Nicotine is the alkaloid of tobacco, and is used as nicotine only experimentally. It is a very poison ous volatile fluid, very irritant to the skin and mucous membranes, and is absorbed from the latter.

It produces nausea, vomiting, and purging. It causes cardiac depression, lowers the blood pressure, and increases secretion, especially the perspiration. It contracts the pupils, depresses the motor nerves and spinal cord, and paralyzes the heart. It causes death by respiratory paralysis.

It is excreted in the urine, saliva, and perspiration.