AMOUNT  OF  ACETIC  ACID  IN  VINEGAR. 
448 
was  collected  on  a  filter,  carefully  washed,  dried,  calcined  and 
weighed.  88-5  of  carbonate  of  baryta,  represented  51  of  acetic 
acid  (1  equiv.) 
It  might  be  objected  against  these  experiments,  that  possibly 
I  did  not  continue  the  digestion  of  the  vinegar  with  the  carbonate 
of  baryta  long  enough,  for  there  is  no  other  means  of  judging  of 
the  completion  of  the  digestion,  except  the  reaction.  For  this 
reason  I  made  the  following  experiments,  which  must  remove  all 
doubt,  and  which  may  easily  be  repeated  in  a  few  minutes. 
27  grms.  of  crystallized  acetate  of  soda  were  dissolved  to  form 
100  grms.  of  solution.  This  solution  contained  10  grms.,  or  10 
per  cent,  of  acetic  acid.  It  had  an  alkaline  reaction  with  red- 
dened litmus  paper.  It  was  rendered  perfectly  neutral  by  2  cub. 
cent,  of  vinegar,  containing  4»5  per  cent,  of  acid,  and  the  addi- 
tion of  1  cub.  cent,  more  vinegar  caused  it  to  react  distinctly 
acid  upon  blue  litmus  paper ;  2.  cub.  cent,  of  vinegar  of  4-5  per 
cent,  do  not  contain  fully  0-1  grm.  of  acetic  acid ;  the  error, 
therefore,  which  results  from  the  alkaline  reaction  of  acetate  of 
soda  in  the  determination  of  the  acidity  of  a  vinegar  of  10  per 
cent.,  can  at  the  utmost  only  amount  to  y0th  per  cent.,  and  is 
certainly  always  less,  as  a  little  too  much  soda  is  usually 
added. 
A  hot  solution,  containing  50  per  cent,  of  acetate  of  soda,  re- 
presenting 18-7  per  cent,  of  acetic  acid,  was  rendered  neutral 
by  2  cub.  cent,  of  vinegar  of  9  per  cent.,  and  distinctly  acid  by 
another  cub.  cent. 
The  process  hitherto  in  use  for  the  determination  of  the  amount 
of  acid  in  vinegar  by  means  of  alkalies  or  alkaline  carbonates 
may  therefore  be  retained,  as  it  gives  sufficiently  accurate  re- 
sults ;  the  alkaline  reaction  of  the  alkaline  acetates  does  not 
affect  the  accuracy  in  a  noticeable  degree. 
When,  many  years  ago,  I  constructed  the  acetometer  to  which 
my  name  has  been  given,  and  by  means  of  which  the  amount  of 
acid  in  a  vinegar  is  ascertained  very  conveniently  and  rapidly, 
and  also  very  exactly  if  the  acetometric  fluid  has  been  correctly 
prepared,  I  was  obliged  to  make  experiments  as  to  the  amount 
of  ammonia  in  liquid  ammonia  of  various  specific  gravities,  and 
sketch  out  a  table  of  them.  Very  recently,  Carius  has  ascer- 
tained the  amount  of  ammonia  in  solutions  of  ammonia  in  a  very 
