190. SO2 a Bleacher.
Experiment 107.-Test its bleaching power by burning S under a receiver under which a wet rose or a green leaf is also placed.
Chapter XXXVIII.
HYDROGEN SULPHIDE.
Examine ferrous sulphide, natural and artificial.
191. Preparation.
Experiment 108.—Put a gram of ferrous sulphide (FeS) into a t.t. fitted with a d.t., as in Figure 32. Add 10cc. H2O and 5cc. H2SO4. H2S is formed. Write the equation, omitting H2O. What is left in solution?
192. Tests.
Experiment 109.-(1) Take the odor of the escaping gas. (2) Pour into a t.t. 5cc.solution AgNO3, and place the end of the d.t. from a H2S generator into the solution and note the color of the ppt. What is the ppt.? Write the equation. (3) Experiment in the same way with Pb(NO3)2 solution. Write the equation. (4) Let some H2S bubble into a t.t. of clean water. To see whether H2S is soluble in H2O, put a few drops of the water on a silver coin. Ag2S is formed. Describe, and write the equation. Do the same with a copper coin. (5) Put a drop of lead acetate solution, Pb(C2H3O2)2, on a piece of unglazed paper, and hold this before the d.t. from which H2S is escap- ing. PbS is formed. Write the equation. This is the characteristic test of H2S.
193. Combustion of H2S