Chemistry : general, medical, and pharmaceutical including the chemistry of the British Pharmacopœia a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield.

  • Attfield, John, 1835-1911.
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British Pharmacopœia a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield. Source: Wellcome Collection.

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    5. It represents two mlumes of the substance (if volatiliz- able) in the state of gas or vapour, and the number of volumes of gaseous elements from which two volumes of any gaseous compound were obtained, A Chemical Equation or a Chemical Diagram is a collection of formulfe and symbols so placed on paper as to form a picture or illustration of the state of things before and after tliat metathesis (interchange) of atoms of molecules which results in the formation of molecules of new substances. A Solid is a substance the molecules of which are more oi* less immobile, though probably not in absolute contact. A Liquid is a substance the molecules of which so freely move about each other that it readily assumes and retains the form of any vessel in which it is placed. A Gas is a substance the molecules of which are so far apart that they seem to have lost all attraction for each other, and, indeed, to have acquired the property of repul- sion to such an extent that they are only prevented from receding to a still greater extent by the pressure of sur- rounding matter. Motion is especially characteristic of the molecules of gaseous fluids. The Three Laws regulating Chemical Comhination (either hy tveight or volume). First. A definite compound always contains the same elements and the same proportions of those elements—by weight or volume. Second. When two elements unite in more than one pro- portion, they do so in simple multiples of that proportion. Third. The proportions in which two elements unite with a third, are the proportions in which they unite with each other. Atomic Weights are, first, the proportions in which elements are found to combine with each other by weight. (The figures showing these proportions are purely relative; but all chemists agree to make this relation fixed by giving the number 1 to hydrogen.) Secondly, they are the weights of equal volumes of gaseous elements (relative to one of hydrogen.) Molecular Weights.—These are the weights of equal volumes of gases or vapours, under equal circumstances of tempera-