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 



