Yes, steamers (sometimes) run on gas. And kerosene, and naphtha, and many other combustibles

As we’ve all learned this week, following Jay Leno’s widely reported incident with a steam car that left part of his face burned, steam cars often use gasoline to fire the boilers that produce the motivating steam. However, that wasn’t always the case, with gasoline coming and going out of fashion for steam car operators over the years and with some steam cars even fitted for burning multiple types of fuel.

Multiple outlets reported early this week that Leno, the former “The Tonight Show” host who currently showcases his and others’ cars via his CNBC show “Jay Leno’s Garage,” suffered burns to his face on Saturday while clearing a clogged fuel line on a White steam car, one of several steamers in Leno’s collection. Leno has told Variety that he is fine and “just need a week or two to get back on my feet.”

The reports raised a number of questions among enthusiasts about the fuels used in steam cars. Even though steam cars are considered external combustion, do they still require gasoline? Weren’t kerosene and other fuels also used to fire the boilers?

Yes and yes, according to Stanley Museum Archivist Jim Merrick, who noted that prior to 1910, Stanley cars used gasoline as both main fuel and fuel for the pilot burner. The Stanley twins, in fact, had pioneered not only the commercially viable steam car but also the use of liquid fuel – in their case, gasoline, at the time a byproduct of kerosene distillation that was widely available at drugstores for use in lighting lamps – in a steam car’s operation. Prior to the Stanleys, steam automobiles used wood, as seen in the operation of the 1769 Cugnot fardier a vapeurfardier a vapeur, or more commonly coal, as was the case with Sylvester Roper’s Boston-based experiments in steam power.

That’s not to say the Stanleys’ decision to use gasoline was universally adopted thereafter. Leon Serpollet, the French steam-car pioneer, discarded coal for a fuel source in favor of kerosene – also known in many parts of the world as paraffin. While gasoline remained relatively inexpensive at the turn of the twentieth century and was known to vaporize easily, making it suitable for use in a steam car, kerosene was even cheaper and perhaps more widely available and offered higher BTU output, though it was known for an unpleasant odor and for incomplete burning, leading to sooty deposits that could clog the burner’s jets.

That said, as Lord Montagu of Beaulieu and Anthony Build wrote in their 1971 book on steam cars, gasoline had one major drawback over kerosene as a fuel for steam cars: the potential for blow-backs and flare-ups.

This not infrequently happened when running downhill using no steam with the main fire shut off so that when the diaphragm valve re-opened, the fire did not re-light and the vapor liquefied in the cooled burner and flooded the fire-box with petrol, which then flared up when the driver tried to relight the burner. Paraffin burners were prime to similar misbehaviour, it is true, but the risk of a serious blaze was less great.

Experienced Stanley owners soon became accustomed to the routine of shutting off the fuel lines to main and pilot burners, throwing open the bonnet and just waiting for the flames to die down; but there is no denying that the spectacle was thoroughly disconcerting to the ordinary bystander.

In fact, as they later expanded, the gasoline-fired type of steam car “did not sell in France where there was official objection to it because of the fire risk (which was probably exaggerated) and where, in some departments, it was illegal to operate.” Similarly, “this propensity to flare up in public… led many ferries and most public garages to insist that steam cars must be manhandled with their fires extinguished.”

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