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 count in its favor. In the case of incomplete combustion the cylinders are less likely to be clogged with carbon and the escaping gases do not have the offensive odor of the gasoline smoke. Alcohol does not ignite so easily as gasoline and the fire is more readily put out, for water thrown upon blazing alcohol dilutes it and puts out the flame while gasoline floats on water and the fire is spread by it. It is possible to increase the inflammability of alcohol by mixing with it some hydrocarbon such as gasoline, benzene or acetylene. In the Taylor-White process the vapor from low-grade alcohol containing 17 per cent. water is passed over calcium carbide. This takes out the water and adds acetylene gas, making a suitable mixture for an internal combustion engine. Alcohol can be made from anything of a starchy, sugary or woody nature, that is, from the main substance of all vegetation. If we start with wood (cellulose) we convert it first into sugar (glucose) and, of course, we could stop here and use it for food instead of carrying it on into alcohol. This provides one factor of our food, the carbohydrate, but by growing the yeast plants on glucose and feeding them with nitrates made from the air we can get the protein and fat. So it is quite possible to live on sawdust, although it would be too expensive a diet for anybody but a millionaire, and he would not enjoy it. Glucose has been made from formaldehyde and this in turn made from carbon, hydrogen and oxygen, so the synthetic production of food from the elements is not such an absurdity as it was thought when Berthelot suggested it half a century ago.