180 Dr. A. Scbrauf on certain Objections to the 



refractive index 93t, and on the right the product PVX„. Since 

 V represents the atomic volume of the unit of mass, PV cor- 

 responds to the so-called specific volume (Sp V). Accordingly 



I J (^)=PVX e -,or3« = X„(SpV). . . (IV.) 



If the derivation of this equation be 'correct, and if, further, as 

 above assumed, the function X v has the character of a constant, 

 then for substances of analogous construction the following equa- 

 tion will be true : — 



Wi b s P v 4 [ ■> 



The agreement of the observed values with this equation is 

 complete and indeed almost surprising. In the examples given 

 below, I may remark that the refractive equivalents Wl refer to 

 the density of air as unit, while the specific volumes are derived 

 by taking the density of water as 1. The proportionality of the 

 two functions is not hereby disturbed; on the contrary, it be- 

 comes more manifest, since for the following series of analogous 

 substances the proportionality becomes numerical identity*, as 

 is shown in (IV.). Of course for the verification of (V.) only 

 substances of analogous formation can be employed. 



a. Propionic acid . . . C 3 H 6 O 2 

 Valerianic acid . . . C 6 H 10 O 8 

 (Enanthylic acid. . . C 7 H 12 2 



b. Aldehyde . . . . C 2 H 4 

 Butyric acid . . . . C 4 H 8 O 2 



c. Acetone C 3 H 6 ' 



Caproicacid . . . . C 6 H 12 



d. Valeral C 5 H 10 O 



Valerianate of amyle . C 10 H 20 O 2 



e. Acetate of ethyle . . C 4 H 8 O 2 

 Carbonate of ethyle . C 5 H 10 O 3 



/. Anhydrous acetic acid . C 4 H 6 O 3 



g. Methylic alcohol . . C 4 H 4 

 Ethylic alcohol . . . C 2 H 6 ' 

 Amylic alcohol . . . C 5 H 12 



These examples abundantly prove that for equal temperatures 

 we are justified in considering X„ as constant, and that, further, 

 the formulae which I have deduced are sufficient. 



* Compare Schrauf, " Ueber die gesetzmassigen Beziehungen der Atom- 

 Volumina und Refractionsaequivalente," Sitzungsbericht der Wiener Aka- 

 demie, 1866 ; also Physik. Studien, p. 119. 



0-0855 

 0-1333 

 0-1810 



SpV. 



85-4 

 131-2 

 173-6 



0-0545 

 0-1093 



56-0 

 107-8 



0-0774 

 0-1568 



77-3 



148-7 



0-1248 

 0-2494 



120-3 

 244-1 



0-1077 

 0-1382 



107-5 



138-8 



01101 



110-1 



0-0387 

 0-0617 

 0-1307 



40-8 



61-8 



128-8 



