350 
Jervic  Acid  and  Jercates. 
\  Am.  Jour.  Pharw. 
1     Aug.  1,  1873." 
talline  ;  the  soda  salt  is  white,  and  consists  of  very  thin  needles. 
Both  have  an  alkaline  reaction,  are  insoluble  in  alcohol  and  ether, 
freely  soluble  in  water,  from  which  solution  alcohol  precipitates  them 
finally  crystalline.  Composition  :  C]4H6Ol2K4+2H20.  The  sodium 
jervate  contains  3  molecules  of  water. 
The  jervates  of  the  alkaline  earths  are  obtained  by  carefully  add- 
ing to  a  boiling  solution  of  the  acid,  recently  precipitated  pure  car- 
bonate suspended  in  hot  water,  until  it  just  ceases  to  be  dissolved. 
The  salts  crystallize  on  cooling,  are  insoluble  in  alcohol,  but  slightly 
soluble  in  water ;  the  solutions  are  neutral  to  test-paper.  Composi- 
tion :  C14H6012Ba2;  the  strontium  jervate  contains  1,  the  calcium  salt 
6  molecules  of  water. 
An  excess  of  nitrate  of  silver  produces  in  aqueous  solutions  of  jer- 
vic  acid  a  crystalline  precipitate  =  C14H8012Ag2--|-2H201,  which  is 
freely  soluble  in  hot  water,  is  not  colored  when  exposed  to  the  direct 
sunlight,  and  not  decomposed  up  to  a  temperature  of  160°  C.  ;  the 
solution  has  an  acid  reaction.  The  neutral  silver  salt  obtained  by 
double  decomposition  of  the  hot  solutions,  crystallizes  in  fine  needles, 
is  affected  by  the  light  (at  least  while  moist),  and  has  a  neutral  reac- 
tion.   It  is  C14Hc012Ag4. 
The  mercurous  salt  obtained  by  double  decomposition  has  the  same 
composition  and  contains  \  molecules  of  water,  is  crystalline  and  in- 
soluble in  water. 
Jervic  acid  is  a  tetrabasic  acid  ;  a  well-defined  ether  has  not  been 
obtained  yet.  Pelletier  and  Caventou  regarded  it  as  gallic  acid;  the 
latter,  however,  is  monobasic  and  tetratomic.  By  doubling  its  mole- 
cule (2C7H6O5=CuH12O10),  it  will  be  seen  that  jervic  acid,  C14H10O12, 
contains  211  less  and  20  more  than  the  former  ;  and  digallic  acid, 
CMH10O9,  differs  in  composition  from  jervic  acid  merely  by  30.  The 
question,  whether  these  acids  are  related  to  each  other,  may  probably 
be  solved  by  the  study  of  their  derivatives. 
The  two  acids  differ  from  each  other  as  follows  : 
Jervic  .Acid.  Gallic  Acid. 
Not  fusible  or  sublimable.  Fusible  with  evolution  of  OO2  and 
formation  of  pyrogallic  arid  metagailic 
acids. 
Soluble  in  100  parts  of  cold  and  Soluble  in  100  parts  of  cold  and  3 
about  10  parts  of  boiling  water.  parts  of  boiling  water. 
Insoluble  in  ether,  difficultly  solu-  With  difficulty  soluble  in  ether,  easily 
ble  in  alcohol.  in  alcohol. 
