466  eochlebee's  proximate  analysis. 
removed,  must  now  be  subjected  to  a  more  minute  investigation.  The  ex- 
amination of  the  mixtures  of  substances  which  are  contained  in  the  fluids 
which  are  filtered  from  the  precipitates  prodaced  by  acetate  and  subacetate 
of  lead  in  one  portion  of  the  watery  decoction,  and  from  the  precipitates- 
caused  by  alum  in  a  second  portion  of  the  same,  is  facilitated  when  the 
former  are  freed  from  lead  by  sulphuretted  hydrogen,  and  the  latter  from 
sulphate  of  potassa  and  ammonia  by  alcohol,  and  then  distilling  off  the  al- 
cohol. Organic  bases,  many  bitter  bodies,  and  other  substances,  will  like- 
wise be  contained  in  those  fluids,  as  well  as  in  the  alcoholic  extract  of  the 
animal  charcoal.  The  concentrated  residue  of  this  alcoholic  extract  is  dilu- 
ted with  vjater.  Should  a  body  diflBcultiy  soluble  in  water  be  thereby 
thrown  down,  it  should  be  collected  on  a  filter,  A  small  portion  of  the 
watery  fluid  is  now  mixed  with  a  solution  of  sugar  of  lead  by  which  a 
precipitate  often  results,  because  coloring  matters  and  other  bodies  pos- 
sessing the  character  of  weak  acids,  afford,  with  lead,  insoluble  compounds- 
The  fluid  filtered  from  the  precipitate  resulting  from  sugar  of  lead  i& 
mixed  vfith  subacetate  of  lead,  to  observe  whether  a  precipitate  thereby 
ensues  or  not.  If  a  precipitate  results,  it  is  separated  by  a  filter  from  the 
fluid,  and  this  is  freed  from  lead  by  sulphuretted  hydrogen,  the  sulphuret- 
ted hydrogen  expelled,  and  the  fluid  evaporated  to  ascertain  whether  a 
residue  remains,  which  is  generally  not  the  case,  as  sulphuret  of  lead  fre- 
quently retains  the  bodies  which  were  taken  up  by  the  charcoal  from  the 
watery  solution.  On  this  account  the  sulphuret  of  lead  must  be  extracted 
with  hot  alcohol,  and  the  hot  liquid  filtered  from  the  sulphuret  of 
lead  in  a  hot-water  funnel.  Both  precipitates  resulting  from  sugar 
of  lead  and  subacetate  of  lead  are  boiled  with  alcohol  to  ascertain 
whether  they  dissolve  partially  or  entirely  in  alcohol.  The  8olu= 
tions,  if  resulting,  are  treated  with  sulphuretted  hydrogen,  the  sul- 
phuret of  lead  heated  to  the  boiling  point  with  the  spirit,  and  filtered  hot. 
In  the  spirit  with  which  the  precipitate  which  resulted  from  sub- 
acetate of  lead  was  heated,  an  organic  base,  or  a  mixture  of  several  such 
bodies,  may  possibly  be  detected.  The  portion  of  the  lead  precipitate  re- 
maining undissolved  in  boiling  alcohol  is  diffused  through  alcohol,  decom- 
posed by  sulphuretted  hydrogen,  the  fluid  heated  with  the  sulphuret  of 
lead,  and  filtered  hot.  These  different  fluids  are  evaporated  in  a  water- 
bath,  and  the  residues  preserved  for  further  examination  with  reagents. 
Having  spoken  of  the  treatment  of  the  precipitates  which  are  produced 
by  sugar  of  lead  and  subacetate  of  lead  in  one  portion  of  the  watery  de- 
coction, and  by  alum  and  ammonia  in  another  portion,  and  described  the 
treatment  of  a  part  of  the  watery  decoction  with  animal  charcoal,  we  will 
now  direct  our  attention  to  the  liquid  residues  which  have  been  obtained 
by  the  methods  already  related  from  the  watery  decoction  after  treatment  by 
the  two  salts  of  lead  or  alum  and  ammonia,  and  after  the  substances  precipi- 
tated by  these  means  have  been  separated  from  the  lead  by  sulphuretted  hy- 
drogen, and  the  sulphate  of  potash  and  ammonia  by  alcohol. 
