It is a remarkable fact, that spontaneous combustion, which takes place without the application of an ignited body, ensues in a variety of instances; and new facts daily occur, which show, that cases of this kind are more numerous than we had reason to suspect. Besides the old and well known effect of quicklime, pyrites, pyritous schist, &c. in producing spontaneous combustion, it is found, that ashes and oil, oil and cotton, and a number of substances have set fire to cotton mills, and other works.
It is known, that, in the slaking of quicklime, a considerable degree of heat is produced. This is owing to the solidification of the water, or its union with the lime in the form of a hydrate, and the consequent change, which the caloric undergoes from a latent to an uncombined state. Hence inflammable substances, in contact with lime, under these circumstances, are necessarily set on fire.
Spontaneous combustion arises simply from a play of chemical affinities. The following general observations on this subject are given by Nicholson, (Chemical Dictionary); and an enumeration of the effects may lead to cautions of importance for preventing serious accidents: "If quicklime, in any quantity, be laid in contact with any combustible, as wood, and be wetted by accident, or to make it into mortar, a sufficient quantity of heat may be extricated to set fire to the wood. Animal or vegetable substances, laid together damp in large heaps, undergo a fermentation, which often excites combustion, as in the case of hay-ricks. Woollen cloth, not freed from the oil used in dressing it, and laid up damp in large heaps, has been known to take fire; and so has painted canvass. Flowers and herbs boiled in oil, as is done by druggists, and then laid in heaps, sometimes do the same. The mixture of linseed oil and lampblack, or of linseed oil and black wad, is very liable to inflame. Torrefied vegetables, as malt, coffee, or bran, put while hot, into coarse bags, are apt to take fire. The spontaneous combustion of phosphorus, and various pyrophori, is well known. It is suspected to be owing to the presence of one or other of these, that charcoal sometimes takes fire without any apparent cause; and the charcoal of peat is said to be particularly liable to this. Hyperoxygenated muriate of potassa, mixed with sulphur, or with sulphur and charcoal, is apt to detonate spontaneously.
"Many cases of spontaneous combustion taking place in the human body too are on record: and it has been observed, that all the persons, who thus suffered, were much addicted to the use of spirituous liquors."
Sec. XXVIII. Of the blue and green Match, for Cyphers Devices, and Decorations.
We had occasion to mention, that blue and green flame may be produced by employing sundry substances, which have the property of changing the colour of flame. This is effected in the present instance.
For the preparation of the match, we melt one pound of roll brimstone in a glazed earthen vessel, over a slow fire, and add one ounce of finely pulverized verdigris, and half an ounce of antimony. The cotton for the match, may be of any length and thickness, as we judge proper; and is to be immersed, and well soaked, in the wetted sulphur, having previously put in the verdigris, and antimony. Sulphur alone will form a blue light.
The matches are afterwards tied to a rod of iron, which is bent according to the design we purpose to form, and to which they are fastened with a very fine iron wire, called the carcase. They are covered with priming paste, and a quick match is tied along the whole length. They are then covered with bands of gray paper, and a piece of port-fire is fixed on the end, to communicate fire.
Sec. XXIX. Of the Purple or Violet Match.
The design is made, and the match is attached, in the same manner as described in the last section; but without bending it. The preparation is as follows: Make a decoction of jujubes, which have been peeled, and stoned, and thicken it by adding as much of the flour of sulphur, as will bring it to a proper consistence. The cotton is then covered with this mixture, in the manner before stated; its thickness to be determined, according to the time required for it to burn. While hot, the match is primed by rolling it in meal powder. It is then suffered to dry. The design, it is to be observed, ought to be supported at the distance of four or five inches from the rods which hold it, by small cross pieces of iron, to prevent it taking fire; a circumstance necessary to be guarded against.