340 . REPORT—1899, 
state. Characteristic absorption bands which appear in one state of 
aggregation, either do not appear at all in another, or the bands are 
markedly altered in position, in intensity, or in appearance. The same 
absorption spectrum is shown by chlorophyll and by copper sulphate in 
the solid as well as in the dissolved state. 
2. The spectra which one and the same substance yields in different 
solvents are indistinguishable in many cases, in other instances they are 
distinguished by the width of their bands, in others by a total difference 
in their characters, so that the spectra in no way correspond. 
3. The rule given by Kundt that the absorption bands are shifted 
farther towards the red the stronger the dispersion of the liquid which is 
used as a solvent, is not satisfied in many cases. Sometimes the bands 
are shifted towards the blue, e.g., uranium nitrate in water and alcohol 
and blue cobalt chloride in water and alcohol. Sometimes there is a 
strong alteration in the sense of Kundt’s rule, and in other cases in the 
same region of rays the alteration is but trifling. Many absorption 
bands show in different media of solution the same or very nearly the 
same position, while at the same time others are shifted. 
4. The position of absorption bands in the spectra of solid and dis- 
solved substances can only in exceptional cases be of value as character- 
istic of the particular substance. Substances which are totally different 
exhibit bands in (almost) exactly the same positions. Very analogous 
substances exhibit in like proportions striking differences in the position 
of their bands.’ 
5. The law for absorption spectra, every substance has its own 
spectrum,’ is only admissible in a very restricted sense. 
The great number of polychroic substances show different colours and 
different spectra in the solid state, and it is a question which of these is 
to be regarded in the case of any one substance as its own special 
spectrum. 
Zur Kenntniss der Alizarin-Farbstoffe und griinen Anilinfarben. 
By HERMANN W. VOGEL. 
The spectra of these substances are described, and the changes caused 
by different reagents acting upon them, which give rise to different 
spectra. 
Relation between the Composition of Organic Compounds and their 
Absorption Spectra.! By G. Krtss and 8. CEconomMIDES. 
It bad been shown by Melde that the absorption spectrum of a mixed 
solution of two or more coloured substances is not the same as the spec- 
trum of each taken in conjunction, but that displacements and concen- 
trations of the absorption bands occur.® The changes being ascribed to 
chemical changes within the solutions, it became of interest to ascertain 
1 Solid uranium salts, according to Morton and Carrington Bolton, Chem. News, 
vol. xxviii. p. 47. 
2 Moser, Pogg. Ann. vol. clx. p. 177. 
3 Ber. vol. ii. p. 1371, 1878. 
4 Ber. vol. xvi. pp. 2051-2056, 1883. 
5 Ber. vol. xv. pp. 1243-1249, 1882, ‘Ueber die Constitution von Losungen,’ G. 
Kriiss, > 
