SULPHUR n.
ur dioxide (Chem.), a colorless gas, SO2, of a pungent, suffocating odor, produced by the burning of sulphur. It is employed chiefly in the production of sulphuric acid, and as a reagent in bleaching; -- called also sulphurous anhydride, and formerly sulphurous acid. -- Sulphur ether (Chem.), a sulphide of hydrocarbon…
TEMPERING n.
the degree required, as indicated by the color produced on a polished portion, or by the burning of oil. Tempering color, the shade of color that indicates the degree of temper in tempering steel, as pale straw yellow for lancets, razors, and tools for metal; dark straw yellow for penknives, screw taps, etc.; brown ye…
UMBER n.
est. Called also umbrette, umbre, and umber bird. Burnt umber (Paint.), a pigment made by burning raw umber, which is changed by this process from an olive brown to a bright reddish brown. -- Cologne, or German, umber, a brown pigment obtained from lignite. See Cologne earth.
UNIT n.
e of the Fahrenheit scale. Rankine. -- Unit of illumination, the light of a sperm candle burning 120 grains per hour. Standard gas, burning at the rate of five cubic feet per hour, must have an illuminating power equal to that of fourteen such candles. -- Unit of measure (as of length, surface, volume, dry measure, l…