1882.] on Spectrum Analysis in the infra red of the Spectrum. 65 



they exist is a moot point, but there is no doubt that they are some- 

 where present in it. That alcohol is to be found in the sun would 

 be perhaps to stretch a point too far ; and it would be unwise to wish 

 to find it there, as it might rouse the animosity of a small section 

 of the community against this branch of spectrum analysis. The 

 ingredients to make it are there, however, without any doubt. 



In regard to these same class of spectra it is interesting to find 

 that there is a marked diflerence in bodies containing the same 

 relative proportions of carbon, hydrogen, and oxygen, but molecularly 

 difierent. Take for example aldehyde and paraldehyde (Fig. 5). A 



soo 



U; I , t 1 J 1 1 1 > I. T'r^fT SE 



Fig. 5. 



mo 



13:3 



irr 



T.i -i'lT 



>h 



I 1 I I Ul i I II It 



t=c 



XX 



iliiiiiiiM^^^^ 



NnpdraldehydQ 



molecule of the latter contains three molecules of the former, and we 

 see that their spectra differ materially. If such be the case in organic 

 compounds, we may surely expect to find the same difference in the 

 spectra of the elements, if there is a different molecular grouping of 

 them at different temperatures. Whether the changes in metallic 

 spectra are due to this cause has still to be proved, though it seems 

 probable that it may be so. 



The latest point in our research in this subject which will be of 

 interest to chemists appears to be the possibility of distinguishing 

 between para- and ortho-organic compounds. Our experiments so 

 far demonstrate that this can be done. If on further research it 

 prove to be the case, this branch of spectrum analysis would be 

 worthy of study by chemists for this reason alone. 



[W. de W. A.] 



Vol. X. (No. 75.) 



F 



