Am  Jour.  Pharm. 
584  Sulphites  and  Thiosulphates. 
From  these  results  the  author  concludes  that  the  decomposition  of 
thiosulphuric  acid  is  not  the  simple  one  generally  believed,  but  that 
the  first  phase  is  a  decomposition  into  hydrogen  sulphide  and  sulphuric 
anhydride,  which  then  further  react  on  each  other.  The  various 
reactions  taking  place  would  then  be  expressed  by  the  equations : 
(I)  H2S203  =  H2S  +  S03.  (II)  H2S  +  S03  =  S02  +  S  +  H,0. 
(Ill)  2H2S  +  S02=3S-f-  2H20.    (IV)  3H2S  -fS08=4S  +  3H20. 
SULPHITES  AND  THIOSULPHATES.1 
By  H.  Sch wicker. 
Sodium  potassium  sulphite,  NaKS03+2H20,  separates  in  yellowish 
crystals,  when  a  concentrated  solution  of  potassium  hydrogen  sulphite 
is  neutralized  with  the  calculated  quantity  of  sodium  carbonate,  and 
evaporated  over  sulphuric  acid.  (Compare  Rohrig,  J.  pr.  Chem.  [2], 
xxxvii,  250.)  When  heated  with  ethyl  iodide  at  140°,  it  yields 
a  compound  4S02Et'OK,!NaI,  which  crystallizes  from  hot  alcohol  in 
colorless  needles. 
Potassium  sodium  sulphite,  IvJsaS03  +  H20,  prepared  from  sodium 
hydrogen  sulphite  and  potassium  carbonate  in  like  manner,  is  a  yel- 
lowish, crystalline  compound.  "When  heated  with  ethyl  iodide  at 
140°,  it  gives  a  colorless  salt,  which  has  the  composition 
4S02EfOXa,KI. 
The  salt  HKNa2(S03)2+4H20,  separates  in  large,  well-defined 
plates,  when  a  solution  of  equivalent  quantities  of  sodium  potassium 
sulphite  and  sodium  hydrogen  sulphite,  or  a  solution  of  sodium  hydro- 
gen sulphite  (2  mols.)  and  potassium-carbonate  (0'5  mol.)  is  evaporated. 
It  is  moderately  stable  in  the  cold,  but  it  is  quickly  decomposed 
when  heated.  It  is  readily  soluble  in  water,  the  solution  having 
an  acid  reaction,  and  concentrated  solutions  combine  with  acetone 
with  development  of  heat.  Compounds  of  the  same  composition, 
and  which  seem  to  be  identical  with  the  double  salt  just  described, 
are  obtained  when  a  solution  containing  sodium  sulphite  and  potas- 
sium hydrogen  sulphite  is  evaporated,  or  when  a  hot  solution  of 
either  of  the  sodium  potassium  sulphites  (see  above)  is  saturated  with 
sulphurous  anhydride  ;  the  solubility  in  water  of  all  these  compounds 
is  approximately  the  same  (69  per  cent,  at  15°),  but  in  some  respects 
they  differ  slightly. 
1  Btrichte,  xxii,  1728-1737  ;  reprinted  from  Jour.  Chem.  Soc,  1889,  p.  942. 
