336         QUANTITATIVE  ESTIMATION  OF  TARTARIC  ACID. 
and  readily  executed  method  of  quantitative  estimation  of  tar- 
taric acid.  After  first  ascertaining-  by  a  series  of  experiments 
that  tartrate  of  lime  is  less  soluble  in  water  than  is  commonly 
reported  in  books  (he  ascertained  that  1  part  of  the  aforesaid 
salt  requires  at  18°  C.  2388*26  parts  of  water  for  complete  so- 
lution), he  discovered  the  almost  complete  insolubility  of  the 
tartrate  of  lime  in  alcohol  of  85  per  cent,  strength.  In  order 
to  estimate  the  tartaric  acid  in  tartrate  of  potash,  for  instance, 
the  salt  is  dried  at  100°  C,  dissolved  in  a  small  quantity  of 
distilled  water,  next  pure  chloride  of  calcium  solution  is  added, 
with  the  precaution  to  avoid  excess  thereof,  afterwards  a  few 
drops  of  lime-water  are  added,  and  the  porcelain  capsule  wherein 
this  operation  is  performed  is  left  standing  for  some  hours.  A 
crystalline  precipitate  is  thus  obtained  ;  it  is  collected  on  a  filter 
previously  dried  at  100°  and  weighed  ;  the  supernatant  fluid  is 
first  poured  upon  the  filter,  then  the  precipitate  is  collected  and 
washed  with  strong  alcohol,  the  precipitate  and  filter  are  thor- 
oughly dried  at  100°  ;  the  precipitate  is  weighed  as — 
2CaO,C8H,OioH-8HO. 
It  is  of  importance  to  take  care  to  use  a  porcelain  basin,  the 
glaze  of  which  is  quite  free  from  cracks,  otherwise  the  precipitate 
has  a  strong  tendency  to  adhere  to  such  portions  of  the  basin. 
When  either  hydrochloric  or  nitric  acids  are  present  along  with 
tartaric  the  fluid  is  first  nearly  neutralised  with  pure  carbonate 
of  lime  and  warmed  to  expel  carbonic  acid,  while  the  last  traces 
of  acid  are  removed  with  lime-water.  The  presence  of  either 
chloride  of  ammonium  or  chloride  of  calcium  in  excess  interferes 
with  the  correctness  of  the  results  and  makes  it  necessary  to 
add  alcohol  to  the  liquid  to  be  operated  upon.  Results  are  ac- 
curate when  proper  care  is  taken. — Lond.  Chem.  News,  April 
9,  1869, /row  Pharm.  Zeifschr.  f.  Buss.,  1869,  No.  1. 
SALT  DEPOSIT  NEAR  BERLIN. 
According  to  M.  Jahn,  a  stratum  of  rock  salt,  669  feet  thick, 
has  been  discovered  near  Berlin,  at  Sperenburg,  and  from  the 
borings  is  considered  a  highly  valuable  mineral  deposit. — Ibid., 
from  Ibid. 
