6io 
Chemical  Notes. 
{Am.  Jour.  Pharm. 
Dec,  1880, 
alloys  are  therefore  best  dissolved  in  hydrochloric  acid,  with  addition  of 
potassium  chlorate.  If  nitiic  acid  had  been  used  it  must  be  removed 
beforehand  completely  by  evaporation  with  excess  of  sulphuric  acid. — 
Ber.  der  Chem.  Ges.^  xiii,  p.  1778. 
On  the  Detection  and  Determination  of  Arsenic  in  Organic  Matter. — 
Chittenden  and  Donaldson  have  given  Gautier's  method  of  decompos- 
ing organic  matter,  when  mixed  with  arsenic,  a  careful  revision  and 
have  modified  it  somewhat.  It  consists  essentially  of  successive  oxi- 
dations with  nitric  and  sulphuric  acids.  100  grams  of  the  suspected 
material,  cut  into  small  pieces,  are  treated  in  a  casserole  with  23  cc.  of 
concentrated  nitric  acid  and  the  dish  heated  to  lOO  to  i6o°C.,  with 
occasional  stirring.  In  one  and  a-half  to  two  hours  the  mass,  after 
having  been  quite  thick,  becomes  liquid,  and  then  the  heat  is  raised  to 
i8o°C.,  when  it  becomes  thick  again  and  of  an  orange  shade.  The 
casserole  is  then  taken  from  the  air-bath  and  3  cc.  of  pure  concentrated 
sulphuric  acid  added  and  the  mixture  well  stirred.  Powerful  oxidation 
and  evolution  of  nitrous  fumes  occurs,  but  no  deflagration,  and  the  car- 
bonization is  effected  without  the  loss  of  any  arsenic.  The  casserole 
being  again  heated  to  i8o°C.,  8  cc.  of  pure  nitric  acid  are  added  drop 
by  drop,  which  effects  a  more  complete  oxidation  and  prevents  the  for- 
mation of  any  sulphurous  acid  and  consequent  production  of  insoluble 
arsenious  sulphide.  On  heating  now  to  200°C.  for  fifteen  minutes  a 
hard  carbonaceous  residue  is  the  result,  free  from  any  nitric  acid.  In 
this  the  arsenic  exists  readily  soluble  in  water.  After  extraction  with  boil- 
ing water  the  reddish-brown  fluid  is  evaporated  to  dryness  on  the  water- 
bath,  the  residue  being  gotten  in  one  casserole.  This  residue  of  arsenic, 
with  a  little  organic  matter,  is  then  dissolved  in  a  definite  quantity  of 
dilute  sulphuric  acid  and  introduced  into  the  Marsh  apparatus.  The 
analytical  results  quoted  show  the  great  accuracy  of  the  method. — Am. 
Chem.  Journ..^  ii,  p.  235. 
Organic  Chemistry. — Synthesis  of  Indigo. — Although  it  was  an- 
nounced some  years  ago  that  the  artificial  formation  of  indigo  had  been 
effected,  yet  the  process  was  so  expensive  and  the  yield  obtained  so 
trifling  that  no  importance  attached  to  the  announcement.  Prof. 
Baeyer  of  Munich,  who  made  the  previous  synthesis,  has,  however, 
succeeded  now  in  effecting  the  synthesis  in  a  more  direct  way,  and  with 
a  yield  almost,  if  not  quite,  corresponding  to  the  amount  calculated 
from  the  material  taken.  He  has,  therefore,  patented  two  processes,  the 
general  outlines  of  which  are  now  made  public.    The  starting  point  of 
