OF THE VAPOURS OF BENZENE AND ITS HOMOLOOUES. 
507 
Observations.— From Table VII. it is at once seen that the absorption bands' at 
100° C. are almost identical with those at lower temperatures. At 100° C., however, 
the series of bands in the region near X 2700 develops strongly, and the bands show 
a peculiar sharpness and definition ; this series at lower temperatures is very ill 
defined, and the bands themselves appear feeble. There are many bands which 
appear faint in Column I. which are strong in Column II., and vice versd ; this 
change is not restricted to any one particular region of the spectrum, but extends 
throughout. As a rule, however, the strongest bands in the one column are the 
strongest in the other. 
It has already been noted in the record of the spectrum of benzene vapour at 
temperatures below its boiling-point, that bands sometimes appear so close together 
that a separate measurement of each is impossible ; at 100° C., on the other hand, 
these pairs are frequently so split up that each band is easily measurable, as, for 
instance, X 2587, Column I., is a close but feeble pair ; in Column II. it becomes 
X 2587'5 and 2586, both being feeble and narrow. 
Table VIII.—Absorption Bands in the Spectrum of Toluene Vapour at Different 
Temperatures and Constant Pressure of 751 mm. 
Abbreviations:—s., strong; £, feeble or faint; n., narrow; v.s., very strong; b., broad; 
v.b., very broad. 
Corresponding groups of bands are indicated on the different toluene spectra by the same 
Greek letters. 
10 ° c. 
A. 
to 
p 
2689 f. 
2689 f. 
a 
\ 
82 
79 If 
75/ L 
731 
70 J s - 
82 f. 
79 If 
74/ L 
721 
70 ; s - 
5il 
U.f. 
43 J 
4il 
41 ] 
P 
\ 
U. 
38 J 
361 
34 J s - 
Is. 
38 J 
35 1 
33 / s - 
31 f. 
40° C. 
A. 
2682 
75 
40 
37 
50° C. 
A. 
s. 
2690 
87 
f. 
f. 
83 s. 
78 "I 
75 j s - 
721 
70 J s - 
40 
37 
11 f. 
60° C. 
A. 
2689 f. 
78 
73 
72 
70 
401 
37/ 
s. 
70° C. 
A. 
2688 
82 
77 
75 
72 
70 
40 
37 
f. 
f. 
s. 
v.s. 
s. 
80° C. 
A. 
2690 
88 
84 
78 
75 
72 
70 
51 
45 
41 
40 
37 
33 
31 
f. 
f. 
f. 
s. 
f.b. 
f.b. 
90° C. 
A. 
s. 
s. 
2695 f. 
90 f. 
85 f. 
82 
77 
74 
71 
69 
51 
42 
40 
36 
35 
33 
v.s. 
v.f. 
s. 
s. 
10 f. 
100° C. 
A. 
2695 
90 
88 
84 
82 
78 
74 
72 
70 
51 
42 
41 
36 
35 
33 
s. 
s. 
s. 
v.f. 
s. 
s. 
3 T 2 
