6 
H. N. MOSELEY. 
observed by viewing the spectrum with the bright sodium 
line in the held. The second, situated between D and E, is 
most intense on its least refrangible border, and shades off 
towards the violet. The third band is a broad, dim one, 
stretching from b to F. Very little of the red end of the 
spectrum is cut off. The whole of the violet is absorbed. 
In very intense solutions (PI. I, fig. 46) the absorption at 
the violet end spreads up to b, and unites with the third 
band, so that the light is entirely cut off up to. b, where 
there is a defined dark edge. The second band is intensi¬ 
fied and becomes black. The first band is black as before, 
but a paler band is added to it in continuation on its red 
side. In very intense solutions the two principal bands 
broaden out and almost run together, being separated only by 
a narrow interval of yellow. The two principal bands coincide 
very nearly with those of turacin. The only difference is 
that the least refrangible band in turacin extends a little 
further to the green side of D than does that of Pentacrinin. 
On the acid alcoholic solution being rendered alkaline by 
addition of ammonia the solution becomes of a bluish-green 
colour, which shows a slight red fluorescence on the concen¬ 
tration of sunlight in it. 
The spectrum is changed. An intensely black band now 
occupies a space to the less refrangible side of B; to the red 
side of D is a broad pale band, whilst the third band between 
b and F remains as before, excepting that it is intensified for 
rather more than half its breadth on its violet side (PL I, 
fig. 5 c). In very weak solutions the first and third bands 
remain visible after the middle one is lost. 
The solution can be rendered acid or alkaline any number 
of times with corresponding change of colour and spectrum. 
By careful addition of ammonia in small quantities to the 
acid solution, in a tall vessel, one part of the solution can be 
obtained green, whilst the remainder is still red. 
Thus the passage of one spectrum into the other may be 
seen at the junction of the two solutions. As the least re¬ 
frangible band of the acid spectrum fades, it takes the form 
of a fine black line to the red side of D, with a fainter 
margin extending just over D towards the green. As the 
ammoniacal portion of the solution is approached a dark, 
broad band is seen to extend gradually towards the red from 
the least refrangible acid band up to the position of the least 
refrangible margin of the dark alkaline band in the extreme 
red. The least refrangible margin of the broad band darkens 
as the least refrangible acid band fades from view, and at 
length assumes the full intensity of the least refrangible alka- 
