History of the Confederate Powder Works

by George Washington Rains

To keep the powder on the bed, a wooden curb, funnel-shaped, two feet high was placed around the circumference, fitting closely, extending outwards at an angle of forty-five degrees. In the centre of the bed was a short cylinder of metal, two feet in diameter and six inches high, through the top of which the vertical shaft passed. This prevented the powder working inwards. It also acted as a steam-chamber to keep the bed-plate warm; but this was not used for the purpose, since the steaming process rendered it unnecessary. A scraper, or plow, followed each roller, which continually broke up the powder-cake, mixed its fragments, and kept them in the path of the rollers.

At the commencement of the operation the charge of sixty pounds of steamed materials was uniformly distributed over the bed; the rollers were then set into motion, revolving about ten times each minute, which continued for an hour; the broken up powder, or mill cake, which was about five-eighths of an inch thick, was then removed from the bed, having a blackish grey color and taken to the cooling magazines. These were excavated in the clay and rock on the other side of the canal, about one hundred yards distant; were four in number and separated from each other; here the mill cake became cold and hard, and was ready for the next operation, that of granulation. The permanent building in which this was done was about fifteen hundred feet distant from the Powder Mills, on the same side, further up the canal; this, as well as each of the other permanent structures, was made of brick, having thin walls and light roofs. Wood in the damp atmosphere of the canal speedily decayed.

A natural growth of trees and brush-wood intervened between the buildings along the canal, which were generally situated about one thousand feet apart; thus the explosion of any one of them would be harmless to the remainder. There was a temporary structure of wood used at first for granulation, about one hundred yards distant from the permanent building, on the opposite side of the canal; this, after a use of some months, exploded with about three tons of gunpowder.

The explosion was heavy, shaking the earth for some distance, and throwing up a convolving column of flame and white smoke [p20] five hundred feet in height. It was composed of a series of confused masses of smoke and heated air revolving in vertical planes with extraordinary velocity, through which the flames flashed outwards in all directions; this was followed by the thundering sound of the explosion, which vibrated the air for a mile around, and was heard within the limits of the city.

There were seven men within the structure, a sentinel outside, and a boy with a mule in a shed adjoining. The bodies of the seven men and the boy, with the debris, were carried up with the ascending column, and by its revolving action, reduced mainly to small fragments and dispersed; the sentinel was killed by the shock, but his body was not otherwise disturbed. A growth of small pines surrounded the place, which effectually intercepted the lateral flying fragments; in fact the force of the explosion did not extend outside a diameter of one hundred feet, but within that area the trees were destroyed and the space where the structure stood was ploughed up and nothing remained. At the time there was no work being done, as the workmen were awaiting the arrival of the boat with the mill cake. The careful foreman, Gibson, had been called away, and probably the accident happened from matches falling on the floor, as it had been found impossible to prevent their use by the workmen, for smoking, when off duty. This was the only explosion at the Works during the war, except the three at the Mills, already mentioned. It demonstrated the safety of the arrangements, since there was no damage to any portion of the Works except the destruction of the glass sashes, and a slight movement of the roof of the permanent granulating building, about one hundred yards distant. This was about to be occupied, having been completed.

In the granulating building the cold mill cake was broken up into fragments by bronze toothed cylinders of small diameter, and then by smooth ones; these worked in pairs, and successively, in connection with vibratory screens and sieving, all in one machine. By the action of this arrangement the powder cake was broken into fragments, separated into different sizes of grain, and each delivered into its proper receptacle. A very large grained powder, each grain being a cube of one inch in dimensions, and weighing about one ounce, was made by a separate manipulation of the powder cake, and used for the very largest guns only.

From the granulating building the powder was taken to the [p21] drying, dusting and glazing department, 2500 feet further up the canal. There was an intermediate building designed and used for several months, as the dusting and glazing department, the drying alone being done in the one above mentioned; afterwards the three processes were carried on together in one structure. It was soon perceived that the drying process, which was done by similar arrangements to those used at the government works at Waltham Abbey, England, that is, by placing the powder in small quantities in shallow trays in a frame work, over steam heated pipes, required considerable manual labor and occupied much time. It occurred to me that the same could be accomplished more speedily and with far less labor, by a single operation, which would likewise perform the glazing and dusting.

To accomplish this the powder from the granulating house was placed in revolving cylinders having hollow axles, and a current of air warmed by passing through an arrangement of steam pipes was blown through, carrying the dust into its receptacle, leaving the grains clear. This also dried and glazed them at the same time. Thus by one operation, by machinery, all three processes were accomplished, resulting in a large saving of labor and time. In addition, a beautiful jet black glazing was given by admitting a small quantity of steam at the proper time to the current of air, while the barrels revolved. This was not generally done, however, as it was regarded of but slight, if any, practical value, the usual glazing answering all required purposes.

Two hundred yards from this department was the boiler house supplying the steam required for the pipes used in the drying process. Its chimney was one hundred yards still further removed, communicating with the furnace by a subterranean arched flue; thus sparks would have had to drift over three hundred yards to reach the clean metal roof of the drying building.

The finished gunpowder was taken to the next building, one thousand five hundred feet beyond, up the canal, where it was weighed out and put into strong wood boxes about two and a half feet long, by one foot square, having the ends let into grooves; one of the ends had a strong wood screw, two inches diameter, with an octagonal head. Experience proved that these powder boxes, a devise of my own from necessity, were superior to barrels, being stronger, occupying less room, standing transportation better, and [p22] safer in use. No explosion ever occurred in their transportation, notwithstanding the occasional Railroad accidents, and the many thousands that were sent from the Powder Works during the war.