Page:Popular Science Monthly Volume 9.djvu/590

them, and capable of being transferred from the combustible body which has it to an incombustible body which has it not, rendering the body that was energetic and combustible inert and incombustible, and the body that was inert and incombustible energetic and combustible, and further rendering some particular body combustible over and over again. That this is a fair representation of the views held by phlogistic chemists is readily recognizable by a study of chemical works written before the outbreak of the antiphlogistic revolution. After Lavoisier's challenge, the advocates of phlogiston, striving to make it account for a novel order of facts with which it had little or nothing to do, were driven to the most incongruous of positions; for, while Priestley wrote of inert nitrogen as phlogisticated air, Kirwan and others regarded inflammable hydrogen as being phlogiston itself in the isolated state. Very different is the view of phlogiston to be gathered from the writings of Dr. Watson, for example, who was appointed Professor of Chemistry at Cambridge in 1764, became Regius Professor of Divinity in 1771, and Bishop of Llandaff in 1782. This cultivated divine, indifferent, it is true, to the novel questions by which in less placid regions men's minds were so deeply stirred, amused the leisure of his dignified university life by writing scholarly accounts of the chemistry it had formerly been his province to teach; and in the first volume of his well-known "Chemical Essays," published in 1781, the following excellent account of phlogiston is to be found:

"Notwithstanding all that perhaps can be said upon this subject, I am sensible the reader will be still ready to ask, What is phlogiston? You do not surely expect that chemistry should be able to present you with a handful of phlogiston, separated from an inflammable body; you may just as reasonably demand a handful of magnetism, gravity, or electricity, to be extracted from a magnetic, weighty, or electric body. There are powers in Nature which cannot otherwise become the objects of sense than by the effects they produce; and of this kind is phlogiston. But the following experiments will tend to render this perplexed subject somewhat more clear:

"If you take a piece of sulphur and set it on fire it will burn entirely away, without leaving any ashes or yielding any soot. During the burning of the sulphur a copious vapor, powerfully affecting the organs of sight and smell, is dispersed. Means have been invented for collecting this vapor, and it is found to be a very strong acid. The acid thus procured from the burning of sulphur is incapable of being either burned by itself or of contributing toward the support of fire in other bodies; the sulphur, from which it was procured, was capable of both: there is a remarkable difference, then, between the acid procured from the sulphur and the sulphur itself. The acid cannot be the only constituent part of sulphur; it is evident that something else must have entered into its composition, by which it was rendered capable of combustion. This something is, from its most remarkable property, that of rendering a body combustible, properly enough denominated the food of fire, the inflammable principle, the phlogiston. . . . This inflammable principle or phlogiston is not one thing in animals, another in vegetables, another in minerals; it is absolutely the same in them all. This identity of phlogiston may be proved from a variety