536 
Estimation  of  ghiinia. 
Am.  Jour.  Pharm. 
Nov.,  1877. 
ard.  To  produce  a  perfect  mixture,  the  tube  is  shaken  after  every 
addition  of  water.  If  the  standard  solution  has  been  prepared  from 
dialysed  iron,  leaving  exactly  5  cc.  of  residue  on  evaporation  on  the 
water  bath,  every  cc.  of  the  diluted  solution  of  the  sample  to  be  com- 
pared will  correspond  to  \  per  cent,  of  residue  of  the  original 
sample,  and  its  volume  expressed  in  cc,  when  of  equal  shade  with 
the  standard,  divided  by  four,  will  give  the  percentage  strength  desired. 
I  have  compared  results  of  this  colorimetric  method  with  those  of 
weight  and  volumetric  analysis,  and  find  it  correct  to  0*05  per  cent. 
In  the  following  I  will  give  a  few  examples  to  illustrate  the  method 
proposed  : 
20  cc. 
Standard :    —  =  5  per  cent,  residue. 
1.  Sample  compared  was  to  be  diluted  to  18  cc.  to  equal  shade  of 
18  cc. 
standard.      —  =  4J  per  cent,  residue. 
2.  Sample  compared  was  to  be  diluted  to  23  cc.  to  equal  shade  of 
23  cc. 
standard.      —  =  5-f  per  cent,  residue. 
From  these  data,  we  easily  can  calculate  to  what  volume  any  quan- 
tity of  dialysed  iron  is  to  be  evaporated  or  diluted  to  obtain  the  desired 
strength  of  5  per  cent.1  As  this  mode  of  analysis  only  requires  a  few 
moments  time,  being  at  the  same  time  sufficiently  correct  for  practical 
purposes,  it  may  be  preferable  to  that  of  evaporation. 
Black  Diamond  Steel  Works,  1 
Pittsburgh ,  Oct.  6,  1877.  J 
ESTIMATION  OF  QUINIA. 
By  Henry  Trimble,  Ph.G. 
Read  at  the  Pharmaceutical  Meeting,  October  16,  1877. 
For  the  ready  estimation  of  quinia,  for  example  in  pills,  and  in  many 
cases  in  which  the  quantity  that  should  be  present  is  approximately 
known,  I  have  devised  and  used  the  following  method,  which  is  based 
1  As  to  the  necessary  glass  tubes,  I  would  recommend  the  same  as  used  in  the 
laboratories  of  steel  works  for  colorimetric  carbon  determinations,  viz.  :  Two  true 
cylindrical  tubes,  closed  at  one  end  ;  capacity  50  to  60  cc,  graduated  into  o*i  cc, 
internal  diameter  about  three-eighths  of  an  inch  5  both  exactly  of  the  same  dimen- 
sions and  of  best  white  glass. 
