An alkaloid obtained from belladonna.

Preparation. - It cannot be profitably prepared on a small scale. The chief parts of the process are the precipitation of acid colouring matters from a strong tincture by means of lime, removal of the alcohol, addition of water and carbonate of potassium, taking up the alkaloid from the alkaline solution by chloroform, and subsequent purification.

Characters. - In colourless, acicular crystals.

Solubility. - Sparingly soluble in water, more readily in alcohol and in ether.

Reactions. - Its solution in water has an alkaline reaction, gives a citron-yellow precipitate with terchloride of gold, has a bitter taste, and powerfully dilates the pupil. It leaves no ash when burned with free access of air. It is an active poison.

The following test has been proposed for the members of the group of mydriatic alkaloids - atropine, hyoscyamine, daturine, duboisine, and homa-tropine. To a small portion of atropine in a test-tube add about 2 c.c. of a 5 per cent. solution of mercuric chloride in 50 per cent. of alcohol, and warm gently. A precipitate will at once appear, and become brick-red in colour. This test does not answer in dilute solutions, neither does it turn out well if atropine be added to the mercury. Other alkaloids give for the most part a white precipitate (Gerrard).

Preparations.

B.P.

Dose.

Atropinae Sulphas.......................................................................................

1/200-1/20 gr.

Liquor Atropinae Sulphatis...........................4 gr. in 1 fl. oz........................

1/2-6 min.

Unguentum Atropinae (with rectified spirit 1/2 fl. dr. and prepared lard 1 oz. ............8 gr. in 1 oz ....................................