Am.  Jour.  Pharm. ) 
April,  1884.  J 
Constitution  of  Chlorophyll . 
221 
consists  essentially  of  two  substances,  the  phyllocyanin  and  phyllo- 
xanthin  of  Fremy,  which  are  undoubtedly  products  derived  from 
chlorophyll,  showing  the  absorption-bands  of  what  is  usually  called 
"acid  chlorophyll."  The  liquid  filtered  from  this  precipitate,  when 
mixed  with  copper  sulphate  and  an  excess  of  caustic  alkali,  becomes 
blue,  and  the  mixture,  on  boiling,  deposits  cuprous  oxide.  The  experi- 
ment may  be  made  in  a  slightly  different  manner.  The  residue  left  by 
the  green  ethereal  solution  of  chlorophyll  having  been  dissolved  in 
alcohol,  sulphuric  or  hydrochloric  acid  is  added  to  the  solution,  which 
is  then  boiled  for  some  time,  evaporated  so  far  as  to  drive  off  most  of 
the  alcohol,  filtered  from  the  products  insoluble  in  water,  made  alka- 
line, then  mixed  with  Fehling's  solution  and  boiled,  when  the  usual 
glucose  reaction  takes  place.  In  order  to  make  sure  that  the  reaction 
was  not  due  to  ready-formed  glucose,  I  took  in  every  case  the  precau- 
tion of  testing  a  portion  of  the  green  chlorophyllic  residue  with  Feh- 
ling's solution  before  acting  on  the  rest  with  acid.  This  was  easily 
done  by  treating  with  weak  alcohol,  to  which  a  little  alcoholic  potash 
and  some  Fehling's  solution  were  added,  and  heating,  when  the  whole 
dissolved  easily,  giving  a  green  solution,  which,  on  boiling,  in  no  case 
deposited  the  least  trace  of  cuprous  oxide,  whereas,  after  adding  an 
excess  of  hydrochloric  acid  to  the  liquid,  boiling,  filtering  off  the  in- 
soluble products,  again  making  alkaline  and  boiling,  the  glucose  reac- 
tion took  place  in  a  marked  manner. 
This  experiment  has  never  in  any  case  failed,  and  it  would  follow, 
if  uniformly  successful,  that  the  green  leaves  of  all  plants  contain  a 
glucoside  insoluble  in  water,  but  soluble  in  alcohol  and  ether.  That 
this  glucoside  is,  in  fact,  chlorophyll  seems  to  me  highly  probable. 
Nevertheless,  absolute  certainty  cannot  be  attained,  because  the  matter 
experimented  on  is  a  mixture,  and  it  is  possible  that  one  plant  out  of 
many  might  give  a  decidedly  negative  result,  which  would  upset  the 
conclusion  drawn  from  the  rest.  Assuming,  however,  that  the  phe- 
nomena will  always  occur  as  above  described,  and  that  the  reaction 
with  Fehling's  solution  indicates  the  presence  of  some  kind  of  glucose, 
it  would  follow  either  that  chlorophyll  is  a  glucoside  or  that  it  is  always 
accompanied  in  the  vegetable  cell  by  a  glucoside  of  very  similar  prop- 
erties. I  may  add  that  I  attempted  to  isolate  the  glucose  or  glucose-like 
substance  formed  under  the  circumstances  described,  spinach  leaves 
being  the  material  employed,  and  obtained  a  pale  yellow  gum-like 
substance  which  showed  no  tendency  to  assume  a  crystalline  form. — 
Chem.  News,  Jan.  4,  1884,  p.  2. 
