our knowledge of the laws which govern the vaporization of liquids, and shows us these laws at work under peculiar conditions, while at the same time it brings the apparently exceptional phenomenon under the domain of a known law. Once more, the examination of residual phenomena may be, and has often been, of immense service to science, in freeing naturalists from the tyranny of an established theory which has for long been regarded as of necessity affording a full explanation of the entire series of facts to which it is applied.
The tyranny of orthodoxy is not unknown in science. The overthrow of that tyranny is one result of the investigation of residual phenomena.
During the greater part of the eighteenth century the theory of Phlogiston was all-prevalent in chemistry. According to this theory, when a body burns, it gives out a something called Phlogiston, the escape of this mystical something being the cause of the phenomena which attend the combustion.
This theory accounted in a fairly satisfactory manner for the greater number of the observed facts. One little fact, however, was scarcely explicable by the Phlogistic theory. So far as rough measurement went, the weight of the burned body appeared to be greater than that of the body previous to combustion. This residual fact was long overlooked, but the genius of Lavoisier forbade him to pass over so important a circumstance. By repeated and exact experiment, Lavoisier established the correctness of the residual phenomenon, and he showed that the phenomenon was inexplicable in terms of the commonly accepted theory.
Modern research has taught us that the fact firmly established by Lavoisier is not absolutely contradictory of a modified Phlogistic theory; but Lavoisier's work necessitated a thorough revisal of the prevalent theory of combustion, and prepared the way for great advances which have at last enabled us to reconcile his theory with that of the Phlogisteans in modified form. Had Lavoisier consented to overlook the seemingly little fact that a body after burning is heavier than it was before, chemical science would probably have been for many years compelled to submit to the thralldom of the Phlogistic theory, which, in its then accepted form, barred the path of true advance.
When Galileo's telescope discovered to the gaze of the astronomer the satellites of Jupiter, did not those in authority protest most vehemently against the residual phenomenon? Why? Because they saw that this phenomenon could not be made to fit into the accepted cosmical theories of the day: not only was it inexplicable in terms of these theories, but it was absolutely opposed to them. Galileo, however, persisted, the phenomenon was more fully investigated, and the science of astronomy was placed upon a sure basis; the reign of mere authority in scientific matters was brought to an end, and Nature was installed as the supreme adjudicator in all matters of scientific inquiry.
