212     ON  SOME  PREPARATIONS  OF  THE  U.  S.  PHARMACOPOEIA. 
employed  and  found  to  be  practicable,  and  easily  conducted  in 
the  shop  on  the  scale  of  the  Pharmacopoeia.  All  that  is  need- 
ful is  to  have  the  luting  tight  to  prevent  the  annoyance  arising 
from  the  escape  of  the  gas.  Common  putty  will  answer  for  all 
the  joints  except  that  at  the  matrass,  which  should  be  made  of 
linseed  meal  and  water,  unless  the  cork  is  very  close,  which  is 
not  always  the  case,  under  pressure. 
Aqueous  Sulphurous  Acid  thus  prepared  should  be  introduced 
into  the  bottles,  so  as  to  nearly  fill  them,  and  secured  by  seal- 
ing wax.  The  direction  to  keep  in  a  cool  place  is  needful  on 
account  of  expansion.  I  have  found  no  difficulty  in  keeping 
it  for  six  months  in  bottles  with  corks  well  sealed,  but  access 
of  air  results  in  the  escape  of  some  of  the  gas,  and  the  conver- 
sion of  the  remainder  into  sulphuric  acid.  In  the  Pharmaco- 
poeia note  to  this  preparation  the  last  sentence  refers  to  this 
tendency  to  change  into  sulphuric  acid,  which  would  be  detected 
by  the  test. 
Acidum  Valerianicum.  The  process  for  this  acid  is  that 
of  Benjamin  J.  Crew,  published  originally  in  the  Amer.  Jour. 
Pharm.,  vol.  xxxii.  page  109,  in  describing  his  process  for  ob- 
taining crystallized  valerianate  of  ammonia.  The  manipulation 
is  based  upon  the  facts  that  concentrated  valerianic  acid  is 
insoluble  in  a  saturated  solution  of  sulphate  of  soda,  and  in 
strong  sulphuric  acid,  which,  on  the  contrary,  abstracts  from  it 
a  part  of  the  water  present.  In  the  subsequent  distillation 
the  aqueous  portion  comes  over  first  and  is  rejected,  or  after 
dehydration  by  S03  is  again  returned  to  the  retort. 
The  only  pharmacopceial  use  of  this  acid  is  in  the  prepara- 
tion of  the  valerianates  of  ammonia  and  quinia,  but  there  is  no 
doubt  it  will  become  useful  for  the  preparation  of  other  salts, 
as  that  of  morphia,  and  that  it  will  be  used  in  a  free  state  in 
mixtures.  It  is  probable  that  commercial  valerianic  acid 
is  often  contaminated  with  substances  derived  from  the  fusel  oil 
from  which  it  is  produced,  but  care  in  its  preparation  will  avoid 
this  fault.  I  am  not  aware  that  the  physiological  and  thera- 
peutic action  of  free  valerianic  acid  has  been  specially  studied 
though  it  seems  worthy  of  attention. 
(To  be  continued.) 
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