56 CG. A. MAC MUNN. 
a spectrum consisting of three well-defined absorption bands. 
On using a very weak solution and gradually strengthening it, 
the least refrangible band, being the most intense, appears first, 
and is visible in solutions which appear very slightly tinted 
indeed to the unassisted eye. The other two bands appear 
together. The middle band is at first darkest about x. The 
most refrangible band, which is much less dark than the middle 
one, is of uniform intensity. Neither the red nor violet ends 
of the spectrum are much absorbed. When the solution is 
very strong all these bands become intense ; violet disappears, 
and all the light, except red and yellow, becomes very faint. 
The bands remain as before, except that the middle band now 
appears of uniform intensity throughout. When the solution 
is rendered stronger still, the least refrangible band extends 
gradually up towards p, and the whole of the spectrum 
becomes absorbed except a band of light consisting of red 
with a little yellow. On adding hydrochloric acid to an alco- 
holic solution the colour changes to orange, and the spectrum 
now consists of two bands, one lying to the red side of 5, and the 
other to the violet side of 6 and extending to F. These bands 
are in weak solutions separated by an interval of light. : 
On adding ammonia to an alcohol solution until alkaline, the 
colour changes to deep violet, and a flocculent purple precipi- 
tate is formed, which can be readily separated by filtration. 
This dried precipitate appears as a violet amorphous powder 
insoluble in alcohol and oil of cloves. The spectrum of this 
when mounted in Canada balsam consists of two bands, the 
first before p, the second between p and zu. These are the 
most important points referred to by Professor Moseley. As 
said before, he found a similar pigment in a Holothurian, 
differing in some unimportant points from those given. 
The spirit solution sent to me by Professor F. Jeffrey Bell 
had a deep yellow colour, being orange yellow by gaslight ; it 
gave one band in orange and one in green, and strongly 
absorbed the violet end of the spectrum. A very deep layer 
transmitted only the red rays and showed a narrow faint band 
in red, As the solution was too dilute for spectroscopic 
