lemperature and the Tension of Vapours. 



5 



obtained by experiment throughout the whole range of measure- 

 ments that have hitherto been made, I have devised the following 

 Table, which contains the tensions corresponding to temperatures 

 from —30° to +230° C. of the air-thermometer, together with 

 the values pertaining to a for increments of 10°. The differ- 

 ences between these values diminish so slowly, that the value of 

 a corresponding to any chosen temperature may be derived with 

 sufficient accuracy from the proportional parts relating to one 

 degree of temperature of those numbers within which it is situ- 

 ated. The calculation of the corresponding tension P is conse- 

 quently greatly facilitated by the use of the formula 



log P= 0-3091 048 + log (273 -f T) + 



log (273 + T) -2-5717088 



The numbers contained under R in the Table are obtained 

 from Regnault's work, page 608. They are the mean values 

 obtained from the graphic representation of his observations. 



The last column of the Table contains the tensions of aqueous 

 vapour from —20° to +110°, as determined by Magnus, which, 

 it wil] be seen, accord well with the preceding values. 



Tension of saturated Aqueous Vapour, in millims. of mercury, 

 for temperatures between —30° and +230° C. of the air- 

 thermometer. 



TO 



ex. 



pp. 



P. 



R. 



M. 



- 30 



005953 



17-8 

 175 

 17-3 

 171 

 169 

 16-8 

 16-5 

 16-3 

 161 

 15-9 

 15-8 

 15-5 

 15-3 

 151 

 14-9 

 14-8 

 14-5 

 143 

 14-1 

 13-9 

 13 8 

 13-5 

 13-3 

 131 

 129 

 12-8 



0*37 



0-39 





- 20 



006131 



0-92 



091 



0-92 



- 10 



0-06306 



2-10 



2-08 



211 







0-06479 



4-50 



4-60 



4-53 



+ 10 



006650 



906 



916 



913 



20 



006819 



17-31 



1739 



17-39 



30 



0-06987 



31-51 



31-55 



31-60 



40 



007152 



54-91 



54-91 



54-97 



50 



007315 



91-94 



91-98 



91-97 



60 



007476 



148-77 



148-79 



148-58 



70 



007635 



23303 



23309 



232-61 



80 



007793 



354-51 



354-64 



35393 



90 



007948 



525-46 



525-45 



524-78 



100 



008101 



76000 



760-00 



760-00 



110 



008252 



107510 



107370 



107726 



120 



0-08401 



1491-07 



148900 





130 



008549 



202918 



202900 





140 



0-08694 



271605 



271300 





150 



008837 



357815 



357200 





160 



008978 



4646-30 



464700 





170 



009117 



5953-40 



596000 





180 



09255 



7534-72 



754500 





190 



009390 



9429-20 



942800 





200 



0-09523 



11672-30 



11660-00 





210 



0-09654 



14309-90 



14308 00 





220 



009783 



17386 00 



1739000 





230 



009911 



20937-40 



20915-00 





