Spontaneous Combustion.--It is conceivable that the property which masses of greasy rags, and such-like matter, possess of igniting when left to themselves, might under some circumstances, be the only means available to procure fire. It is at all events well that this property should be borne in mind when warehousing stores, in order to avoid the risk of their taking fire. Any oil mixed with a hatful of shavings, tow, cotton, wool, or rags, heaped together, will become very hot in one, two, or more days, and will ultimately burst into flame. The rapidity of the process is increased by warmth.
Tinder.--General Remarks.--There are two divisions of tinder: those that are of a sufficiently strong texture to admit of being grasped in the hand, and those that are so friable as to require a box to hold them. In the first division (a) are the following:--amadon, a roll of rag, a cotton lamp-wick, a roll of touch-paper, a mass of hair of certain plants, and a long string of pith sewed up in a sheath. To ignite these, we must hold them as in fig. 1, and use the steel to strike downwards upon the flint. In the second division (b) are:--tinder of burnt rags, tinder of any kind with grains of gunpowder strewed over it, and touch-wood. All these require tinder-boxes, as explained below. There are also many other substances belonging to both divisions of tinder, in use. A traveller should inform himself about those peculiar to the country that he visits.
a Amacou, punk, or German tinder, is made from a kind of fungus or mushroom that grows on the trunks of old oaks, ashes, beeches, etc.; many other kinds of fungus, and, I believe, all kinds of puff-balls, will also make tinder. "It should be gathered in August or September, and is prepared by removing the outer bark with a knife, and separating carefully the spongy yellowish mass that lies within it. This is cut into thin slices, and beaten with a mallet to soften it, till it can easily be pulled asunder between the fingers. It is then boiled in a strong solution of saltpetre."
A Roll of Rag.--Cotton rag will easily take fire from the spark from a flint, in a very dry climate, if well struck. It must be rolled up moderately tight, so as to have the end of the roll fluffy; the rag having been torn, not cut. A rag rolled in this way is not bad tinder, if the sparks are strong, and one commences to blow it the instant one of the fibres is seen to be alight. If its fluffy end be rubbed into a little dry gunpowder, its property as tinder is greatly improved.
Cotton Lamp-wick.--A piece of it drawn through a tin tube, to shield the previously charred part from being rubbed off, is excellent in dry climates. (See fig. 1, p. 180.)
Touch-paper is merely paper dipped in a solution of saltpetre, or what comes to nearly the same thing and is somewhat better, paper smeared with damp gunpowder until it is blackened. Some grains of uncrushed gunpowder should be left adhering to the paper, and a few more should be allowed to lie loosely upon it. Unsized paper, like that out of a blotting-book, is the best suited for making into touch-paper; paper is rendered unsized by being well soaked and washed in water. (See next paragraph.)
Saltpetre for Tinder.--In all cases the presence of saltpetre makes tinder burn more hotly and more fiercely; and saltpetre exists in such great quantities in the ashes of many plants (as tobacco, dill, maize, sunflower), that these can be used, just as they are, in the place of it. Thus, if the ashes of a cigar be well rubbed into a bit of paper, they convert it into touch-paper. So will gunpowder, for out of four parts of it, three are saltpetre; damaged gunpowder may be used for making touch-paper. If it be an object to prepare a store of tinder, a strong solution of saltpetre in water should be obtained, and the paper, or rags, or fungus, dipped into it and hung to dry. This solution may be made by pouring a little water on a charge of gunpowder, or on the ashes above-mentioned, which will dissolve the saltpetre out of them. Boiling water makes a solution forty-fold stronger than ice-cold water, and about eight times stronger than water at 60 degrees Fahr.
Hair of Plants.--The silky down of a particular willow (S. lanata) was used by the Esquimaux, with whom Dr. Kane had intercourse; and the botanist Dr. Lindley once informed me that he had happened to receive a piece of peculiarly excellent tinder that was simply the hair of a tree-fern. The Gomuti tinder of the Eastern Archipelago is the hair of a palm.