300 REPORT—1899; 
contains a, the second 6 naphthol, they differ considerably in their absorp- 
tive power. The first transmits all rays through ;},th of a molecule, 
while No. 2 absorbs all beyond !/A 1780, when only ;},jth of a molecule 
is present. 
a-Naphthol-azonaphthylsulphonie Acid (Acid Brown), 
OH, : Cy), N, tN 3C pH, - HSO.;. 
B-Naphthol-azonaphthylsulphonie Acid (Fast Red), 
OH, *C,)H,< Na: N, °C,,H,° HS0,;. 
Although these two bodies only differ slightly in constitution, in fact, 
merely as regards the position of the OH group, their absorption curves 
differ widely. 
Murexide.— Uric acid, which is closely related to murexide, exhibits an 
extraordinary absorption band when an aqueous solution of the acid is 
examined in layers 15 millimetres in thickness. Since the substance 
requires 15,000 parts of water for its solution, this is some indication of 
the extraordinary absorptive power of uric acid and of the effect of the 
linking of several carbon and nitrogen atoms, and the combination of 
oxygen atoms with carbon. Urea is extraordinarily diactinic. 
The curves of the rosaniline series of dyes are modifications of the 
benzene curve, standing, however, in a closer relationship to the curve of 
triphenylmethane than to that of benzene itself. The curves are modified 
in such a manner that the molecules of greatest mass transmit least light, 
and the light is composed of rays vibrating with least rapidity, thus indi- 
cating greater amplitude and less rapidity of vibration of the molecule. 
The curves of the azo-colours are likewise modifications of the azobenzene 
curves. 
A general conclusion drawn from this work is that when absorption 
takes place in the visible region the ultra-violet rays are also absorbed, It 
appears, therefore, hopeless to expect. a strongly coloured organic sub- 
stance to transmit the ultra-violet rays. 
Bexiehungen zwischen Zusammensetzung und Absorptionsspectrum 
organischer Verbindungen. 
Althausse! and G. Kriiss communicated a paper in which they observed 
that, first, an increase in the percentage of carbon causes the absorp- 
tion bands to pass towards the less refrangible portion of the spectrum ; 
secondly, the wave-lengths of bands of absorption are the same in different 
thionine salts, whether the solution contains hydrochloride, hydriodide, or 
other salts of this base; thirdly, the addition of hydrogen causes the 
bands to pass towards the blue; fourthly, if a substance is examined 
spectroscopically in a solution suitable to commercial requirements, the 
colour of an unknown derivative of the compound in question may be 
foretold from its spectrum with tolerable accuracy. 
Tuer ABSORPTION SPECTRA OF ISOMERS OF THE AROMATIC SERIES. 
In the examination of aromatic derivatives (Hartley and Huntington) 
and of some of the homologues of benzene (Hartley), three isomeric 
nitranilines were examined and three xylenes ; the spectra of the latter 
} Ber, vol, xxii. p. 2065, 1889. 
