ANovemb^hi9^'}      Inorganic  Chemistry  of  the  U.S. P.  517 
manganese  hypophosphite  (PH202)2Mn  +  H20."  This  salt  enters 
into  the  preparation  of  syrupus  hypophosphitum  compositus.  It  is 
a  pink  crystalline  powder,  very  soluble  in  water  though  not  so  in 
alcohol.  Tests  for  the  detection  of  carbonate,  phosphate,  calcium 
and  arsenic  are  described. 
Sodii  Arsenas  Exsiccatus,  Exsiccated  Sodium  Arsenate  (Na2H  As04). 
— "  It  should  contain  not  less  than  98  per  cent  of  pure  anhydrous  di- 
sodium-ortho-arsenate  (AsO(OH)ONa2)."  It  is  an  amorphous  white 
powder,  odorless  and  permanent  in  dry  air.  It  is  made  from  sodii 
arsenas  (Na2HAs04  -j-  yH20),  which  is  also  official,  and  which  it  is 
certainly  a  mistake  to  have  retained.  The  latter  contains  over  40 
per  cent,  of  water,  and  is  therofore  nearly  one-half  the  strength  of 
the  exsiccated  salt.  Confusion,  mistakes  and  danger  are  liable  to 
occur.  That  the  exsiccated  salt,  which  is  more  stable,  should  be 
made  official  is  commendable,  but  it  is  an  evident  mistake  to  retain 
the  other  salt.  The  only  excuse  it  has  for  being  official  is  that  the 
exsiccated  salt  is  made  from  it,  but  then  the  directions  for  making 
the  exsiccated  salt  might  better  have  been  omitted.  The  hydrous 
sodium  arsenate  was  official  also  in  the  U.S. P.,  1880,  under  the 
name  of  sodii  arsenias,  and  a  process  for  its  manufacture  given.  It 
is  efflorescent  in  dry  air,  and  deliquescent  in  moist  air.  Therefore, 
unless  the  salt  was  perfectly  fresh  the  percentage  of  arsenic  was  un- 
certain. Hence  the  introduction  of  the  new  anhydrous  salt,  which 
is  more  stable,  and  therefore  of  more  certain  composition,  is  a  great 
advantage.    It  enters  into  liquor  sodii  arsenatis. 
The  Pharmacopoeia  describes  four  tests  for  identity ;  one  test  for 
presence  of  arsenite  as  an  impurity,  and  one  for  the  detection  of 
lead,  copper  and  iron  by  the  use  of  ammonium  sulphide  T.S. 
Sodii  Carbonas  Monohydratus,  Monohydrated  Sodium  Carbonate 
(Na2COs  -f  H20). — "  It  should  contain  not  less  than  85  per  cent, 
of  pure  anhydrous  sodium  carbonate  CO(ONa)2,  corresponding 
to  not  less  than  99-5  per  cent,  of  the  crystallized  monohydrated 
salt."  This  salt  is  introduced  with  the  object  of  furnishing  a  sodium 
carbonate  of  uniform  strength  and  of  stable  character.  Sodii  carbo- 
nas and  sodii  carbonas  exsiccatus,  U.S.P.,  1 890,  have  been  dis- 
missed. Sodii  carbonas  was  a  very  efflorescent  salt;  it  contained  10 
molecules  of  water  of  crystallization,  which  amounts  to  about  63 
per  cent,  of  its  weight.  Upon  exposure  to  air  much  of  this  is  lost, 
so  that  the  salt  is  of  uncertain  strength.    Sodii  carbonas  exsiccatus 
