Method of testing lead acetate cotton for arsenic
Where arsenic is measured, lead acetate cotton is commonly used. The method of making it is to prepare an appropriate amount of cotton first, and infiltrate it with a pure lead acetate solution. Soak it well, so that the cotton can be dyed with its liquid. Then take it out, drain the excess liquid, and dry it in a ventilated place. After it dries, the lead acetate cotton is ready.

When testing, place the lead acetate cotton in a specific device. If the sample contains arsenic, under certain conditions, the gas produced by the reaction of arsenide passes through the lead acetate cotton. If the cotton changes color, it can be known that the sample contains arsenic. Because the arsenic gas and lead acetate chemically react, the color of the cotton will change. The degree of discoloration, or the amount of arsenic can be slightly inferred. For this test, the device must be well sealed and operated in a certain order, so that accurate results can be obtained.