ON  DIGIT  ALINE. 
513 
As  the  green  color  is  developed  the  solution  becomes  turbid, 
and  emits  an  odor  resembling  that  of  powdered  digitalis  or  the 
tincture,  and  deposits  a  brown  substance,  which  seems  to  be  a 
compound  of  digitaline  or  of  one  of  the  principles  accompany- 
ing with  hydrochloric  acid. 
When  exposed  to  the  vapor  of  hydrochloric  acid  this  soluble 
digitaline  turns  rapidly  brown,  but  exhibits  no  green  color. 
Examined  by  a  microscope  with  a  high  power  the  powder  is 
seen  to  consist  of  small  semi-transparent  fragments,  sometimes 
presenting  sharp  edges,  but  of  no  definite  crystalline  form.  An 
alcoholic  solution  evaporates  spontaneously  to  a  clear  varnish, 
and  no  traces  of  crystallisation  can  be  observed. 
2.  French,  or  Insoluble.  Digitaline, — The  color  of  French 
digitaline  varies  from  a  yellowish  white  to  a  bright  yellow.  It 
is  but  very  slightly  soluble  in  cold  water,  a  litre  only  dissolving 
about  0*50  gramme ;  it  is  very  soluble  in  alcohol.  Sulphuric 
ether,  sulphide  of  carbon,  and  benzole  dissolve  a  small  quan- 
tity ;  tannin  precipitates  it  from  a  saturated  aqueous  solution. 
The  powder  dropped  into  hydrochloric  acid  gives  a  yellow 
solution  which,  in  a  few  minutes,  passes  from  a  bright  to  a  deep 
green,  according  to  the  quantity  of  digitaline  employed ;  but 
as  the  green  tint  is  produced,  a  deep  green-colored  substance  is 
deposited,  and  a  smell  of  digitalis  is  evolved. 
When  exposed  to  the  vapor  of  hydrochloric  acid  it  is  first- 
colored  yellow,  then  brown,  and  afterwards  green,  the  charac- 
teristic smell  of  digitalis  becomes  very  apparent.  The  green 
powder  (like  the  fresh  powder  of  fox-glove  leaves)  becomes 
partially  decolorised  by  exposure  to  sunlight,  but  the  color  can. 
be  restored  by  another  exposure  to  the  vapors  of  the  acid. 
This  last  reaction  suffices  to  distinguish  between  soluble  and 
insoluble  digitaline,  and  the  author  considers  it  sufficient  to 
prove  the  presence  of  the  latter. 
An  alcoholic  solution  of  French  digitaline  (Menier's,)  left  to 
evaporate  spontaneously,  and  then  examined  by  the  microscope,, 
showed  a  multitude  of  small  spots,  sometimes  round  and  some- 
times oval,  which  gave  to  the  residue  the  cellular  aspect  of  or- 
ganised structure.  This  appearance  the  author  considered  to 
support  the  opinion  of  Homolle,  who  supposed  that  insoluble 
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