ON  THE  ESTIMATION  OF  CREAM  OF  TARTAR,  ETC. 
ad 
have  analysed,  because  their  total  acidity  much  exceeds  that  of 
the  cream  of  tartar  they  contain.  Now,  the  co-existence  of 
neutral  tartrate  of  potash  and  an  organic  acid  is  not  admissible, 
for  a  solution  of  tartrate  of  potash,  to  which  is  added  a  trace 
of  acetic  or  any  other  acid,  then  treated  by  the  ethero-alcohol- 
ic  mixture,  gives  a  precipitate  of  cream  of  tartar. 
We  have,  moreover,  verified  the  exactness  of  the  process  by 
adding  small  quantities  of  tartaric  acid  to  Formichon  wine,  and 
afterwards  recovering  it  in  the  precipitate. 
3.  Applying  this  process  to  the  examination  of  various  wines, 
we  found  that  most  of  them  contain  no  free  tartaric  acid.  We 
have  ascertained  this  fact  especially  with  regard  to  the  follow- 
wines:— Formichon,  1860-61-62;  Savigny,  1859-60-61,  frozen  ; 
Savigny,  1862  (red  and  white  Pinot) ;  ordinary  Montpellier  ; 
MSdoc,  1858  ;  Saint  Emilion,  1857. 
In  a  very  few  instances  the  addition  of  potash  increases  the 
precipitate,  as  with  Formichon,  1858,  and  Brouilly,  1858  (free 
acid  equal  to  half  the  acid  contained  in  the  cream  of  tartar),  and 
with  Formichon,  1859.  In  the  latter  wine  the  free  tartaric  acid 
was  double  that  of  the  cream  of  tartar,  and  equal  to  2-2  gr,  per 
litre  ;  the  total  tartaric  acid,  free  and  combined,  =3-3  gr.,  the 
largest  proportion  of  tartaric  acid  we  have  found  in  any  wine.  The 
smallest  quantity  was  in  frozen  Savigny,  1861  (tartaric  acid= 
0»7gr.  per  litre),  and  in  altered  Sautenay,  1858  (04  gr.).  In 
most  instances  the  total  weight  of  tartaric  acid  is  given  in  that 
of  the  cream  of  tartar,  of  which  it  represents  four-fifths. 
The  absence  of  free  tartaric  acid  in  most  of  the  wines  ex- 
amined is  a  very  important  fact.  Indeed,  the  acidity  of  the 
cream  of  tartar  represents  but  a  fraction  of  their  total  acidity. 
In  the  Formichon  of  1858,  for  instance,  the  total  acidity.*  is 
equal  to  7-4  gr.  of  tartaric  acid  per  litre,  while  that  of  cream 
of  tartar  represents  only  1*1  gr.  of  tartaric  acid,  and  that  of 
tartaric  acid  exceeds  0-5  gr.  ;  there  is  then  an  acidity  equiva- 
lent to  5-8  gr.  resulting  from  other  acids.  Succinic  acid  makes 
at  the  most  1*5  gr.,  according  to  M.  Pasteur's  experiments,  and 
acetic  acid,  a  few  decigrammes,  according  to  those  of  M.  Be*- 
champ.     There  then  remains  an  acidity  equal  to  about  4 
This  acidity  does  not  include  carbonic  acid,  which  we  took  car<e  to 
eliminate,  but  which  does  not  exist  yery  abundantly  in  old  wines. 
