Am.  Jour.  Pharm. 
Jan.,  1894. 
The  Action  of  Zinc,  etc. 
47 
using  hematoxylin  as  indicator  (i  gm.  hematoxylin  dissolved  100 
gm.  diluted  alcohol  with  2  to  3  drops  of  ammonia).  From  the  results 
of  a  large  number  of  assays  I  cc.  ^  hydrochloric  acid  is  the  equiva- 
lent of  0-0315  gm.  calisaya  alkaloids  and  of  0-0304  gm.  succirubra 
alkaloids. 
Fluid  extract  of  cinchona  is  assayed  by  diluting  6  gm.  fluid  extract 
with  15  gm.  water,  adding  90  gm.  ether  and  5  gm.  ammonia  water 
and  agitating  repeatedly  during  one-half  hour;  from  75  gm.  of  the 
clear  ethereal  solution,  representing  5  gm.  of  the  fluid  extract,  the 
ether  is  distilled  off  and  the  alkaloids  weighed  at  95  to  100°  C. 
The  alkaloids  must  be  titrated  by  dissolving  in  10  gm.  alcohol, 
adding  40  gm.  water,  two  drops  hematoxylin  solution  and  suffi- 
cient     hydrochloric  acid  to  produce  a  permanent  yellow  coloration. 
In  assaying  extract  of  cinchona  1-5  gm.  are  triturated  with  15  gm. 
water,  transferred  to  a  vial  of  150  cc.  capacity,  90  gm.  ether  and  5. 
cc.  ammonia  water  added,  thoroughly  agitated  during  one-half  hour 
and  60  gm.  of  the  clear  ethereal  solution  representing  one  gram 
extract  proceeded  with  as  above. 
The  thalleioquin  test  can  be  made  with  these  several  titrated 
solutions  by  diluting  1  cc.  with  9  cc.  water,  adding  2  to  3  drops 
bromine  water  and,  lastly,  1  cc.  ammonia  water. —  Oesterr.  Ztschr.f 
Pharm.,  1893,  563  ancJ  5^6. 
THE  ACTION  OF  ZINC  AND  MAGNESIUM  UPON 
METALLIC   SOLUTIONS,  AND  THE 
DETERMINATION  OF  POTASSA. 
By  A.  Villiers  and  F.  Borg. 
The  electrolytic  methods  which  enable  us  to  determine,  and  often, 
indeed,  to  separate,  metals  are  becoming  more  and  more  utilized  in 
analytical  chemistry.  It  seems,  however,  at  first  sight  that  we 
might  in  a  great  number  of  cases  substitute  for  them  a  more  rapid 
method,  which  consists  in  displacing  metals  by  another  metal,  such 
as  zinc  or  magnesium. 
In  reality,  this  latter  procedure  is  applicable  only  in  a  very  lim- 
ited number  of  cases  (copper,  gold,  platinum).  The  metals  are  not, 
in  general,  precipitated  in  a  state  of  purity,  but  as  alloys  containing 
larger  or  smaller  quantities  of  magnesium  or  zinc. 
The  proportion  of  these  latter  varies  with  the  acidity  of  the 
