442 
AMOUNT  OF  ACETIC  ACID  IN  VINEGAR. 
acetic  acid,  which  was  found  by  the  various  methods  of  testing 
in  concentrated  or  dilute  acetic  acid. 
Presenilis  &  Will's 
Carbonate  of  Soda.        Carbonate  of  lime.        Carbonate  of  baryta.  Method. 
87-9  99-6  994  99-3 
45-3  52-8  52-3  52-0 
22-1  25-5  25-7  25-3 
How  different  are  the  numbers  of  the  first  series  from  the  cor- 
responding numbers  in  the  others,  in  which  the  greatest  accord- 
ance is  exhibited ! 
The  experiments  of  Nicholson  and  Price  were  exceedingly  un- 
welcome to  me,  as  I  was  just  engaged  in  the  preparation  of  a  new 
edition  of  my  Text-book  of  Vinegar  Manufacture.  I  should  have 
to  condemn  the  former  method  in  general  use,  for  the  determina- 
tion of  the  amount  of  acid  in  vinegar,  as  well  as  my  acetometer, 
in  which  a  dilute  ammonia  is  used  as  the  acetometric  fluid.  Not 
so  much  to  check  the  correctness  of  the  experiments  in  question, 
which  appeared  to  me  to  be  beyond  a  doubt,  as  to  see  whether, 
in  the  case  of  an  acetic  acid  so  diluted  as  the  vinegars,  the  error 
was  not  so  small  that  it  might  be  passed  unnoticed,  or  whether 
it  was  not  constant  in  amount,  I  made  a  few  experiments.  I 
will  communicate  these  in  the  following.  The  numbers  represent 
centesimal  parts  of  anhydrous  acetic  acid  in  the  vinegar  ex- 
amined. 
Acetometer.  Carbonate  of  soda.        Carbonate  of  baryta. 
6-3  6-5  6-2* 
91  9-2  90 
The  acetometric  ammoniacal  fluid  was  prepared  with  the  great- 
est exactitude. 
For  testing  with  carbonate  of  soda,  a  normal  solution  of  the 
anhydrous  salt  containing  104  grms.  in  the  litre  was  employed, 
and  a  Mohr's  burette  was  used.  5  cub.  cent,  of  the  solution  in- 
dicate 1  per  cent,  of  acetic  acid  in  50  grms.  of  vinegar.  The 
point  of  neutralization  was  ascertained  in  the  heated  vinegar  by 
means  of  pale  blue  litmus  paper. 
In  testing  with  carbonate  of  baryta,  a  weighed  quantity  of  the 
salt  was  put  into  a  weighed  quantity  (10  or  50  grms.)  of  vinegar, 
and  digested  therewith,  at  last  at  a  high  temperature,  until  the 
solution  produced  had  an  alkaline  reaction.  For  this  purpose  a 
long  time  was  required.    The  undissolved  carbonate  of  baryta 
*  In  two  perfectly  concordant  experiments. 
