284 ON THE DETECTION OF ARSENIC. 
little distance front of it in the form of a brilliant metallic 
ring, and which may be driven farther along the tube by 
the approach of the flame. Cut the tube at the place where 
the metal is found, then heat, it keeping the nose at some dis- 
tance above it, and the arsenical odor will be perceived in the 
most sensible manner. This experiment may be made upon 
a piece of arsenious acid so small that a piece sufficiently large 
to be taken from its place and introduced in the tube, will 
give a decided result. (Berzelius.) 
The following table from Lassaigne, displays the sensibility 
of the reactives employed in these experiments. 
Barytes wa- 
ter. 
None. 
None. 
. None. 
None. 
None. 
None. 
None. 
Lime water, j 
Flocculent 
white preci- 
pitate. 
First noth- 
ing-, then [be- 
comes tur- 
bid and pre- 
cipitates.' 
None. 
None. 
None. 
None. 
None. 
Ammoniacal 
sulphate of 
copper. 
Herb green 
precipitate. 
Idem. 
Idem but 
less intense. 
Pale green 
precipitate. 
Idem. 
Ulear green 
precipitate. 
Very pale 
green preci- 
pitate. 
s s 
S3- 
felt, 8 
Pale yellow 
precipitate. 
Idem. 
Idem. 
Whitish 
yellow pre- 
cipitate. 
Idem. 
None. 
None. 
Quantity of 1 j 
arsenious \ Hydro-sul- | 
acid dissolv- 1 pnuric acid, 
ed in water. J j 
Yellow. 
Yellow. 
Yellow. 
None. 
None. 
None. 
None. 
lo 
lo 
Ho 
lo 
h 
lo 
lo 
lo 
H 
r~ 
lo 
lo 
H o 
o 
l« 
lo 
lo 
Ho 
lo 
14 
lo 
lo 
~|o 
lo 
jc*> 
16 
