44 



Dr. A. Ferguson on the Variation of 



as the equation to be tested. In comparing experiment with 

 theory I have, for simplicity in calculation, assumed in every 

 case that n has its mean value 1*21, while for the value of b 

 I have simply taken the reciprocal of the known critical 

 temperature. Values of w (the weight of a single drop at 6°) 

 were then calculated from (xi.) and compared with tin 

 observed values. Better results would probably be found 

 by calculating values of b and of n for each substance 

 separately, but the agreement as shown in Tables V., VI., 

 and VII. is sufficiently good to prove the validity of the 

 formula. 



Table V. 

 Benzene. 



b= -003466, w = -03699 gm. 



Table VI. 

 Methyl formate. 



b= -004673, w = -02991 gm. 



e. 



w obs. 



w calc. 



Diff. 





e. 



6°-7 



w obs. 



w calc. 



Diff. 



ll°-4 



•03524 



•03523 



-•00001 



•02886 



•02878 



-•00008 



30-2 



•03235 



•03235 



±•0000 





10-0 



•02824 



•02822 



-•00002 



530 



•02887 



•02894 



4--00007 





164 



•02736 



•02716 



- -00020 



68-5 



•02653 



•02664 



+•00011 





27-8 



02561* 



•02527 



-•00034 



Table VII. 



Chloro-benzene. 



£ = •002784, ™ = -04226 gm. 



0. 



w obs. 



w calc. 



Diff. 



8°-2 



•04108 



•04110 



+ -00002 



39-2 



•03663 



•03676 



+ -00013 



50-8 



•03499 



•03514 



+ -00015 



63-9 



•03320 



•03334 



+•00014 



72-2 



•03205 



•03221 



+ •00016 



It remains to discuss the effect of composition and consti- 

 tution on the values of b and of n. The variation in n is 



* Misprinted in the original paper (Morgan & Schwartz, I. c. p. 1047) 

 as -02661 gm. The formula served to detect the error, as the difference 

 seemed to be too great to be accounted for by errors in either formula or 

 experiment. Recalculating from the fundamental observations given in 

 tiie paper, the mistake was found to be due to a slip in the arithmetical 

 work. 



