1881.] 



Influence of Molecular Grouping, §c. 



417 



They show that the termination of the bands in liquids containing 

 carbon, hydrogen, and oxygen corresponds with the position of these 

 hydrogen lines. It therefore appears to them that the bands are in 

 reality a blocking out of radiation between two hydrogen lines. By 

 increasing the thickness of the fluid in front of the slit, the bands may 

 be widened to another hydrogen line, each hydrogen line acting as a 

 stepping-stone, or they may remain constant if both edges are defined^ 

 or they may be obliterated by general absorption. On the other hand, 

 lines may be spread out to bands as the thickness of liquid is increased. 

 When the thickness of the fluid is diminished the lines may disappear, 

 and the bands become lines, or the bands may remain constant though 

 fainter. 



The authors then point out that each radical has its own definite 

 absorption in the infra-red, and that such a radical can be detected in 

 a more complex body. It also seems possible that the hydrogen which 

 is replaced may be distinguished by a comparison with other spectra. 

 They next point out coincidences between some of the lines obtained, 

 the absorption spectra of the hydrocarbons, and the spectra of bodies 

 containing no carbon with solar lines, from which they reason that at 

 present it is not safe to infer that such lines in the solar spectrum are 

 not necessarily due to water. Whether the lines mapped are due to 

 hydrogen or not, it is perfectly evident that every organic body has a 

 definite absorption spectrum which connects it with some series. The 

 paper closes with an appendix giving tables of the bands and lines 

 found in the following substances, of which also there are maps : — 



Methyl iodide. 



Ethyl sulphide. 



Acetoacetic ether. 



Ethyl iodide. 



Aldehyde. 



Diethyl acetoacetic ether 



Propyl iodide. 



Paraldehyde. 



Benzylethyl ether. 



Aniyl iodide. 



Eormic acid. 



Methyl salicylate. 



Phenyl iodide. 



Acetic acid. 



Cinnamic alcohol. 



Ethyl bromide. 



Propionic acid. 



Pheirylpropyl alcohol. 



Amyl bromide. 



Isobutyric acid. 



DibenzTi acetic ether. 



Methyl alcohol. 



Valerianic acid. 



Allyl alcohol. 



Ethyl alcohol. 



Glycerine. 



Ally! sulphide. 



Propyl alcohol. 



Benzene. 



Anethol. 



Isopropyl alcohol. 



Phenyl bromide. 



Citraconic anhydride. 



Isobutyl alcohol. 



Benzyl chloride. 



Water. 



Pseudobutyl alcohol. 



Nitrobenzole. 



Nitric acid. 



Amyl alcohol. 



Aniline. 



Hydrochloric acid. 



Diethyl ether. 



Dimethyl aniline. 



Sulphuric acid. 



Amyl ether. 



Turpentine. 



Ammonia. 



Ethyl nitrate. 



Olive oil. 



Chloroform. 



Ethyl oxalate. 



