442  Comparison  of  Galenical  Preparations.  {^"seprjiss*™* 
make  100  parts.  The  specific  gravity  is  1*160.  U.  8. — Dilute  solu- 
tion of  ferric  chloride  sp.  gr.  1*281,  10  parts  with  water  50  parts  and 
add  to  ammonia  water  10  parts,  diluted  with  water  200  parts;  wash 
the  precipitate,  express  strongly,  dissolve  in  acetic  acid  sp.  gr.  1*041, 
8  parts,  and  add  sufficient  distilled  water  to  make  the  sp.  gr.  1*081- 
1*083.    P.  G.    In  making  these  preparations  heat  must  be  avoided. 
Liquor  Ferri  Chloridi,  U.  S.  Liquor  Ferri  sesquichlorati,  P.  G. — 
Treat  iron  15  parts  with  hydrochloric  acid  54  parts  and  water  25  parts; 
when  saturated  filter,  add  to  the  filtrate  hydrochloric  acid  27  parts  and 
oxidize  with  nitric  acid  8  parts  or  a  sufficient  quantity;  cool  and  add 
hydrochloric  acid  5  parts  and  sufficient  water  to  make  100  parts.  Spec, 
grav.  1*405.  U.  S. — Treat  iron  with  4  times  its  weight  of  hydro- 
chloric acid,  and  wash,  dry  and  weigh  the  undissolved  iron.  For  every 
100  parts  of  iron  dissolved,  add  hydrochloric  acid  260  parts  and 
nitric  acid  112  parts,  oxidize  completely,  evaporate  to  483  parts,  and 
while  warm  dilute  with  distilled  water  to  1,000  parts.  Spec,  gravity 
1*280-1*282.  P.  G.  The  solution  contains  18*6  per  cent,  of  ferric 
oxide,  U.  S.,  10  per  cent,  of  iron  =  14*28  per  cent,  of  ferric  oxide, 
P.  G, 
Liquor  Ferri  Tersulphatis,  U.  8.  Liquor  Ferri  sulfurici  oxydati, 
P.  G. — Except  in  manipulation  and  final  strength  the  two  formulas 
are  identical.  Ferrous  sulphate  80  parts  are  oxidized  with  nitric  acid 
sp.  gr.  1*42,  11  parts  U.  8.,  or  sp.  gr.  1*185,  18  parts  P.  G.,  or  a  suf- 
ficient quantity,  and  yield  200  parts,  U,  8.,  160  parts  P.  G.,  of  solu- 
tion of  the  specific  gravity  1*320  U.  8.,  1*430  P.  G, 
Liquor  Plumbi  8uhacetatiSy  U.  8.  Liquor  Plumbi  subacetici,  P.  G, 
— Boil  for  30  minutes  lead  acetate  170  parts,  lead  oxide  120  parts, 
and  distilled  water  800  parts;  cool,  add  water  to  make  1,000  parts 
and  filter.  Specific  gravity  1*228  U.  8. — Melt  with  the  heat  of  a 
water-bath  lead  acetate  6  parts,  levigated  litharge  free  from  carbonate, 
2  parts  and  distilled  water  1  part ;  when  the  mass  has  become  white  or 
reddish  white  add  distilled  water  19  parts;  let  subside  and  filter.  Spe- 
cific gravity  1*235-1*240  P.  G, 
Liquor  Plumbi  8ubaetatis  dilutus,  U,  8.  Aqua  Plumbi,  P.  G. — 
Mix  solution  of  lead  subacetate  3  parts  with  distilled  water  97  parts, 
U,  8.,  147  parts  P.  G, 
Liquor  Potassce,  U.  8.  I^iquor  Kali  caustici,  P.  G. — Directions  for 
preparing  this  solution  are  given  only  by  the  U.  S.  Pharmacopoeia. 
