So important indeed did the matter appear to Lavoisier's countrymen that in the year 8 of the French Republic (1800) a prize--consisting of a gold medal, the value of which, expressed in terms of the newly introduced metric system, was that of one kilogram of gold--was offered by the Institute for the best answer to the question: "What are the characteristics by which animal and vegetable substances which act as ferments can be distinguished from those which they are capable of fermenting?" [p004] This valuable prize was again offered in 1802 but was never awarded, as the fund from which it was to be drawn was sequestrated from the Institute in 1804. The first response to this stimulating offer was an important memoir by citizen Thenard [1803], which provided many of the facts upon which Liebig subsequently based his views. Thenard combats the prevailing idea, first expressed by Fabroni (1787-1799), that fermentation is caused by the action of gluten derived from grain on starch and sugar, but is himself uncertain as to the actual nature of the ferment. He points out that all fermenting liquids deposit a material resembling brewer's yeast, and he shows that this contains nitrogen, much of which is evolved as ammonia on distillation. His most important result is, however, that when yeast is used to ferment pure sugar, it undergoes a gradual change and is finally left as a white mass, much reduced in weight, which contains no nitrogen and is without action on sugar. Thenard, moreover, it is interesting to note, differs from Lavoisier, inasmuch as he ascribes the origin of some of the carbonic acid to the carbon of the ferment, an opinion which was still held in various degrees by many investigators (see Seguin, quoted by Thenard).