COMPOSITION  OF  THE  AQUA  LAURO-CEEASI. 
449 
As  it  is  not  likely  that  in  this  country,  where,  from  long 
usage,  laurel  water  has  become  firmly  established,  the  much  more 
stable  and  reliable  hydrocyanic  acid  will  ever  supersede  it,  I 
would  suggest  two  methods  by  which  the  evil  may  be,  if  not 
wholly  remedied,  at  least  palliated,  and  the  preparation  at  the 
same  time  be  retained. 
The  first  of  these  is,  that  as  laurel  leaves  can  be  obtained  at 
all  times  of  the  year,  the  preparation  should  be  much  more  fre- 
quently made,  and,  when  made,  be  standardized  in  the  manner 
directed  by  the  London  Pharmacopoeia  for  fixing  the  strength 
of  its  dilute  hydrocyanic  acid.  In  this  way  a  uniform  product, 
as  far  at  least  as  the  acid  is  concerned,  would  be  obtained. 
By  the  second  method  the  pharmaceutist  would  be  rendered 
independent  of  circumstances  which  might  prevent  fresh — and 
especially  young— leaves  being  obtained,  and  moreover  the  pro- 
portion of  volatile  oil  in  the  liquid,  which  by  the  first  method 
could  not  be  constant,  would  be  always  the  same.  I  propose, 
then, — firstly,  that  the  volatile  oil  be  distilled  from  the  leaves, 
and,  by  any  of  the  well-known  means,  wholly  deprived  of  hydro- 
cyanic acid,  the  subsequent  formation  of  which  might  be  guarded 
against  by  keeping  some  peroxide  of  mercury  in  the  bottle  which 
contains  it ;  secondly,  that  a  fixed  proportion  of  this  oil  be  dis- 
solved in  distilled  water,  and  that  hydrocyanic  acid  of  known 
strength  be  added  to  the  solution  in  such  quantity  as  to  make 
it  bear  an  easily  remembered  relation  of  strength  to  the  dilute 
acid  of  the  Pharmacopoeia, 
It  is  clear  that  the  time  for  such  a  change  will  be  upon  the 
advent  of  the  new  Pharmacopoeia  ;  but  by  way  of  example,  sup- 
posing that  a  dilute  acid  of  2  per  cent,  be  decided  upon,  the  fol- 
lowing would  be  an  advantageous  formula  for  the  preparation  of 
aqua  lauro  eerasi 
Dilute  hydrocyanic  acid       .       .       .35  grains. 
Volatile  oil  of  cherry  laurel  .       .       .  5 
Distilled  water      ...       .       .      4  oz. 
This  solution  would  contain  2  per  cent,  of  hydrocyanic  acidi 
(which  in  its  turn  would  contain  2  per  cent,  of  real  acid),  or 
in  the  other  words,  50  minims  would  be  equivalent  to  one  minim 
of  dilute  hydrocyanic  acid.    From  the  facility  with  which  this 
water  could  be  made,  no  valid  excuse  could  be  found  for  not 
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