106 
MERCURIAL  OINTMENT, 
gas ;  J,  a  screw  to  empty  the  residual  sulphate  of  soda  ;  K  K 
are  stuffing  boxes  to  keep  the  joints  tight. 
In  charging  the  apparatus,  the  operator  proceeds  as  follows  : 
Assuming  that  the  fountain  is  of  size  No.  1,  he  pours  into  it  13 
gallons  of  pure  water.  The  soda  vessel  B  is  removed  by  un- 
screwing the  joint  C,  and  filled  with  bi-carbonate  of  soda,  and  at 
the  same  time  three  pints  of  sulphuric  acid  is  poured  into  tho 
cylinder  D,  when  the  soda  vessel  is  replaced.  The  washer,  E, 
is  filled  two-thirds  full  with  water.  The  stop-cocks  are  now 
opened,  and  a  portion  of  the  soda  allowed  to  fall  into  the  acid 
vessel  by  depressing  the  handle,  A,  when  the  gas  passes  rapidly 
into  the  fountain  through  the  washer,  E.  When  all  the  soda 
has  been  decomposed,  about  200  gallons  of  gas  will  have  been 
evolved  and  condensed  under  great  pressure.  The  whole  opera- 
tion takes  from  twenty  to  thirty  minutes. 
Eigure  1  exhibits  the  double  fountain  and  generator,  which  is 
capable  of  meeting  the  demand  of  the  largest  establishments,  by 
charging  one  whilst  the  other  is  being  emptied  from  the  counter 
draught-pipe.  There  are  three  sizes  of  each  kind  of  these  ma- 
chines, the  cost  varying  from  $100  to  $200.* 
AN  EXPEDITIOUS  MODE  OF  MAKING  MERCURIAL  OINTMENT. 
By  Jno.  M.  Maisch. 
One  of  the  most  tedious  works  in  the  laboratory  of  an  apothe- 
cary, is  the  preparation  of  mercurial  ointment.  A  number  of 
substances  have  been  recommended  to  be  added  in  small  quanti- 
ties for  the  purpose  of  extinguishing  the  mercury,  and  thus  facili- 
tating the  work  and  abbreviating  the  process.  But  almost  all  of 
them  have  met  with  the  opposition  of  physicians;  some,  such  as 
sulphur,  and  rancid  fat,  on  account  of  their  chemically  altering  the 
mercury;  others,  like  turpentine,  render  the  ointment  too  irrita- 
ting. 
It  is  known  that  mercury,  when  pressed  through  leather,  is 
minutely  divided  ;  in  this  state  it  may  be  readily  mixed  with  the 
*  This  apparatus  is  manufactured  by  A.  J.  Morse,  of  New  York,  but 
the  apparatus  may  be  had  from  T.  Morris  Perot,  Philadelphia :  V.  C. 
Price  &  Co.,  Buffalo :  J.  H.  Reed  &  Co.,  Chicago ;  and  A.  Leitch  &  Co., 
St.  Louis. 
