ARCHIVED RESEARCH INQUIRIES and RESPONSES

The ARC LAMP (overhead generator)

22. The ARC LAMP (overhead generator) by Fil Graff
    Posted: Nov. 01, 2000 @ 10:31.
    Friends and fellow searchers:
    Over the past few months, I have become interested in the function of the first portable gasoline lamps, the "Arc Lamp/Lantern", an overhead generator mantle lighting device that dates from Arthur Kitson's 1898 US patent up to the period when Coleman's vertical torch lit generator system became common (ca 1910-15). In all the trials (and yes, the samples tested are somewhat limited), we run into the same problem: the mantle will incandesce at a point about 1/2 what expected, and any additional fuel will cause an orange flame to come from the top of the mantle. I had exactly the same experience lighting a much more primative but roughly contemporary device, the PETROLITE, at the Ipswitch show in England a few weeks ago.Experiments have pretty well convinced us we have FUEL problem. It appears the "gasoline" sold in this time period was much different than what we can buy today. The following letter, summing up the experiments to date, was sent to Dan Gommell ( and the other interested parties), who has some contacts in the petroleum industry, so he would have experimental "data" and a picture of how the lamp in supposed to function, to send to his friends.If there are any petrochemists (overt or closet) out there, here is a project that could use some technical input! It may well turn out that these early lamps ARE nothing but curiosities that can be burned, but never at full capability. But one never knows what arcane knowledge lurks out there among collectors! Opening this up to general scrutiny aand input may turn up the answer! The more working on this, the more likely we'll come to a conclusion! :: Fil :: Subject: Arc Lamp function...testing results
    Date: Mon, 30 Oct 2000
    From: Fil Graff
    To: Dan Gommel
    Lou and Jim Hopf
    Neil McRae
    Dan: There are 3 "complete" arc lamps between Lou Hopf and I. We have tried regular gasoline and "Painters and Varnish Makers Naphtha" (Coleman fuel); mantle weave (both the tight gas mantle and a loose Aladdin) and pressure (low and higher). The results (3 different brands, somewhat different configurations, but all the same basic principle) are essentially the same with all three lamps. With gasoline, all three lamps will bunsen "properly", with naphtha, somewhat less so, and when the burner body is checked, it is filling with liquid fuel, even when the generator is cherry red. This indicates that the NAPHTHA fuel is NOT sufficiently volatile, and that the mixture sent into the air chamber (the bell at the end of the generator is an air bell, to facilitate air passage into the "down" tube/air mixing chamber) contains much liquid (rather than all vaporized) fuel which just puddles at the bottom.
    When gasoline is used, and a city gas (tight weave, which would be proper for these, as they ARE pressure lamps, albeit low pressure) mantle is installed, we can get about half incandescence in the mantle. If the fuel flow valve is opened more, then we get a 1" ORANGE flame coming from the top hole of the mantle. This is a stable flame, and does not seem to soot the mantle, although we have not left it burn that way very long. The ORANGE says incomplete combustion, in this case, excess fuel. The incomplete incandescence says there is not enough HEAT in the fuel mixture to fully incandesce the mantle. I got identical results when an open weave Aladdin mantle was used, and amount of tank pressure had NO effect!
    This is similar to the problem one has trying to burn a city gas lamp with propane...insufficient "BTU's (if that is the correct term)" in the fuel to make the mantle fully incandesce, or an open flame to burn YELLOW, rather than more of it Bunsen blue. Old manufactured gas evidently had more hydrocarbons in it, as it was designed more for LIGHT than heat; modern gas ("natural gas") CAN be goosed with the addition of naphthalene to give a more yellow flame, thus more light (the principle of the "Albo-Carbon" lamp that I saw demonstrated at Ara's...the naphthalene source is mothballs in water).
    I got exactly the same results at Ipswitch with Henry Plew's PETROLITE, and early and supremely simple gasoline vapor lamp. The gasoline seeps out of the pumice stone (cannot spill fuel with THIS lamp!) in the fuel tank, and evaporates. The fumes are collected in the bottom of a double-walled vertical tube, mixed with air and lit off at the top of the tube (the burner) where they incandesce a mantle (same mantle we used in the Arc lamp tests). Again, about 50% incandescence, and when more fuel/air mix was offered, the same ORANGE 1" flame out the mantle top! As with the Arc Lamps, the Petrolite burns happily and stable, but only at about Aladdin light output, not the ca. 150 cp it should deliver.
    Conclusion (aided by what your Canadian told you) is that modern fuel has been stripped of something that produces more HEAT when the almost inevitable fuel-air mixture of 6%-94% is burned for lighting purposes. Modern units ("modern" seems anything after the overhead generator stage, say 1915) were made for the modern fuel demanded by higher compression automobile engines. Thus Coleman (and AGM) lamps from the later torch lit period, right through the Quick-Lite and Easy-Lites all work fine on (unleaded) modern motor fuel. The fact that your friend's company sold"straight run" gasoline up to the 50's or so for use in the "old" gasoline devices tells me something, but I'm not sure what. MOST of these devices would be stoves, heaters, etc. (HEAT producers), and the analysis above doesn't seem to hold water from that perspective, unless the overhead generator was common in stoves, etc. long after it disappeared from lighting!
    The one variable we cannot evaluate, even though the Arc lamps in 2 of the three cases have original gas jets and prickers intact, is the port size in the gas jet. All in test have approx. .005" ports, roughly the same as the modern Coleman/AGM/Diamond, etc. IF the fuel port has becomeenlarged over the years, we would be getting inherently too much fuel in the mix, and this would account perhaps for the orange flame. Testing on more modern lamps shows such port enlargement will almost always produce a flame that soots the mantle (un- or partially burnt fuel). This is fine theory, BUT...I got the same results on the Petrolite, which has absolutely NO valves, prickers or anymore sophisticated control than two doors that open (one gas vapor, one air) when the control stem is rotated, turning the inner part of the central tube to open them.
    So there we are. Two different types of gasoline lamps from the early period (ca. 1898 to maybe 1915), both exhibiting the SAME ORANGE flame shooting from the mantle top.
    Any help any Petrochemical Engineer/Chemist can offer would be greatly appreciated. Right now, we seem to be at a point where these OLD pressure lamps are mere curiosities...burnable, but at a light output much less than originally claimed, and thus just a sort of ugly, andunsafe (fuel-wise) lamp that doesn't do any better than an Aladdin.
    :: Fil ::