822 | REPORT—1899. 
of this will possibly be evident from a consideration of the theory which 
accounts for the occurrence of absorption bands. 
Two most distinct advances were made at this period which connect 
the molecular structure of organic substances with their absorption 
spectra. The first is the work of Russell and Lapraik and the second 
that of Abney and Festing. Both of these memoirs show what change is 
caused in the spectra of substances when alkyl radicals and hydroxyl are 
substituted for hydrogen. About this period the following work was also 
published. J. L. Schénn! examined the absorption spectra of methyl, 
ethyl, and amy] alcohol in layers from 1-6 to 3-7 metres in thickness, and 
observed narrow absorption bands in their spectra. Kriiss, from Schénn’s 
measurements, calculated their wave-lengths. They lie in the red, orange, 
and yellow. 
i Ait IIl. 
Methyl alcohol \ 643:0  632°8. 
Ethyl alcohol 2d 651°5 632°8 = 559-1. 
Amyl alcohol 2 6591 636°2 562:7. 
On ABSORPTION-BANDS IN THE VISIBLK SPECTRUM PRODUCED BY CERTAIN 
Cotourtess Liquips.2 By W. J., Russewt, PAD. F.RS., and 
W. Lapraik, I.C.S. 
These observations were made on long columns of liquid from 2 to 
8 feet in length, and the substances examined were water, methylic, 
ethylic, propylic, and amylic alcohols, Amylic iodide, amylene, ether, 
ethyl iodide, aldehyde, acetic acid, benzene, toluene, xylene, phenol, 
monochlor-benzene, diclor-benzene, ammonia in water and in ether, methyl- 
amine in a 6-foot tube and ina 4-foot tube, ethylamine, diethylamine, 
triethylamine, aniline, toluidine, di-methyl aniline, turpentine, nitric 
acid, chloroform and naphthalene. All these substances in the thick- 
nesses mentioned give very well defined but rather narrow absorption 
bands between (600 and A740. Toluidine gave a general absorption 
extending to \ 480. The bands of the different substances, it must be 
understood, differ altogether from those peculiar to water. All the 
alcohols give a similar band, but with different alcohols it has in each case 
a different position. Zhe higher the alcohol stands in the series, the nearer 
is the band to the red end of the spectrum. The illustrations in the ‘Jour. 
Chem. Soe.’ (figs. 2. 3, 4, and 5) show these bands, p. 168. The esters 
gave interesting results ; for in all cases a very similar band to that of 
alcohol was observed, but always in a position slightly nearer the blue end 
of the spectrum. In the case of ethyl iodide another band was visible, 
extending from A716 to 724. It is stated that probably this band is 
characteristic of all ethereal salts, but in other cases is hidden by the 
general absorption. Fig. 9 shows the spectrum of the iodide. In the 
amylic series the nitrate, acetate, and iodide were examined. They behave 
exactly in the same way as the compound ethylic ethers, viz., they ali 
give bands similar to the alcohol band (fig. 5), but slightly nearer the 
blue. The same band running through each alcoholic series shows that 
the band-producing body is unaffected by the acid radical. 
1 Wiedemann’s Ann. vol. vi. p. 267, 1879. 
* Trans. Chem. Soe. vol. xxix. p. 168, 1881. 
