Lead Acetate Test Paper
Used for detecting hydrogen sulfide, this rapid qualitative test paper when wetted with distilled water can detect as little as 5 ppm of H2S in the atmosphere or in a gas stream. Hydrogen peroxide can be detected with this paper by pre-blackening the paper in H2S. Concentrations as low as 4 ppm can be detected.

Potassium Iodide Test Paper
Used for detecting chlorine and other oxidizing agents. In acid solution, oxidizing agents react with the iodide in the test paper to liberate iodine. The paper will turn blue in the presence of an oxidizing agent (e.g., CI2, Br2, H2O2, HNO2, etc.).