^'^£y%s75^'"''}    Gleanings  from  European  Journals.  207 
directed  more  prominently  than  heretofore  to  the  value  of  the  cheaper 
cinchona  alkaloids,  we  shall  acknowledge  with  pleasure  that  a  real 
benefit  has  been  conferred  thereby  upon  those  who  need  those  alkaloids 
either  as  tonics  or  antiperiodics. 
GLEANINGS  FROM  THE  EUROPEAN  JOURNALS. 
BY  THE  EDITOR. 
Gentisin  [gentisic  acid)  was  discovered  by  Henry  and  Caventou  in 
gentian  root.  Hlasiwetz  and  Habermann  have  examined  this  compound^ 
which  was  prepared  by  H.  Tromsdorff  according  to  Baumert's  process. 
Its  formula  was  found  by  Baumert  to  be  C^^H^gOg,  and  this  result  is 
corroborated  by  the  authors,  who  obtained  crystallized  compounds  hav- 
ing the  formula  C^^H^K 05+1120  and  Ci^H9Na054-2H20,  by  heating 
gentisin  with  strong  alcohol  to  boiling  and  dropping  in  the  caustic  alkali 
until  completely  dissolved,  when  the  salts  will  crystallize  on  cooling  or 
on  the  addition  of  ether. 
By  fusing  gentisin  with  five  times  its  weight  of  caustic  potassa, 
until  the  aqueous  solution  of  the  mass  is  not  rendered,  turbid  on  the 
addition  of  an  acid,  a  decomposition  has  been  effected  as  follows  : 
2C^im  +  O,  +  4H,0  =  2C,H  A  +  2C,H,0,  +  Cfl,0, 
Gentisin.  Phloroglucin.  Gentisinic  acid.         Acetic  acid. 
The  mass  is  dissolved  in  water,  rapidly  supersaturated  with  sulphuric 
acid  and  agitated  with  ether.  From  the  etherial  solution,  the  ether  is 
recovered  by  distillation,  the  acetic  acid  is  removed  by  distillation  with 
water,  and  the  residue  in  the  retort  neutralized  with  carbonate  of  barium  ; 
ether  now  dissolves  out  the  phloroglucin.  The  remaining  solution  is 
decomposed  by  sulphuric  acid,  and  the  gentisinic  acid  dissolved  by  ether. 
This  acid  fuses  at  197°  C,  has  a  faintly  acid  and  astringent  taste  and  is 
soluble  in  cold  and  hot  water,  in  alcohol  and  ether,  but  insoluble  in  ben- 
zol. Its  aqueous  solution  acquires,  with  ferric  chloride,  a  beautiful  deep 
blue  color,  turning  to  dirty  red  with  a  little  soda  ;  the  aqueous  solution 
rendered  alkaline  turns  on  exposure  to  the  air  to  a  fire-red,  afterwards 
brown  color.  It  is  isomeric,  but  not  identical  with  protocatechuic, 
dioxybenzoic,  oxysalicyllc  and  hypogallic  acids.  On  dry  distillation  it 
yields  carbonic  and  pyrogentisinic  acids,  the  latter  having  the  formula 
CgHg02  being  isomeric  with  hydrokinon,  pyrocatechin  and  resorcin  ; 
it  has  a  sweetish  taste,  fuses  at  169°  C,  and  reduces  silver  nitrate,  on 
