ON  THE  DETERMINATION  OF  HYDROCYANIC  ACID. 
551 
and  with  acetic  acid ;  it  moistens  bodies  without  rendering  them 
greasy ;  like  oil,  it  is  unctuous  to  the  touch,  and  does  not  evapo- 
rate when  exposed  to  the  air.  It  is  easily  charged  with  the 
aroma  of  volatile  oils  ;  it  does  not  become  rancid,  nor  does  it  fer- 
ment. 
M.  Bruere-Perrin  has  introduced  gtycerine  into  toilet  soap3, 
and  has  used  it  in  the  preparation  of  cosmetic  vinegar,  aroma- 
tized spirits,  and  several  other  articles  of  perfumery.  We  are 
assured  that  the  soap  with  glycerine  retains  its  original  soft  con- 
sistence, and  that  the  unctuosity  of  the  glycerine  is  imparted  to 
the  skin.  We  have  tried  several  of  these  preparations  and  verified 
the  descriptions  given  of  them. — Pharm.  Journ.,  Sept.  1853, 
from  Journal  de  Chimie  Medicate. 
ON  THE  DETERMINATION  OF  THE  STRENGTH  OF  PHARMACEU- 
TICAL PREPARATIONS  CONTAINING  HYDROCYANIC  ACID. 
By  Mr.  James  Roberton. 
Of  all  medicinal  preparations  there  are  none  which  are  more 
liable  to  variation  of  strength,  and  none  which  require  greater 
care  in  their  preservation,  than  those  which  contain  hydrocyanic 
acid.  From  recent  examinations  it  has  been  found,  that  in  that 
particular  preparation  known  as  Scheele's  acid,  these  variations 
have  ranged  from  4  to  5  per  cent.  And  in  the  aq.  lauro-cerasi 
I  have  sometimes  failed  in  detecting  the  presence  of  the  acid 
beyond  the  slightest  trace. 
In  medical  practice  the  evil  attending  such  a  want  of  uniformity 
in  such  a  remedy  is  at  once  apparent. 
To  the  Pharmaceutist  the  possession  of  a  reliable  test  for 
ascertaining  from  time  to  time  the  actual  condition  of  such  com- 
pounds is  of  great  practical  value.  For  accuracy  of  determina- 
tion and  ready  application  I  am  unacquainted  with  any  means  so 
useful  as  the  cyanometric  process,  proposed  by  MM.  Fordos  and 
Gelis  for  the  estimation  of  the  commercial  value  of  cyanide  of 
potassium,  founded  upon  the  reaction  of  iodine  upon  the  cyanides, 
and  which  consists  in  the  absorption  of  the  iodine  up  to  the  point 
of  saturation,  beyond  which  the  free  iodine  becomes  immediately 
apparent. 
In  the  practical  use  of  this  test  it  is  only  necessary  to  arrive 
