OCTOBEB 23, 1908] 



SCIENCE 



553 



the element, prepared by Schilling, shows 

 over three hundred and fifty analyses of 

 tantalum minerals comprising about forty 

 species which occur widely distributed 

 throughout the world. In our own coun- 

 try, South Dakota and Colorado reported 

 a commercial production of the ores in 

 1906, and fair sized deposits have been 

 found in North Carolina, Texas, and else- 

 where. Last year ore carrying 80 per 

 cent, of TaaOg was sold at from three to 

 four dollars a pound. Since one pound of 

 the metal will make some tens of thousands 

 of lamp filaments, material for the new 

 lights would seem to be plentiful and cheap. 



Notable as a matter of purely chemical 

 interest is the work of Edgar F. Smith and 

 his associates upon the compounds of tan- 

 talum and columbium or niobium. 



In Group (6) we have the elements Mo, 

 "W, U, Se and Te. Molybdenum, like vana- 

 dium, on account of its many well-defined 

 oxidation stages presents interesting prob- 

 lems in analytical and synthetical chem- 

 istry ; and the last half decade contains the 

 record of considerable work upon the com- 

 plex organic and inorganic compounds. 

 The ores are in steady demand, chiefly for 

 the production of ammonium molybdate, 

 which is used in phosphate determinations, 

 in fire-proofing, in coloring pottery glazes, 

 and as a germicide. Molybdic acid is em- 

 ployed to some extent in dyeing. The 

 metal is used in steels, but on account of its 

 low fusing point can not be employed in 

 filaments for incandescent lighting. 



Few of the so-called rarer elements oc- 

 cupy so prominent a position at the present 

 time as tungsten. Its production in this 

 country alone has increased from about 

 three hundred short tons, valued at about 

 $44,000 in 1903, to over nine hundred short 

 tons, valued at about $350,000 in 1907— an 

 increase in amount of 200 per cent, and in 

 value of 600 per cent. The principal 

 source of tungsten ore in this country has 



been the deposits of wolframite in Boulder 

 County, Colorado, while Arizona, Montana, 

 New Mexico, Washington and Idaho have 

 furnished some ore. Recently deposits of 

 hiibnerite in the Snake Range, Nevada, and 

 of wolframite near Raymond, Cal., have 

 been investigated. Ores are also mined in 

 Europe, Africa, South America and Aus- 

 tralia. 



Without doubt, the most spectacular use 

 of tungsten at present is in the filaments 

 of the incandescent electric light bulbs. 

 This metal with its melting point over 

 3,000° C, a little higher than that of tan- 

 talum, makes a lamp which has the advan- 

 tage of giving one candle power of light 

 per 1.25 watts of electrical energy, as 

 against 2 watts in the case of the tantalum 

 lamp, and which has a life of one thousand 

 or more hours as against about five hun- 

 dred hours for the carbon and tantalum 

 lamps. The chief disadvantage of the 

 tungsten lamp is the extreme fragility of 

 the filament, which makes losses in trans- 

 portation large imless the packing is 

 very carefully done. Tungsten-titanium, 

 tungsten-tantalum and tungsten-zirconium 

 lamps have been recently suggested, but so 

 far as I can learn they are still in the 

 experimental stage. 



Among the better and longer known uses 

 of tungsten are its employment in ferro- 

 tungsten for the hardening of steels, and 

 in sodium tungstate for fireproofing dra- 

 peries and as a mordant in dyeing. Cer- 

 tain salts are also used in weighting silks. 

 The high melting point of the element has 

 suggested its possible use in the manufac- 

 ture of crucibles. 



Notable among the recent purely chem- 

 ical work upon this element has been the 

 study of the complex tungstates with titan- 

 ium, zirconium and thorium, and the double 

 poly tungstates of alkali earths with the 

 alkalies. The formation of the silicides of 



