118         RED  SANDAL  WOOD  AND  XANTHOSANTALIC  ACID. 
copper  in  solution.  Xanthosantalate  of  ammonia  affords  a  yel- 
lowish green  salt  with  sulphate  of  copper ;  and  this  is  also 
readily  decomposed  by  acetic  acid,  as  well  as  by  the  mineral 
acids. 
The  blood-red  precipitate  of  santalin  from  its  potash  solution 
was  well  washed,  and  then  boiled  with  nitric  acid  till  its  color 
wras  changed  to  an  orange  hue  and  a  solution  effected.  The  fil- 
tered solution  wTas  evaporated  to  dryness.  The  xanthosantalic 
acid  thus  prepared  was  found  to  be  soluble  in  water,  ether,  alco- 
hol and  acids ;  to  have  a  very  astringent  taste  ;  just  perceptibly 
to  redden  litmus  paper  ;  to  form  orange-colored  salts  with  potash 
and  with  ammonia  ;  a  gamboge-colored  precipitate  with  neutral 
acetate  of  lead  and  writh  chloride  of  barium  ;  a  light  brown  pre- 
cipitate with  protochloride  of  tin  and  with  the  salts  of  iron  ;  but 
no  precipitates  with  sulphate  of  copper,  bichloride  of  mercury, 
alum,  chloride  of  ammonium,  nor  sulphate  of  zinc.  Xanthosan- 
talate of  ammonia,  however,  and  sulphate  of  copper,  decompose 
each  other,  and  form  a  precipitate  of  xanthosantalate  of  cop- 
per of  a  yellowish  green  color.  A  similar  reaction  takes  place 
with  sulphate  of  zinc,  resulting  in  the  formation  of  a  tar-colored 
precipitate.  A  solution  of  alum  produced  in  a  few  seconds  a 
like  precipitate.  So  does  chloride  of  platinum.  But  I  obtained 
no  precipitates  with  xanthosantalate  of  ammonia  and  chloride  of 
gold,  nor  with  chloride  of  mercury,  nor  chloride  of  ammonium. 
The  protochloride  of  tin  and  sesquichloride  of  iron,  the  chloride 
of  calcium  and  chloride  of  barium,  all  yielded  precipitates,  but  the 
last  by  far  the  most  abundant  one.  The  nitrate  of  barytes,  like 
the  chloride  of  lime,  produced  but  a  scanty  precipitate.  Chlorate 
of  potash,  tartarized  antimony  and  ferro-cyanide  of  potassium, 
none. 
The  action  of  nitric  acid  on  protein  and  santalin  is  followed 
by  the  evolution  of  gas,  the  production  of  oxalic  acid  and  the 
formation  of  similar  yellow,  solid  acids,  the  xanthoproteic  and  the 
xanthosantalic.  Both  these  acids  slightly  redden  litmus  paper, 
both  form  soluble  orange-colored  salts  with  alkalies,  both  form 
colored  precipitates  with  metallic  salts.  But  xanthoproteic  acid 
is  without  taste;  xanthosantalic  acid  is  remarkably  styptic  ;  xan- 
thoproteic acid  is  insoluble  in  w7ater,  alcohol  and  ether,  xantho- 
santalic is  readily  soluble  in  them  all.  These  latter  characters 
are  sufficient  to  distinguish  the  two  acids. 
