io8 



INFRA-RED ABSORPTION SPECTRA. 



of their great opacity beyond 7 fx, as well as on account of the difficulty 

 in freeing them from water. Only one alcohol was studied, viz, myricyl, 

 CgoHeiOH, which is a solid obtained from beeswax. Its maxima occur 

 at 1.71, 2.95, 3.43, and 5.8/1,. The water bands were found at 2.% fi 

 and 6.0 fi, so that, if the alcohol bands are due to the OH-group, then 

 one would expect the 5.8 /u. hand likewise to coincide with that of water, 

 at 6.0 fi. 



The various compounds having an absorption band in the region of 

 2.95 ju, have been collected in the following table : 



It will be noticed that ammonia also has a band near that of water, 

 and at a slightly less wave-length. Considerable time was spent in 

 showing that it is not due to water vapor. The gas was fractionally 

 liquefied and distilled, and then placed in a glass pipette containing 

 freshly heated calcium oxide Over mercury, for eight days. At the end 

 of this time the absorption band coincided exactly with the one previously 

 found, showing that the band is characteristic of ammonia. Further- 

 more, it will be noticed that the compounds containing the amido 

 (NHg) group and certain ones containing nitrogen have a character- 

 istic band in this region. These compounds were dried with potassium 

 carbonate, which would have removed traces of water. Other com- 

 pounds, like the aldehydes and fatty acids, do not show this band. 

 Commercial ethyl ether contains about 3 per cent of water, but there is 



