Since all living beings are formed of the same elements as those of the mineral world, the term "organic" as applied to combinations can only be used in order to emphasize the complexity of their constitution. It was formerly believed that these organic combinations were the result of life, and could not be reproduced except by living organisms. To-day many of these organic substances are produced in the laboratory from inorganic materials. In the past history of the globe it is easy to imagine conditions which would facilitate the synthesis of organic substances without the interposition of life. At the temperature of the electric furnace, which was that of the earth at an early period of its evolution, chemical combinations are possible quite other than those obtaining under the present conditions of temperature and pressure. At the higher temperature of the early {169} geological era, silicides, carbides, phosphides, and nitrides were formed in stable combinations instead of the oxides, silicates, carbonates, phosphates, and nitrates of the present time. These combinations existed on the earth at a time when the conditions of temperature precluded the existence of water in a liquid state. As the temperature cooled, and the water vapour became condensed, it entered into chemical combination with the various rocks, producing organic compounds like acetylene, which results from the action of water on calcium carbide. H. Lenicque has developed a theory as to the formation of various rocks under these conditions, which he communicated in 1903 to the French Society of Civil Engineers. The chemical evolution of the globe has undergone great changes as the temperature gradually fell and the constitution of its crust altered. As long as the temperature was higher than that at which water can exist, all chemical reactions must have taken place between anhydric substances, elements and salts in a state of fusion. These conditions are very different from those of the present-day chemistry, which is the chemistry of aqueous solutions. We may hope to be able to reproduce the earlier conditions by the experimental study of anhydric substances in a state of fusion.