72 
Commercial  Vinegar. 
/Am.  Jour.  Pharm. 
I    February,  1899. 
In  spirit  vinegar  there  is  no  difficulty  in  reducing  the  mass  to  ash. 
Spirit  vinegar  yields  much  less  ash  than  cider  vinegar,  and  the 
latter  differs  from  the  former  in  containing  only  traces  of  sulphates 
and  chlorides,  and  considerable  quantities  of  alkaline  carbonates 
and  phosphates,  the  phosphates  being  present  in  the  proportion  of 
two  parts  of  soluble  to  one  part  of  insoluble  phosphates.  In 
samples  to  which  water,  containing  calcium  and  magnesium,  has 
been  added  the  amount  of  soluble  phosphates  is  much  reduced,  and 
insoluble  phosphates  increased.  A  solution  of  the  soluble  ash  will 
show  a  potassium  flame  unobscured  by  sodium  light,  while  samples 
containing  added  water  will  usually  show  a  sodium  flame. 
In  the  analysis  of  vinegar  the  total  solids  are  determined  by  evap- 
orating io  grammes  to  a  constant  weight  on  a  water  bath.  Total 
acidity  is  estimated  volumetrically  with  standard  alkali,  using  phenol- 
phtalein  as  an  indicator,  5  grammes  of  vinegar  being  first  diluted  to 
50  c.c.  with  distilled  water. 
To  estimate  the  ash,  10  grammes  are  evaporated  and  burned  at  a 
low  temperature,  the  product  weighed  and  the  soluble  portion  re- 
moved by  washing  with  water,  this  solution  being  tested  for  sul- 
phates and  chlorides,  as  well  as  for  the  color  of  flame. 
For  alkalinity  of  ash,  25  grammes  are  evaporated  and  burned,  the 
soluble  carbonates  and  phosphates  removed  by  repeated  washing 
with  hot  water,  and  the  solution  titrated  with  deci-normal  oxalic 
acid,  using  methyl-orange  as  an  indicator,  and  the  result  expressed 
in  the  number  of  cubic  centimetres  of  acid  required  for  100  grammes 
of  vinegar.  The  soluble  and  insoluble  phosphates  in  the  ash  from  25 
grammes  of  vinegar  being  separated,  the  amount  of  P205  in  each 
is  determined,  Pcmberton's  method  being  employed  by  the  writer. 
In  the  following  table  the  result  of  the  examination  of  three 
commercial  samples  is  given  : 
