ANo™^M!e-}      Inorganic  Chemistry  of  the  U.S. P.  513 
Of  measures,  may  say  the  same  as  under  thermometric  equiva- 
lents. They  were  formed  by  dividing  till  tired.  Where  can  I  find 
a  minim  measure  showing  the  ten  thousandth  of  a  minim  ? 
A  CRITICAL  REVIEW  OF  THE  INORGANIC  CHEMISTRY 
OF  THE  NEW  UNITED  STATES  PHARMACOPOEIA. 
By  Henry  W.  Schimpf. 
Among  the  newly  added  articles  of  the  Pharmacopoeia  there  are 
nine  which  belong  to  the  class  of  inorganic  substances.  These  are  : 
Acidum  hydriodicum  dilutum,  Acidum  hypophosphorosum,  Kao- 
linum,  Mangani  hypophosphis,  Sodii  arsenas  exsiccatus,  Sodii  car- 
bonas  monohydratus,  Sodii  phosphas  exsiccatus,  Talcum  and  Talcum 
purificatum.  Besides  these  there  are  seven  metallic  salts  of  organic 
acids:  Ammonii  salicylas,  Bismuthi  subgallas,  Bismuthi  subsalicylas, 
Sodii  citras,  Strontii  salicylas,  Zinci  phenolsulphonas  and  Zinci 
stearas.  Also  the  following  preparations  containing  principally 
inorganic  substances:  Cataplasma  kaolini,  Liq.  sodii  phosphatis 
compositus,  Magnesii  sulphas  efTervescens,  Sodii  phosphas  efferves- 
cens,  Unguentum  acidi  borici,  Unguentum  hydrargyri  dilutum,  and 
Unguentum  zinci  stearatis. 
Acidum  Hydriodicum  Dilutum,  Diluted  Hydriodic  Acid  (HI). — 
"  A  solution  containing  not  less  than  10  per  cent,  by  weight  of  the 
absolute  acid  and  about  90  per  cent,  of  water."  This  preparation 
was  official  in  the  US.P.,  i860,  but  was  dismissed  because  of  its 
unstable  nature  and  the  consequent  difficulty  experienced  in  pre- 
serving it.  It  decomposed  readily  on  exposure,  liberating  iodine. 
In  the  present  preparation  the  introduction  of  about  I  per  cent,  of 
potassium  hypophosphite  produces  sufficient  hypophosphorous  acid 
to  act  as  a  preservative ;  this  it  does  by  reducing  any  iodine  set  free 
to  hydriodic  acid.  The  acid  should  be  kept  in  small  amber-colored 
glass-stoppered  bottles.  The  method  of  preparing  it  is  the  same  as 
that  recommended  in  the  U.S.P.,  1890,  for  Syrupus  acidi  hydriodici. 
The  syrup  is  still  official,  but  it  is  prepared  from  the  dilute  acid  by 
the  addition  ot  syrup  and  water. 
The  preparation  of  the  acid  depends  upon  the  reaction  of  potas- 
sium iodide  in  concentrated  aqueous  solution  with  a  solution  of 
tartaric  acid  in  diluted  alcohol.    The  mixed  solutions  are  placed  in 
