Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1904 edition. Excerpt: ... CHAPTER XII. THE CHEMICAL SYSTEM OF GERHARDT AND LAURENT. Our champions and teachers have lived in stormy tinn s: influences hai c obstructed a careful consolidation of their judgments. -- NEWMAN. Two methods may be taken in the study of the different systems of chemistry. The first method is fulfilled by a comparison between the atomic-weight data, and between the formulae of the old and the current systems. The second method, regarding the first as merely preliminary, devotes attention to other considerations; here it is of importance to ascertain principles, and to investigate how far old principles are consistent with one another, and with the principles of to-day. Of the consequences of attending to coincidences of formulae and figures, and of ignoring principles, an example is to be found in the account, in Ernst von Meyer's " History of Chemistry," of the changes suggested by Dumas in the atomic weights of Berzelius. The vapour densities of mercury, phosphorus, sulphur, and arsenic having been determined, the atomic weights of these elements were calculated by applying the volume theory of Berzelius. As it turned out, these atomic weights were different from those arrived at on other grounds, by Berzelius himself. Atomic Weights. O=i6. Arrived at liy Arrived at on the Iferzelius. Volume Theory. Hg - 200 - - 100 P 3t 62 As - 75 150 S - 32 96 Hereupon, by way of criticism, von Meyer remarks, "A comparison of the atomic weights of Berzelius and Dumas with those of to-day shows us how fully justified the former was in adhering to his own, which he had arrived at after the most mature consideration; Berzelius' values have proved to be the right ones." 1 Yet von Meyer does not leave principles altogether out of account. Assuming that...
