The  temperature  must  not  be  raised  much  be-
yond the  point  necessary  to  effect  this.  Pow-
der the  coal  thus  obtained  and  add  about
thirty  drops  of  oil  of  vitriol,  and  heat  until
vapours  begin  to.  rise ;  when  sufficiently  cool,
add  water,  and  boil  for  ten  minutes.  Filter
and  evaporate  the  filtrate  until  the  fumes  of
sulphuric  acid  begin  to  be  evolved,  when  10
gr.  of  metallic  tin  and  an  excess  of  nitric  acid
must  be  added,  together  with  water,  drop  by
drop,  until  action  between  the  acid  and  metal


commences.  When  all  the  tin  is  oxidised,  add
water,  aud  filter.  Evaporate  the  filtrate  until
fumes  of  sulphuric  acid  are  again  visible,
when  more  water  most  be  added,  and  the
liquid  again  filtered  if  necessary.  To  the
clear  solution  now  add  tartaric  acid,  then  am-
monia in  excess,  and  sulphide  of  ammonium.
Evaporate  the  liquid  containing  the  precipitate
suspended  to  it,  in  a  dish,  until  all  the  smell
of  sulphide  of  ammonium  has  disappeared.
Filtei',  evaporate  to  dryness,  and  ignite  to  get
rid  of  the  organic  matter.  Powder  the  black
ash,  boil  it  in  moderately  strong  hydrochloric
acid,  filter,  add  a  crystal  of  chlorate  of  potash,
and  boil  for  a  minute.  Now  add  chloride  of
ammonium  and  ammonia,  and  boil  for  five
minutes.  If  at  the  end  of  that  time  any  pre-
cipitate is  observed,  it  will  be  alumina.  From
the  filtered  solution,  if  oxalate  of  ammonia  be
added,  the  lime  will  be  precipitated;  and  if
to  the  filtrate  from  this,  ammonia  and  phos-
phate of  soda  be  added,  the  magnesia  will
come  down.
