ON  PROTOSULPHATE  OF  NICKEL. 
415 
ON  PROTOSULPHATE  OF  NICKEL. 
By  C.  Marignac. 
According  to  Marignac,  the  protosulphate  of  nickel  in  quad- 
ratic crystals,  to  which  the  same  amount  of  water  has  hitherto 
been  ascribed  as  to  the  rhombic  salt  NiO,  S03-j-7HO,  only  con- 
tains 6  equivs.  of  water.  From  a  solution  of  pure  protosulphate 
of  nickel  he  obtained,  at  59°  to  68°  F.,  the  rhombic  crystals, 
isomorphous  with  sulphate  of  zinc  and  sulphate  of  magnesia;  at 
86°  to  104°  F.  quadratic,  and  at  122°  to  158°  F,  monoclino- 
metric  crystals.  These  crystals  showed  the  following  composition : 
Rhombic  crystals.  Quadratic  crystals. 
Calculated.       Found.  Calculated.  Found. 
NiO  26-71  ..  26-38  NiO  28-53  28-32 
SO3  28-46  ..  28-47  SO3  30  41  30-42 
7HO  44-83    44-62   45-15       6HO    41-06    41-26  41-59 
Monoclinometric  crystals. 
  JV  . 
Found. 
Calculated.       ,  '  —  , 
NiO  28-53  27-79 
SO3  3041  29-82 
6HO  41-06  42-39  41-55  41-58  41-08 
Marignac  remarks  that  even  Mitscherlich  found  30-14  and 
29-88  per  cent,  of  sulphuric  acid  in  the  quadratic  salt.  When 
the  rhombic  crystals  are  converted  by  exposure  to  the  light  of 
the  sun  into  aggregations  of  quadratic  crystals,  a  loss  of  water 
takes  place,  which  Marignac  determines  at  6-87  per  cent.;  the 
conversion  of  NiO,  S03+7HO  into  NiO,  S03+6HO,  requires  a 
loss  of  weight  of  6-40  per  cent.  The  monoclinometric  crystals 
remain  transparent  above  104°  F. ;  at  ordinary  temperatures 
they  gradually  become  opake  without  loss  of  weight,  and  are 
probably  converted  into  aggregations  of  quadratic  crystals. 
Dimorphism  was  therefore  ascertained  to  occur  in  NiO,  SO" 
+6HO,  but  not  in  NiO,  S03-f  7HO. 
From  solutions  of  sulphate  of  magnesia  at  about  158°F.,  of 
sulphate  of  zinc  at  l22p  to  13 1Q  F.,  and  of  protosulphate  of 
cobalt  at  104°  to  122p  F.,  the  author  obtained  crystals  of  the 
composition  RO,  S03-j-6HO,  isomorphous  with  the  monoclino- 
metric protosulphate  of  nickel,  NiO,  S03-[-6HO — Qhem.  Graz., 
July  1,  1856,  from  Liebig's  Annalen,  March,  1856. 
