Jr. still maintains: "The most direct route which we now know for converting energy from its source, the sun, into a material that is suitable for use in an internal combustion motor is through vegetation to alcohol… It now appears that alcohol is the only liquid from a direct vegetable source that combines relative cheapness with suitability (although other sources might be found)… Alcohol will stand very high initial compressions without knocking, and at high compressions is smooth and highly satisfactory.". In 1921, British engineer Harry Ricardo patents racing fuels RD1 and RD2 (for Ricardo Discol) that contained methanol and ethanol, acetone and small amounts of water. These were widely used on race tracks throughout Europe and the US in the 1920s and 30s. In 1923 leaded gasoline is marketed, and by 1924 GM and Standard Oil Co. form the Ethyl Corp. Ethyl claims it has "solved" the problem of engine knock, but public health scientists (e.g. Alice Hamilton of Harvard University) are appalled at the prospects for lead poisoning and insist that alternatives such as ethanol blends are available. In 1923 Rolls-Royce engine designer Harry Ricardo writes: "…It is a matter of absolute necessity to find an alternative fuel. Fortunately, such a fuel is in sight in the form of alcohol; this is a vegetable product whose consumption involves no drain on the world’s storage and which, in tropical countries at all events, can ultimately be produced in quantities sufficient to meet the world’s demand, at all events at the present rate of consumption. By the use of a fuel derived from vegetation, mankind is adapting the sun’s heat to the development of motive power, as it becomes available from day to day; by using mineral fuels, he is consuming a legacy – and a limited legacy at that – of heat stored away many thousands of years ago. In the one case he is, as it were, living within his income, in the other he is squandering his capital. It is perfectly well known that alcohol is an excellent fuel, and there is little doubt but that sufficient supplies could be produced within the tropical regions of the British empire…" In 1923, the price of alcohol from molasses was less than 20 cents per US gallon, while retail gasoline prices had reached an all-time high of 28 cents per gallon. Standard Oil experiments with a 10% alcohol, 90%