SULPHO-CARBOLIC  ACID  AND  THE  SULPHO-CARBOLATES.  13-5 
soluble  in  five  parts  of  water  at  60°  Fahr.,  and  also  soluble  in 
alcohol  and  glycerin.  It  is  not  precipitated  hj  solution  of  chloride 
of  barium  unless  sulphate  of  soda  is  present,  and  as  the  latter  is 
the  most  probable  impurity  when  made  in  this  way  it  is  a  good 
test  of  purity.  When  heated  in  a  gas  jet  the  acid  is  decom- 
posed, leaving  sulphate  of  soda  and  sulphuret  of  sodium. 
SulphO'Carholate  of  Zinc  is  made  by  the  direct  process  by 
saturating  the  hot  aqueous  sulpho-carbolic  acid  with  carbonate 
of  zinc  free  from  iron,  filtering  and  concentrating  the  solution 
at  150°  F.,  and  setting  it  aside  to  crystallize.  The  evaporation 
must  not  be  pushed  too  far,  else  some  sulphate  crystals  will  be 
found.  By  throwing  the  mother  liquid  into  sufficient  alcohol, 
the  sulphate  will  be  precipitated  and  the  sulpho-carbolate  re- 
tained. This  salt  crystallizes  readily  in  brilliant  scaly  crystals, 
which  are  soluble  in  two  parts  of  water  at  60°  F.,  and  in  five 
parts  of  alcohol,  according  to  Hager. 
Sulplio-Carholate  of  Lead. — This  salt  is  easily  made  by  satu- 
rating the  hot  watery  solution  of  impure  sulpho-carbolic  acid 
with  carbonate  of  lead,  filtering  hot  and  evaporating,  if  neces- 
sary, to  the  point  of  crystallization.  As  in  making  the  baryta 
salt,  the  free  sulphuric  acid  present  is  precipitated  as  an  in- 
soluble sulphate,  thus  separating  it  completely.  It  crystallizes 
less  readily  than  the  soda  and  zinc  salts,  is  very  soluble  in 
water  and  soluble  in  alcohol  and  glycerin,  is  not  precipitated  by 
chloride  of  barium  in  weak  solution,  but  gives  the  usual  reaction 
with  iodide  of  potassium  and  sulphide  of  ammonium,  and  its  base 
is  not  precipitated  by  a  current  of  carbonic  acid.  When,  how- 
ever, the  salt  is  dried,  on  redissolving  either  in  water  or  alcohol 
a  residue  is  left,  which  is  at  once  dissolved  by  acetic  acid.  Sul- 
pho-carbolate of  lead  may  be  used  as  a  cheaper  substitute  for  the 
baryta  salt  to  procure  other  salts  by  employing  it  in  equivalent 
proportions  with  the  sulphate  of  the  base  wanted — the  lead 
falling  as  sulphate — when  on  filtration  and  evaporation  the  salt 
is  obtained.  Its  therapeutical  character  is  yet  to  be  determined, 
but  it  is  quite  probable  that  in  those  diarrhoeas  where  the  ace- 
tate of  lead  is  indicated,  and  especially  those  accompanied  by  a 
condition  corrected  by  carbolic  acid,  this  salt  may  be  found 
