AmMa?ri^oarm'}        Volumetric  Solutions  of  U.S.P.  205 
mate;  Riegler  (Ibid.,  35,  305)  uses  iodic  acid;  Fessel  (Ibid.,  41, 
187)  uses  potassium  iodate ;  Aleineke  (Ibid.,  35,  338)  uses  potas- 
sium biniodate;  Kratschmer  (Ibid.,  24,  546)  uses  sodium  bromate ; 
while  Metzl  (lour.  Chem.  Soc,  90,  ii,  194)  uses  potassium  antimonyl 
tartrate. 
We  may,  perhaps,  also  gain  an  idea  as  to  some  of  the  reasons 
why  apparently  not  a  single  one  of  the  substances  above  mentioned 
has  met  with  entire  satisfaction  generally,  if  we  recall  some  of  the 
remarks  made  by  various  authors  concerning  some  of  the  substances 
in  the  above  list  which  appear  to  have  been  used  most.  Thus,  ac- 
cording to  Morse,3  the  substance  which  has  been  longest  and  prob- 
ably most  frequently  employed  for  the  standardization  of  acids  is 
the  neutral  anhydrous  carbonate  of  sodium.  The  latter  is  also 
recommended  by  Sutton.4  As  is  well  known,  however,  this  salt 
is  hygroscopic  and  hence  great  care  must  be  taken  in  handling  it. 
Thus,  according  to  Morse,  the  portion  of  the  material  which  is  to 
be  used  in  any  experiment  should  be  reheated  in  a  small  platinum 
crucible  or  boat,  cooled  in  a  desiccator,  and  protected  from  the 
moisture  of  the  air  while  weighing  by  inclosing  it  in  a  weighing 
glass.  It  has  also  the  disadvantage  that  it  is  liable  to  appreciable 
decomposition  if  the  temperature  is  not  strictly  regulated  while  it 
is  being  heated  in  order  to  convert  all  the  bicarbonate  into  the  normal 
salt.  Thus,  according  to  Seyda,3  sodium  carbonate  is  likely  to 
retain  excess  of  C02,  or  if  overheated  it  may  contain  sodium 
hydroxide.  Similarly,  in  the  case  of  potassium  tetroxalate,  which 
is  recommended  for  standardizing  purposes  by  Kuhling  6  and  also 
by  Morse,7  Lunge  8  states  that  he  has  never  been  able  to'  prepare 
a  potassium  tetroxalate  in  which  the  water  of  crystallization  corre- 
sponds accurately  with  the  formula  C204HK.C204H2.2H20.  In  the 
case  of  oxalic  acid,  the  disadvantages  which  may  be  mentioned,  on 
the  authority  of  Morse,9  are  that  the  commercial  article  contains 
acid  oxalates  from  which  it  cannot  be  readily  freed  by  the  ordinary 
process  of  recrystallization  from  water  and  that  it  cannot  be  dried 
3  Morse :   Exercises  in  Quantitative  Chemistry  (1905),  p.  127. 
4  Sutton :    Volumetric  Analysis,  9th  ed.,  p.  42. 
5  lour.  Chem.  Soc,  78,  ii,  44  (1900). 
6  Ibid.,  86,  ii,  80  (1904) 
7  Morse :    Exercises  in  Quantitative  Chemistry   (1905),  p.  126. 
8  Jour.  Chem.  Soc,  86,  ii,  771  (1904). 
9  Morse :   Exercises  in  Quantitative  Chemistry  (1905),  pp.  116-117. 
