INSTRUMENTS AND < HI.MK AL TI:STS :>x7 



copper foil added and heated slightly, when the molybdenum is 

 reduced, coloring the >oliiti.n him-. Tungsten i> reduced hut 

 slightly hy copper, hut will yield a hlue >olution with /inc. 



Illustration. Use molybdenite, 



Tungsten (wolframum) W. Atomic weight, 184. Fusing 

 point, 2800 C. 



a. Bead test. Oxide of tungsten when dissolved in the S. Ph. 

 head in O. F. is colorless or nearly so; in R. F. the moderately 

 charged head is dirty green while hot and when thoroughly cold 

 is blue. 



6. Wet test. Compounds containing tungsten are dissolved 

 in the S. Ph. bead, removed from the wire, and reduced be>ide 

 tin on coal. After reduction, it is powdered and dissolved 

 in 1 cc. dilute HC1, when the solution becomes blue, or it may be 

 necessary to heat the solution with powdered tin. 



Illustration. Use wolframite (Fe.Mn)WO 4 . 



Tellurium, Te. Atomic weight, 127.6. Fusing point, 446 C. 



a. Coat. Tellurides when heated in R. F. on coal yield a 

 white coat of TeC>2, much like the antimony coat, which also 

 imparts a pale greenish color to the flame. 



6. Wet test. Powdered tellurides when heated in a test tube 

 with 2 or 3 cc. of concentrated H 2 S0 4 will color the acid reddish 

 violet. 



c. The substance is fused in the closed tube with 3 parts soda 

 and coal dust ; after fusion the tube is cooled and water added ; if 

 tellurium is present the solution will be reddish violet. 



Selenium, Se. Atomic weight, 79.2. Fusing point, 217 C. 



a. Odor. Compounds of selenium when heated in the R. F. 

 on coal yield a very disagreeable but characteristic odor, which is 

 a very delicate test for the element, even in small quantities. 



6. Coat and flame. If there is much Se present when treated 

 as in a, a white oxide coat will form, at times bordered with red. 

 The coat when treated with the R. F. volatilizes, coloring the flame 

 an intense azure-blue. 



Non-metallic acid elements. 



Sulphur, S. Atomic weight, 32.07. Fusing point, 115 C. 



a. Odor. Sulphides when roasted on coal in the O. F. yield 

 sulphur dioxide, SO 2 , which is detected by the characteristic odor, 

 as of a burning sulphur match. 



6. Soda test. Sulphur in any form may be detected by fusing 

 the powdered mineral in R. F. with 4 parts soda and coal dust. 



