Am'DJe0cU,r'i9Pi8arm'?     Manufacture  of  Chloramine — T.  88 1 
not  accounted  for.  Part  of  this  is  lost  by  evaporation  during  mixing 
and  subsequent  sulphonation,  and  a  small  part  is  left  in  the  sulphuric 
acid.  Probably  most  of  the  remainder  is  lost  by  evaporation  in 
vacuo  during  the  filtration  of  the  crude  acid. 
The  cake  of  crude  />-acid  is  dissolved  in  water,  slightly  more  than 
enough  calcium  carbonate  is  added  to  precipitate  the  sulphuric  acid 
as  calcium  sulphate,  and  the  still  acid  liquid  is  filtrated.  It  is  then 
nearly  neutralized  with  caustic  soda,  made  distinctly  alkaline  with 
sodium  carbonate,  boiled,  and  again  filtered.  It  is  important  to  re- 
move the  calcium  as  completely  as  possible,  as  it  may  become  a 
troublesome  impurity  in  the  later  stages.  This  method  gives  a  solu- 
tion containing  only  sodium  sulphonate  and  sodium  carbonate,  and 
on  acidifying  with  hydrochloric  acid  and  evaporating  to  dryness 
there  remains  a  pure  white  salt  consisting  of  the  required  sodium 
sulphonate  with  a  trace  of  sodium  chloride.  The  sulphonate  is  so 
soluble  in  water  that  this  seems  to  be  the  best  method  of 
preparation. 
Preparation  of  the  Sulphonic  Chloride. — This  can  easily  be  pre- 
pared by  heating  together  on  the  water  bath  approximately  equal 
weights  of  sodium  salt  (dried  at  1400  C.)  (191  Gm.)  and  phos- 
phorus pentachloride  (208.5  Gm.).  In  this  case  the  reaction  takes 
place  very  rapidly  and  easily  and  a  large  amount  of  phosphorous 
oxychloride  is  obtained.  Mr.  C.  S.  Hicks,  working  in  my  labora- 
tory, found,  however,  that  the  oxychloride  itself  can  be  used  ac- 
cording to  the  equation,  2XS0sNa  +  POCl3  =  2XSOXI  +  NaPCL 
+  NaCl,  and  he  obtained  a  76  per  cent,  yield.  Hence  if  less  than 
half  the  weight  of  pentachloride  be  taken  and  the  mixture  be  heated 
some  hours  on  the  water-bath  under  reflux  condenser  the  following 
reaction  takes  place:  3XSOsNa  +  PC15  =  3XSOXI  +  2NaCl 
+  NaPOs.  The  proportions  of  salt  and  pentachloride  according 
to  this  equation  are  573  to  208.5,  or  2-3/4  to  1 ;  but  the  reaction  is 
very  slow  towards  the  end  as  the  mass  becomes  too  solid  and  the 
yield  is  apt  to  decrease.  This  trouble  might  be  avoided  by  using  the 
theoretical  proportion  of  pentachloride  and  sufficient  oxychloride, 
which  should  then  be  recovered  unchanged.  An  experimental  trial 
of  this  gave  92  per  cent,  yield  but  the  oxychloride  was  not  recover- 
able. We  therefore  use  2  parts  of  sodium  salt  for  each  part  of 
pentachloride  and  the  action  then  completes  itself  more  easily  and 
only  small  amounts  of  oxychloride  are  left  over — the  reaction  being 
