560 
Acetum  Scill^,  B.  P. 
Am,  Jour.  Pharm. 
Dec.  1875. 
the  cyanates  into  carbonate  during  boiling,  and  also  to  economize  alco- 
hol, it  is  advisable  to  add  to  the  latter  at  each  boiling  only  about  as 
much  of  the  mixture  as  can  be  thoroughly  exhausted  by  it.  The  fil- 
tration takes  place  so  rapidly  that  it  is  not  necessary  to  employ  a  hot- 
water  funnel,  and  the  crystallization  of  the  cyanate  may  be  hastened 
by  immersing  the  vessel  containing  its  alcoholic  solution  in  cold  w^ater. 
The  mother-liquor  may  be  used  an  indefinite  number  of  times  in  subse- 
quent boilings.  In  a  favorable  experiment  the  resulting  cyanate,  equal  to 
about  42  per  cent,  of  the  dried  ferrocyanide,  contained  less  than  i  per 
cent,  of  impurity. 
To  obtain  the  insoluble  cyanates,  lead,  silver,  &c.,  it  is  only  neces- 
sary to  exhaust  the  black  mass  with  very  cold  water,  to  treat  the  fil- 
tered solution  with  barium  nitrate,  in  order  to  remove  the  chromate 
and  any  unaltered  ferrocyanide,  and  finally  to  precipitate  with  a  nitrate 
of  the  metal. 
From  the  above  aqueous  solution  urea  may  obviously  be  prepared  by 
the  addition  to  it  of  parts  of  ammonium  sulphate,  evaporation  to 
dryness,  extraction  with  boiling  alcohol,  &c.  Even  from  so  small  a 
quantity  as  one  ounce  of  the  dried  ferrocyanide  it  is  thus  possible  to 
obtain,  in  a  short  time  and  with  little  trouble,  about  25  per  cent,  pure 
urea.  In  this  form  the  experiment  would  furnish  a  capital  exercise  for 
students. 
I  may  here  remark  that  for  the  purification  of  urea,  on  the  small 
scale,  amylic  alcohol  will  be  found  a  much  more  convenient  crystalliz- 
ing medium  than  ordinary  alcohol.  —  Chem,  News  [Lond.],  Aug.  27, 
1875. 
Stenjens's  Hospital  Laboratory,  Dublin. 
ON  ACETUM  SCILL^,  B.P. 
BY  E.  GREGORY. 
About  a  year  since,  taking  up  in  an  idle  moment  an  old  copy  of  the 
London  Pharmaceutical  yournal.^  I  read  in  answer  to  an  inquiring  cor- 
respondent a  recommendation  to  prepare  acetum  scillae,  according  to 
the  formula  of  the  "  British  Pharmacopoeia,"  "  carefully  avoiding,  how- 
ever, the  directions  to  add  one  and  a  half  fluidounces  of  proof  spirit  at 
the  end  of  the  process."  On  theoretical  grounds  I  had  long  omitted 
the  spirits,  but  the  strangeness  of  this  advice,  proceeding  from  such  a 
source,  determined  me  to  open  the  whole  question,  and  endeavor  to 
