Kauffmann (Ber., 1906, 39, p. 1 959) attempted an evaluation of the effects of auxochromic groups by means of the magnetic optical constants.
Mention may be made of the phenomenon of halochromism, the name given to the power of colourless or faintly-coloured substances of combining with acids to form highly-coloured substances without the necessary production of a chromophoric group. The researches of Adolf von Baeyer and Villiger, Kehrmann, Kauffmann and others, show that this property is possessed by very many and varied substances.
(2) The chromophore-auxochrome theory (Kauffmann) regards colour as due to the entry of an " auxochrome " into a " chromophoric " molecule.
Kauffmann (Ber., 1900, 33, p. 1 73 1; 1904, 35, p. 2 94; 1905, 3 8, p. 7 8 9; Ann., 1906, 344, p. 30) suggested that the property is due to the presence of at least two groups.
Kauffmann, and in the large new Dictionnaire d'archeologie chretienne et liturgie, published at Paris under the editorship of Dom F.
Kauffmann, Balder: Mythus u.
Gr., Halle (1878) of Giildenpenning and Iffland, the last-named work discussing the relation of Socrates to Sozomen), the barbarian migrations (Wietersheim, Dahn), the Goths (Waltz, Bessel, Kauffmann and Scott's Ulfilas, 1885).