Schunck . — The Chemistry of Chlorophyll. 83 
et de phyllocyanate de potasse.’ It is certain that nearly all 
the substances described by Fremy are products of decom- 
position, formed by the action either of acids or of alkalis on 
chlorophyll. 
Filhol 1 made a step in advance by showing, in accordance 
with the previous statement of Professor Stokes, that chloro- 
phyll in solution is very easily decomposed by acids, even 
weak acids, such as acetic, sufficing for the purpose and 
yielding products which after removal of the acid do not, 
when dissolved together in ether, afford solutions showing the 
bright green colour of the original solution. Filhol’s descrip- 
tion of the 4 matiere solide brune ’ which is deposited when an 
acid is added to an alcoholic solution of chlorophyll shows 
that it is essentially the same substance as that which, when 
dissolved in hydrochloric acid, constitutes the phyllocyanin of 
Fremy, and is probably also identical with the second chloro- 
phyll modification of Berzelius. 
In the year 1874, Filhol 2 presented to the French Academy 
a note on chlorophyll, in which he states that by the action 
of hydrochloric acid on the chlorophyll of dicotyledonous 
plants he obtained 4 une matiere noire amorphe,’ while by 
operating in the same manner on the chlorophyll from mono- 
cotyledons he obtained 4 une matiere noire cristallisable.’ The 
crystals of the latter substance are only visible under the 
microscope ; they form little tufts consisting of fine needles. 
This is perhaps the first time that a crystalline derivative of 
chlorophyll is mentioned in any publication 3 . After giving 
a general account of its properties, Filhol states that the 
solution of his substance in acetic acid acquires a magnificent 
green colour when it is boiled with the addition of a little 
1 Comptes Rendus, LX VI. 1218. 
2 Ibid. LXXIX.612. 
3 Several years ago, when my attention was first directed to this subject, Pro- 
fessor Stokes very kindly wrote me several letters giving an account of his 
researches on chlorophyll conducted long previously. In one letter he describes a 
substance crystallising in rosettes, nearly opaque, which he identifies with Fremy’ s 
phyllocyanin, without, however, referring to any publication in which the product 
was described. 
