In the last chapter we saw how dextrose or glucose could be converted by fermentation into alcohol.  Since corn starch, as we have seen, can be converted into dextrose, it can serve as a source of alcohol.  This was, in fact, one of the earliest misuses to which corn was put, and before the war put a stop to it 34,000,000 bushels went into the making of whiskey in the United States every year, not counting the moonshiners’ output.  But even though we left off drinking whiskey the distillers could still thrive.  Mars is more thirsty than Bacchus.  The output of whiskey, denatured for industrial purposes, is more than three times what is was before the war, and the price has risen from 30 cents a gallon to 67 cents.  This may make it profitable to utilize sugars, starches and cellulose that formerly were out of the question.  According to the calculations of the Forest Products Laboratory of Madison it costs from 37 to 44 cents a gallon to make alcohol from corn, but it may be made from sawdust at a cost of from 14 to 20 cents.  This is not “wood alcohol” (that is, methyl alcohol, CH_{4}O) such as is made by the destructive distillation of wood, but genuine “grain alcohol” (ethyl alcohol, C_{2}H_{6}O), such as is made by the fermentation of glucose or other sugar.  The first step in the process is to digest the sawdust or chips with dilute sulfuric acid under heat and pressure.  This converts the cellulose (wood fiber) in large part into glucose ("corn sugar”) which may be extracted by hot water in a diffusion battery as in extracting the sugar from beet chips.  This glucose solution may then be fermented by yeast and the resulting alcohol distilled off.  The process is perfectly practicable but has yet to be proved profitable.  But the sulfite liquors of the paper mills are being worked up successfully into industrial alcohol.

The rapidly approaching exhaustion of our oil fields which the war has accelerated leads us to look around to see what we can get to take the place of gasoline.  One of the most promising of the suggested substitutes is alcohol.  The United States is exceptionally rich in mineral oil, but some countries, for instance England, Germany, France and Australia, have little or none.  The Australian Advisory Council of Science, called to consider the problem, recommends alcohol for stationary engines and motor cars.  Alcohol has the disadvantage of being less volatile than gasoline so it is hard to start up the engine from the cold.  But the lower volatility and ignition point of alcohol are an advantage in that it can be put under a pressure of 150 pounds to the square inch.  A pound of gasoline contains fifty per cent. more potential energy than a pound of alcohol, but since the alcohol vapor can be put under twice the compression of the gasoline and requires only one-third the amount of air, the thermal efficiency of an alcohol engine may be fifty per cent. higher than that of a gasoline engine.  Alcohol also has several other conveniences that can