_Mercury, Quicksilver._—A metal fluid at ordinary temperatures. Congealable at about 40° below zero. Boils at 660° and forms a colorless dense vapor. It is used in barometers and thermometers, and in alloy with tin in coating mirrors. It unites with chloroform, forming calomel and corrosive sublimate. The only acids that act on it are sulphuric and nitric. To unite with the latter it must be heated. _Mercury, Chloride of._—See Chloride of Mercury. _Mercury, Horn._—Called Chloride of Mercury. _Mercury, Muriate of._—Chloride of Mercury. _Muriate Tincture of Steel._—See Muriate of Iron. _Muriate of Iron._—Called Chloride of Iron. Made by dissolving iron filings in muriatic acid and crystalizing by evaporation. Crystals of green color being the result. _Nitrate of Silver._—Made by dissolving silver in nitric acid and evaporating the solution in crystals. Will dissolve in warm water. Is used for indelible ink to mark clothing and in photography. When fused and cast in small sticks is called lunar caustic. _Nitric Acid._—See Acid, nitric. _Nitric Ether._—See Ether, nitric. _Oil of Vitriol._—See Acid, sulphuric. _Pearlash._—Carbonate of potassa. An alkali obtained from the ashes of trees by leaching. When evaporated to dryness in iron kettles it is called potash, but when calcined to burn off the coloring matter it is called pearlash. _Potash._—See Pearlash. Sometimes called salts of tartar. _Pumice Stone._—A substance resembling the slag from furnaces, ejected from volcanoes. The pulverized material is used to remove the gloss and imperfections on varnished surfaces by rubbing with a woolen cloth and water. _Quicksilver._—See Mercury. _Rotten Stone._—A soft stone used for fine grinding and polishing. Generally used after pumice stone, and is applied with a soft woolen cloth and sweet oil. _Salts of Tartar._—See Potash. _Sandarac._—A resin that exudes from tree growing in Africa. Fusible by heat and soluble in alcohol. Used in varnishes. _Sesqui-Chloride of Iron._—See Iron, Sesqui-chloride of. _Shellac._—Lac is a resinous substance produced mainly from the banyan tree of the East Indies. It is the product of an insect. Stick lac is the resin in its natural state; seed lac when broken up, cleaned of impurities and washed; shellac when it is melted and formed in thin flakes. United with ivory-black or vermilion it makes sealing wax. Dissolved in alcohol it makes lackers and varnishes. _Silver, Nitrate of._—See nitrate of silver. _Soda._—Common. See potash. _Spanish Whiting._—Ground chalk carefully cleaned from all stony matter. _Spirits of Nitre._—An alcoholic solution of nitrous ether. _Steel, Tincture of._—See muriate tincture of steel. _Sulphate of Iron._—Copperas or green vitriol. See copperas. _Sulphate of Manganese._—See manganese, sulphate of.