M. Cadet, of Paris, has invented artillery rods to supersede the matches in common use. They may be made of birch, elm, poplar, or of the linden tree. They are saturated with nitrate of lead and undergo two ebullitions in spirit of turpentine. They then burn very well and are not extinguished by the air. A metre of each will last an hour and a half, while the common matches burn only seven minutes. General Gassendi has made a calculation, which proves, that matches, which now cost the French government twenty-thousand livres, will not cost more than fifteen hundred, if made on M. C's new principle.
One pound of rope-match, such as is used in the military academy of Segovia, lasts nearly thirty-five hours, and rather more provided it be damp. In that state it is generally surcharged with from six to seven per cent. of moisture. In short it would be better to dry the rods in an oven, before they are saturated with the nitrate as well as afterwards. The following table shows the difference of duration between the matches made of rope and the new invented rods; and the quantity of nitrate, each wood absorbs per quintal, is specified in the last column.
| Woods. | Durat. per | 25 lbs. | lbs. | French |
| Cord-match | 850 | 4 | ||
| Linden, | 2400 | 10 | ||
| Pine, | 2400 | 42 | ||
| Cedar, | 2400 | 42 | ||
| Elm, | 2430 | 19 | ||
| Oak, | 2200 | 18 | ||
| Green oak, | 1400 | 18 | ||
| Walnut, | 1400 | 7 | ||
| Poplar, | 1400 | 37 | ||
| Willow, | 2400 | 30 |
Hence we find that the poplar, pine, cedar and willow, exclude themselves when compared with the linden tree; since they absorb three or four times more nitrate than the latter, without burning longer.
The linden unites the advantages of economy and duration, since it absorbs only a tenth of its weight. The common oak, elm, walnut and green oak, occupy but the second rank. We may remark also, that the hardest woods are not of the greatest duration; for a rod made of green oak, which is much harder than the common oak, supports combustion only eight hours, while the latter will burn for twelve hours. Half a kilogramme of nitrate of lead will saturate forty-five metres of elm, seventeen of birch; twenty-one of poplar, and twelve of the linden tree. The woods were cut in parallelepipeds and boiled in a fish-pan.
MM. Carnot, Guyton Morveau, and Deyeux, were appointed to examine this invention, who reported favorably. An extract of their report may be seen in the Archives des Découvertes, v, p. 240.
Born also recommends for the same purpose, nitrate of lead, and used in the same manner. Proust, it appears, repeated the experiments of Born, and came to the same conclusion;—that it was an expeditious, and, on a large scale, an economical process for making matches. Proust, however, used hazle wood. He observes that the solution must be strong; that when cold it requires three days immersion in the fluid, and when boiling, only one and a half hours. He also found that nitrate of copper may be substituted for either the acetate or nitrate of lead.
Sec. II. Of Priming Tubes.
Priming tubes, (fusées d'amorce) serve to communicate fire to the powder in a cannon. They were formerly made of tin, but in consequence of the inconvenience of rusting they were laid aside. James (Military Dictionary, p. 416) remarks, that, owing to this defect in the tin, a colonel Harding had invented a pewter tube in lieu of tin tubes. Tubes are used in quick firing. When made of tin their diameter is two-tenths of an inch, being just sufficient to enter into the vent of the piece. They are about six inches long. Through this tube is drawn a quick-match, the cap being primed with meal powder moistened with spirits of wine. To prevent the mealed powder from falling out by carriage, a cap of paper or flannel, steeped in spirits of wine, is tied over it.