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Show MERCURY-ONLY UPIDMETAL Mercury Is one of the most talked of metals we use. It is what the "mercury "mer-cury says" that tells us the number of degrees Fahrenheit it takes to wilt crops in August or to freeze water in December. But the mercury thermometer ther-mometer is only a single use for a wonderful metal which is used in a hundred arts and trades today. Mercury Mer-cury is one of the most modern metals in scientific discovery, and electric research and investigation. Without it the Mazda lamp, the mercury vapor lamp, the Coolidge vacuum tube, and many other modern electrical conveni. ences could never have approached their present efficiency and utility. The skillful surgeon, up-to-date dentist, dent-ist, engineer, photographer, chemist all use mercury or instruments which contain it. It enables the U. S. weather weath-er bureau to take its observations throughout the country. Yet despite these modern applications, mercury is a metal which has been known to scientists sci-entists of all ages. At first not recognized rec-ognized ns a true metal, mercury nevertheless nev-ertheless played an important part in the work of the alchemists of the middle mid-dle ages who first succeeded In isolating isolat-ing it in a metallic form. ' Mercury occurs In nature as red sulphide or cinnebar, a substance .which the North American Indian first used as a facial pigment long before the present day cometic came into use. Its discovery dates back to 300 years before the Christian era when the parly alchemists separated it from cinnebar with copper and vinegar. Soon afterward powerful compounds of mercury were discovered amd first used by Arabian physicians. From this beginning, mercury has become an Important nnd valuable article ar-ticle of commerce today. The early alchemists maintained mercury was not a metal because no other metal assumed the form of a liquid at normal nor-mal temperature. This may be disproved dis-proved by Immersing a quantity of mercury in liquid air. The intense cold soon freezes the mercury into a solid block and its metallic nature may be established by driving nails into the hardest wood, the frozen mercury producing pro-ducing a ring like steel against the nail head. The earliest supplies of mercury were all obtained abroad from Alma-den Alma-den and Idrlan mines. Later, deposits of cinnebar were discovered in this country and today California and Tex-as Tex-as are the main sources of the coun try's supply. Utah, Nevada, Oregon and Arizona also produce the metal, while Spain, Austria-Hungary, Russia, Italy and Mexico are other countries' where large amounts of the metal are extracted. By far the largest quantK ties mined today are manufactured into in-to explosives. This has forced tho price up to n point where the metal has often changed hands at two and three times its normal value. It is reported re-ported that 40,000 flasks of tho metal were exported from this country to Great Britain in 1915. It is shipped in steel bottles or flasks, ea'ch flask containing con-taining 76 pounds. Smaller reducing plants send out mercury In small sheepskin bags, each bag containing about 55 pounds of metal. After shipment ship-ment superficial Impurities are removed re-moved by forcing It through chamois skin. Compared with the difficulties encountered en-countered in the separation of other metals from their ores, the reduction of mercury from cinnebar Is a simplo process. Two methods of extraction are used. Heat is the reducing agent in both cases. In one method the heat is applied to cinnebar in the presence pres-ence of air; In the other, the air is excluded and the cinnebar is heated in a vessel containing lime or Iron. Both methods are conducted with heat sumcient 10 cnange tne mercury mio a vapor which is later condensed and purified. The process in which air Is excluded yields the largest amount of mercury and therefore a greater profit but this process is exceedingly dangerous danger-ous to workmen. Metallic mercury as it comes from tho reducing plant is used for a variety vari-ety of purposes. Today the greater part of it Is manufactured in fulminate for detonating explosives. This is a substance, the perparation of which is fraught with the greatest danger. Fulminate Ful-minate Is made by dissolving mercury in nitric acid. The solution is then slowly added to alcohol. During the mixing processes the vapors given off arc dangerous, because of their high degree of inflammability. When dry the fulminate must be handled with the greatest care, for It explodes with great force when struck or jarred. This substance is widely used to set off charges of dynamite, gunpowder and nltro-glycerine. How Mercury Is Used in Electrical Apparatus. In the electrical trades mercury is used principally in mercury arc rectifiers recti-fiers and mercury vapor lamps. The mercury arc rectifier is an ingenious device for converting alternating into j direct current. It consists of a glass bulb containing mercury and mercury vapor and operates on the principle of a ratchet, permitting the alternating alternat-ing current to flow in one direction but offering high resistance to its passage in the opposite direction, i Thus the current is changed from alternate al-ternate waves flowing back and forth into pulsating waves flowing In the ! same direction. The operation of the ( rectifier depends upon the peculiar be J havior of electricity in a vacuum tube containing mercury vapor. The cur- rent will readily flow from a solid electrode the resistance presented to i its passage is too great. The resist-1 ance to its passage in one direction only thus acts like a check valve, and with each change in the direction of the current flow, a part of the current; is retained and converted into con- tinuous current which passes outj through the mercury electrode. The mercury vapor lamy is a tube j and bulb with an operating mechanism mechan-ism attached. The tube contains a quantity of mercury but practically no air and has an electrode at each end. ' Electricity passing through the tube and its electrodes changes a part ot the mercury into vapor. The vapor, unlike most vapor, has the peculiar property of becoming luminous when a sufficient quantity of electric current cur-rent Is passed through it in a vacuum. The light produced is of a penetrating greenish tint and is used in places where it Is desired to illuminate a large area at slight expense, and where the color of the light is not objectionable. ob-jectionable. The government printing print-ing office in Washington, manufacturing manufactur-ing establishments, coal yards and machine shops are extensive users of the mercury vapor lamp. Owing to the actinic power of the light they are often used in motion picture and photographic pho-tographic studios. This is the only form of electric light which Is more economical than the incandescent house lamp. The color of the light, however, makes it undesirable as house illuminant. Mercury Separates Gold From Its Ores. Mercury has a great affinity for gold. A small quantity of mercury dropped on a gold ring cannot be removed re-moved without the greatest difficultv. It is this property which has made it valuable in the metallurgical processes proces-ses for the extraction of gold from its ores. The powdered quartz is mixed with mercury and the gold and the mercury unite to form an amalgam. The amalgam is placed in a vessel and heated. The mercury is distilled off in the form of a vapor and the gold is left in a pure state. Silver is also extracted in a similar manner. A fair Idea of the importance of mercury in the electrical field may be obtained from the appended list which gives only a few of the purposes for which mercury is used in the operation oper-ation of things electrical: Wireless instruments, electric batteries, bat-teries, flow meters, vacuum . pumps, electric-plating. switches. mercury vapor lamps,, Mazda lamps, rectifiers. X-ray apparatus, Coolidge tubes, electric elec-tric interrupter, barometers. nn |
