1889 - 90 .] Mr C. Micliie Smith on Absorption Spectra. 123 
between 1665 (W. L. 789) and 1625 (W. L. 639*8), while the chief 
hand in a thin film of trichosanthes would almost exactly fill up 
the interval between hands I. and II. in chlorophyll. Bands 
III., IV., and V. of trichosanthes may he coincident with faint 
chlorophyll bands. 
The positions of some of the chlorophyll hands, as is well known, 
can he changed by the action of reagents, and the trichosanthes 
bands are even more strongly affected. The first reagent experi- 
mented with was sulphide of ammonia, which probably has a 
reducing action. The result is shown in spectra (e), (/) and (y), 
which represent the appearance after 2, 11, and 39 days respect- 
ively, after which there was no further change. Figure ( h ) gives 
the spectrum of chlorophyll similarly treated. The change in the 
trichosanthes spectrum is complete. Band I. gradually becomes 
weaker, and finally vanishes ; two new bands appear in the space 
between bands I. and II. of the original spectrum; band II. is 
apparently displaced towards the violet end and intensified ; and 
band IV. is greatly widened. Chlorophyll is much less affected, 
and the difference between two spectra could hardly be more 
complete than that between ( g ) and ( li ). 
When the original trichosanthes solution is treated with strong 
hydrochloric acid the spectrum consists of three principal bands. 
The first band begins (penumbra) 1606, and extends to 1576 ; the 
maximum absorption is from 1593 (W. L. 608*6) to 1576 (W. L. 
593*4). From this there is considerable absorption to the second 
band, of which the maximum absorption extends from 1557 
(W. L. 577*6) to 1532 (W. L. 558*8). Slight absorption continues 
to the third band, which extends from 1497 (W. L. 536) to 1467 
(W. L. 519). The relative intensities of these three bands are 
about 8, 7, 4. These three bands may perhaps represent the three 
first bands of the natural spectrum moved by different amounts 
towards the more refrangible end. When this spectrum (i) is 
compared with the spectrum of chlorophyll similarly treated (j), it 
is seen that the three bands correspond with three of the chloro- 
phyll bands, while there is nothing to represent the first and most 
prominent chlorophyll band. It is of importance to notice, too, 
that the unrepresented^chlorophyll band is the one least affected 
by reagents. 
