448 
COMPOSITION  OF  THE  AQUA  LAURO-CEEASI. 
importance,  would  then  exercise  considerable  influence  over  the 
amount  of  active  matter  contained  in  the  product.  Closely  con- 
nected with  this  part  of  the  question  are  the  results  obtained  by 
Pereira  in  experimenting  on  bitter  almond  oil.  He  found  that 
a  quantity  of  this  substance  which  had  been  carefully  purified, 
and  in  which  he  could  not  detect  a  trace  of  hydrocyanic  acid, 
gave,  after  having  been  kept  for  a  few  months,  distinct  evidences 
of  its  presence.  If  we  assume — as  we  can  scarcely  avoid  doing 
— that  an  analogy  exists  between  this  oil  and  oil  of  cherry  laurel, 
another  condition  of  change  is  introduced,  and  an  increase  of 
hydrocyanic  acid  in  the  water  must  result  from  its  being  kept. 
Experiments  in  this  direction  are,  however,  still  wanting. 
My  next  step  is  naturally  to  inquire  in  what  degree  this  in- 
constancy in  the  composition  of  laurel  water,  which  we  assume 
upon  theory,  is  borne  out  by  experience  of  its  effects,  and  we 
find  that  here  facts  bear  us  out  more  fully  even  than  before.  A 
short  summary  of  these  facts  will,  while  occupying  less  space 
than  a  more  detailed  account,  at  the  same  time  illustrate  the 
case  more  clearly. 
Fonquier  has  given  twelve  ounces  in  the  course  of  a  day  with- 
out any  evident  effect. 
In  1781,  Sir  T.  Boughton  was  poisoned,  death  resulting  in  half 
an  hour  by  Uvo  ounces. 
In  another  case,  quoted  by  Taylor,  one  ounce  and  a  ^a?/*caused 
death  in  an  adult. 
Then  as  regards  chemical  analysis,  Pereira  (quoted  by  Taylor) 
gives  the  average  strength  as  equal  to  a  solution  of  hydrocyanic 
acid  containing  0.25  per  cent.  Two  samples  which  I  have  ex- 
amined, and  which  were  obtained  from  two  of  our  first  pharma- 
ceutical laboratories,  yielded  respectively  0.01  i  and  0.009  per 
cent.  ;  in  fact,  mere  traces,  the  numerical  value  of  which  could 
not,  but  that  large  quantities  were  operated  upon,  have  been 
stated  at  all. 
Surely  further  evidence  is  not  needed  to  show  that  this  pre- 
paration is  most  inconstant,  and  that  even  if,  on  the  one  hand, 
no  bad  results  often  ensue  from  its  administration;  on  the  other, 
the  practitioner  must  frequently  experience  much  disappointment 
from  the  inactivity  of  a  medicine  which  he  believes  to  contain  12 
per  cent,  of  pharmacopoeial  hydrocyanic  acid. 
