of compressed air is necessary, the pressure ranging from 5 to 10 pounds, and the various parts of the apparatus are joined together by 5/16-inch rubber hose, which is securely wired to the apparatus to insure tight connection. This is made necessary by the air pressure advised. The mixing valve is a very simple fitting, comprising of two shut-off cocks attached to a common outlet pipe. One of the cocks regulates the gas supply, the other controls the amount of air. Naturally, the mixed air and gas issue from the outlet pipe. The burner is a special form, which gives a very hot flame. When the flame is properly adjusted for burning it will have a greenish color. If there is too much gas, the flame will be yellow and be very ragged. If the flame is a blue color, gradually becoming less visible, too much air is provided, and as

a result it is lacking in heating power. The hottest part of a properly adjusted flame is just past the end of the inner point. Do not hold the flame too near the work, as the heating effect of the flame will be diminished if it is spread. If the air pressure is obtained from a tank holding a supply for blowing up automobile tires, for instance, a reducing valve must be introduced in the air line between the tank and the burner. The best method of producing the air pressure is by a small blower.

The apparatus needed for arc burning is shown at Fig. 32 A. The advantage of this method is that current from a six-volt battery may be used, not requiring the fitting of auxiliary apparatus. Although called an "arc-burning outfit," it is said that the best results are obtained by using the carbon as a soldering iron after it becomes heated without actually drawing an arc. The outfit is very simple, consisting of a carbon holder with cable, a clamp and a number of 1/4-inch diameter carbons. The method of using it for reburning connectors is easily understood. The connector to be burned is connected to one terminal of the storage battery by a piece of cable, which can be made fast to the latter by means of a clamp. It is essential that the contact surfaces be scraped bright to secure a good electrical connection. The cable attached to the carbon holder is connected to the other battery terminal. If a battery is partially discharged the three cells will be needed, but if the battery is fully charged three cells may give too much voltage. The amount of current passing through should be sufficient to raise the temperature of the carbon to at least a bright cherry red while it is in contact with the joint. The carbon should be sharpened to a long point and should not project from the holder more than two or three inches. The holder should be cooled off occasionally by plunging it into a pail of water. After being used for a short time the carbon will not heat properly because of a scale film produced on the surface. This should be cleaned off till the bare carbon is exposed before proceeding with the vork.

The hydrogen-gas outfit, such as shown at B, Fig. 32, while more expensive and troublesome than the illuminating gas burner, produces a much superior flame for lead burning, and is very gen

erally used where a large amount of work is done. The hydrogen outfit shown is supplied by the Electric Storage Battery Company, and consists of the following parts: One generator; one washbottle; one air pump and tank combined; one branch pipe; one finger pipe and set of tips; one 50-foot length 5/16-inch rubber tubing; one two-foot length 3/4-inch rubber tubing; two rubber stoppers; one triangular scraper. The material for charging is: zinc, 15 pounds; water, 12 quarts; sulphuric acid, 212 quarts.

Fig. 33.-How Hydrogen Gas Generating Outfit is Set Up.

The apparatus is connected up as shown at Fig. 33. The instructions for using are sent with each outfit, but a brief outline of the method of joining the parts may be of some value. The bottom of the reservoir A must be higher than the top of the gas chamber F. Connect the lower outlet M of the reservoir A with the pipe G, coming out of the top of the gas chamber F. Put a short piece of 5/16-inch hose on the outlet E coming from the gas chamber F, and kink this hose to constrict the passage and prevent anything coming through it. Put a rubber stopper in outlet H of gas chamber F, and inspect carefully to see that it is tightly in place. Remove the hand-hole cover X from the top

of the gas chamber, place a quantity of zinc on the grating. Next replace the hand-hole cover, making sure that it is securely fastened, and screw down tight on its gasket. An amount of water is placed in reservoir A and then a certain amount of vitriol is poured into the water. The wash-bottle J is filled half full of water, and its outlet K is connected to one side N of the branch pipe. The other side of the branch pipe S is joined to the outlet W on the air tank Q. The finger pipe U is connected with

Fig. 34.-Method of Using Oxygen-Illuminating Gas Blow-Pipe Outfit.

the outlet T of the branch pipe. Both cocks S and M are closed. Next take the kink out of the hose connected to outlet E of the gas chamber and allow the air to escape until the charge of water and vitriol runs down from the reservoir into the gas chamber, then slip the free end of this hose over the outlet marked L on the wash-bottle.

As the acid solution acts on the zinc, hydrogen gas is liberated. This gas is not only hot, but is apt to be laden with globules of

acid. The function of the water in the wash-bottle is to cool the gas and to clean it before it goes to the finger pipe. Air pressure is pumped up into the tank. The petcock N in the branch pipe is then opened and the hydrogen gas issuing from the burner is ignited. The air is then admitted by opening the petcock S and adjusted until a hot-pointed flame of a greenish color is obtained that is suitable for burning. If any of the solution is spilled its

Fig. 35. Showing Antimony-Lead Alloy Grids Before Filling and How Plates are Joined Together by Connecting Straps.

action may be neutralized by using Gold Dust, Pearline, washing soda, slaked lime, or ammonia. If burned when pouring acid into the reservoir, which, of course, will not occur unless this is carelessly done, apply olive oil to the burn and not water.

Another outfit suitable for lead burning consists of apparatus for burning a mixture of oxygen and illuminating gases. As oxygen is widely used in many garages for carbon removal, the same tank may be easily connected up to a single blow-pipe outfit. The connections are very clearly shown at Fig. 34. As the oxygen is carried under very high pressure in the tank it is necessary to pro