ARC FURNACE INCASED IN TWO FLOWERPOTS

A SMALL electric arc furnace for experimental purposes can be made from two flowerpots, one 2 in. in diameter and the other either 6 or 8 in. Drill two holes opposite each other just below the lip of the smaller pot. (An ordinary steel drill will do this.) Make them large enough to receive carbon arc-light rods.

Cover the hole in the bottom of the large pot and fill with sand until the top of the small one, when set firmly on the sand, is about 1 in. below the top of the large one. Now drill a hole in the large pot at the same level of those in the small one. Push a rod through the three holes and mark the point of contact on the other side of the large pot. Be sure that the rod is level and the small pot is properly centered. Drill the second hole in the large pot and push the rod through it. Now pour sand around the small pot nearly to the level of the rod. Settle this by pouring a little water on it. Pack fire clay around the rod in the spaces between the two pots, being careful to get it close to both walls. This keeps the sand from jamming the carbons, which must slide easily. Pour sand even with the top of the small flowerpot and settle it with water. Withdraw the rod and set the furnace aside to dry. Lids may be made from flowerpot saucers.

Prepare the carbons by clamping a strip of brass or copper around each to furnish a good electrical contact. Tape a piece of glass tubing to one rod for adjustment as illustrated. The other rod should be held rigid while operating. The necessary resistance can be made by putting a teaspoonful of soda in a gallon of water. My furnace draws current through a 15-ampere fuse, which is safe for ordinary house wiring. To start, touch the carbons together.

Dark goggles must be used. Do not touch the carbons with the bare hands. Do not use a resistance of the type described when it is hot enough to boil.