ON  SOLUTION  OF  ACETATE  OF  AMMONIA. 
47 
The  medicinal  solution  of  acetate  of  ammonia, — liquor 
ammonias  acetatis,  or  spirit  of  Mindererus, — is  directed  to  be 
made,  by  our  National  Pharmacopoeia,  by  saturating  dilute 
acetic  acid  with  carbonate  of  ammonia  ;  and  it  is  ordered,  when 
dispensed,  to  be  freshly  made,  the  solution  then  containing  a 
portion  of  the  liberated  carbonic  acid  gas. 
In  regard  to  the  exact  amount  of  each  of  the  constituents  to 
be  employed  in  the  above  process,  it  happens  unfortunately 
that  neither  of  them  is  found  in  any  very  definite  state  of  com- 
position. 
The  sesqui- carbonate  of  ammonia,  varying  continually  from 
exposure,  absorbing  carbonic  acid  and  losing  ammonia,  be- 
comes a  bi-carbonate,  so  that  only  the  translucent  pieces  in  the 
interior  of  a  lump  have  any  very  near  approach  to  a  definite 
chemical  compound.  The  acetic  acid,  although  permanent,  is 
made  with  little  uniformity,  and  its  strength  can  only  be  ascer- 
tained by  chemical  tests.  It  follows,  therefore,  in  carrying  out 
the  directions  of  the  pharmacopoeia,  we  are  under  the  necessity 
of  falling  back  on  that  responsible,  and,  to  many,  vague  phrase, 
of  q.  s.  ad  saturandum.  As  the  amount  of  salt  in  this  solution 
depends  entirely  upon  the  strength  of  the  acetic  acid  employed, 
apothecaries  should  be  aware  that  acid  of  a  proper  strength  is 
not  readily  obtained.  Acetic  acid  No.  8,  sp.  gr.  1*047,  is  rarely 
met  with  ;  the  article  usually  called  No.  8  being  generally  only 
No.  6, — i.  e.,  one  pint  to  make  six  of  officinal  dilute  acetic  acid. 
The  precaution,  therefore,  of  diluting  to  a  lesser  extent  when 
weaker,  should  be  strictly  observed. 
The  acetic  acid  employed  in  this  preparation  should  be  en- 
tirely free  from  empyreumatic  odor,  derived  from  the  pyro- 
ligneous  acid,  from  which  it  is  generally  obtained.  If  free  from 
this  and  other  impurities,  it  should  be  diluted  with  pure  water 
until  its  density  be  reduced  to  1'007  at  60°  R  ;  the  ordinary 
No.  8  acid  requiring  about  five  times  its  bulk  of  water  to  dilute 
it  sufficiently.  In  taking  the  specific  gravity  of  liquids  vary- 
ing little  from  the  density  of  water,  particular  care  should  be 
observed  in  reducing  the  temperature  of  the  liquid  to  60°  F. 
Ottos  acetometer  will,  however,  be  found  a  more  reliable 
method  of  determining  the  strength  of  acetic  acid, — the  princi- 
