PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 
81 
with the observed ones ; this is less the case with metallic acids and oxygen salts, for 
which calculation mostly gives results far too large. Garnier* drew, further, from 
the above proposition the conclusion, that the atomic weight of hydrogen, chlorine, &c. 
must in fact be taken only half as great as the equivalent weight ; for only by assuming 
this smaller atomic weight is the mean atomic weight such that its product with the 
specific heat is near 3. 
In 1852 BANCALARif repeated that the specific heat of an atom of a compound body 
(that is, its atomic heat) is equal to the sum of the specific heats of the individual con- 
stituent simple atoms, and showed, from a series of examples (oxides, chlorides, sulphates, 
and nitrates), that, according to that proposition, the atomic heats of many compounds 
may be calculated in tolerable approximation with those derived from Regnault’s expe- 
rimental investigations, if, for the elements which he investigated, the atomic heats 
derived from his determinations be taken as a basis, that is, for oxygen (0 = 8) the 
atomic heat 1'89; for chlorine (Cl=17*75) 3-21 * for nitrogen (N = 7) 3*11. 
Cannizaro (in 1858$) has used the proposition, that, in the sense above taken, uni- 
AC 
versally -^-=a constant, for the purpose of ascertaining the value of n for the atomic 
weight of different compounds, and therewith ascertaining the atomic weight of elements 
which are contained in these compounds. 
14. Besides those of Regnault, but few experimental determinations of the specific 
heats of solid bodies have been published. Bede§ and Bystrom|1 have published inves- 
tigations on the specific heat of several metals at different temperatures : both sets of 
experiments were made by the method of mixtures. From the year 1845, Person**, in 
his investigations on the specific heat of ice, then on the latent heats of fusion, and 
their relations to the specific heats in the solid and liquid condition, has determined the 
specific heat for several solid Substances, especially also for some hydrated salts. He 
worked more especially by the method of mixture. He observedff , in the case of these 
* Comptes Rendus, vol. xxxvii. p. 130. 
f An abstract from Memorie della Accademia delle Scienze <li Torino, [2] vol. xiii. p. 287, in the Archives des 
Sciences Physiques et Naturelles, vol. xxii. p. 81. I only know the contents of this memoir from this abstract. 
X II Nuovo Cimento, vol. vii. p. 321. Piazza also gives a statement of this speculation in his pamphlet, 
‘ Formole atomistiche et typi chimici,’ 1863. I only know this from a notice in the Bulletin de la Societe 
Chimique de Paris, 1863. 
§ An abstract from the Bulletin de PAcademie des Sciences de Belgique,, vol. xxii. p. 473, and the Me'moires 
Couronnes par l’Academie de Belgique, vol. xxvii., appeared in the Bericht iiber die Fortschritte der Physik im 
Jahre 1855, dargestellt von der physicalischen Gesellschaft zu Berlin, p. 379. 
|| Abstract from the Oversigt of Stockholm Yetenskaps-Akademiens Forhandlingar, 1860, in the same Jahr- 
eshericht, 1800, p. 369. 
if To the experiments of Dulong and Petit on this subject, mentioned in § 3, Pouiilet’s determinations of 
the specific heat of platinum at different temperatures must be added (Comptes Rendus, vol. ii. p. 782). 
** Comptes Rendus, vol. xx. p. 1457 ; xxiii. pp. 162 & 366. Ann. de Chim. et de Phys. [3] vol. xxi. p. 295 ; 
xxiv. p. 129 ; xxvii. p. 250 ; xxx. p. 78. 
tt Peiison expressed this in 1845 (Comptes Rendus, vol. xx. p. 1457), with regard to his determinations of 
N 2 
