2 Fred J. Bates 



tion dropped below the normal. This he interpreted to indicate 

 two points of inflection in the rotary dispersion curve for each 

 band. He never succeeded, however, in establishing a curve for 

 both sides of the' same band, nor in the interior of the band. In 

 1900 Schmauss^ observed an apparent anomaly in fuchsin, cyanin, 

 naphthalene-red, eosin, and didym glass. He studied the first four 

 in very dilute alcoholic solution, the greatest concentration by 

 weight for each substance being 0.000024, 0.000039, 0.000005, 

 0.000004 (parts by weight) respectively. His rotary dispersion 

 curves for these liquids all show four points of inflection, and a 

 very marked rise above the curve of the solvent as the violet 

 region is approached. The fuchsin solution 0.000024 gave a 

 rotation of 2.81° for wave-lengths 544 /x/a and 2.34° for 545 /x/a. 

 The former is 0.44° greater than that of the solvent, and the 

 latter 0.13° less. For wave-length 450 /x/x the solution gave a 

 rotation of 0.58° greater than that of the solvent. In subse- 

 quent papers- he studied didym glass, Hquid oxygen, and solu- 

 tion of litmus, anilin blue, and three rare earths. 



Schmauss's results indicate that the anomalous efifects increase 

 with increasing concentration ; that the maximum rotation is inde- 

 pendent of the field strength, and that the negative rotation in 

 the interior of a band decreases with increasing field strength. 

 The observations of Zeeman on moderately dense sodium vapor 

 as well as all of Schmauss's results seem to confirm the theoreti- 

 cal deductions of Voigt. 



The writer has been studying solution of anomalous dispers- 

 ing substances and thus far has not succeeded in observing an 

 anomaly. The substances were fuchsin, cyanin, anilin blue, and 

 litmus. The first two were in alcoholic, the latter two in water 

 solutions. 



The method employed consisted in placing a tube of the solu- 

 tion between the pierced poles of an electromagnet. Light par- 

 allel to the lines of force was successively passed through a half- 

 shade polarizing system, the tube, and an analyzing nicol. After 

 measuring the rotation, the tube was removed and the rotation 



lA. Schmauss, Ann. d. Phys. 2, p. 280. 1900. 



2A. Schmauss, Ibid., 8, p. 842, 1902, and 10, p. 853. 1903. 



266 



