Ragnarok : the age of fire and gravel

102 THE COMET.

earth was actually fused and melted, probably by cometic contact.

This earth of ours is really a great powder-magazine ; there is enough inflammable and explosive material about it to blow it into shreds at any moment.

Sir Charles Lyell quotes, approvingly, the thought of Pliny : “It is an amazement that our world, so full of combustible elements, stands a moment unexploded.”

It needs but an infinitesimal increase in the quantity of oxygen in the air to produce a combustion which would melt all things. In pure oxygen, steel burns like a candle-wick, Nay, it is not necessary to increase the amount of oxygen in the air to produce terrible results. It has been shown * that, of our forty-five miles of atmosphere, one fifth, or a stratum of nine miles in thickness, is oxygen. A shock, or an electrical or other convulsion, which would even partially disarrange or decompose this combination, and send an increased quantity of oxygen, the heavier gas, to the earth, would wrap everything in flames. Or the same effects might follow from any great change in the constitution of the water of the world. Water is composed of eight parts of oxygen and one part of hydrogen. “The intensest heat by far ever yet produced by the blow-pipe is by the combustion of these two gases.” And Dr. Robert Hare, of Philadelphia, found that the combination which produced the intensest heat was that in which the two gases were in the precise proportions found in water.t

We may suppose that this vast heat, whether it came from the comet, or the increased action of the sun, preceded the fall of the déhris of the comet by a few minutes or a few hours. We have seen the surface-rocks

* “Science and Genesis,” p. 125. + Ibid., p. 127.