Robert Angus Smith (1817-1884), an English chemist who first coined the phrase "acid rain" in 1852 when he noted the connection between London's polluted skies and the acidity of the region's rainfall. In Air and Rain (1872), he published results of his analysis of rainwater throughout the British Isles in the 19th century. Smith described three zones of air pollution: carbonate and ammonia in fields and open country; ammonium sulfate in suburbs; and acid sulfate and sulfuric acid in town. The most acid rain recorded was in Glasgow, Scotland; the reported value (representing an average of several individual samples) was 109.16 grains of sulfuric anhydride per gallon of rainwater. When sulfuric anhydride (SO₃) is dissolved in water, each mole of SO₃ becomes a mole of sulfuric acid, H₂SO₄.

Robert Angus Smith (1817-1884), an English chemist who first coined the phrase "acid rain" in 1852 when he noted the connection between London's polluted skies and the acidity of the region's rainfall. In Air and Rain (1872), he published results of his analysis of rainwater throughout the British Isles in the 19th century. Smith described three zones of air pollution: carbonate and ammonia in fields and open country; ammonium sulfate in suburbs; and acid sulfate and sulfuric acid in town. The most acid rain recorded was in Glasgow, Scotland; the reported value (representing an average of several individual samples) was 109.16 grains of sulfuric anhydride per gallon of rainwater. When sulfuric anhydride (SO₃) is dissolved in water, each mole of SO₃ becomes a mole of sulfuric acid, H₂SO₄.