Schunck . — The Chemistry of Chlorophyll . 85 
who have given a detailed account of the successive changes 
observed in the normal chlorophyll-spectrum on the addition 
of acids to chlorophyll solutions. For those who take only a 
general interest in the matter the following short account will 
probably suffice : — If to an ethereal solution of chlorophyll — 
prepared in the manner above described — contained in a test 
tube a few drops of hydrochloric acid be added, the colour of the 
solution changes at once from bright green to yellowish-green. 
Examined with the spectroscope it will be found that bands I 
and II have become more distinct than before in consequence 
of the clearing up of the space between them, while band III 
has moved further away from the red end appearing at the 
same time very much paler, and band IV on the other hand 
has become very much darker ; on the solution standing for 
some days a fifth band (IV b) begins to appear between the 
lines E and F, becoming gradually as dark as the fourth 
band, a sign that the action of the acid is completed. The 
same series of changes occurs when a crystal of tartaric acid 
is dropped into the ethereal solution and shaken up with 
it, but a much longer time elapses before the final stage 
is reached. On adding a quantity of acetic acid to the 
chlorophyll-solution, no change is observed at first as re- 
gards either its colour or its absorption-spectrum ; but after 
standing for some days the solution appears yellowish-green, 
and now shows the same bands as are produced at once by 
hydrochloric acid, bands I and II being very distinct, band 
III very faint, and band IV very dark, the fifth band not 
appearing at all even after a considerable time. Hence it 
appears — relying on the results of spectroscopic observation 
— that by the action of a strong acid chlorophyll undergoes 
at once a change, which is only brought about after a long 
time under the influence of a weak acid, while the final effect 
of the action of a strong acid is not produced at all by a 
weak acid, a moderately weak acid like tartaric acid acting 
less rapidly than a strong acid, but more rapidly than a 
weak one. That the change due to the action of acids is not 
the result of a process like that of the decomposition of a 
