By Norris Chambers
You don't hear much about carbide anymore. In the old days it was a household word, especially among the boys who hunted and performed mean tricks at school. Calcium Carbide came in two forms, granulated and lump. The granulated form was a rock-like substance composed of small granules. The lump type was composed of irregular sizes of stone-like chunks. This chemical was available just about everywhere in the size container you desired. When we went hunting, we wore miner's lamps that operated on lump carbide. The lamp consisted of a small tank which unscrewed and into which you placed the lumps. There was another portion above that you filled with water. A valve let you drop water into the carbide. This chemical formed a combustible gas when combined with water, or just about any other liquid. In the lamps, the gas escaped through a jet and was ignited. A reflector behind it cast a beam of light several hundred feet into the darkness. When hunting, this beam caused the eyes of any 'possums, skunks or most other animals to glow. Different animals had different colors, and experienced hunters could tell you what was looking at you from the reflection. You could look up into a tall tree and spot the game instantly.
Many farms used carbide for lighting. The gas produced a bright jet of flame, and did a much better job of lighting a room than the regular kerosene lamp. For this use, a steel tank was buried, much as the later butane tanks were buried. Water was placed in the bottom of the tank and the carbide in an enclosure above. Granulated carbide was usually used in these tanks, and was allowed to fall into the water through a large wafer valve. This valve was pressure activated, and when the pressure reached an operating value, it closed. As you used the gas, the pressure dropped and allowed more carbide to fall into the water. There were a few small burner hot plates made to work off of carbide, and these did a good job of cooking bacon, eggs, etc.
Another more or less questionable use that school boys made of it was to play mean tricks at school. Those early schools were before the day of ball points and fiber points, and all desks contained an ink well. Usually a student kept a bottle of ink on the desk instead of using the ink well. You've all heard of mean boys dipping the curls of the girl seated in front in the ink well. But not many have heard about putting a lump or two of carbide in an ink bottle and pushing the cork in tight. As soon as enough pressure built up, the cork would burst out with an explosive noise and bang against the ceiling of the room. This created quite a distraction, and helped to tint the teacher's hair prematurely. Sometimes, if the explosion was violent enough, ink came out with the gas and made quite a mess.
But all this talk about carbide is just leading up to the furnace that my brother made in our blacksmith shop to replace coal for most forge operations. It would heat iron for shaping on an anvil with a hammer, or would even melt it if left in long enough. As you probably know, carbide is used in modern welding torches in the form of acetylene gas mixed with oxygen. A torch flame with acetylene and oxygen will melt just about any metal, and does an excellent job of welding.
Our old forge was built of rock and about three feet in diameter. A three inch stove pipe came up through the middle, which was of concrete and sloped downward toward the center. In regular coal operation, the coal was ignited in the middle, and air was blown through the hole in the center with a hand cranked blower. The blower was geared so that slow cranking produced high speed of the fan, and child labor was often recruited to turn the crank. The coal, fanned by the extra oxygen in the air, made a brilliant fire that would heat or melt steel.
My older brother constructed a carbide tank from an old steel tank he found abandoned by an oil field operation. The gas was injected into the fire area of the forge by four 1/8 inch pipes placed in the center of one inch pipes that extended to the outer edge of the concrete and rock table. The one inch pipes were connected to the blower, and when the acetylene was introduced into the fire area through small jets on the end of the 1/8 inch pipes, the air added to the intensity of the fire. By the proper adjustment of air and gas, a fire could be produced that would melt iron and act almost as stable as a coal fire. As far as I know, we had the only forge in the county that was fired with carbide gas.
This technique has been used with natural gas to produce high heat in many commercial applications.
This little lesson on the uses of carbide is not intended to inspire anyone to try using it. It is dangerous, and the fact that we played with it does not mean that it is safe.