ON  THE  ESTIMATION  OF  CREAM  OF  TARTAR,  ETC.  61 
matrass  with  a  little  of  the  ethero-alcoholic  mixture,  which  is 
thrown  on  the  same  filter.  Place  this  filter  on  the  matrass, 
break  it,  wash  with  water,  put  the  filter  in  the  matrass,  heat 
it,  and  immediately  afterwards  determine  the  acid  standard 
by  means  of  normal  baryta  liquid. 
We  have  arrived  at  this  method  by  experiments  made  on  an 
aqueous  solution  of  cream  of  tartar,  to  which  was  added  before- 
hand 10  per  cent,  of  alcohol.  Left  for  several  days,  we  obtain- 
ed a  liquid  similar  to  the  majority  of  wines  ;  it  contained  three 
grammes  of  cream  of  tartar  per  litre.  The  baryta  liquid  was 
so  adjusted  that  ten  cubic  centimetres  of  the  above  solution 
should  require  about  fifty  divisions  of  baryta.  This  process 
has  been  likewise  verified  for  liquids  containing  either  an  excess 
of  tartaric  acid  or  small  quantities  of  other  organic  acids.  It 
is  sufficiently  correct,  even  in  presence  of  a  considerable  propor- 
tion of  foreign  organic  acids.  Only  in  presence  of  a  very 
large  excess  of  these  acids  does  this  method  fail.  We  will  in- 
dicate further  on,  in  treating  of  the  estimation  of  potash,  the 
means  by  which  this  exceptional  excess  can  be  ascertained. 
II.  By  applying  this  process  to  the  study  of  various  wines, 
we  found  that — 
1.  In  some  wines  the  quantity  of  cream  of  tartar  contained 
in  solution  was  precisely  the  same  as  in  the  saturated  solution 
of  cream  of  tartar  containing  the  same  proportions  of  water 
and  alcohol  as  the  wine.  This  fact  was  ascertained  especially 
with  regard  to  the  following  wines,  of  which  the  total  acid  stan- 
dard was  about  six  times  that  of  the  cream  of  tartar  ;  Formich- 
on,  1860  and  1862,  (3  grammes  per  litre).  This  testis  so  much 
the  more  valuable,  that  these  two  wines  contain  no  free  tartaric 
acid,  though  they  contain  other  free  organic  acids. 
2.  In  most  instances  the  proportion  of  cream  of  tartar  is 
less  than  that  of  a  saturated  liquid.  The  difference  amounts  to 
one-half  in  the  Formichon  of  1860,  in  the  Medoc  of  1858,  and 
ordinary  Montpellier.  The  Savigny  of  1859  and  the  Saint- 
Emilion  of  1857  contain  only  about  a-third  of  the  cream  of  tar- 
tar necessary  to  saturate  them.  The  smallest  quantity  was 
found  in  the  Savigny  wine  of  1861,  which  had  been  frozen 
(less  than  a  gramme  per  litre),  and  in  Sautenay  wine,  1858, 
