AFebrXv!?9aor8m-}     Chemistry  of  Alkaloid  Estimations.  71 
and  tartaric,  or  when  only  sufficient  strong  acid  is  present  to  just 
neutralize  the  alkaloid,  extraction  with  chloroform  will  remove  an 
appreciable  amount  of  alkaloid  from  its  aqueous  solutions. 
It  has  also  been  shown  that  many  alkaloidal  salts,  as  such,  are 
soluble  in  chloroform,  especially  the  salts  of  hydrochloric  and 
hydrobromic  acid.  The  alkaloid  sulphates  were  not  found  to  be 
appreciably  soluble  in  chloroform  or  ether. 
The  practical  lesson  to  be  drawn  irom  this  is  that,  in  the  estima- 
tion of  alkaloids,  sulphuric  acid  should  be  given  preference  when- 
ever possible.  This  is  especially  true  when  in  forensic  estimations 
small  amounts  of  alkaloids  are  to  be  detected.  Where  tartaric  or 
phosphoric  acid  is  now  generally  used,  sulphuric  acid  should  be 
given  the  preference. 
Interference  of  Ammonia,  Volatile  Bases  and  Fats  in  the  Estima- 
tion of  Alkaloids. — It  was  first  pointed  out,  especially  by  Professor 
Thorns,  that  drugs — particularly  leaf  drugs — contain  volatile  bodies 
of  alkaline  reaction.  These  in  some  cases  are  ammonium  salts  ;  in 
other  cases  they  are  volatile  amines.  To  this  factor  are  due  the 
variable  results  formerly  reported  for  the  mydriatic  drugs,  especially 
henbane,  and  which  are  still  obtained  with  methods  such  as  those  of 
the  German  pharmacopoeia,  in  which  the  volatile  bases,  or  ammo- 
nium hydroxide,  whichever  is  present  in  the  drug,  is  carried  over 
into  the  ether  used  to  extract  the  drug.  Although  it  is  directed 
that  a  portion  of  this  ether  be  distilled  off  before  the  remaining 
etheral  fluid  is  titrated  for  its  alkaloid  content,  yet  these  methods 
often  give  high  results  because  the  volatile  bases  are  not  completely 
eliminated.  In  some  cases  even,  where  a  complete  evaporation  of 
the  ether  is  directed,  high  results  are  obtained  unless  special  pre- 
cautions are  taken  to  insure  the  complete  evaporation  of  the  vola- 
tile basic  bodies.  Several  attempts  have  been  made  to  eliminate 
errors  of  this  kind.  Thorns  precipitates  with  potassium  bismuth 
iodide,  which  reagent  precipitates  the  vegetable  bodies  commonly 
classed  as  alkaloids  and  eliminates  the  volatile  organic  bases, 
ammonium  salts  and  free  ammonia.  Another  way  of  eliminating 
this  error,  at  least  in  so  far  as  it  is  due  to  the  presence  or  formation 
of  ammonium  hydroxide,  has  recently  been  proposed  by  H.  M. 
Webster.  Webster  finds  that  while  alkaloid-hydrogen  tartrates  are 
quite  insoluble  in  alcohol,  just  as  are  ammonium-hydrogen  tartrate 
and  potassium-hydrogen  tartrate,  the  alkaloid-hydrogen  tartrates 
