894 
CAPTAIN ABNEY AND LIEUTENANT-COLONEL FESTING 
We may go a step further than this, however. We find both edges of some 
bands to accord with the position of known hydrogen lines, whilst in others we find 
that only one edge can be so marked. Though direct evidence is wanting to enable 
us to say that the other edge marks the position of a hydrogen line, yet the circum¬ 
stantial evidence that such is the case is excessively strong. In point of fact, of the 
hydrogen lines and edges of bands to be found in hydrocarbons lying between 900 
and 972 of our empiric scale, more than half are to be found coincident with lines in 
the non-carbon bodies. The following table shows the coincidences :— 
Hydrocarbons .... 900 902 905 9]0 912 920 927 935 942 949 952 959 972 
Hydrogen and oxygen, j 
or nitrogen, > 900 . 912 920 927 .. .. 949 .. 959 972 
or chlorine 
On the more refrangible side of 900 the coincidences in the latter series are always 
to be found in the former. If other bodies containing no carbon be examined no 
doubt some of the gaps in the table will be filled up. It must distinctly be understood 
that in all the absorptions in which bands, lines, or both appear, the position of the 
whole of the known hydrogen lines will not be found, each weighted radical making a 
selection of them. 
Effect of the presence of oxygen. 
It is seen that bodies containing carbon and hydrogen alone or with chlorine, 
bromine, or iodine, gave absorption spectra in which there are defined bands together 
with lines. 
The next point that required solution was the effect of the presence of oxygen on 
the body under examination, and here we had ample material on which to make our 
observations. It appears that in every case where oxygen is present otherwise than 
as a part of the radical it is attached to some hydrogen atom in such a way that it obli¬ 
terates the radiation between two of the lines which are due to that hydrogen. Take, 
for example, ethyl alcohol. We find that one band of absorption takes place between 
927 and 942, another between 900, and 905 on the less refrangible, and 892 on the 
more refrangible side. Mow, all these different numbers are localities where hydrogen 
lines are to be found. Iso-butyl alcohol is another good example. Besides the last- 
named bands of the ethyl alcohol it has bands lying between 912 and 920, between 
927 and 942, and a narrow band about 959. These, again, are all localities where 
hydrogen lines can exist. If more than one hydroxyl group be present we doubt if 
any different effect is produced beyond that produced by one hydroxyl group, except 
a possible greater general absorption ; a good example of this will be found in cinnamic 
alcohol and phenyl-propyl alcohol, which give the same spectra as far as the special 
absorptions are concerned. 
