The magneto-optical rotation

The molecular magneto-optical rotation D is a function of the refractive index n, the density d, the Verdet constant V and the molecular weight M  

This function shows a certain resemblance to that of the molecular refraction rmoi.  

However, in the analysis of saturated hydrocarbon mixtures, D has proved to be not only highly sensitive to the presence of rings (like rmol.), but also to ramifications in the molecules. When comparing D and rmo. of paraffinic or naphthenic hydrocarbons with those of corresponding w-alkanes of equal molecular weight (Z)M-aikane and mol.(w-alkane), respectively), it can be stated that 

For paraffinic hydrocarbons the following expression is a good approximation  

The method has been applied to saturated aromatic and olefin-free mineral oil fractions and hydrogenated polymers cf. Table III and IV). 

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When determining the degree of branching of hydrocarbon mixtures by means of physical constants, especially those physical constants or functions thereof should be chosen that show the necessary sensitivity to the presence of branchings. Particularly the parachor and the magneto-optical rotation have found application. 

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