550     DEPORTMENT  OF  ALKALOIDS  WITH  REAGENTS,  ETC. 
into  concentric  groups.  These  successive  changes  of  the  pre- 
cipitate may  be  traced  distinctly  even  with  the  naked  eye. 
4.  Ammonia  produces  in  solutions  of  salts  of  brucia  a  whitish 
precipitate,  which  appears  at  first  like  a  number  of  minute  drops 
of  oil,  but  changes  subsequently — with  absorption  of  water — to 
small  needles.  The  precipitate  redissolves,  immediately  after 
separation,  very  readily  in  an  excess  of  the  precipitant ;  but 
after  a  very  short  time — or,  in  dilute  solutions,  after  a  more 
considerable  lapse  of  time — the  brucia,  combined  with  crystal- 
lization water,  crystallizes  from  the  ammoniacal  fluid  in  small 
concentrically  grouped  needles,  which  addition  of  ammonia  fails 
to  redissolve. 
5.  Bicarbonate  of  Soda  produces  in  neutral  solutions  of  salts 
of  brucia  a  precipitate  of  brucia,  combined  with  crystallization 
water  ;  this  precipitate  separates  after  the  lapse  of  a  short  time, 
in  form  of  concentrically  aggregated  needles  of  silky  lustre, 
which  are  insoluble  in  an  excess  of  the  precipitant,  but  dissolve 
in  free  carbonic  acid  (compare  strychnia.)  Bicarbonate  of  soda 
fails  to  precipitate  acid  solutions  of  salts  of  brucia ;  and  it  is 
only  after  the  lapse  of  a  considerable  time,  and  with  the  escape 
of  the  carbonic  acid,  that  the  alkaloid  separates  from  the  fluid 
in  regular  and  comparatively  large  crystals. 
6.  Concentrated  nitric  acid  dissolves  brucia  and  its  salts  to  in- 
tensely red  fluids,  which  subsequently  acquire  a  yellowish-red 
tint,  and  turn  yellow  upon  application  of  heat.  Upon  addition 
of  protochloride  of  tin  or  sulphide  of  ammonium  to  the  heated 
fluid,  no  matter  whether  concentrated  or  after  dilution  with 
water,  the  faint  yellow  color  changes  to  a  most  intense  violet. 
7.  If  a  little  brucia  is  treated  with  from  four  to  six  drops  of 
pure  concentrated  sulphuric  acid,  a  solution  of  a  faint  rose  color 
is  obtained,  which  afterwards  turns  yellow.  If  from  eight  to 
twenty  drops  of  sulphuric  acid  mixed  with  some  nitric  acid 
(p.  394)  are  added,  the  fluid  transiently  acquires  a  red,  after- 
wards a  yellow  color.  Addition  of  binoxide  of  manganese 
transiently  imparts  a  red,  then  a  gamboge  tint  to* the  fluid.  If 
the  fluid  is  then,  with  proper  cooling,  diluted  with  four  parts  of 
water,  ammonia  added  to  nearly  neutral  reaction,  or  even  to 
alkaline  reaction,  the  solution  acquires  a  gold-yellow  color,  (J. 
Erdmann.) 
