THE  NATIVE   COUNTRY  OF  THORNAPPLE. 
541 
ON  BUIGNET'S  METHOD  FOR  THE  QUANTITATIVE  DETERMINA- 
TION OF  HYDROCYANIC  ACID. 
By  A.  Ferrein. 
The  Bulletin  General  deTherapie,  1858,  Janv.  15,  publishes  this 
volumetric  method  for  the  determination  of  hydrocyanic  acid,  which 
is  founded  on  the  peculiarity  of  two  copper  compounds,  the  double- 
salt  of  cyanide  of  copper  and  ammonium  being  colorless,  while  the 
sulphate  of  copper  and  ammonia  is  of  a  deep  blue  color. 
Accordingly,  if  a  liquid  containing  hydrocyanic  acid  is  oversatu- 
rated  with  ammonia,  and  a  solution  of  sulphate  of  copper  of  known 
strength  added  until  the  blue  color  becomes  permanent,  the  sul- 
phate of  copper  has  been  just  sufficient  for  the  reaction  with  the 
cyanide  of  ammonium,  and  thus  indicates  twice  an  equivalent 
quantity  of  hydrocyanic  acid. 
M.  Ferrein  dissolved  2.308  grm.  sulphate  of  copper,  (1  equiv. 
CuO,S03  +5HO,)  in  100  CC.  water,  which  just  suffice  for  the  de- 
composition of  1.000  grm.  or  a  double  equivalent  of  hydrocyanic 
acid,  according  to  the  following  calculation  : 
2x27;  124.6  =  1000:  2308. 
On  examining  a  medicinal  hydrocyanic  acid,  5.78 i  grm.  of  it 
required  4.8  CC  of  the  copper  solution,  corresponding  with  0.048 
grm.  HCy,  or  0.830  per  cent,  while  by  precipitating  with  nitrate  of  sil- 
ver, the  above  quantity  of  medicinal  acid  furnished  0.046  grm.,  or 
0.795  per  cent.  HCy. 
The  results  being  so  nearly  alike,  the  author  recommends  the 
above  volumetric  method. —  Wittstein's  Vierteljahresschrift,  vii. 
388-89.  J.  M.  M. 
THE  NATIVE  COUNTRY  OF  THORNAPPLE. 
By  Prof.  v.  Schlechtendal. 
The  author  in  Botan.  Zeitung,  1856,  849,  states,  that  Datura 
strammonium  is  a  native  of  southern  Russia,  where  it  is  very  com- 
mon in  the  countries  bordering  on  the  Black  Sea,  and  in  southern 
Siberia.  Older  botanical  works  do  not  mention  the  thornapple 
growing  wild  in  Europe,  but  several  authors  refer  to  it  as  a  garden- 
plant,  and  Clusius  states  positively  that  its  seeds  were  first  brought 
to  Innsbruck  and  Vienna  in  1583,  and  in  the  following  year  the 
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