Young — Vapour-Pressures, Sfc, of Thirty Pure Substances. 411 



In the remaining tables the following data are given for each of the 

 thirty substances : — 



1. The centigrade temperatures. 



2. The observed vapour-pressures, or, for temperatures below the boiling- 

 point, those read from the curves. 



3. Tlie pressures calculated by means of Biot's formula, with the 

 constants given in Table 1. 



4. The differences between tlie calculated and observed pressures. 



5. The volumes of a gram of liquid as read from the curves (temperature 

 — volume). 



6. The volumes of a gram of saturated vapour as read from the curves 

 (temperature — log of volume). For the lower temperature the curves were 

 reconstructed in the manner already described (p. 377). 



7. The heats of vaporization, calculated by Dr. J. E. Mills. 



8. The densities of the liquids, calculated from the volumes of a gram. 



9. The densities of the saturated vapour, similarly calculated. 



10. The mean densities of liquid and saturated vapour, calculated from 

 the data in columns 8 and 9. 



11. The mean densities of liquid and saturated vapour, calculated from 

 the modified formula of Gailletet and Mathias, with the constants given in 

 Table 2. 



12. The differences between the mean densities in columns 11 and 10, 

 multiplied by 10'. 



13. The ratios of the actual densities of saturated vapour to those 

 calculated from the observed temperatures and pressures on the assumption 

 that the vapours behave as perfect gases. 



TaBLSiS. 



