ON  THE  APPLICATION  OF  DIALYSIS,  ETC. 
207 
scope  they  were  found  to  be  six-sided  and  to  twist  a  ray  of 
plane  polarized  light,  were  not  volatile,  gave  a  violet  tint  to  flame, 
and  deflagrated  on  charcoal  ;  the  aqueous  solution  gave  a  yellow 
crystalline  precipitate  with  bichloride  of  platinum,  no  odor  on 
heating  with  caustic  alkali,  a  black  color  with  sulphate  of  iron 
and  sulphuric  acid,  and  yielded  ammonia  on  heating  with  potash, 
zinc  and  iron.  It  was  deemed  desirable  to  apply  all  these  tests 
in  this  and  similar  examinations,  as  a  pound  of  vegetables  sel- 
dom yielded  more  than  a  few  grains  of  crystals,  a  quantity 
sometimes  too  small  to  purify  crystallisation,  and  always 
too  small  to  admit  of  the  production  of  strongly  marked 
analytical  reactions.  In  the  case  of  potato,  however,  I 
went  to  the  trouble  of  operating  upon  thirty  or  forty  pounds  of 
the  tops  and  thus  obtained  about  the  same  number  of  grains  of 
nitrate  of  potash,  and  the  extra  labor  was  rewarded,  for  the 
mother-liquor  of  the  nitre,  after  standing  aside  two  or  three 
days,  yielded  a  small  crop  of  beautiful  little  crystals,  of  which 
I  can  at  present  say  but  little  more  than  that  they  were  not 
nitrate  of  potash.  They  were  perfect  little  hexagons,  not  much 
longer  than  broad,  with  flat  heads  ;  I  suspect  them  to  be  a  mag- 
nesium salt.  Besides  these  constituents,  the  juice  of  potato 
yielded  cubes,  hollow  pyramids,  and  prisms  of  chloride  of  po- 
tassium, much  ammonia  and  sugar,  even  immediately  after  ex- 
pression, and  other  matters,  the  nature  of  which  was  not  as- 
certained. 
Atropa  Belladonna  The  leaves  and  soft  parts  of  the  Deadly 
Nightshade  also  yielded  nitrate  of  potash  by  the  above  process. 
But  in  addition  some  acicular  crystals,  single  and  in  tufts,  were 
obtained.  These  were  carefully  separated  from  the  nitre  crys- 
tals and  were  recrystallized.  They  were  then  found  to  be  square 
prisms,  either  deliquescent  nor  efflorescent,  and  containing 
magnesium  as  the  sole  inorganic  constituent.  The  nature  of 
the  organic  matter  associated  with  the  magnesium  could  not  be 
ascertained,  apparently  it  was  not  any  of  the  ordinary  organic 
acids.  The  juice  of  Belladonna  also  contains  ammonia,  a  mat- 
ter which  reduced  copper  salts  as  sugar  does,  and  other  bodies 
not  examined. 
Bimm  sativum  Several  quarts  of  peas,  in  the  shell,  were 
similarly  treated.  The  product  was  a  thick  syrup  of  light-brown 
