^rrna^ieStirisST ^^oyal MicTOSCo^pical Socidy. 131 
extracted without mucli difficulty. Nearly all blue flowers yield 
yellowish or pinkish-yellow solutions. Alkalies deepen these 
colours and bring them nearer to green. Acids on the other hand 
mostly convert them into reds, they then produce the same effect 
on the spectrum as reds. The extraction of colour from the 
leaves of plants of a deep red, as Coleus, &c., appears to take 
place by deoxidation ; on immersing such leaves in alcohol the red 
colour is quickly extracted, and the leaves become quite green; 
after standing by twenty-four hours the green becomes paler, and 
ultimately on decanting the solution the leaves are left colourless. 
Upon removing and drying them in the air a considerable portion 
of colour returns. The solution first obtained produces a more 
decided reaction on the spectrum than subsequent solutions, although 
the latter apparently contain a larger quantity of chlorophyll. 
Most red solutions produce, as I have said, a general absorption 
of the spectrum below the red, but if properly diluted to a pink, 
they give two or more bands in the yellow and green, deepening 
the blue end. If a small quantity of blue enters into the composi- 
tion of such solutions, bands will also be noticed in the blue, or the 
violet, and this portion of the spectrum will be seen to be more 
intense ; good illumination and dispersion, as well as proper 
dilution, being indispensable to bring out the bands in the violet. 
The red end of the spectrum is at the same time often more 
brilliant. 
A solution of Brazil wood, to which an alkali and alum had been 
added, remained of a yellow colour ; but on dilution it became pink, 
and on standing in a strong light it changed to a deep red. This 
solution produced absorption of the whole of the green portion of 
the spectrum ; but upon again diluting it down to a pink, a broad 
well-defined band appeared in the green and yellow, deepening the 
blue end. 
Methylic alcohol requires caution in using. It is very hable 
to produce decomposition of the colour obtained, from the circum- 
stance that the commercial spirit sold under the name of " Methy- 
lated spirits," is often contaminated by impurities. The fine scarlet 
cactus flower readily parted with its colour to methylic spirits, but 
it is soon changed to a yellow, and finally became colourless. 
Memorandum of Spectroscopic Besearches on the Chlorophyll of 
various Plants. By the late William Bird Herapath, M.D., 
F.E.S., F.E.M.S., &c. 
The late lamented Dr. Herapath was actively engaged during the 
summer of last year in the study, by means of the spectroscope, of 
the optical characters of chlorophyll. At the time of his death he 
