It is not my intention to give an elaborate description of how acids are made or to attempt to describe all of the different fittings employed in that work, because while all plants are similar in construction no two are alike. For that reason I will confine myself to the methods employed in handling lead in large quantities, as the lead used in this work ranges in weight from 18 to 24 pounds to the foot and is therefore very heavy to handle. These chambers are known as condensing chambers, and their use is to catch and condense a mixture of sulphur and steam which is blown into them through a large lead pipe. For that reason they are usually built out of doors, and sometimes have a sort of temporary roof built over them. Consequently in repairing they are easily gotten at, which, by the way, is seldom necessary.

To begin with, the sheet lead should be purchased of such a width as to make as few seams as possible. The bottom of the chamber for this lead to lie upon should be made of 2-inch cypress plank, the same to be tongued and grooved as for floors, and should be planed down, if necessary, so that it will present a perfectly smooth surface for the lead to rest upon, for if there are any uneven spots that is where the lead will eventually crack. The frame work for the sides should also be put in place before the lead work is started, or at least enough of it to prevent dirt and other stuff from bothering the burner. One end of the chamber, however, should be left open, so as to enable the workmen to bring in the lead or other material. The sides should not be closed up, but should be framed, as shown in Fig. 37, so as to allow the lead to be securely fastened to the frame work, which should be made of heavy stock, depending, of course, upon the depth and size of chamber, as they are in all sizes, from 10 feet to 60 feet long and longer.

After seeing that this part of the work is all right, begin to place the bottom in position. This lead should be cut large enough to allow of its being turned up about 2 inches all around for tight tanks. The sides are not burned to the bottoms of some chambers, but the bottom lead is turned up different hights, depending upon how deep it is required to carry the acid in the chamber, which is from 4 to 10 inches or deeper. The studding should be notched out to allow the turned up lead to face with the face of the studding, otherwise there would be a bend in the side lead where it overlaps the sides of the bottom. The flat seams in the bottom should be butted together, so as to give a perfectly smooth surface, which will allow all the acid to be drawn off.

It is rather a difficult task for some men to cut heavy lead straight. This is easily accomplished by first marking a chalk line on the lead where it is desired to cut it off; then, taking the hammer and chipping knife, as shown in Fig. 38, dip the blade of the knife in water, lay the blade square on the line and strike the back of the blade lightly with the hammer. Mark the sheet the whole length in this manner. Then go over it again and repeat the operation, making sure that the knife is held straight. The blade of the knife must be kept wet or it will stick in the lead and cause it to glance off sideways. After it is cut any uneven spots can be planed off smooth with a small smoothing plane, set so as to take off a very light chip. The lead should now be placed in position and dressed smoothly by using a piece of pine, or other soft board, as a dresser. This must be laid on any uneven spots and then pounded down smooth with a heavy wooden mallet, after which the seams should be shaved and burned at once; or if the seams are short and it is desired to put in enough work one day to keep the burner busy the next, strips of paper 6 inches wide should be pasted over the seams to keep the dust out. Only the edges of the paper should be pasted, so that when ready to burn all that will be necessary is to take hold of one end of the paper and strip it off, leaving the seam clean and free from dust and paste and ready to shave and burn.

After the bottom is finished the sides must be put in, in such a manner as to have as few seams in an upright position as possible, as it saves considerable time to burn them when horizontal. On small chambers or tanks not over 10 feet deep the carpenter should make a staging wide enough to receive two sheets of lead and as long as the tank is deep. The bottom of the chamber should then be covered with boards, so as to prevent damage to the lead. The staging is then brought in and set up on horses, and the sheets of lead are cut off and laid on the staging. The seams are lapped, shaved and burned, after which the lead tacks or straps are cut and burned on, to support the lead when in position.

There are different ways of putting on these straps. For side lead I use strips of the lead itself about 3 inches wide and long enough to lap well onto the studding. My way is to split this strip about ½ inch deep and bend the ends in alternate directions. The edges are then cut off, as shown at A, Fig. 39, after which they are burned in place. These straps should be spaced not more than 15 inches apart, and should be placed in such a manner as to come on the upper side of the studding.

Another method of putting on these tacks, and one which is most commonly practiced, is to trim the end of the strip of lead as shown at B, Fig. 39. The strip is laid flat on the lead sheet, with the bevel end down, and is then burned onto the sheet in that position, after which it is bent over the studding and nailed. The exponents of this method claim that a better job is done in that manner, as there is always a lifting pull on the strap. I claim for the first method that there is more strength in the lead seam, and that as the edge of the studding comes directly under the strap it acts as a sort of shelf for the strap and thereby becomes a strong brace. But it is probably only a matter of habit, as they hold all right either way.

Now, after having the seams burned and the straps in place, the lead must be put in position. This can be accomplished by any arrangement of block and tackles, but if the chamber be very large it will be found to be a saving of time and labor to rig up a derrick. This is not such an expensive thing to do, as a carpenter is always on hand and most likely all the material needed is already on the ground. This derrick should be constructed with a swinging boom, so that it can be raised, lowered or swung into any desired position.

Now to raise the side lead into position: The derrick is hooked onto the hook or rope that is on the upper end of the staging. It can then be easily raised in position. If the tank be very deep, or if it should be too narrow to follow this method, the sheet lead should be rolled up on a piece of 2, 3 or 4 inch iron pipe, depending upon the weight of the lead. This pipe should be long enough to project at least 6 inches from both ends of the roll. Two timbers, long enough to cross the frame work, should be obtained. About 18 inches from one end of each timber a notch should be cut to prevent the pipe from rolling. These timbers must now be placed across the frame work just over the place that is intended for the lead. The whole roll can now be raised with the derrick and the ends of the pipe placed in the notches. The lead can then be pulled down, similar to pulling down a window shade, after which the tacks can be burned on in place. This is shown at a, Fig. 40. Or if there be room enough the piece of lead can be cut from the roll, dressed smooth and have the tacks burned on while on the floor. The upper end of the lead can then be rolled over and nailed to a piece of timber 2 × 6 inches or heavier, and the derrick hooked onto this and raised in position. This is the easiest method where there is room to do it. These are a few of the methods used, but there are numerous other ways.

To place the top lead in position requires a staging, which can be built as follows: Enough hooks should be made to properly support the staging, shown at A, Fig. 41. Two timbers should be laid across the top of the chamber, far enough apart to allow two strips of lead to be placed in position at once. The hooks are now hooked over these timbers, while two pieces of 3 × 3 or 4 × 4 are placed in the other end of the hook. Planks are now laid over these timbers and the screws set up until the tops of the planks come just level with the top of the lead—not higher, or else they will prevent the joist from being placed in position.

The lead can now be cut off on the ground and hoisted up to the top, where it becomes an easy matter to place it in position. The lead tacks can now also be cut and burned on. They should be cut sufficiently long to allow them to lap over the top of the joist, as shown at a, Fig. 42, where they should be nailed with large headed nails. It will be noticed that the tacks are doubled up on the top lead and that they are not set opposite each other. The joist can now be set and the tacks nailed on, after which ropes can be tied onto the projecting ends of the 4 × 4 timbers and the whole staging be lowered to the floor at once. This operation can be repeated until the whole top is on.

It will be necessary to leave small holes between the lead seams at intervals for the hooks to pass through. However, these can be burned over at any time, and where the ends of the top should overlap the end of the chamber the lead can be left turned up until the staging is removed, after which it can be turned over and burned. The hooks are made of ? round iron and have a long thread cut on one end, so as to allow for adjustment. The details are shown in Fig. 41. There are also numerous fittings used in connection with these condensing chambers, but they are all easily made and are too simple to take up space here in explanation. Should it be necessary to use nails for any purpose on the inside of the chamber, the heads should be dipped into a pot of melted lead that has not quite set until the adhering ball of lead is about ½ inch in diameter, as shown in Fig. 43. These nails can be driven in place and the lead burned to the sheet lead, which will prevent corrosion.