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Page:Popular Science Monthly Volume 70.djvu/261

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burner in almost any place, is such that it would undoubtedly be preferred to all other fuels for all purposes if it were not for the cost.

The presence of any denaturing agent robs it, to a greater or a less extent, of some of its natural advantages. The odor of the denaturant is apt to be detected either before, during or after combustion.

Denatured alcohol has been found to dissolve some metals, notably brass. Of course the solvent effect is not rapid, but yet it is constantly under way and necessitates repairs to metallic lamps. The metal dissolves as a salt which is left on the wick when the more volatile alcohol burns, encrusting the wick and necessitating occasional cleaning or trimming. This crust interferes with the efficiency of the lamp whether it be used for heating or for light. But that is not the worst feature of the solution of metals in the alcohol. The small quantities of metal are in part volatilized and are deposited on any object which is being heated. Platinum crucibles are quickly ruined by this action and this alone is sufficient to absolutely prohibit the use of denatured alcohol in chemical laboratories.

Some investigations have been made to determine which constituent of denatured alcohol is responsible for this solvent action. Neither pure ethyl alcohol nor pure methyl alcohol nor pure pyridine, nor yet pure 'benzine' would dissolve metals. The most recent work appears to fix the blame on small quantities of organic esters, formed during fermentation and left in the alcohol itself, which of course is not so carefully purified, if it is to be denatured, as if it were intended for drinking purposes. This might appear to be a small detail, but is not, for it affects the usefulness of denatured alcohol for heat, light and power also. Anything corrosive in action could not be tolerated in the cylinder of an engine any more than it could in contact with a platinum crucible in the chemical laboratory.

The efficiency of a gas engine is the greater the greater the compression of the charge, the mixture of gas or vapor and air, before the explosion. Compression can not be carried far with gasoline, for compression, of course, heats gases, and gasoline catches fire so easily it is apt to explode prematurely, i. e., while the piston head is traveling the wrong way. The fact that alcohol is less readily inflammable makes it possible to compress mixtures of air and alcohol much more without danger of premature ignition. Therefore a larger percentage of the power in alcohol can be utilized, it is more efficient. In parallel experiments Diesel obtained 17.6 per cent, of the power in kerosene as mechanical energy, 20.5 per cent, of the power in gasoline, and 31.7 per cent, of the power in ethyl alcohol. Those competent to judge say it will not be difficult to obtain 40 per cent, of the power in alcohol as mechanical work done. But, on the other hand, there is less power in alcohol than there is in the petroleum products, weight for weight, as