keep them from oxidizing and to help the metals to fuse.

The following list gives the names of various fluxes in common use, how they are applied, and on what material they are most commonly used:

Rosin.—Rosin is purchased by the pound and comes in chunks. It is very brittle and powders easily. Plumbers generally take a piece of 11⁄4 N. P. brass tubing, solder a trap screw in one end and a cone-shaped piece of copper on the other. The point of the cone is left open. Rosin is put into this tube and is easily sprinkled on work when needed.

Tallow.—A plumber's tallow candle answers the purpose for tallow flux. Some plumbers carry a can for the tallow, making it cleaner to handle.

Muriatic Acid.—Muriatic acid or hydrochloric acid is used both raw and reduced. Raw acid is not diluted or reduced. Reduced acid is made as follows: Put some zinc chips in a lead receptacle and then pour in the muriatic acid. The acid will at once act on the zinc. The fumes should be allowed to escape into the outer air. When chemical action ceases, the liquid remaining is called reduced acid.

PLUMBERS' SOILS AND PASTE

It is necessary when soldering or wiping a joint to cover the parts of pipe adjoining the portion that is to be soldered or wiped so that the solder will not stick to it. There are a number of preparations for this. The one used by the best mechanics today is paste, made as follows:

• 8 teaspoons of flour.
• 1 teaspoon of salt.
• 1 teaspoon of sugar.
• Mix with water and boil down to a thick paste.

The advantages of paste as a soil are many:

1. First, it is made of materials easily obtained.
2. Second, solder will not stick to it.
3. Third, if pipe is thoroughly cleaned, the paste will not rub off easily.
4. Fourth, poor workmanship cannot be covered up.
5. Fifth, when the work is completed, a wet cloth will wipe it off and leave the work clean.

Another soil used is lampblack and glue. A quantity of glue is melted and then lampblack is added. This needs to be heated and water added each time it is used. This soil is put on pipes with a short stubby brush. The work when completed with the silvery joint and jet black borders appears to the uninitiated very artistic and neat, but when the black soil is worn away the uneven edges of the joint appear, disclosing the reason for using a black soil that covers all defects. The mechanic of today who takes pride in his ability for good workmanship will not cover his work with black soil.

It can readily be seen that the use of lampblack soil encourages poor workmanship, while the use of paste forces, to a certain extent, good workmanship on the part of the mechanic.

Before soil or paste is applied, the pipe needs to be cleansed. Grease and dirt accumulate on the pipe. The methods employed to remove all foreign matter are simply to scrape the surface with fine sand or emery paper; sand and water will also answer for this purpose. This cleans the surface and allows the soil or paste to stick to the pipe.

MAKING DIFFERENT SOLDER JOINTS

The tools used in making the different solder joints as described and illustrated in this chapter are shown in Fig. 14.

Cup Joint.—The materials necessary for the work (Fig. 15): 12 inches of 1⁄2-inch AA lead pipe, paste, rosin, 1⁄2 and 1⁄2 solder.

If a gas furnace is not on the bench to heat the iron, then a gasoline furnace is necessary.

Each of the following operations must be done thoroughly to insure a perfect job:

1. First, with the saw cut off 12 inches of 1⁄2-inch AA lead pipe from the coil. When cutting off a piece of lead pipe from a coil or reel, always straighten out 1 foot more than is needed. This leaves 1 foot of straight pipe always on the coil.

Fig. 14.—Tools used for making solder joints.

1. Second, with the flat side of the rasp, square the ends of the 12-inch piece of pipe. (A good way to do this is to hold the pipe at right angles with the edge of the bench, run the rasp across the end of the pipe, keeping the rasp parallel with the edge of the bench. Apply this to all work when necessary to square the ends of pipe.)

   Third, cut the pipe with the saw, making two pieces each 6 inches in length.

   Fourth, square the ends just cut.

   Fifth, rasp the edges of one end as shown in the cut. Hold the work in such a way that the stroke of the rasp can be seen without moving the pipe.

   Sixth, take the other 6-inch piece of pipe and with the turn pin spread one end of it. The turn pin must be struck squarely in the center with the hammer, the point of the turn pin being kept in the center of the pipe. The pipe should be turned after each blow of the hammer. The pipe must not rest on the bench but should be held in the hand while using the turn pin. If the pipe bends, it can be straightened with bending irons. If the pipe is spread more on one side than the other, the turn pin should be hit on the opposite side so as to even the spread.

Fig. 15.

Fig. 16.—Cup joint.

1. Seventh, when the pipes are properly fitted, moisten the tips of the fingers with paste and rub the paste on