18. At the epoch when the terrestrial globe was an incandescent mass, it contained not one atom more or less than it does today. Only under the influence of this high temperature, the greater part of the substances composing it, and which we see under the form of liquids and solids, earth, stones, metals, and crystals, were found in a very different state. They have only been submitted to a transformation. In consequence of the cooling process and mixtures, the elements have formed new combinations. The air, considerably inflated, became extended to an immeasurable distance. All the water forcibly reduced to vapor was mingled with the air. All the substances susceptible of volatilization – such as metals, sulphur, carbon – were there found in a gaseous state. The state of the atmosphere was then in no way comparable with its present condition. The density of all these vapors gave it an opacity through which no ray of sunlight could penetrate. If a living being could have existed on Earth at this period, he would have had for light only the sinister brightness of the fires beneath his feet, the burning atmosphere, and not even the existence of the sun would be noticed.