Norwich bulletin., 1922-06-17

screens, lamp chimneys, canopies and
 shades, particularly for gas mantels, al-
 so for military lanterns and in lantern
 slides.
 It's ability to withstand shocks and strains combined with its transparency
 has led to wide use in motor goggles, l spectacles, divers helmets, smoke hel
 nets, compass cards, gage fronts. and in windows subject to shock as in the coming towers of warships.
 Owing to the resonance of mica, cir | cular sheets of high muscovite are used l extensively in photographs. as sound roducing devices. Such sheets are used l also in other sound detecting instru-.
 ments such as submarine detectors. Among miscellaneous uses are its ap- plication for ornamental uses, particu- l larly in India, as a dressing for wounds l and as a substitute for canvas in por- trait painting.
 | Mica trimmings and materials that
 cannot be utilized for sheet mica or l splittings are fround and sold in pull verized form, The recent development of l wide uses for ground mica has open | ed up a field of utilization for more mi-
 ca that was formerly wasted, and has l thus helped to, place the industry on a more profitable basis. The more i'm I pure and coarser types are used as coating on tar roofing to prevent stick l ing when rolled. Purer and finer grain I ed mica are used in paints, ornamental | ties and concrete. A mixture of ground
 mica and powdered aluminium is said to make a rust-preventing paint of good | quality. On account of It's feat-resist- l ing qualities ground mica Is used in l railroad ear axle packings, in pipe and l boiler coverings, in fre-proof paints, and T in rubber tires. Ground mica is used liT7or 0fd ak FA- ] nitro-glyeerin- in the manufacture of cer- tain explosives, as a component in roof ing, as a filler in rubber and other pro- 1 ducts, in calico printing and as tire l powder. It. is used also in tinsel- dec I orations and as Santa Claus snow" for Christmas tree and window decoration. l It is used widely for ornamentation in l India on lamps, pottery, curtains, cloth l Ground mica mixed with starch is ap- I piled to cheap cotton to improve it's 1 appearance. It is used to some extent
 for medicinal purposes, but fortunately this use has not extended outside In-
 dia. The purest and finest ground mi
 ca is used for wallpaper decorations | as a lubricant for wooden bearings, and
 mixed with oil as lubricant for metal
 bearings. On account of its potash con
 tent ground mica may have some value
 as a fertilizer but its insolubule form
 would render 1t very slowly available foI
 plant food. It has been found that mica may be used successfully as a Aux ir
 ceramic wares.
 The mica industry Is characterized by numerous small operations conducted 1T 7 many instances by farmers who min, mica when the demand is strong, ol | at times when farming work are temper fly suspended. There are few mines op erated continuously or on a large scale Mica mining methods noted by the Bu l reau of Mines have for the most Tar been of the very simplest type, and mi t ca has been won by slow and laboriou | nichols Another factor that has dis couraged proper development of the in e dustry is the low price at which i'm : ported India mica is sold.
 - Feldspar is the most annbundan n gangue mineral in mica mines, and a s much of it is rure and of suitable com n position it may be employed in the pot = tery trades. Feldspar Is now being sol ] as a by-product of mica mines in Mort Carolina and New Hampshire. About 90 per cent. of all the mic mined in the Unites States is scra1 n Most of it consists of material unsuite $ for sheet mica, while part of 1t is refus = from trimmings There are tremendou 5, accumulations of scrip mica in Indis : but very little of 1t has been utiliz T | ed