Am.  Jour.  Pharm.  1 
January,  1910.  J 
Standards  and  Changes. 
23 
Cook  in  the  NJ.P.A.  Proceedings  for  1905,  will  be  found  to  be 
satisfactory.    The  following,  taken  from  that  source,  is  suggested : 
A  convenient  quantity  of  camphor  liniment,  approximating  10 
Gm.,  should  lose  not  less  than  20  per  cent,  nor  more  than  22  per 
cent,  of  its  weight  when  heated  upon  the  water-bath  during  twenty- 
four  hours  and  weighed  occasionally  until  a  practically  constant 
weight  is  reached.    The  following  might  also  be  included : 
When  observed  in  a  200  mm.  tube  in  a  polariscope  having  a 
sugar  scale,  the  number  of  degrees  observed  divided  by  the  factor 
2.925  will  give  the  percentage  of  camphor  in  the  preparation. 
Or  this :  The  specific  rotatory  power  of  the  sample  divided  by 
4.694  equals  the  percentage  of  camphor  in  the  sample. 
Linimentum  Chloroformi. — This  preparation  is  one  that  is  fre- 
quently found  of  deficient  quality,  particularly  as  to  the  amount  of 
chloroform  present.  The  specific  gravity  is  an  excellent  criterion 
in  this  respect  and  a  minimum  figure  of  1.065  a^  25°  C.  would  prac- 
tically insure  uniformity  with  the  U.S. P.  formula.  A  ready  method 
of  approximately  estimating  the  chloroform,  which  is  separated  from 
the  preparation  by  the  simple  addition  of  water,  is  offered  by  the 
following : 
Thirty  c.c.  of  chloroform  liniment,  placed  in  a  100  c.c.  graduated 
cylinder  and  diluted  to  a  volume  of  100  c.c.  by  the  addition  of 
water,  after  thorough  agitation  followed  by  subsidence  for  at  least 
one  hour,  should  show  a  substratum  of  heavier  liquid  (chloroform 
containing  some  volatile  oils,  etc.)  of  not  less  than  9.5  c.c.  at  25 0  C. 
Liquor  Chlori  Compositus. — A  method  for  the  valuation  of  this 
preparation  as  to  the  amount  of  free  chlorine  should  be  included. 
Liquor  Magncsii  Citratis. — Absence  of  magnesium  sulphate 
should  be  one  of  the  additional  requirements  for  this  preparation. 
The  test  for  barium  chloride  in  the  preparation  after  acidulation 
with  hydrochloric  acid  is  satisfactory  for  this  purpose,  if  a  slight 
turbidity  but  no  definite  precipitate  is  the  requirement.  It  would 
be  still  more  satisfactory  to  follow  this  up  with  directions  for  making 
a  quantitative  estimation  of  the  magnesium  present  and  establish  a 
rubric  for  the  minimum  amount  of  magnesium,  expressed  as  mag- 
nesium pyrophosphate  or  calculated  back  to  the  official  magnesium 
carbonate,  although  the  former  would  be  preferable.  As  the  for- 
mula now  stands,  this  would  lead  to  a  requirement  of  4.1  Gm.  of 
magnesium  carbonate  in  each  100  c.c.  of  finished  preparation  or  3.56 
Gm.  in  each  100  c.c.  when  expressed  as  magnesium  pyrophosphate. 
