The progress of scientific chemistry in our own times : with biographical notices / by William A. Tilden.

  • William A. Tilden
Date:
1913
Catalogue details

Licence: Public Domain Mark

Credit: The progress of scientific chemistry in our own times : with biographical notices / by William A. Tilden. Source: Wellcome Collection.

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    the specific heat is *108 and—-=59*2. Also the vapour density of its carbonyl compound is 86*5 compared with hydrogen. Hence the molecular weight of this compound is 173, and it is found by analysis to contain 33‘3 per cent, of nickel; 173 parts therefore contain 57’6 parts of nickel, which is in practical agreement with the value derived from the specific heat. But just as the law of Avogadro had to wait nearly fifty years for general recognition, so the principle asserted by Petit and Dulong remained unapplied and almost unnoticed, save casually as a matter of curiosity, down to com¬ paratively recent times. It is true that Regnault, as a result of his researches, commenced in 1840,1 was led to regard the law as universally applicable, but Kopp, who resumed the question a quarter of a cen¬ tury later, came to the conclusion2 that the law of Dulong and Petit is not strictly valid, even when the exceptional cases of boron, carbon, and silicon are ex¬ cluded. I he want of exact concordance among the pro¬ ducts of the multiplication of specific heat by atomic weight does not, however, prevent the very general application of the law for the purpose of controlling atomic weights in the manner already described. And chemistry is indebted chiefly to the representa¬ tions of Cannizzaro 3 in 1858 for the recognition o 1 Especially Ann. Ch. Phys. [2], 73, 66, and [3] 26, 261, and 46, 257. 2 Phil* Trans,, 1865. 3 II Nuovo Cimcnto, 7, 321. English version in Alembic Club Reprints, No. 18.
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