Elements of chemistry, in two volumes / by John Murray.

  • Murray, John
Date:
1828
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry, in two volumes / by John Murray. Source: Wellcome Collection.

    16/768 page 4
    Several of the earths, particularly barytes and strontites, approach so nearly to the alkalis in their properties, that are obvious and easily defined, and of which the student, even in beginning the study of the science, may have some general idea; and to place in connection with the history of each substance, the ac- count of its constituents and their combinations, bodies which are less familiarly known to us. Thus, under the history of atmo- spheric air, its elements, oxygen and nitrogen, were described : un- der that of water, hydrogen was noticed: under sulphuric acid, sul- phur and its various compounds were described. In like manner, in connection with the chemical history of potash, that of potassium will be given : sodium will be noticed in connection with soda, &c. The opposite mode has been followed in most chemical works. The simple bases, of which no one, uidess he is previously acquainted with the science, has any knowledge, are described first, and after- wards their compounds, such as they occur in nature, or are ob- tained in the processes of art,—a method which certainly appears to me to reverse the proper manner of teaching a science, by be- ginning with those substances which are more recondite, and more difficult to be obtained and examined, and proceeding afterwards to those which are more familiar to us. In this latter method it has been mentioned the classes of Alkalis and Earths are expung- ed, and these important agents are placed amongst metallic oxides, —an arrangement liable to other objections of considerable weight. Thus, the class of metals, which was before so extensive, that it was difficult to recollect and to discriminate the individual bodies which it included, is, in this way, still farther enlarged. Instead of 29 metals, which are classed together in Dr Murray’s arrangement, in the common method not less than 40, and these varying from each other in every degree, are enumerated in one series. A con- sequence of this is, that the characters of a class so extensive, and composed of bodies of such different properties, must be vague and deficient; and accordingly, the class of metals, as commonly de- fined, has not a single distinctive character. In Dr Murray's ar- rangement, all the substances placed together as metals agree in a property, than which none can be more obvious or more certain,—
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