ABSORPTION SPECTRA AND CHEMICAL CONSTITUTION. 357 
General Description of Spectra of Carbostyril, C,H-NO. 
Complete absorption of all rays beyond '/A 2700 until we arrive at a 
dilution of 1 milligram-molecule of the substance in 500 c.c. of liquid 
with 5 mm. of thickness, when the rays extend to 2770. 
At 3 mm. thickness an absorption band becomes visible, which extends 
to 1 milligram-molecule in 2500 c.c., and 1 mm. thickness of liquid. 
At 2 milligram thickness at ] in 500 c.c. it lies between !/A 2900 and 
3300, the rays are transmitted then to 1!/\ 3500, after which there is 
total absorption. The transmission of the continuous spectrum extends 
to '/\ 4000 beyond the absorption band, which has almost disappeared 
at 1 milligram-molecule in 2500 cc. at 2 mm. thickness. 
=C 
) a . 
*\N(CH,)UO 
Total absorption of all rays beyond !/A 2680 in from 25 mm. to 
15 mm. of liquid, and beyond '/\ 2780 down to 1 mm. thickness 1 milli- 
gram-molecule in 100 e.c. 
Complete absorption to 1/A 2850 by 3 mm. of solution containing 
1 milligram-molecule in 500 ¢.c. absorption band from !/\ 2850 to 3370, 
Very feeble transmission of rays from 3370 to 3500. 
This absorption band is distinctly seen-down to 2 mm. of liquid or 
1 milligram-molecule in 2500; the continuous rays then extend to 
about 4050, 
It will thus be seen that this spectrum curve very closely resembles 
that of carbostyril, the general absorption being slightly increased, which is 
what is usual when methyl takes the place of hydrogen or CH, is added 
to the molecule. 
Methylpseudocarbostyril, C,H. 
CH=CH 
Methylearbostyril, CH mt | 
N=. CO0GH, 
Complete transmission of all rays to 1/\ 3000, with 1 milligram~ 
molecule in 500 c.c, and 5 mm. of liquid. Rays beyond are all absorbea. 
At 3 mm. the rays extend to !/A 3050, and are then completely absorbed 
to about 3350, and are transmitted to 3500; in other words there is an 
absorption band between 3050 and 3350 ; rays beyond it are transmitted 
to 1/ 3500. 
This band is very feeble at 5 mm., but is just visible down to a thick- 
ness of 4 mm. of liquid, containing 1 milligram-molecule in 2,500 c.c. 
The rays showing absorption lie between | /X 3000 and 3050. Beyond 
that they are transmitted imperfectly to about 3800. 
The chief differences between this spectrum and that of the pseudo 
compound are the greater length of spectrum transmitted, the different 
position of the absorption band, and its less persistent character. 
General Description of the Spectrum of Isatin, CgH;NO,. 
Total absorption of all rays as far as ! /X 2780 by 10 mm. thickness of 
a solution of 1 milligram-molecule in 100 ce. 
Total absorption of all rays by 5 mm. of 1 milligram-molecule in 100 
c.c. as far as1/dX 2780, very feeble transmission to 3000, The same a 
little stronger by 4 mm. 
