Sec. L. Of Extemporaneous Fire.
There are several preparations, which have the effect of producing fire either by friction, or chemical action. Some of these preparations, we have noticed. The causes of spontaneous combustion may be referred to chemical decomposition, and the change of quiescent into distributable heat. We remarked, that a mixture of chlorate of potassa and sugar is inflamed, when brought in contact with sulphuric acid; that, in the slaking of quicklime, the heat is sufficient to inflame oils; that pyrites by decomposition very frequently sets fire to combustible bodies; that oil of turpentine is inflamed by nitric acid; that pyrophorus, when exposed to the air, takes fire, and also phosphorus by slight friction; and that, in all cases of combustion, either friction, an increase of temperature, or the action of some body, which is brought in contact, are necessary to produce the effect.
Water, when added to some substances and preparations, will produce fire. Thus potassium readily decomposes it, and the potassuretted hydrogen gas, which is produced in flames. The same may be said of phosphuret of lime and water; for the phosphuretted hydrogen gas inflames, when it comes to the air.
On some occasions, these substances may be employed as incendiaries.
Hanzelet remarks, that the following composition will produce inflammation with water.
Extemporaneous Fire.
| Linseed Oil | 3 lbs. |
| Spirit of Turpentine | 1 — |
| White of egg | ¼ — |
| Quicklime | 8 — |
It is doubtful, however, whether this composition will have that effect; although the heat produced by the slaking of quicklime is very considerable, and, as we remarked, spontaneous combustion, in several instances, has been referred to its agency. Lime, in the act of slaking, absorbs, and chemically unites with, water, which becomes solidified, converting it into a hydrate, whilst its latent caloric is set at liberty. This is a process, which puts quiescent heat in motion, to become distributable heat. See [Introduction.]
If the quantity of free caloric, thus generated, be sufficient, the turpentine and oil will necessarily inflame.
We may add, therefore, that a rapid transition of caloric, from a latent to a free state, as in combustion, is all that is required to produce effects of this kind; and, in short, all cases of spontaneous combustion may be accounted for on this principle; by considering the cause, which acts in those instances so powerfully, and in some instances instantaneously, and which changes caloric from a quiescent to a distributable state.