Boil a portion of the sample gently with strong hydrochloric acid, add barium chlorid. A white precipitate of barium sulfate will form if sulfuric acid is present.
GYPSUM
Calcium Sulfate
Ash a portion of the sample and make the usual qualitative tests for calcium sulfate.
AMMONIUM SALTS
Extract a few grams of the sample with cold water, boil the extract with sodium hydroxid and place a piece of moist red litmus paper in the steam. It will be colored blue if ammonia is present.
ALUM
Reduce to an ash about 2 grams of the powder in a platinum dish. Extract with boiling water, add ammonium chlorid solution to the filtrate until a distinct odor of ammonia is given off.
If a flocculent precipitate forms it indicates the presence of alum.