592 MINERALOGY 



d. Many silicates when treated with acids decompose, leaving 

 a residue of flocculent silica, which on evaporation does not gelat- 

 inize. 



Boron, B. Atomic weight, 11. Infusible. 



a. Flame coloration. Some borates when heated alone in the 

 forceps yield a green flame ; all borates when heated with Turner's 

 flux yield a green flame. 



6. The green flame may be due to copper or phosphoric acid. 

 When in doubt, the mineral is fused with soda and dissolved in 

 dilute HC1. A piece of turmeric paper is moistened in this solution, 

 and carefully dried, when if boric acid is present the paper will 

 turn reddish brown. 



Illustration. Grind some tourmaline in the mortar, mix with 

 it 3 parts of Turner's flux and a drop of water. With a platinum 

 wire fuse some of this mixture in the side of the Bunsen burner 

 flame. Just after it begins to fuse, the bright green flame of boron 

 will appear. Mix some of the powdered tourmaline with 4 parts 

 soda and fuse several beads of the mixture on wire. These beads are 

 dissolved in 1 cc. of strong HC1 ; the solution is then diluted with 

 4 volumes of water. A piece of turmeric paper is moistened with 

 the solution, placed on a clean watch glass, and dried on the water 

 bath. When dry it will be reddish brown. 



