Ajaiuarryfi906.in'}      Inorganic  Chemistry  of  the  U.S. P.  17 
titrated  with  decinormal  potassium  sulphocyanate  solution;  ferric 
alum  being  used  as  the  indicator. 
There  has  been  introduced  an  assay  process  for  Sulphur  Iodide — 
titration  of  a  potassium  iodide  solution  with  decinomal  thiosulphate 
solution,  starch  mucilage  being  used  as  the  indicator. 
The  basis  of  acidimetry  and  alkalimetry  has  been  shifted  from 
the  old  standard  of  a  carefully  prepared  normal  solution  of  oxalic 
acid  (from  specially  purified  crystals)  to  a  normal  alkali  solution, 
standardized  by  titrating  with  a  solution  containing  a  definite 
amount  of  potassium  bitartrate,  which  has  been  carefully  purified. 
As  to  indicators,  the  new  pharmacopoeia  shows  an  evident  fond- 
ness for  methyl  orange,  using  it  in  several  cases  where  phenol- 
phtaleir  is  usually  employed  and  that  far  more  satisfactorily.  While 
methyl  orange  may  be  more  accurate  than  phenolphtalein  in  some 
cases  and  that  to  an  eye  trained  to  color  changes,  it  must  be  admit- 
ted that  for  the  average  observer  the  change  from  orange  to  pink 
is  so  gradual  that  it  frequently  means  the  addition  of  one  cubic 
centimeter  of  the  volumetric  solution  to  determine  the  end  of  the 
reaction.  For  carbonates,  its  use  is  perhaps  a  necessary  evil,  but 
its  application  instead  of  phenolphtalein  in  such  cases  as  estimation 
of  soda  and  solution  of  soda,  and  in  place  of  rosolic  acid  in  estima- 
tions of  ammonia,  seems  a  mistake. 
In  many  cases  the  attempt  at  accuracy  in  getting  the  desired 
quantity  of  the  chemical  to  be  tested  gives  rise  to  directions  that 
when  followed  out  can  lead  to  naught  but  complex  or  clumsy 
processes. 
Thus  in  the  case  of  acetic  acid,  instead  of  directing  the  weighing 
of  5  96  grammes  of  the  acid,  it  is  directed  that  10  grammes  be 
weighed,  then  diluted  with  water  enough  to  make  100  c.c.  and 
59*6  c.c.  of  this  latter  solution  be  employed.  The  only  method  of 
accurately  measuring  59  6  c.c.  is  by  means  of  a  burette,  and  as  the 
average  burette  delivers  but  50  c.c.  liquid  it  means  the  filling  of  the 
burette  twice,  to  say  nothing  of  the  annoyance  of  then  getting  the 
burette  into  commission  as  measurer  of  the  volumetric  alkali  solution 
next  to  be  used  ;  for  it  is  no  exaggeration  to  say  that  few  pharma- 
cists keep  more  than  one  burette  on  hand.  Far  better  would  it 
have  been  to  have  retained  the  formerly  prescribed  quantity — 6 
grammes  of  acetic  acid. 
