102 
PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 
doubt it while engaged in my experiments. I first, when they were finished, became 
acquainted with Regnault’s * investigations on the specific heat of liquids at various 
temperatures; according to these experiments the specific heat of some liquids con-, 
siderably increases with the temperature. I have not directly investigated coal-tar 
naphtha in this respect, but it is probable that the specific heat of this mixture of 
hydrocarbons G n H 2 n _6, alters but little with the temperature, and it is certain that this 
change is without influence on the accuracy of my determinations of the specific heats 
of solid substances. Regnault’s experiments f , made by the method of cooling, show no 
change for benzole, € e H e , between 20° and 5°, while there is a distinct change in the 
case of alcohol. For pure benzole % I found the specific heat by the method of mix> 
ture to be 0-450 between 46° and 19°; Regnault § found it between 71° and 21° to 
be 0-436. These numbers, obtained with different preparations, are not indeed com- 
parable for a decision of the question just discussed, but they render improbable a com 
siderable increase in the specific heat of benzole with the temperature. What I more 
especially lay weight upon is this : the specific heats of solids which I have determined 
at various temperatures, by their agreement with the numbers previously found by 
others, do not indicate any influence of a change of specific heat of naphtha with the 
temperature. 
30. My stock of the naphtha, discussed in § 27, was used before I had investigated all 
the solid substances, for which a determination of the specific heat appeared necessary. 
Another quantity of the same coal-tar naphtha was subjected to the same treatment as 
indicated there, and the portion passing over between 105° and 120° used for the 
remainder of the experiments. To ascertain the specific heat of this naphtha B, I made 
the four following series of experiments : — 
I. — Experiments with Glass 1. Temperature of the Air 18°-l-18°-3. 
T. 
T'. 
i. 
t. 
M. 
/• 
X. 
sp. H. 
O 
O 
0 
0 
grms. 
grms. 
g™. 
51-5 
19-6 
9-33 
17-22 
26-96 
2-70 
0-651 
0-419 
52-7 
19-9 
19-64 
17-49 
26-95 
59 
55 
0-413 
50-5 
19-8 
19-54 
17-51 
26-99 
0-420 
49-9 
20-0 
19-73 
17-75 
26-995 
2-695 || 
59 
0-422 
Mean . . . 0-418 
* Relation des experiences .... pour determiner les lois et les donnees physiques necessaires au calcul des 
machines a feu, vol. ii. p. 262 (1862). 
t Ann. de Chim. et de Phys. [3] vol. ix. pp. 336 & 349. 
£ Poggendorff’s ‘ Annalen,’ vol. lxxv. p. 107. § Relation, etc vol. ii. p. 283. 
|| After drying the stopper. 
