(flourished 1st century BC) Roman architect, engineer, and author of the celebrated treatise De architectura, a handbook for Roman architects. Little is known of his life except what can be gathered from his writings. The treatise is divided into 10 books covering almost every aspect of architecture and city planning. His wish was to preserve the Classical Greek tradition in the design of temples and public buildings, and his prefaces contain many pessimistic remarks about the architecture of the time. His work was the chief authority on ancient Classical architecture throughout the antique revival of the Renaissance, the Classical phase of the Baroque, and the Neoclassical period.

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Dense, colourless, oily, corrosive liquid inorganic compound (H₂SO₄). A very strong acid, it forms ions of hydrogen or hydronium (H⁺ or H₃O⁺), hydrogen sulfate (HSO₄⁻), and sulfate (SO₄²⁻). It is also an oxidizing (see oxidation-reduction) and dehydrating agent and chars many organic materials. It is one of the most important industrial chemicals, used in various concentrations in manufacturing fertilizers, pigments, dyes, drugs, explosives, detergents, and inorganic salts and acids, in petroleum refining and metallurgical processes, and as the acid in lead-acid storage batteries. It is made industrially by dissolving sulfur trioxide (SO₃) in water, sometimes beyond the saturation point to make oleum (fuming sulfuric acid), used to make certain organic chemicals.

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