184  Determination  of  Calcium  Tartrate.    { Am f853arm- 
tion  of  insoluble  matter,  uncombined  arsenium  and  arsenious  oxide, 
but  we  will  only  take  into  account  those  samples  which  come  fairly 
within  the  B.  P.  requirements. 
(1)  1-866  gramme  treated  with  warm  water,  insoluble  matter  col- 
lected on  filter  and  well  washed,  gave  -024  gramme,  =  1-28  per 
cent,  insoluble. 
^700  gramme  dissolved  in  water  with  excess  of  nitric  acid  gave 
1*077  gramme  Agl,  =  -582  gramme,  Iodine,  =  83-15  per  cent. 
83-55  required  for  Asl3. 
(2)  The  same  salt  recrystallized  from  water  and  dried  by  exposure 
to  the  air.  -408  gramme  gave  -180  Agl,  =  -097  Iodine,  =  23-84 
per  cent. 
•535  gramme  gave  -444  As2S3,  =  -2707  Arsenic,  —  50- 59  per  cent. 
(3)  1-469  gramme  treated  with  water,  as  in  No.  1,  left  -009  gramme 
insoluble,  =  -6i  per  cent.;  and  the  solution  gave  2-134  grammes 
Agl,  =1-153  Iodine,  =  78-5 1  percent.  The  di-iodide  Asl2  requires 
77-20. 
(4)  2-8  grammes  arsenious  oxide  were  dissolved  in  64  cc.  hydri- 
odic  acid  (1 1  per  cent.),  and  solution  evaporated  to  dryness  with 
heat  of  a  water-bath,  -891  gramme  gave  1*199  Agl,  =-648  iodine, 
=  72-73  per  cent. 
These  results  prove  that  it  is  practicable  to  prepare  a  salt  of 
composition  nearly  agreeing  with  the  formula  Asl3,  but  that  the 
tendency  is  towards  a  deficiency  of  iodine,  that  treatment  with  water 
produces  extensive  decomposition  with  separation  of  a  very  basic 
salt,  and  that  the  alternative  method  referred  to  in  the  Pharmacopoeia 
does  not  yield  a  salt  of  the  composition  required.  We  may  perhaps 
infer  that  this  is  an  instance  in  which  it  would  be  better  for  the 
Pharmacopoeia  not  to  refer  to  the  methods  of  preparation  but  rather 
to  content  itself  with  giving  sufficient  tests  for  purity. — Phar.  Jour, 
and  Trans.,  p.  619,  Jan.  28,  1893. 
DETERMINATION  OF  CALCIUM  TARTRATE. 
By  Ch.  Ordonneau. 
We  take  20  grms.  calcium  tartrate,  an  average  sample,  pulverize 
them  finely  in  the  mortar,  and  add  20  cc.  of  commercial  hydro- 
chloric acid  at  200,  diluted  in  100  grms.  of  water.  The  solution 
may  be  promoted  by  heating  to  ebullition.    We  make  up  202-203 
