146 
Chemical  Notes. 
(  Am.  Jour.  Pham. 
t      Mar.,  1880. 
can  be  made  from  bismuth  containing  arsenic  by  adding  the  coarsely 
powdered  metal  gradually  to  five  times  its  weight  of  nitric  acid,  heated 
to  between  75°  and  90°C.,  and  by  application  of  heat,  keeping  the 
reaction  going  actively.  There  is  formed  by  the  oxidation  of  the 
arsenic,  bismuth  arsenate,  which  Schneider  has  found  is  insoluble  in  a 
concentrated  solution  of  bismuth  nitrate,  and  separates  out  as  a  white 
powder.  After  the  settling  out  of  the  arsenate,  the  solution  is  filtered 
through  asbestos,  evaporated  to  crystallization,  and  the  neutral  salt  so 
gotten  changed  into  the  basic  salt  by  the  usual  method. — 'Jour,  fur  Pr. 
Chem.^  p.  20. 
Combustion  of  Hydrogen  Sulphide  Gas  in  Nitrous  Fumes. — Kessel 
describes  an  interesting  experiment  in  which  this  combustion  is  beauti- 
fully shown.  In  a  half-liter  flask  60  to  80  cc.  of  cold  fuming  nitric 
acid  (i'53  specific  gravity)  is  poured,  and  a  rapid  stream  of  sulphuretted 
hydrogen  gas,  purified  by  passing  through  a  wash-bottle,  is  passed  into 
the  acid.  This  becomes  rapidly  heated  and  the  flask  is  filled  with  red 
fumes.  If  now  the  delivery-tube  of  the  gas  be  withdrawn  from  the 
acid,  and  slowly  raised  to  the  mouth  of  the  flask,  the  hydrogen  sulphide 
gas  ignites  and  burns  with  a  bluish  flame,  tinged  with  a  reddish-yellow 
color.  If  the  flame  becomes  extinguished  the  addition  of  fresh  acid 
calls  it  forth  again.  The  neck  of  the  flask  becomes  filled  during  the 
combustion  with  white  sulphuric  acid  vapors,  while  the  space  below 
the  flame  remains  filled  with  red  fumes.  If  the  combustion  proceed 
properly  very  little,  if  any,  sulphur  separates  out. — Ber.  der  Chem.  Ges.^ 
xii,  p.  2305. 
Organic  Chemistry.— Z)/^^^//^;^  Ferment  of  Carica  Papaya. — A 
description  of  this,  the  so-called  melon  tree,  appeared  in  this  journal 
November,  1879,  p.  559.  A.  Wurtz  and  E.  Bouchut  have  made  an 
examination  of  the  juice  obtained  from  incisions  in  the  bark  of  the  tree. 
This  juice  separates  spontaneously  into  two  portions,  an  insoluble  pulp 
and  a  limpid,  colorless  liquid.  From  the  latter  of  these  alcohol  pre- 
cipitates a  body  which,  after  suitable  purification,  presents  the  charac- 
ters of  a  strong  digestive  ferment,  resembling  that  secreted  by  car- 
niverous  plants.  When  pure,  it  is  an  amorphous  white  powder,  entirely 
soluble  in  water — a  property  which  shows  the  absence  of  vegetable 
albumin.  It  contains  I0'6  per  cent,  of  nitrogen.  Its  aqueous  solution 
has  an  astringent  taste,  gives  an  abundant  precipitate  with  alcohol,  also 
with  nitric  acid,  soluble  in  excess  to  a  yellow  liquid ;  acetate  of  lead 
and  tannin  also  precipitate  it  from  its  solution.    Placed  in  contact  with 
