Am.  Jour.  Pharm.  "I 
Jan.  2, 1871.  j 
Sidi^liocarholic  Acid,  etc. 
11 
it  is  necessary  to  take  six  equivalents  of  the  latter  and  one  of  the 
former ;  3d,  sulphocarbolates  are  composed  of  two  equivalents  of  the 
acid  and  three  of  the  base. 
The  process  of  examination  I  employed  is  simple  enough :  it  con- 
sists in  heating  together  various  proportions  of  the  two  acids,  and  by 
means  of  carbonate  baryta  determining  what  quantity  of  sulphuric 
acid  is  converted  into  sulphocarbolic  acid,  what  proportion  of  it 
remains  free,  and  how  much  carbonate  of  baryta  is  transformed  into 
the  sulphocarbolate  of  the  same  base. 
This  is  effected  in  this  wise :  Known  weights  of  carbolic  and  sul- 
phuric acids  are  mixed  together,  heated,  and  when  cool  diluted  with 
water.  To  this  a  certain  weight  of  carbonate  baryta,  always  in  excess, 
is  added,  and  the  liquid  brought  to  ebullition,  so  as  to  avoid  the  for- 
mation of  bicarbonate  of  baryta.  The  mixture  is  then  poured  on  a 
filter  and  the  filter  well  washed  with  water  ;  the  filtrate,  which  I  will 
call  liquor  is  kept  aside.  The  filter  is  then  washed,  first  with  dilute 
muriatic  acid,  and  then  q.  s.  water,  the  washings  being  kept  aside^ 
and  called  liquor  h.  This  done,  the  filter  is  dried  and  the  weight  of 
the  precipitate  taken,  which  I  will  call  precipitate  c. 
Then  liquors  a  and  h  are  treated  by  an  excess  of  sulphuric  acid, 
and  the  weights  of  the  precipitates  ascertained.  I  will  call  them 
respectively  precipitate  a  and  h. 
These  three  precipitates  a,  h  and  c  consist  of  sulphate  baryta,  but 
each  of  them  has  a  different  meaning. 
Thus,  precipitate  a  indicates  what  quantity  of  the  carbonate  baryta 
has  been  transformed  into  sulphocarbolate. 
Precipitate  h  shows  how  much  of  the  carbonate  baryta  was  in 
excess. 
Precipitate  c  tells  us  what  proportion  of  the  sulphuric  acid  remained 
uncombined  in  the  mixture. 
A  few  words  about  the  modus  operandi  may  not  be  unnecessary : 
for  ascertaining  the  weight  of  the  precipitates,  I  cut  two  filters  from 
the  same  sheet  of  paper,  trim  them  precisely  to  the  same  weight,  and 
fold  them  together.  The  precipitate  is  collected  on  the  inner  filter, 
both  filters  are  washed  together  by  the  same  reagents,  and  dried 
together.  The  difference  in  weights  gives  quite  accurately  the  actual 
weight  of  the  precipitate. 
By  this  process  I  have  examined  successively  mixtures  of  one  equi- 
