Memoirs presented to the Cambridge philosophical society on the occasion of the jubilee of Sir George Gabriel Stokes, bart., Hon. LL. D., Hon. SC. D., Lucasian professor.

Ccambridge Philosophical Transactions, Vol. XVIII., Plates 6, 7.
PLATE 6.
Absorptions by solutions of didymliu nitrate, concentrat e d, and extremely dilute. The most concentrated had 611-1 grams of the salt per litre; the other was part of the same solution diluted to
45-5 times its bulk.
c0 T-I O O cs a! Ct^ o oo c
305 mmn. thick
There is very little difference between these two spectra except that the band in the yellow is
broader with the stronger solution, and those at X476 and 427 more washed out.
PLATE 7.
Absorptions by solutions of didymniunm chloride of concentrations equivalent to those of the nitrate
used for plate 6: the stronger containing 462'9 grants of the chloride per litre.
C D O ro ~ t- ~ O
î H o c: z S c1 o 0
1 s 7solutico
6'7 min. thick
~~~Te2 tls noo definit1/45-5 strength
305 1min. thick
There is no definite difference between these two spectra.