CHAPTER III.
OF PORT FIRES.
Port fires (_lances à feu_) are a species of fuse of a slow composition, designed for different purposes, and particularly for guns, when they are to fire rapidly. The paper, is first rolled in cases. The rod or mandril should be of hard wood, 16 or 18 inches long, and 5-1/2 lines in diameter. Two brass rods to load them, one of 17 inches in length, the other of only 8, are required. A wooden rammer, with a heavy head, may be used. A small funnel with a spout 5-1/2 lines in diameter, and a ladle to lift the composition, are also required. The instructions of M. Bigot for the formation of _Port-fire_ are that the paper must be cut in bands, 3-1/2 to four inches wide, and 15 inches long, and six strips of this paper are to be arranged on a level table, one above the other in such a way, that each strip extends about half an inch beyond the next below it, and pasting the projecting parts of it; that the wooden rod is then placed upon the upper strip, near the side, and the paper is rolled several times round it; pressing it at the same time, and shutting the case, thus formed, at one end, by bending the paper up 3 or 4 lines on the rod, and striking it on the table to flatten it; that the rod is then removed, and the case is dried, which is afterwards filled by introducing the composition through the funnel, and ramming it as fast as it falls down; which is done by alternately raising and lowering the copper rod, without drawing it entirely out; that in charging, care must be taken to beat it uniformly, with such a force, that the paper may not be torn, and the composition equally solid throughout; that when the composition is within an inch of the end of the paper case, a tow match is put over it, of 1-1/2 inches in circumference, the two ends of which project from the paper case, and are covered with priming paste; and finally, that the port-fire is finished, by pasting upon its end a small bit of paper, which is torn off, when the match is to be used.
Port-fires are tied up in a sheet of paper, in parcels of ten.
_Composition of Port-fires._
---------------------------+--------+--------+--------+---------+------ | Meal | Salt- | | | KINDS OF PORT-FIRE. | powder.| petre.|Sulphur.|Charcoal.|Rosin. ---------------------------+--------+--------+--------+---------+------ To last 12 min. moistened }| 10 | 12 | 6 | | with linseed oil. }| | | | | ---- 10 do--do | | 19½ | 7¼ | ½ | ---- 7 do--commonly used. | | 19½ | 8 | ½ | ½ ---------------------------+--------+--------+--------+---------+------
The articles are pulverized, and mixed by passing them through fine sieves at least twice. After the addition of linseed oil, the composition is again mixed with the hand. If too much oil be added, the port-fire will not keep. Fourteen pounds of composition, and 2-1/2 reams of paper, are required for 100 port-fires.
Port-fires are usually 16-1/2 inches, and seldom more than 21 inches in length. The paper cases must be rolled, wet with paste. The distinction, made between what is called the wet, and dry port-fire, is, that, in the former, linseed oil is used, and, in the latter, the composition is mixed dry. Dry port-fire, according to the British formula, is composed of saltpetre 4 parts, sulphur 1, meal-powder 2, and antimony 1.
The following formulæ for port fire are given in the Pyrotechny of the Encyclopedia Britannica.
1. Saltpetre 12 oz. Sulphur 4 -- Meal-powder 2 -- 2. Saltpetre 8 oz. Sulphur 4 -- Meal-powder 2 -- 3. Saltpetre 1 lb. 2 oz. Meal-powder 1½ lbs. Sulphur 10 oz. 4. Meal-powder 6 oz. Saltpetre 2 lbs. 2 -- Sulphur 10 -- 5. Saltpetre 1 lb. 4 oz. Meal-powder 4 -- Sulphur 5 -- Sawdust 8 -- 6. Saltpetre 8 oz. Sulphur 2 -- Meal-powder 2 --
_Illuminating port-fires_, used in fire-works for exhibition, &c. have been noticed heretofore.
The composition of the charge for fire-lances (port-fire,) is thus given by Ruggeri;
_Substances._ _Proportions._ Saltpetre 16 parts. Sulphur 8 ---- Powdered antimony or powdered pitcoal 4 ----
Mixed, and passed three times through a sieve.