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The Joy of High Tech


Rodford Edmiston

Being the occasionally interesting ramblings of a major-league technophile.

Getting Gassed

     Gaseous fuels have been important to human civilization for a relatively short time. The early Nineteenth Century saw the first widespread use of gas lamps for illumination. These burned coal gas, first deliberately produced (as opposed to being an industrial byproduct of making coke) about a century earlier. Despite the recognition of the flammability of coal gas, and the ability to produce it on demand decades were to lapse before someone realized it might not be a bad idea to burn it in a controlled fashion to produce light and heat.

     Coal gas is a mixture of methane, hydrogen, carbon monoxide and other substances. It is the carbon monoxide which makes it particularly hazardous for indoor use. While most of the other ingredients would merely suffocate you, this would actively poison you, while imparting a nice, healthy ruddy hue to your skin.

     In the 1790s William Murdoch began experimenting with ways to use flammable gas. For lighting he settled on coal gas, using it in 1798 to light the main building of the Soho Foundry. An employee of the Foundry saw the potential for making lots of money with this technology, and quit to found a gas light business.

     Over the next twenty years several such enterprises sprung up in multiple countries. Their earliest lamps were all simple gas jets, the gas mixing with air outside the nozzle and then burning. For the most part commercial success was nonexistent, with most uses being demonstrations, rather than practical exercises in providing artificial light.

     Huge effort was put into quantifying the intensity and illumination capacity of gas flame by source and type of gas. Not for many years was the fact that most of these sources were producing methane mixed with various other substances the reason behind the variability. Indeed, the fact that coal gas was not a homogenous substance but rather a mixture, which varied depending on what coal was used and how the gas was produced, escaped notice for decades. Still, this was eventually recognized, and one important step in the successful application of coal gas was the development of methods of quantifying its composition and purifying it to produce a uniform product.

     With that out of the way, and metered gas jets (that is, gas jets with precise holes to mix air into the coal gas before it went out the nozzle to be burned) coal gas lamps became much more practical. These metering ports were often formed at an angle, generating a swirl effect which helped mix coal gas and air before the combination was burned. Much research was applied to them, and many patents awarded for designs of them.

     Factories, homes and offices began to adopt the new lights. These greatly reduced fire risks over candles and oil lamps, required much less fiddling and produced much less mess (anyone who has spilled kerosene can understand the importance of that feature) and were cheaper. Naturally, one of the first devices invented to go with the practical gas lamp was the rotary gas meter.

     Many alternatives to coal gas were tried, and some even proved commercially successful. One driving force for this was the desire for brighter light with a more natural color than coal gas could produce. The same stimulus drove those working with coal gas to improve it and/or the lamps which burned it. The more successful alternatives are detailed below.

     Acetylene was a very good method of creating light for portable usage. It gives a bright, white light, and can be produced as needed by dripping water onto calcium carbide. Acetylene is also popular for welding, but before the invention of safe storage tanks (see below) the gas had to be generated on site. Carbide-fueled acetylene lamps were compact and safe sources of bright, white light for mining, caving, and night riding of early automobiles and bicycles. (And the flame can be used for writing with soot. :-) The waste product of the carbide + water reaction is calcium hydroxide (caustic lime), which is toxic, but this eventually reacts with carbon dioxide in the air to form calcium carbonate, which isn't.

     Unfortunately, acetylene is a metastable compound, with a disturbing tendency to detonate in storage. Eventually, the invention of anticatalyst compounds for storage tanks did away with the generator method for welding and some other uses. Modern electrical lamps have almost entirely replaced acetylene lamps for illumination in mines, caves and so forth, though they still have their adherents.

     Limelight required more elaborate apparatus, but the amount of light was greater and even whiter. Oxygen and hydrogen were mixed and ignited, with the resulting flame directed onto a piece of lime (calcium oxide). This mineral can withstand very high temperatures, and glows a brilliant and very white light when heated by such a flame. Due to needing hydrogen and oxygen and the amount of heat produced, plus the skill needed to keep things working properly, these light sources were generally only used in commercial settings where a great deal of natural-colored light was needed, such as theaters. (And thus technology drives language.)

     Gradual improvements made things slowly better in the illumination field for several decades. Then, in 1890, German scientist Carl Welsbach invented the mantle lamp. This produced a much brighter light for the same amount of gas, and the light was also much closer to natural sunlight in color. In fact, light from gas mantle lamps was "whiter" than that from the early electrical incandescent lights.

      These lamps were so good, in fact, that electrical incandescent lights had a long, uphill struggle to supplant them. What is most likely the major factor in the eventual triumph of electricity over gas is convenience. Flipping a switch is simply quicker and easier than lighting a lamp. And it's hard to fuse (in the sense of having a way to interrupt the current in case of a too great flow) a gas line.

     Even today, the gas mantle lamp has far from disappeared. Decorative or emergency lighting kerosene mantle lamps abound, and gas mantle lamps for natural gas or propane are used for emergency lighting or camping, and even as a primary light source in remote locations.

          This document is Copyright 2007 Rodford Edmiston Smith. Anyone wishing to repost it must have permission from the author, who can be reached at: stickmaker@usa.net