Testing Paris Green. 373 
test consists in adding sulfuret of hydrogen to a 
solution of the poison, when, if arsenic is pres- 
ent, a yellow precipitate (or sediment) will be thrown 
down. 
In a bottle holding five or six ounces, place a 
quarter of a teaspoonful of Paris green. Add water 
until the bottle is nearly full; shake well, and then 
allow the material to settle. The clear liquid which 
remains on top will contain what soluble arsenic 
may be present. Carefully turn off this clear liquid 
into a long, slender bottle, or test-tube, add two or 
three drops of muriatic or sulfuric acid, then add 
a tablespoonful or more of the solution of sulfuret 
of hydrogen. If any arsenic is present in the clear 
liquid, a yellow discoloration will at once appear, 
and if the liquid is allowed to stand for a few 
minutes, patches or grains of a sand-like material 
will settle to the bottom. This yellow precipitate 
is sulfide of arsenic. If very little soluble arsenic 
is present, the sulfuret solution should be warm 
when used, for the reaction is then more delicate. 
The sulfuret is easily made by anyone who has had 
even an elementary instruction in chemistry, by add- 
ing sulfuric acid to iron pyrites. 
This sulfuretted hydrogen is not a commercial 
preparation, but it is present in all sulfur mineral 
water, and the water sometimes gives the test. One 
can make sure of the presence of this material, 
for its odor is strong and offensive. It is the odor 
of spoiled eggs. If mineral water is used, it should 
be strong and fresh, and about equal in quantity 
