12 2'4S

I I '04



Carbon

Hydrogen -

Chlorine

Nitrogen

Hydroxyl oxygen - 1 16 i"58

Carbonyl oxygen 16 I 2-34



35'5 6-02

14 3'02



44



THE SPECTROSCOPE



Table B. Molecular Refractions at 20° C.
Compound.
Molecular Weight.
Value of ^ (.
Methyl alcohol


32


8-22


Ethyl alcohol


46


1278


Propyl alcohol


60 ^


i7'34


Butyl alcohol


74


21 -90


Benzol


78


2 5 '93


Toluol -


92


3079


Glycerin


94


20'50



It must not be thought that the molecular refractive power
is only of interest in the case of organic bodies. Bender's*
investigations with solutions of sodium chloride have shown
the molecular refraction of NaCl for the D line to be g'273,
whence the atomic refraction of sodium can be found, and
is 3"493. The index of refraction of metallic sodium is
therebj' deduced, and for it

/iD=i"236oi.
There is little doubt that in the near future most extensive
applications to general chemistry will be made of work
depending on refraction constants.
If a hollow prism be filled with a solution of carbon disul-
phide a continuous spectrum is obtained therewith, the dis-
persive power of CS2 being considerable. But if for carbon
disulphide we substitute a solution of fuchsin, the green
portion of the spectrum will be absorbed, and the red and
violet portions transmitted ; these will be refracted so that
the violet portion lies on the opposite side to the red com-
pared with ordinary dispersion — i.e., the red is refracted
more than the violet. Such a phenomenon was termed anoma-
lous dispersion by Le Roux, who made the discovery with

* Ann. Physik, 1902 (iv.), 8.
