(1737-1820), who, in 1775, in a prospectus of lectures, proposed to discourse of "his notions and experiments concerning the primary elements and properties of matter," and of "experiments, observations and arguments, persuading that each primary element consists of atoms homogeneal: that these atoms are impenetrable, immutable in figure, inconvertible, and that, in the ordinary course of nature, they are not annihilated, nor newly created." He also conceived of atoms, of simple particles, and even of gases, as uniting sometimes, in approximately, if not completely, fixed proportions. Yet, he never arrived at true causes, because his experiments failed to dove-tail with his advanced theoretical suggestions. Accordingly, the explicit variety of the former destroyed the implicit unity of the latter, and the status quo ante was maintained.[1] William Higgins, the claimant of 1814, published his book[2] in 1789. It contains forecasts of the atomic theory, such as the following:
I am likewise of opinion that every primary particle of phlogisticated air is united to two of dephlogisticated air, and that these molecules are surrounded with one common atmosphere of fire.[3]
But, after all, less than a dozen pages of the 300 deal with the subject; and, although he assigned causes for definite proportion and saturation in a few cases, he never suspected a simple, universal and necessary law. His real acuteness led him to see that combining particles had the same weight (multiple proportions), but he missed his chance to generalize in a maze of suspicions directed against the phlogistic theory, which had already lost its primacy; his indolence also hindered him, like his eccentricity.
III
Finally, coming to Dalton's characteristics as a thinker, we may find the clue in his forcible independence. In the preface to Part II. of "A New System of Chemical Philosophy" (1810), he declares:
Having been in my progress so often misled, by taking for granted the results of others, I have determined to write as little as possible but what I can attest by my own experience. On this account, the following work will be found to contain more original facts and experiments, than any other of its size, on the elementary principles of chemistry.
Here the strong man places himself on record, and the question of priority takes to flight. Accordingly, I state it as my clear impression that the merits and defects of his achievement are alike traceable to the fact that our laureate lay under direct obligation to but one of his
