io 4 THE POPULAR SCIENCE MONTHLY. 



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 phe- 

 nomena 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 over- 

 throw of that tyranny is one result of the investigation of residual phe- 

 nomena. 



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 the- 

 ory ; but Lavoisier's work necessitated a thorough revisal of the preva- 

 lent 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 vehe- 

 mently against the residual phenomenon ? Why ? Because they saw 

 that this phenomenon could not be made to fit into the accepted cosmi- 

 cal 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. 



