Am.  Jour.  Pharm.  ) 
June,  1920.  ) 
Calcium. 
indicate  that  the  addition  of  lo  per  cent,  alcohol  is  without  favorable 
influence  upon  the  stability. 
A  1.5  per  cent,  infusion  (10  per  cent,  alcohol)  was  examined  with 
the  following  results : 
Date.  Time.  Activity,  %.  %  Deterioration. 
4-14-20   3  hours  105  o 
4-15-20   27  hours  85  19 
4-16-20   51  hours  65  38 
4-17-20   75  hours  55  48 
SUMMARY. 
1.  A  comparison  of  the  relative  activity  of  digitalis  infusions 
and  tinctures  of  equal  concentration  shows  that  there  is  a  difference, 
the  infusion  being  slightly  less  active. 
2.  The  infusions  deteriorate. 
3.  Placing  a  20  per  cent,  limit  on  deterioration:  The  infusions 
should  be  discarded  in  3-5  days'  time.  At  lower  temperatures  this 
time  limit  may  be  extended  to  6-7  days. 
4.  The  addition  of  alcohol  adds  nothing  to  the  stability  of  the 
infusion. 
Research  Laboratory, 
The  Upjohn  Company, 
Kai^amazoo,  Michigan,  May  i,  1920. 
CALCIUM.* 
COMPARISON  OI^  TKN  DIFFERENT  METHODS  OF  ESTIMATION. 
By  George  E.  E)we. 
Standard  Material. — Practically  white,  doubly  refractive  calcite. 
Preparation  of  Standard  Material  for  Analysis. — The  calcite  was 
ground  to  a  fine  powder  in  an  agate  mortar,  dried  to  constant  weight 
in  a  platinum  dish  over  a  flame  which  was  not  permitted  to  touch 
the  dish.  The  dried  calcite  was  free  from  caustic  as  shown  by  its 
failure  to  turn  red  litmus  paper  when  i  Gm.  was  made  into  a  paste 
with  a  little  water  and  tested  with  litmus  paper.  The  dried 
calcite  was  preserved  in  a  glass  stoppered  weighing  bottle. 
Impurities  in  the  Standard  Calcite. — The  usual  impurities  of  cal- 
cite are  silica,  ferric,  aluminum,  magnesium  and  manganese  com- 
pounds. 
*  From  Bulletin  of  the  International  Metallurgical  and  Chemical  Society. 
