220 
Constitution  of  Chlorophyll. 
(  km  Jour.  Pharm, 
i       April,  1884. 
stances  in  which  the  tinctorial  properties  of  the  parent  substance  are 
much  more  pronounced.  To  this  division  belong  the  coloring-matters 
of  madder,  quercitron,  cochineal,  etc.  Now  chlorophyll  in  its  general 
properties  so  much  resembles  the  members  of  the  last  class  that  one 
cannot  help  suspecting  that  to  this  class  it  may  belong — that  it  is,  in 
fact,  a  glucoside.  It  shows  considerable  stability  in  the  presence  of 
alkalies,  but  acids  decompose  it  rapidly,  giving  rise  to  substances  which 
are  intensely  colored  and  show  a  power  of  absorbing  particular  parts 
of  the  spectrum  much  more  strongly  than  chlorophyll  itself.  Whether 
along  with  the  latter  bodies,  it  yields  by  decomposition  with  acids  some 
kind  of  glucose  seemed  to  me  a  question  worthy  of  attentiou. 
If  it  was  possible  to  obtain  chlorophyll  in  a  state,  of  purity  it  would 
be  very  easy  to  settle  this  question  ;  unfortunately  all  attempts  hitherto 
made  to  separate  and  purify  chlorophyll  have  ended  in  its  decomposi- 
tion. I  consider  it  as  certain  that  the  so-called  crystallized  chlorophyll 
which  has  been  described  by  several  authors  is  in  fact  a  derivative  of 
chlorophyll  formed  during  the  process  employed  tor  preparing  it.  It 
is,  however,  very  easy  to  obtain  a  solution  of  chlorophyll  which  shall 
be  quite  free  from  everything  soluble  in  water  extracted  at  the  same 
time  from  the  plant,  and  therefore  free  from  ready-formed  glucose.  In 
order  to  effect  this  I  proceed  as  follows: — Having  extracted  leaves  of 
any  kind  with  boiling  alcohol,  I  allow  the  extract  to  stand  for  some 
time,  filter  off  the  deposit  which  usually  forms,  and  then  mix  it  with 
its  own  volume  of  ether  and  with  about  two  volumes  of  water,  shak- 
ing up  well.  The  liquid  now  separates  into  two  layers,  an  upper  green 
one,  containing  all  the  chlorophyll  of  the  extract,  and  a  lower  bright 
yellow  one,  which  contains  tannin,  a  yellow  coloring-matter,  a  substance 
giving  the  glucose  reaction  with  Fehling's  solution,  and  probably  other 
substances  besides.  The  two  liquids  are  separated  in  the  usual  way, 
and  the  upper  one  is  shaken  up  with  fresh  water,  which  now  usually 
only  shows  a  trace  of  color.  This  process  of  washing  may  be  repeated, 
adding  each  time  a  little  fresh  ether,  until  the  lower  layer  ceases  to 
give  the  glucose  reaction.  The  upper  liquid  leaves  on  spontaneous 
evaporation  a  bright  green  residue,  which,  though  far  from  being  pure 
chlorophyll,  is  free  from  everything  soluble  in  water,  and  may  there- 
fore be  employed  to  determine  whether  anything  soluble  in  water,  such 
as  glucose,  is  formed  by  the  action  of  acids  on  it.  If  some  of  the 
residue  be  treated  with  concentrated  sulphuric  acid  in  the  cold  it  dis- 
solves, forming  a  green  solution,  which,  after  standing  for  some  timer 
gives,  on  the  addition  of  water,  a  dark  green  precipitate.  This  precipitate 
