SOLUBILITY  OF  CREAM  OF  TARTAR,  ETC.  39 
ON  THE  SOLUBILITY  OF  CREAM  OF  TARTAR  IN  ACIDS  AND 
ITS  PURIFICATION  FROM  LIME  BY  MURIATIC  ACID. 
By  Dr.  Tenner,  of  Bern. 
It  was  proposed  by  Wittstein  and  adopted  by  the  Prussian 
Pharmacopoeia  to  digest  for  24  hours  in  a  water-bath  ten  parts 
finely-powdered  cream  of  tartar,  with  the  same  quantity  of 
water  and  one  part  of  concentrated  muriatic  acid.  If  well 
washed,  the  greatest  part  of  the  lime  is  removed.  On  evapo- 
rating the  acid  liquid,  and  cooling,  a  gelatinous  mass  is  obtain- 
ed, but  faintly  smelling  of  muriatic  acid,  and  consisting  of  a 
mixture  of  crystals  of  bitartrate  of  potassa,  chloride  of  potas- 
sium, chloride  of  calcium,  muriatic  and  tartaric  acids.  To  ascer- 
tain the  reaction,  the  behaviour  of  the  neutral  tartrate  of  lime 
and  of  pure  cream  of  tartar  to  muriatic  acid  was  observed. 
Tartrate  of  lime  was  prepared  by  precipitating  neutral 
tartrate  of  potassa  with  chloride  of  calcium.  Two  ounces  of  this 
limesalt  were  digested  for  several  hours  at  a  temperature  of 
about  44°  C.  (111°  F.)  in  a  mixure  of  i  ounce  muriatic  acid 
sp.  grav.  1.1644  and  oz.  water;  solution  took  place  rapidly 
and  completely.  After  standing  two  days  at  ordinary  tem- 
perature the  precipitate  was  collected,  washed  and  dried  ;  it 
weighed  11  drachms  14  grs,,  and  286  grs.  were  consequently  dis- 
solved. Half  an  ounce  of  muriatic  acid  of  1.1644  sp.  gr.  contains 
33.3  per  ct.  anhydrous  HC1,  or  80  grs.  ;  tartrate  of  lime  is  there- 
fore dissolved  with  complete  decomposition  and  the  formation 
of  chloride  of  calcium  ;  for 
72.92  HC1:  260,  2CaO,C8  H4  O10  =  80  :  285. 
This  behaviour  suggested  the  idea  that  the  increased  solu- 
bility of  cream  of  tartar  in  some  acids  was  owing  to  its  decom- 
position amid  the  production  of  the  corresponding  potassa  salts. 
The  following  experiments  were  then  made :  Pure  cream  of 
tartar  in  excess  was  treated  with  diluted  acids  and  with  the 
potassa  salts  of  the  same.  Starting  with  muriatic  acid,  which 
contained  80  grs.  HC1  in  8  oz.,  the  acids  and  salts  were  employed 
of  such  strength  as  to  correspond  by  their  equivalent  weight 
with  the  muriatic  acid.  They  were  all  digested  for  24  hours 
at  about  41°  C.  with  frequent  agitation,  and  then  exposed  for 
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