Hypnotic drugs, drugs that induce sleep, sometimes called soporifics. In general, hypnotics are central nervous system depressants. Alcohol, laudanum (see opium), bromide salts, and herbs such...

Silver chloride, chemical compound, AgCl, a white cubic crystalline solid. It is nearly insoluble in water but is soluble in a water solution of ammonia, potassium cyanide, or sodium thiosulfa...

Tetraethyl lead, (C2H5)4Pb, viscous, colorless, poisonous liquid. It is an organometallic compound prepared by reacting ethyl chloride with a sodium-lead alloy. When added to gasoline, it impr...

Burgess, Gelett (Frank Gelett Burgess), 1866–1951, American humorist, b. Boston. His ability as an illustrator led him into magazine work, and he was soon writing humorous articles and stories...

Swan, Sir Joseph Wilson, 1828–1914, English chemist and physicist. He made an incandescent lamp using a carbon filament (1860), 20 years before Edison's lamp. Noted for important contributions...

Tear gas, gas that causes temporary blindness through the excessive flow of tears resulting from irritation of the eyes. The gas is used in chemical warfare and as a means for dispersing mobs....

Sedative, any of a variety of drugs that relieve anxiety. Most sedatives act as mild depressants of the nervous system, lessening general nervous activity or reducing the irritability or activ...

Free radical, in chemistry, a molecule or atom that contains an unpaired electron but is neither positively nor negatively charged. Free radicals are usually highly reactive and unstable. They...

Bromine [Gr.,=stench], volatile, liquid chemical element; symbol Br; at. no. 35; at. wt. 79.904; m.p. –7.2°C; b.p. 58.78°C; sp. gr. of liquid 3.12 at 20°C; density of vapor 7.14 grams per lite...

Grignard reagent, any of an important class of extremely reactive chemical compounds used in the synthesis of hydrocarbons, alcohols, carboxylic acids, and other compounds. Chemically, a Grign...