This document discusses the isolation and properties of nicotine. It describes how nicotine is extracted from tobacco plant leaves using dilute acid and purified through steps like steam distillation, crystallization, and extraction with ether. Nicotine exists as a colorless, volatile liquid with a boiling point of 246°C. It has a tobacco-like smell and is soluble in water and organic solvents. The document also examines the structure of nicotine through analysis and reactions. Nicotine is shown to have the molecular formula C10H14N2 and structure of a pyridine ring with an attached N-methylpyrrolidine side chain.