olh REPORTS ON THE STATE OF SClMCE. 



curves in lig. 1, exhibiting the internal energy, have been constructed. 

 The actual observations are also shown in the same figure. Each of these 

 observations represents the mean of a large number of experiments, in 

 some cases as many as thirty. The results of the individual experiments 

 in such a group ranged about 2 or 3 per cent, above and below the mean. 

 These casual errors would no doubt cancel out to a sreat extent in taking 



icmheratixre , decrees Ccnti,0rj,ote 



the mean, which, ajiart from systematic errors inherent in the method of 

 expei"iment, is probably correct within about 2 per cent. 



This degree of accuracy is not sufficient to enable any deduction to be 

 made as to the manner of variation of the volumetric heat beyond a rough 

 estimate of its average rate of increase over the whole range of experi- 

 ment. The following are the values of the volumetric heats of air, steam, 

 and CO, at 100°, 600°, and 1100" respectively :— 



The corresponding values of y are also shown : y=l + 



1-98 



