Scale of molecular rotations 
ON OPTICAL POTATORY DISPERSION. 
267 
the casual errors had been reduced to a few hundredths of a degree. Table I. shows the 
observed rotations, a, and the specific rotatory powers [a] derived from them, for 11 
solutions containing from 5 to 55 grams of acid in each 100 grams of solution ; the 
corresponding molecular rotatory powers are also shown in the table. 
The data used in testing Biot’s linear law and Winther’s parabolic formula are 
shown in Table II. Biot’s linear law, although based originally upon somewhat rough 
measurements, is very good as a first approximation. Thus, in fig. 1, in which the 
Scale of molecular rotations 
