AaaNoviri ^arm' }  Decomposition  of  Hydrocyanic  Acid.  813 
The  aqueous  distillate,  distinctly  acid  with  hydrochloric  acid, 
gave  366  Gm.  of  piperazine  hydrochloride  on  evaporation  to  dryness. 
The  crude  salt  may  be  recrystallized  from  dil.  alcohol  or  converted 
into  the  free  base  by  distilling  from  sodium  hydroxide. 
Anhydrous  piperazine  is  a  solid  with  distinctly  caustic  properties. 
For  this  reason  it  has  been  marketed  in  the  form  of  various  salts 
and  as  the  hydrate. 
It  is  sincerely  hoped  that  the  information  here  given  may  result 
in  the  manufacture  of  this  greatly  needed  medicinal  preparation 
by  some  American  laboratory. 
A  NOTE  ON  THE  DECOMPOSITION  OF  SOLUTIONS  OF 
HYDROCYANIC  ACID.1 
By  W.  Lewcock,  B.Sc. 
The  characteristic  decomposition  which  hydrocyanic  acid  under- 
goes whereby  a  dark  brown  precipitate  is  formed,  was  noted  during: 
the  source  of  experiments  on  the  production  of  the  anhydrous  gas-- 
on  the  large  scale.  One  product  of  the  decomposition  is  stated  ire 
the  literature  to  be  amino-malononitrile  NH2  CH(ON)2 — the  reac- 
tion, however,  is  complex,  and  in  this  note  attention  is  paid  solely  to 
the  cause  of  the  decomposition,  on  which  light  is  hardly  likely  to  be 
thrown  by  an  enumeration  of  the  various  products  of  the  decom- 
position. 
As  is  known,  on  mixing  a  solution  of  sodium  cyanide  with  a 
mineral  acid,  a  yellow  color  appears  as  soon  as  any  local  excess  of 
cyanide  occurs,  and  if  this  excess  is  permanent,  the  decomposition 
proceeds  with  the  separation  of  brown  flocks.  The  reaction  is  so 
rapid  at  higher  temperatures  that  in  attempting  to  run  a  continuous 
flow  plant,  in  which  the  gas  was  rapidly  driven  of!  by  steam  heat- 
ing, it  was  essential  always  to  keep  the  mixture  acid,  otherwise  the 
outflow  pipe  soon  became  blocked  with  the  deposit.  The  decomposi- 
tion, which  is  due  solely  to  excess  of  sodium  cyanide,  is  thus  pre- 
vented by  having  excess  of  acid  present,  but  too  much  mineral  acid 
effects  the  normal  hydrolysis  to  ammonium  formate,  and  it  may  be 
1  Reprinted  from  The  Pharmaceutical  Journal  and  Pharmacist,  August, 
1918.  Communication  to  the  British  Pharmaceutical  Conference  for  publica- 
tion in  the  "  Year  Book  of  Pharmacy/'  1918. 
I 
