358 



Mr. Carl Barus on the 



Table X. — Isometrics. Digest of probable Results. 



Substance. 



A0. 



Ap. 



Substance. 



A0. 



A p . 



Ether. 



00 = 18°. 



jt? =30 atm. 



°C. 



50-5 



81-8 



142-5 



205-0 



atm. 



439 



705 



1206 



1649 



Thymol. 



0o = 17 . 



j3 =80 atm. 



°G. 



51-5 



83-3 



109-7 



atm. 



718 



1154 



1486 



*Para- 



toluidine. 



o =8Oatm. 



31-4 

 56-5 

 90-4 



435 



792 



1117 



Ether. 



00 = 17°. 



j» =30atm. 



52-5 



82-6 



142-1 



205 



466 



727 



1219 



1670 



* Diphenyl- 

 amine. 



O =68°. 



31-3 



57-7 



477 

 884 



Alcohol. 



O =7O°. 



/> =50 atm. 



53-0 



830 



143-6 



554 



887 



1573 



*Diphenyl- 

 amine. 

 O = 68°. 



30-7 

 57-5 

 94-5 



469 



886 



1324 



Alcohol. 



O =17°. 

 /> =50 atm. 



51-2 



83-4 



144-5 



551 



888 

 1580 





Thymol. 



O =17°. 



^ =80 atm. 



51-3 



82-7 

 107-7 



700 

 1141 

 1472 









* jp=400 atm., approximately. The Table assumes that for A0=O, Ap=0. 



Deductions, 



42. It conduces to clearness to express graphically both the 

 data of Table VIII. and of Table X., as has been done in 

 PI. XI. figs. 9 and 10 respectively. In the latter the points are 

 connected by straight lines, to emphasize the changes of cur- 

 vature. Turning first to fig. 9, it is seen that below 1000 

 atmospheres the curves are so nearly linear that they may be 

 accepted as such with an error no larger than 2° or 3° at 

 1000 atmospheres. An inspection of the individual points 

 shows this to be within the limits of error. Regarding 

 diphenylamine and toluidine, it is well to remember that the 

 initial temperature is nearly 70°. 



Above 1000° all the isometrics show definite curvature, in 

 a way which often appears somewhat abrupt. This is parti- 

 cularly the case with diphenylamine and with toluidine, and 

 to a smaller degree with ether. As a rule the curves are 

 concave downwards, showing that the pressure-increments do 

 not keep pace with the temperature-increments. The reverse, 

 however, is to some extent true for alcohol, while the isome- 

 trics of thymol are practically straight within 1500 atmo- 

 spheres. It is well to note that thymol has been undercooled 



