HOME STUDIES IN CHEMISTRY AND PHYSICS.
BY PROF. J. T. EDWARDS, D. D.
Director of the Chautauqua School of Experimental Science.
FIRE.—PHYSICAL PROPERTIES.
Clearness, accuracy, and brevity are the essentials of good definition. That it is no easy task to combine these, every teacher realizes.
Perhaps it is near the truth to say that fire is that operation in nature which at the same time evolves heat and light. The operation is, at the present time, supposed to be a certain vibration of ethereal or more solid substances. All matter is in motion. Whence this motion was first derived no philosopher can tell, unless he goes back to that primal source of both matter and motion, which in the beginning created the heavens and the earth, and said, “Let there be light, and there was light.”
Prof. James Dwight Dana[1] declares that the first act of creative power must have been heralded throughout the universe by a flash of light. Thus the geologist unites with the scriptural narrator, in the statement that light and heat belonged to the first day of creation, although scoffers for a long time ridiculed the idea that light could exist without the sun.
All space is supposed to be filled with a substance called ether, and that it permeates even solid material. When, for any reason, the natural motion of the molecules of matter is much increased, these molecules have the power of imparting their vibration to the ether in contact with them, and that in turn may produce vibrations in other substances, and if these vibrations come in contact with the nerves of touch, there follows the sensation of warmth or heat. If the vibrations of the ether are still more rapid, when they fall upon the retina, we have the sensation of sight, and we call the agent light. Heat and light, then, are the same. In one instance the vibration is capable of affecting one set of nerves, and in the other, two sets of nerves. The heat-vibration can be discovered by the sense of touch alone, but the light-vibration may be detected both by the eye and the touch.