Spring, W. Arch. SC. phys. Genève (1897), 3(4), 437-63; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010). The spectra water, several alcohols, ester, acids, halogen compounds, nitro compounds, the acetone, sugar canes, Benzaldehyde and several aliphatic and aromatic hydrocarbons were examined. The lengths of the tubes stood in the relationship of the molecular weights and amounted for example for methanol 4 m, for amyl acetate 15 m. If one fills the one of two behind tubes each other present with water, the other one with alcohol, then one obtains the absorption spectrum of both liquids beside each other, and the same also takes place, if a layer aqueous alcohol is observed by appropriate thickness. The temperature does not exert influence, reference of the color of the liquids the earlier by the new observations (Bulletin of the Royal Academy of Belgium, [3.] 31. 246; C. 96. II. 75) confirms the observations. With the cyclic hydrocarbons blue fluorescence could be observed by lateral lighting of long tubes. This seems to be peculiar with the benzene core; only in the turpentine oil fluorescence is missing, perhaps the long side chains cover the influence of the benzene core. By the apparent colorless liquids those seem of symmetrical building to give for example carbon tetrachloride and carbon disulfide no absorption bands while an asymmetrical distribution of the substituents causes band spectrum. The number and situation of bands additives a characteristic is multiple, for example the esters possess the absorption bands alcohol and the acid. Only when very close combination of two groups, the same affect of each other in such a manner that the bands of the two components of the molecule shift their situation or to fall a resulting band together. This present is for example with the homologous of the case of benzene, with the benzene band approaches the methyl band are the more groups of methyls in the molecule. With the halogen derivatives occur a weak shift of the bands toward the breakable part of the spectrum, if chlorine by bromine, and if bromine is replaced by iodine. When general result of the numerous, discussed in detail relations between structure and absorption spectrum of the colorless compounds regard in conformity with the opinions of Kekule an organic compound is to be regarded as a system, in which the individual groups lost their individuality not yet completely. Reprinted with the permission of the American Chemical Society. Copyright © 2010. American Chemical Society (ACS). All Rights Reserved.