184 
PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 
For magnetic iron ore, Fe 3 0 4 , §85 M 37‘7 
„ chromate of potass, K 2 Or 0 4 , § 87 M 36‘4 
„ sesquioxide of iron, Fe 2 0 3 , § 85 M 26-8 
„ arsenious acid, As 2 0 3 , § 85 25’3 
„ the nitrates, RNG 3 , named in § 88 23 - 0 
„ arseniate of potass, K As 0 3 , § 88 25-3 
But there is even in a more extended sense approximate equality of atomic heat in 
bodies of analogous atomic composition. If the formulae of the oxides, R 0 2 (oxide of 
tin for instance) are doubled, they become R 2 G 4 , and are then analogous to those of 
the sulphates, R S G 4 , or of tungstate of lime or of perchlorate of potass and other salts. 
To the formulae thus made analogous equal atomic heats correspond. The following 
atomic heats have been found : — 
Oxide of tin, Sn 2 0 4 , compare § 85 . M 27*6 
Titanic acid, Ti 2 0 4 , „ M 27’3 
The sulphates, R S0 4 , in § 87 M 26T 
Tungstate of lime, Ga W 0 4 , compare § 87 27 - 9 
Perchlorate of potass, KC10 4 , compare § 88 26*3 
Permanganate of potass, KMnG 4 , compare § 88 28-3 
If the formulae of the oxides, RQ 2 , are trebled they become R 3 O e , analogous to those 
of the nitrates RN 2 G 6 (nitrate of baryta, e.g.), and similar salts. Here also approxi- 
mately equal atomic heats correspond to the formulae thus made analogous. The atomic 
heats are as follows : — 
Oxide of tin, Sn 3 G 6 , compare § 85 M 41-4 
Titanic acid, Ti 3 0 6 , „ M 41*0 
The nitrates, RN 2 G 6 , in § 88 M 38T 
Metaphosphate of lime, €a P 2 0 6 , compare § 88 39-4 
How little the atomic heat of compounds depends on their chemical character may 
he proved from a greater series of examples than those adduced in the preceding. It 
is, however, unnecessary to dwell upon this. The comparisons and considerations con- 
tained in the sequel complete what has here been developed as a proof of the principle 
that the atomic heat of bodies is independent of their chemical character. 
95. The foregoing comparisons give examples of cases in which bodies of analogous 
atomic structure, with a totally different chemical character, have approximately the same 
atomic heat ; they show that with reference to the atomic heat, monoequivalent and poly- 
equivalent elementary atoms have the same influence, which, indeed, followed already 
from Regnault’s comparisons ; that the atomic heat of a substance for its polyfold atomic 
formula may be compared with that of another substance for a simple atomic formula. 
