CHAPTER XV
FUEL AND LUBRICANTS
There is greater misconception and real ignorance about gasoline than concerning any other subject or material connected with automobiles. The explosive nature of gasoline seems to act the same as gunpowder, whereas, in fact, it is entirely different.
Knowledge on this important subject is lacking, because not enough care and study has been bestowed on it to bring out the proper information. Most people know that in order to explode gasoline in an engine, air is required; but few of them stop to consider that air is also the important thing necessary to burn gasoline in the open air.
An Experiment With Gasoline.—Experiments have been made with gasoline which show better than anything else where the danger lies, and what should be avoided. A can, partly filled with gasoline, was permitted to stand for a few minutes, until some of the gasoline was allowed to evaporate. The escaping vapor of course readily ignited and burned, but no explosion followed. It burned, but the blaze was at the top only. The gasoline in the can did not burn; only the vapor which was collecting and escaping at the top.
Gasoline was next put into a half pint cream bottle, so that it was half full. The opening of such a bottle is nearly as large diametrically as the bottle itself. After allowed to stand so as to permit evaporation to take place, a lighted match was thrust down into the gasoline. While the vapor at the top burned, the gasoline extinguished the match, the reason being that there was not enough oxygen within the bottle at the region of the surface of the gasoline to make an explosive mixture, and there was not an explosive mixture formed until the vapor had issued from the mouth of the bottle, and came into contact with the surrounding atmosphere.
Air Necessary for Explosion.—The fact is, the hydro-carbon in the gasoline needs air to support combustion, and it must have at least three parts of oxygen (which means fifteen parts of air), to one part of carbon, before it can be ignited. Air, for this purpose, cannot by any possibility, find its way down into the bottle, hence it will be seen that no danger need be anticipated from this source.
The inexperienced, however, will tell you, that he knows it will explode, because he has had some experience of that kind. Let us explain what happened in these explosions, and then the difference in the conditions will be understood.
Making an Explosive Mixture.—The same bottle used with the previous experiment was then taken, and the same amount of gasoline put into it. Air was then fanned into it, and a match applied. An explosion followed, because enough air has been admitted to make an inflammable gas.
If the mouth of the bottle is large enough to permit the products of combustion to pass out, no harm results; but if the opening of the bottle is too small, then the expanding gases will shatter the bottle.
Gunpowder.—Gunpowder acts differently, for the following reasons: Enough oxygen is compounded with the gunpowder to support combustion, and when a sufficient heat is applied it requires no outside air to cause combustion. The principal constituent of gunpowder is a fuel; so with gasoline. Every fuel requires oxygen before it will burn.