10 Prof. Magnus on the Propagation of Heat in Gases. 



The defiant gas was obtained pai-tly by Wohler's method, 

 from a mixture of alcohol, sulphuric acid, and sand; and partly by 

 Mitscherlich's method, of passing alcohol vapour with sulphuric 

 acid at 165° C. All these gases were dried by chloride of calcium. 

 The ammonia was prepared from sal-ammoniac and burnt 

 marble, and dried by passing through a tube of caustic soda. 



The sulphurous acid was generated from sulphuric acid and 

 mercury, and dried by chloride of calcium and sulphuric acid. 

 The cyanogen was prepared from dry cyanide of mercury. 

 The great concordance between the heating of the thermo- 

 meter in oxygen and in atmospheric air, shows that this would 

 be the case in nitrogen, and makes a determination in this gas 

 unnecessary. 



If the temperatures obtained in the different gases with the 

 use of a screen and under the pressure of an atmosphere are 

 compared, we obtain for 



Atmospheric air . . 

 Oxygen .... 

 Hydrogen . . , 

 Carbonic acid . . 

 Carbonic oxide . 

 Protoxide of nitrogen 

 Marsh-gas . . . 

 Olefiant gas . . 

 Ammonia .... 

 Cyanogen. . . . 

 Sulphurous acid . 

 The temperatures obtained in these gases when greatly rare- 

 fied, are not very concordant, because the small quantity of gas 

 still present doubtless exercises an influence ; but if a tempera- 

 ture of 26 7 — 15°=11 0, 7 C. be assumed as the most likely for 

 vacuum, and if this be put = 100, the proportion between the 

 temperatures obtained in the other gases under the pressure of 



96 



or 



100-0 



96 





1000 



130 





135-4 



8-2 



}J 



85-4 



95 





98-9 



8-8 





916 



9-4 





979 



90 





937 



8-1 





843 



8-8 



n 



916 



7-8 



}) 



81-2 



an atmosphere, are as — 



Vacuum .... 

 Atmospheric air 

 Oxygen .... 

 Hydrogen . . . 

 Carbonic acid . . 

 Carbonic oxide . 

 Protoxide of nitrogen 

 Marsh-gas . . . 

 Olefiant gas 

 Ammonia . . . 

 Cyanogen . 

 Sulphurous acid 



Temperature. 



100 

 82-0 

 820 



111-1 

 70 

 81-2 

 75-2 

 80-3 

 76-9 

 69-2 

 75-2 

 66-6 



