PURIFICATION  OF   ESSENCE  OF  ALMONDS. 
355 
being  so  much  diluted  with  spirit  as  greatly  to  diminish  the  dan- 
ger attending  its  use. 
Dr.  Normandy  could  not  assent  to  the  last  observation.  He 
thought  the  essence  the  more  dangerous  preparation  of  the  two, 
from  its  being  more  palatable,  and  therefore  more  likely  to  be 
drank.  A  case  had  come  under  his  observation  in  which  a  ser- 
vant, finding  a  bottle  of  the  essence,  which  he  mistook  for  noyeau, 
was  instantly  killed  from  tasting  it. 
Mr.  Allchin  said,  as  the  difficulty  attending  the  distillation 
of  the  oil  in  glass  vessels,  for  the  purpose  of  purifying  it,  had 
been  alluded  to,  he  might  mention  that  he  had  found  a  very  easy 
means  of  preventing  the  bumping  of  the  liquid  to  consist  in  ad- 
ding common  salt  to  the  liquid,  so  as  to  increase  the  density  of 
the  aqueous  part. 
Mr.  Redwood  thought  that  something  still  remained  to  be 
determined  experimentally,  before  the  subject  under  the  notice 
of  the  Meeting  could  be  considered  to  be  satisfactorily  settled.  It 
was  certainly  very  desirable  that  oil  of  bitter  almonds  and  its 
preparations,  which  were  principally  used  for  flavoring  articles 
of  diet,  should  be  rendered  innocuous  by  the  separation  of  the 
hydrocyanic  acid  which  the  crude  oil  contained,  but  it  was  also 
important,  and  indeed  essential  to  the  successful  application  of 
any  process  of  purification,  that  the  product  should  retain  the 
true  almond  flavor,  and  that  it  should  be  sufficiently  permanent 
to  admit  of  its  being  kept  for  a  reasonable  time.  Some  of  the 
processes  which  had  been  proposed  for  the  purpose,  did  not  com- 
pletely remove  the  hydrocyanic  acid,  and  this  would  perhaps 
serve  to  explain  the  differences  of  opinion  which  had  prevailed 
with  reference  to  the  effects  of  the  purified  oil.  There  was 
reason  to  believe  that  the  hydrocyanic  acid  existed  in  the  crude 
oil  so  that  Prussian  blue  was  no  longer  formed  in  the  usual  way, 
if  the  purified  oil  was  kept  for  some  time,  free  hydrocyanic  acid 
again  appeared.  Some  of  the  processes  which  had  been  sug- 
gested, however,  completely  removed  the  whole  of  the  poisonous 
ingredient,  and  the  oil  was  then  perfectly  innocuous,  but  after 
being  thus  purified,  it  was  found  to  be  much  more  susceptible  of 
oxidation  than  when  in  its  crude  state,  indeed,  so  much  so,  as 
greatly  to  diminish  its  value  as  a  flavoring  substance.  The  puri- 
fied essence,  after  a  time,  became  little  else  than  a  solution  of 
