Atropine imparts a color to neither concentrated nitric  nor sulfuric acid in the cold, but dissolves to a clear solution.

A1. A crystal of atropine when moistened with three or four drops of fuming nitric acid leaves a yellowish residue when evaporated to dryness on a steam-bath. Let a drop of a solution of potassium hydroxide in 90 percent alcohol run over the residue.  Where they come in contact a reddish-violet color is produced.

A2. If a milligram of atropine is heated in a dry test tube until vapors begin to appear and then 1 cc of concentrated sulfuric acid is added and the heating continued, the odor of flowers is observed. By cautiously diluting with 2 cc of water and warming further it may be made more distinct.  On addition of small crystals of potassium dichromate to the concentrated acid solution the odor changes to that of oil or bitter almonds.

A3. Platinum chloride does not precipitate atropine or its salts (difference from most alkaloids).

A4. A very dilute aqueous solution of atropine (1:100,000) when applied to the eye causes a dilation of the pupil which lasts for a long time.