Browning, on the Spectra of the Dichroic Fluid. 71 
firm coagulum, these threads leading down from the surface 
where contact first begins to the film lying at the bottom of 
the glass. When the film is dipped into undiluted albumen 
it appears to become coated with an imperfect coagulum, and 
when this has happened I have in no instance seen any chro- 
matic change take place. 
Notes on the Spectra of the Dichroic Fluid described in 
the above paper. By John Browning, F.R.A.S. 
The spectrum of the fiuid seen by transmitted light, which 
shows it as a blueish purple, is somewhat remarkable as being 
the only blue fluid, Mr. Sorby has found to give particular 
bands. The chief characteristics of this spectrum, represented 
in diagram 1, may be briefly described thus: — Commencing 
at the least refrangible or red end of the spectrum, we find it 
cuts pretty sharply a short piece of the extreme red. Then 
we have a strong absorption band also in the red, correspond- 
ing to 2-i- of the twelve lines given by Sorby ’s standard inter- 
ference spectrum.* Ten lines of this interference spectrum 
I have drawn underneath spectrum 1. 
A second absorption band in the green commences at line 
4, and tones off gradually into the spectrum just beyond 
line 5. 
After the preceding paper had been read it occurred to me 
that it would be a matter of much interest if a spectrum of 
the fluid viewed by transmitted light could be produced. 
* Mr. Sorby’s scale, jnst referred to, is an interference spectrum, pro- 
duced by a plate of quartz ‘(MS inch thick, cut parallel to the principal axis 
of the crystal, and placed between two Nicol’s prisms. In this spectrum 
the whole visible space is divided into twelve divisions. These are counted 
from the red and towards the blue. The sodium line, as shown in the dia- 
gram, corresponds to three and a half. Mr. Sorby has very kindly presented 
me with an exact duplicate of his own standard spectrum, from which I am 
enabled to prepare others, which will give exactly similar reuflts. 
