$8 M. E. Wiedemann on the Specific Heats of Gases. 



My numbers agree among themselves as well as those ob- 

 tained by Regnault ; for instance, he obtained values for 

 the specific heat between 210° and 10° varying from 0*21416 

 to 0*21844 &c. It appears, alike from Regnault' s and from 

 my experiments, that there is a great change in the specific 

 heat of the gas under examination with change of temperature. 



The true specific heats calculated from the foregoing num- 

 bers for certain temperatures are as follows : — 



For 0-1952 



100 0-2169 



200 0-2387 



Renault's numbers are : — 



For 6 0-1870 



100 0-2145 



200 0-2397 



Taking the specific gravity of carbonic acid as 1*529, the 

 following numbers express the relative heats : — 



For 6 0-2985 



100 0-3316 



200 0-3650 



Carbonic Oxide. 



The gas was prepared by Fowne's method, viz. heating 

 one part of yellow prussiate of potash with eight parts of con- 

 centrated sulphuric acid. The gas was led through caustic 

 potash and then through sulphuric acid : it was entirely ab- 

 sorbed by a solution of cuprous chloride in hydrochloric acid ; 

 it contained no carbonic acid. Oxalic acid was not used for 

 the preparation of the gas, inasmuch as the carbonic acid 

 simultaneously produced can only be separated with great dif- 

 ficulty. 



The numbers given in the two following Tables yield almost 

 exactly the same values for the specific heat ; so that we may 

 conclude that the specific heat of carbonic oxide is independent 

 of the temperature. Regnault's number between 200° and 

 20°, viz. 0*2450, does not differ materially from mine. 



The relative heat of carbonic oxide is 0*2346 (the specific 

 gravity being taken as 0*967), which is nearly the same as that 

 of air -0*2389. 



