344 
ESSENTIAL  OIL  OF  BITTER  ALMONDS. 
To  test  this  quality,  a  small  splinter  of  the  copal  is  put  into  a 
small  test  tube ;  a  little  of  the  solvent  fluid  is  then  poured  in, 
and  the  whole  is  heated.  If  the  copal  dissolves  completely  in  a 
few  minutes  without  becoming  gelatinous,  it  is  good. 
When  the  desired  quantity  of  good  copal  has  been  got  toge- 
ther in  this  manner,  it  is  to  be  pounded  to  a  tolerably  fine  pow- 
der, which  is  to  be  put  into  a  glass  retort  or  flask,  the  necessary 
quantity  of  the  solvent  added,  and  the  whole  heated  and  shaken 
until  solution  is  effected.  To  clear  the  varnish,  which  may  appear 
somewhat  dull,  from  dust  or  other  impurities,  it  may  be  allowed 
to  stand  a  long  while  until  these  settle ;  or  if  it  be  desired  to 
effect  this  quickly,  it  may  be  filtered  through  blotting  paper, 
placed  as  a  filter  in  a  glass  funnel ;  the  filter  must  not  project 
above  the  edge  of  the  funnel,  so  that  the  latter  may  be  closed 
by  a  glass  plate  laid  over  it.  The  passage  of  the  thick  varnish 
is  of  course  very  slow,  but  the  varnish  is  obtained  perfectly  clear 
in  this  manner ;  and  if  the  copal  employed  were  very  clear,  it  is 
nearly  colorless.  It  dries  rapidly,  but  like  all  turpentine  var- 
nishes, retains  a  slightly  sticky  surface  for  some  days. — Qhem. 
Graz.,  May  1,  1854,  from  Dingier' s  Polytech.  Journ. 
THE  ESSENTIAL  OIL  OF  BITTER  ALMONDS. 
By  Dr.  Douglass  Maclagan. 
He  commenced  by  observing,  that  attention  had  been  directed 
in  Edinburgh  to  this  subject  by  the  recent  occurrence  of  a  case 
of  accidental  poisoning,  with  a  bottle  of  a  flavouring  substance 
marked  quintessence  of  ratafia,  and  which  was,  in  reality,  oil  of 
bitter  almonds.  Dr.  George  Wilson,  who  examined  the  poison 
in  this  case,  had  brought  under  the  notice  of  the  authorities  the 
well-known  fact  that  by  chemical  means  the  hydrocyanic  acid 
might  be  separated  from  the  hydruret  of  benzule,  which  forms 
the  real  flavoring  ingredient,  and  that  thus  the  great  source  oi* 
its  poisonous  properties  might  be  removed.  It  was  still  matter 
of  doubt,  however,  whether  even  after  complete  removal  of  the 
hydrocyanic  acid,  the  hydruret  of  benzulo  was  or  was  not  poiso- 
nous, and  Dr.  Maclagan  had  made  a  series  of  experiments  to 
satisfy  himself  on  this  point.  The  author  first  reviewed  the  pro- 
cesses for  separating  the  prussic  acid  from  the  oil.  Agitation 
