-tinder of the Germans. It first emits sulphuretted hydrogen gas, and in a few seconds becomes red-hot, burning with a bluish flame. Pyrophorus consists of alumina, charcoal, and sulphuret of potassa, and also, according to some, of potassium, which is alleged to be formed in its preparation. Be this as it may, it seems, that water is decomposed in its combustion, that sulphuretted hydrogen gas is emitted, which is inflamed by the oxygen gas of the atmosphere, and that, during the combination of oxygen, a degree of heat is produced, which causes the ignition of the charcoal, as well as the inflammation of the remaining sulphur.
Pyrophorus may be formed in several ways, all of which produce the same result. The usual process is the following: Take equal parts of brown sugar and alum, and melt them in a ladle. Continue the heat, stirring them constantly until a spongy black mass is formed. Let this mass be reduced at once to powder, and introduced into a common green glass phial, of the capacity of about six ounces, previously coated outside with a mixture of pipe-clay and solution of borax. Immerse the phial in a crucible, filled with sand, closing the mouth of the former with a piece of charcoal, or a glass tube inserted in it. Upon the crucible being exposed to a red heat, an inflammable gas will escape, which will take fire.[21] When this effect ensues, the heat must be continued for about twenty minutes longer, at the expiration of which time, the crucible must be removed from the fire, and the phial taken out and closely stopt. The pyrophorus is to be preserved in a ground stoppered bottle. The addition of one-sixteenth part of sulphate of soda, or Glauber's salt, to the alum and sugar, is said to make the pyrophorus with more certainty. Various vegetable substances, besides sugar, as flour, starch, &c. may be used. Three parts of alum, and one part of wheat flour will make a good pyrophorus.