3  8  8  The  Tannic  Acid  of  Guar  ana.        { Amx{^87h7a.rm' 
color  with  sesquichloride  of  iron  and  also  produced  a  precipitate  with 
solution  of  gelatin. 
G  was  freed  from  lead  by  means  of  sulphuretted  hydrogen  and  fil- 
tration ;  the  resulting  liquid,  about  two  pints,  was  of  a  light  yellow 
color  ;  it  was  evaporated  on  a  water  bath  to  a  semi-fluid  consistence. 
Two  ounces  of  a  red  colored  thick  syrupy  liquid  was  the  result,  having 
a  sweet  taste.  Trommer's  test  gave  an  abundant  red  precipitate,  prov- 
ing the  presence  of  glucose. 
E  was  separated  from  the  water,  and  washed  with  petroleum  benzin 
until  it  ceased  to  pass  through  colored  ;  about  two  pints  of  the  benzin 
solution  were  obtained,  having  a  dark  color,  yielding,  after  evaporation, 
about  one  ounce  of  fixed  oil  mixed  with  some  coloring  matter^  and  form- 
ing soap  on  being  boiled  with  caustic  alkalies.  The  portion  left  on  the 
filter  undissolved  by  the  benzin  was  of  a  greenish-yellow  color  and 
hard  enough  to  be  powdered  ;  it  was  soluble  in  alcohol  and  found  to 
be  chlorophyll. 
The  sulphide  of  lead  C  was  treated  with  hot  alcohol,  but  besides  a 
little  sulphur  nothing  was  dissolved. 
A  portion  of  the  dregs  left  after  exhaustion  with  alcohol  was  dried, 
macerated  with  water  for  24  hours,  and  expressed.  The  expressed 
liquid  was  mucilaginous  and  almost  tasteles  ;  evaporated  to  a  syrupy 
consistence  and  mixed  with  an  equal  bulk  of  alcohol,  an  abundant  pre- 
cipitate of  gum  and  an  almost  tasteless  solution  were  obtained. 
Five  grams  of  the  air-dry  bark  were  ignited  in  a  porcelain  crucible  ; 
the  ashes  weighed  0*3  gram,  or  6  per  cent.,  and  contained  potassium, 
sodium,  calcium,  magnesium,  iron,  sulphuric  and  phosphoric  acids. 
The  organic  constituents  of  cotton  root  bark  are  a  red  and  a  yellow 
resinous  coloring  matter,  fixed  oil,  gum,  sugar,  tannin  and  chlorophyll* 
ON  THE  TANNIC  ACID  OF  GUARANA. 
By  Francis  V.  Greene,  M.D.,  U.S.N. 
Although  guarana  has  been  known  in  Europe  since  the  year  181 7, 
when  it  was  described  by  Cadet  de  Gassicourt,  it  does  not  appear  that 
any  complete  chemical  analysis  of  the  substance  has  as  yet  been  made, 
or  that  the  component  parts  have  been  examined  with  sufficient  care 
to  afford  an  explanation  of  its  peculiar  action  on  the  economy,  when 
used  as  a  therapeutic  agent. 
