Mo Monsieur Mariet From the Author. AN INQUIRY INTO THE NATURE OF THE SIMPLE BODIES OF CHEMISTRY. BY DAVID LOW, F.R.S E., PROFESSOR OF AGRICULTURE IN THE UNIVERSITY OF EDINBURGH. SECOND EDITION, ENLARGED. AZ 2160 Axiomata a particularibus rite et ordine abstracta nova particularia rursus LONDON: LONGMAN, BROWN, GREEN, AND LONGMANS. MDCCCXLVIII. PREFACE. A FUNDAMENTAL principle, long admitted in Chemistry, is, that there is an extensive group of bodies, from which all the others are derived, and which, having resisted the usual agents of decomposition, we are to regard as Elementary or Simple. I will endeavour to shew that we are not entitled to regard these bodies as elementary or simple, because we have been unable to overcome the affinities of their constituent parts; that they cannot be separated from the bodies which we know to be compound by any such distinction as the terms simple and compound imply; and that it is not necessary, in our inquiries into the phenomena of chemical actions, and the laws which determine them, to assume the existence of many elements, distinct, in their corpuscular constitution, from one another, and from the bodies which experiment has determined to be composed of more than one element or member. I Several years ago I published a sketch of the argument by which I conceived this proposition to be established. now propose to resume my former argument, to extend it by a more detailed examination of the relations which connect the bodies termed simple with one another, and with those admitted to be compound, and to obviate, as far as possible, any fair objections to the conclusions arrived at. It has been said, in answer to the arguments by which I have endeavoured to establish the compound constitution of the bodies regarded as simple, that it is useless to prove these bodies to be compound by induction, until we shall have been able to resolve them into simpler elements by experiment. Baron Berzelius, in commenting upon my previous work, observes, that it will be time enough to take up seriously the question as to the chemical constitution of these bodies, when any one of them shall have been shewn to be compound by analysis. I cannot assent to this proposition. The illustrious chemist has himself from time to time indicated doubts regarding the nature of this class of substances, and even in certain cases expressed opinions regarding their probable constitution. Such reasoning, if based on just analogies, falls within the fair range of chemical inquiry, and cannot be answered by the homely argument of cui bono, because we may be as yet unable to employ the direct experiments of the laboratory to confirm the conclusions arrived at. The end of all science is the discovery of truth, and truth may be enunciated and discovered although we may not yet have the means of testing it by the evidence of sense. The discovery of the bases of the alkalies and alkaline earths may be said to have been made by Lavoisier, when he inferred these substances to be metallic oxides, many years before the brilliant experiments of Davy demonstrated their composition by the application of a new power. An objection to the conclusions which I have ventured to draw regarding the nature of the Simple Bodies of Chemistry, and which to some may seem insuperable, is founded on the hypothesis so generally admitted, that these bodies are composed of corpuscles or atoms, of different weights or magnitudes, proper to each body, and distinct from those of the others. I propose to inquire into the foundation of this hypothesis, and to shew that it rests upon assumptions incapable of proof, and contradictory to the only conclusions by which we can venture to predicate the existence of ultimate corpuscles as the principles or elements of matter. I admit that if the hypothesis in question be true, and can be applied to the corpuscular constitution of the bodies we term simple, these bodies cannot be resolved into simpler elements; while, on the other hand, if they can be proved to be compound and not simple, the Atomic Theory, so called, must be held to be disproved, and so cannot be employed to establish the nature and constitution of these substances. In following out the train of investigation to which these inquiries lead, I have found it necessary to call in question some opinions generally received, and supported by high authority. But I trust that the candid inquirer will examine my argument in whole, and not in parts, nor too hastily infer that, because opinions may be expressed which are not in accordance with those generally admitted, the essential conclusions are invalidated. While there is no department of physical science in which so great a collection of facts has been made as in chemistry, there is no other in which so many hypotheses are continually hazarded, and in which so great a discordance exists in the opinions of those who draw their conclusions from the same admitted data. The reasoning, then, by which hypotheses |