Am.  Jour.  Pharm. 
Oct.,  1884. 
Melting  Points  and  Solubility  of  Salts. 
513 
the  observations  make  no  pretence  to  great  accuracy.  This  is  due 
chiefly  to  the  fact  that  many  salts  are  resolved  into  a  mixture  of  liquid 
and  solid,  and  the  temperature  at  which  this  occurs  is  sometimes  diffi- 
cult to  observe.  The  fact  is  these  salts  seem  to  be  incapable  of  enter- 
ing into  true  fusion,  the  partial  liquefaction  being  the  result  of  the 
formation  of  a  crystalline  hydrate  containing  a  smaller  proportion  of 
water.  This  happens  notably  with  the  sulphate  of  zinc,  cobalt,  nickel 
and  iron.  On  the  other  hand,  there  is  often  no  sign  of  dissociation, 
as  in  the  alums  and  many  other  salts,  if  the  experiment  is  carefully 
performed.  Of  the  following  salts,  the  melting  points  have  been 
given  in  two  or  three  cases  by  other  observers,  but,  except  where  an 
authority  is  mentioned,  I  have  verified  them  all. 
Simple  Sulphates,    m.  p. 
MgS04,7H20   70° 
ZnS04,7H20   50° 
CoS04,7H20   96—98° 
NiS047H20   98-100° 
FeSQ4,7H20   64° 
MnS04,5H20   54° 
CdS04,fH20   D1 
CuS04,5H20   D 
A12(S04)3,18H20   D 
Na2SO4,10H2O   340 
Double  Sulphates. 
KA1(S04)2,12H20   84-5° 
NH4A1(S04)2,12H20..  92° 
NaAl(S04)2,12H20....  61° 
RbAl,S04)2,12HO   99° 
Cs  A1(S04)2,12H20  1 05—106° 
KCr(S04)2,12H20   8902 
Co(NH4)2(S04)26H20  D 
Ni(NH4)2(S04)2,6H20  D 
NiK2(S04)2,6H90   D 
MgK2(S04)2,6H20   D 
Mg(NH4)2(S04)2,6H2OD 
Chromate. 
Na2CrO4,10H2O   23°(Bertbelot) 
Arsenate. 
Na2HAs04,12H20   28° 
Phosphate. 
Na2HP04,12H20   35° 
Phosphate.  m.p. 
KH2P04  (anhydrous)  96° 
Chlorides. 
BaCl2,2H20   D 
SrCl2,6H20  112° 
CaCJ2,6H20   28° 
Carbonate. 
Na2CO3,10H20   34° 
Oxalates. 
H2C2O4,2H20   98-5° 
(NH4)2C204,H20   D 
Acetates. 
NaC2H302,H20   58*5° 
Cu(C2H302)2,H20   D 
Borate. 
Na2H2B408,9H20          75  5 
Theiosulphate. 
Na2S203,5H20   48-5 
Nitrates. 
Ca(N03)2,4H20.... 
....  44°  (Ordway 
Mg(NO,)2,6H20  ... 
....  90° 
Ni(N03)2,6H20  
....  56-7° 
Cd(N03),,4H20  
Mn(N03)2,6H.,0.... 
....  25'8°  " 
Ca(N03)2,6H2a.... 
....  26-4° 
Cu(NO,)2,3H20  
..  .114-5°  " 
1 D  =  gives  off  its  water  without  melting 
2  Converted  into  green  salt. 
33 
