Excerpt from The Elements of Natural Philosophy The forces of affinity, electricity, heat, and light, are so closely allied that many philosophers consider them as modifications of the same force, in the same sense that magnetism is a modification of electricity. We know that the action of either of these forces may induce the action of any other of them; thus the action of affinity may induce heat, then light, as is shown by the burning of a candle. For this reason, they are called the correlative forces. Heat, light, and electricity are sometimes termed the imponderable agents, from an erroneous notion that they are matter without weight. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.