Outlines of theoretical chemistry / by Lothar Meyer ; translated by P. Phillips Bedson and W. Carleton Williams ; with a preface by the author.

  • Meyer, Lothar, 1830-1895.
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of theoretical chemistry / by Lothar Meyer ; translated by P. Phillips Bedson and W. Carleton Williams ; with a preface by the author. Source: Wellcome Collection.

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    Richter’s views on the laws which govern the combination of acids with bases to form salts remained for a long time neglected and almost unnoticed. The credit of establishing the value of these laws (so far as they were correct) belongs to J. J. Berzelius, who obtained important aid from an hypothesis propounded by John Dalton. The fundamental law of stoechiometry, discovered by Richter and confirmed and developed by Berzelius, states that all true chemical changes (i.e. changes of composition) take place between definite volumes or weights of the substances. This is equally true whether a substance decomposes into its constituents or is formed from its constituents, or when different compounds ex- chancre one of their constituents. O When water is formed from its constituents 7'98 parts by weight of oxygen unite with one part by weight of hydrogen, never more or less, and the two constituents are produced in exactly these proportions when water is decomposed. All other substances, whether elements or compounds, behave in the same way ; that is to say, they only enter into combination or undergo decomposition in definite and fixed proportions by weight. It often happens that the bodies unite together in several distinct proportions, but these different proportions always bear a simple relation to each other. This empirical law is known as the law of multiple propor- tions. For example, there is another compound of hydrogen and oxygen, hydrogen peroxide, which contains 15'96 parts by weight of oxygen to 1 part by weight of hydrogen—that is, twice as much oxygen as unites with 1 part by weight of hydrogen in water. By mixing these two oxides of hydrogen a liquid is obtained in which the quantity of oxygen lies between that con- tained in water and in hydrogen peroxide. The resulting liquid is not a chemical compound, but merely a mechanical mixture, for its properties are those of its constituents, and the act of ad- mixture is not followed by those changes in the material nature of the substances, which are characteristic of chemical combination. Nitrogen forms a larger number of oxides, in which one part by weight of nitrogen is combined respectively with 0-5696, 1-1392, 1-7088, 2-2784, and 2-84-80 parts by weight of oxygen.