modernmicroscopy : columns : "how to" tutorial series

"How To" Tutorial Series
How to Make/Modify and Use an Alcohol Lamp
by  John Gustav Delly, Scientific Advisor, Hooke College of Applied Sciences, Westmont, IL

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Figure 6 illustrates three alcohol lamps that are components of chemistry sets for youngsters; similar alcohol lamps have been supplied in such kits for over 80 years.  The lamps illustrated here are all relatively small – about one ounce capacity – but that size is totally adequate for both these sets and for general microscopy; indeed, similar lamps are often a part of microscope sets for youngsters.  The three lamps here are all 40-50 years old.  The alcohol lamp on the left, from a Gilbert Chemistry Outfit, is fitted with an arrangement for elementary blowpipe work; the tip is constricted to a narrow opening, and in use a piece of rubber tubing is fitted to the lower end, and the user blows through the other end of the tubing, keeping the cheeks fully puffed out, inhaling through the nose in typical blowpipe fashion, so as to maintain a steady stream of air to produce a very sharp, intensely hot flame.  The alcohol lamp in the middle, from a Gilbert Chemistry Outfit of a different era, is typical and unremarkable.  The alcohol lamp on the right is from a Chemcraft Chemistry Outfit (Porter Chemical Company), and has the molded-in legend “Porter Alcohol Lamp”; the wick is badly in need of trimming!  None of these lamps feature a vent hole.


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Figure 6


Figure 7 is a page from a Chemcraft Chemistry Outfit manual, describing and illustrating the use of the blowpipe feature of the alcohol lamp.


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Figure 7


Figure 8 is The Alcohol Lamp page from the Skilcraft® Chemlab® Manual.  The text says “Do not fill to the top of the bottle” and “Fill the lamp bottle with alcohol only to the start of the neck or lower”.  The “Fill Line” in the illustration is, however, too high.  This manual also says “The best fuel for the alcohol lamp is any commercially available denatured ethyl alcohol (grain alcohol), available only by prescription …. Do not use methyl alcohol (wood alcohol) because it has additional poisonous properties, isopropyl alcohol is readily available, but it will burn with a sooty flame”.


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Figure 8


Figures 9 and 10 are pages from other “Do-it-Yourself” sources; interestingly, the text in Figure 10 recommends making a wick cap from a brass rifle cartridge (this reference is from a UNESCO source).


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Figure 9
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Figure 10


It was Short (Microscopic Determination of the Ore Minerals, M.N. Short, Geological Survey Bulletin 914, USGPO, Washington, D.C., Second Edition, 1940) who illustrated and described the use of a narrow brass tube and cotton string to make an alcohol lamp for microchemical methods – See Figure 11. 


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Figure 11


Figure 12 illustrates two British-made alcohol lamps – both are excellent.  The capacity of both lamps is about two ounces.  They are both dimensionally stable, and both employ ground-glass hoods of different design.  The lamp on the left has a loosely laid in ceramic wick holder, and is vented by its loose fit.  The lamp on the right has a female-threaded brass fitting cemented to the glass neck, and a threaded screw-in brass top/wick holder, which does have a vent hole drilled through!  Filled no more than about half way, this lamp is ideal for general heating purposes.  In Britain, these “spirit lamps” commonly burn “Methylated Spirit”, often slightly tinged with Gentian Violet, as illustrated in Figure 12.


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Figure 12


Figure 13 illustrates an interesting alcohol lamp for portable or field use.  It is part of a World War II Field, Needle Sterilization Kit.  It is nickel-plated brass, and fit in the bottom of a cigarette-package-size, front-opening metal box with this burner at the bottom, and an elongated, round-bottomed sterilization tray on top, which was just large enough to hold one or two hypodermic needles.  A quarter-ounce of alcohol provides enough fuel for this lamp to burn for one hour.  This is the alcohol lamp I use in my Field Kit.


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Figure 13


I recently had the opportunity to modify a commercially-available alcohol lamp for one of the staff members, and then two others on the staff also requested one.  I started with the purchase of an alcohol lamp from McCrone Microscopes & Accessories; this lamp is illustrated on the left in Figure 14.  It is not a bad design – small, stable, metal cap/wick holder and hood made of brass; the only thing it was missing for microscopical work was a pressure-equalization vent, and a smaller wick.  A vent was made by drilling a 1/16” hole through the top of the cap.  For the smaller wick I decided to custom-make a piece of brass that would fit inside the supplied opening, but that would itself have a much smaller opening that would accept a fine woven-cotton string, or a fine woven glass fiber wick.  The custom-made piece is shown lying between the two lamps in Figure 14, and installed in the lamp on the right.


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Figure 14


Specifically, the outside diameter of the wick tube was 0.275”, and the inside diameter was just under 0.250”.  I started by chucking a 2” length of ¼” diameter brass rod into my Unimat, a small hobbyist’s lathe, and turned a 5/32” length at the end down to 0.16” diameter.  This end was then center drilled, and a 3/32” hole was drilled something more than 1” deep.  The rod was then turned down to 0.24”.  The other end of the rod was then cut-off and faced so that it was 1” long, plus the 5/32” extension; this is the piece shown lying down in Figure 14.  This adapter was then epoxied into the wick tube, and the new string wick threaded through.  Figure 15 shows a close-up of the completed modification, wick reducer and breather vent.  As a final touch for my colleagues, I embellished the shoulder of their personal lamp with their own initials, by employing a rapidly rotating zirconium rod chucked into a hobbyist’s motorized hand tool.


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Figure 15


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