Elements of chemistry, including the history of the imponderables and the inorganic chemistry of the late Edward Turner / [Edward Turner].

  • Edward Turner
Date:
1846
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Licence: Public Domain Mark

Credit: Elements of chemistry, including the history of the imponderables and the inorganic chemistry of the late Edward Turner / [Edward Turner]. Source: Wellcome Collection.

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    as great as that above given. Neither of these latter groups is as large as that first referred to. They, however, serve to indicate a law of dilatation and conden¬ sation on the part of the solid oxygen entering into these various compounds, of remarkable simplicity, the several combining volumes having the relation of the numbers 1, 2, 4.] [Applying similar reasonings and calculations to the salts, we find that in the nitrates the (N06),# associated with the metallic base, has an invariable equiva¬ lent volume = 28*64 Thus Equivalent volume of Nitrate of Lead, or Pb NC>6 = 37-76) _oQ.na Do. do. of Lead, or Pb = 9-12) Equivalent volume of Nitrate of Silver, or Ag NC>6 = 39.04) _ Do. do. of Silver, or Ag = 10*40 £ In the sulphates we find the eq. vol. of the S04 combined with the metal, to have two different values. For one class of the sulphates the eq. vol. of S04 is 18*88. Sulphate of copper, Cu S04, is an example of this class. For the other the eq. vol. is 14*88. Sulphate of lead, Pb S04, illustrates this. These twro numbers are very nearly in the ratio of 4 to 5.] [According to the researches of Kopp, the equivalent volume of a compound is very rarely equal to the sum of the primitive equivalent volumes of its elements. Hence the eq. volumes in which these elements exist in the compound are to be sought for by comparisons, such as those above given of the various compounds of analogous character. It will be seen, from the preceding results, that the changes of equivalent volume, due to the different combinations into which a given element enters, is, like the condensation or expansion in gaseous combi¬ nation, governed by certain numerical laws peculiar to each group of compounds, although, according to Kopp, these condensations and rarefactions of the solid volumes, are not expressed by the same simple ratios, as in the case of the gases. This very interesting inquiry has, as yet, been too little advanced to furnish, in a positive form, any more general results than those above indicated; but there is good reason to hope for new and important generalizations in its further prose¬ cution. (Pogg. Ann. xlvii.)] CHEMICAL SYMBOLS. The impracticability in many cases of contriving convenient names expres¬ sive of the constitution of chemical compounds, especially of minerals, suggested the employment of symbols as an abbreviated mode of denoting the composition of bodies. It was thought that the names of elementary substances, instead of being written at full length, might often be more conveniently indicated by the first letter of their names; and that the combination of elements with each other might be expressed by placing together, in some way to be agreed on, the letters which represent them. The advantage of such a symbolic language was felt so strongly by Berzelius, that he some years ag» contrived a set of symbols, which he has since used extensively in his writings ; and other eminent chemists as well as mineralogists, believing symbols to be useful, adopted those which Berzelius had proposed. The consequence is, that symbolic expressions, called chemical formulae, are now so much resorted to, and are so identified with the language of chemistry, that essays of great value are in a measure as sealed books * See general remarks on salts in a subsequent part of the work.
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