132     SULPHO-CARBOLIC  ACID  AND  THE  SULPHO-CARBOLATES. 
In  a  recent  letter  from  Dr.  Frederick  Hoffmann,  of  Sixth 
Avenue,  New  York,  he  says,  in  speaking  of  the  sulpho-carbolate 
of  zinc  :  "  Recently  it  has  been  introduced  into  the  hospitals  of 
the  Berlin  Charite  with  such  success  that  it  has  been  adopted 
among  the  remedies  of  that  famous  institute.  To  all  appearance, 
this  salt,  and  perhaps  other  sulpho-phenates,  may  become  a 
valuable  and  permanent  addition  to  the  materia  medica. 
"  The  zinc  sulpho-phenate  is  said  to  combine  the  therapeutical 
virtues  of  both  its  constituents ;  its  preference  to  phenol  or  to 
the  phenates  is  said  to  depend  on  the  gradual  disengagement, 
and  consequently  upon  the  more  continuous  and  uniform  action 
of  the  phenol.  The  same  may  hold  good  with  still  greater  pro- 
mise for  the  internal  use  of  this  or  other  sulpho-phenates. 
I  have  prepared  the  sulpho-phenates  of  zinc  and  of  sodium. 
The  former  has  been  tried,  at  my  suggestion,  by  several  physi- 
cians of  New  York,  with  entire  satisfaction,  in  solutions  of  3  to 
5  grains  per  ounce,  as  a  dressing  to  wounds  and  burns,  as  a  gargle 
for  the  mouth  or  nose,  and  as  an  injection  in  gonorrhoea,  etc." 
In  this  city  Dr.  Freeman  and  others  have  used  these  salts  to 
a  considerable  extent,  and  with  decided  success,  especially  in 
ozoena,  and  as  it  is  therefore  probable  that  they  will  get  into 
general  use,  we  have  prepared  the  following  notice  : 
Sulpho-carbolic  acid  is  constituted  like  sulphovinic  acid,  though 
much  more  stable  than  the  latter.  According  to  Gmelin  (Hand- 
book, vol.  xi,  p.  157),  its  formula  is  Ci2Hg02,  2SO3,  whilst  Mr. 
C.  H.  Wood  gives  it  as  (C6*H5)H  SO4.  It  is  formed,  according 
to  Laurent,  by  mixing  carbolic  acid  with  an  excess  of  sulphuric 
acid,  letting  the  mixture  stand  twenty-four  hours,  and  then,  after 
dilution  with  water,  saturating  it  with  carbonate  of  baryta  at  the 
boiling  temperature,  filtering  out  the  excess  of  carbonate  and  the 
sulphate  formed,  evaporating  the  filtrate  to  crystallization,  the 
crystals  recrystallized  from  alcohol  and  washed  with  a  small 
quantity  of  alcohol,  and  finally  decomposing  its  solution  with  an 
equivalent  of  SO3,  HO,  and  evaporating  the  filtrate  in  vacuo. 
The  acid  in  a  free  state,  however,  is  not  needed  in  purity,  and 
the  latter  part  of  the  process  may  be  avoided.    The  baryta  salt 
*C»12. 
