86 CHEMICAL PROPERTIES OF MINERALS. 



2. Natrolite. — Fusible in small splinters in the candle 

 flanie. 



3. Almandine, or bright red garnet. — Fusible in large 

 pieces with ease in the blowpipe name. 



4. Actinolite. — Fusible in large pieces with difficulty in the 

 blowpipe flame. 



5. Orthoclase, or common feldspar. Fusible in small 

 splinters with difficulty in the blowpipe flame. 



6. Bronzite. — Scarcely fusible at all. 



The color of the fiame is an important character in connection 

 with blowpipe trials. When the mineral contains sodium the 

 color of the flame is deep yellow, and this is generally true in 

 spite of the presence of other related elements. When sodium 

 (or soda) is absent, potassium (or potash) gives a pale violet 

 color; calcium (or lime) a pale reddish yellow ; lithium, a deep 

 purple-red, as in lithia-mica ; strontium, a bright red, this ele- 

 ment being the usual source of the red color in pyrotechny; 

 copper, emerald green ; phosphates, bluish green ; boron, yellow- 

 ish green ; copper chloride, azure blue. Beads should be exam- 

 ined by daylight only, and should be held in such position that 

 the color is not modified by green trees or other bright objects 

 when examined by transmitted light. Colored flames are seen 

 to best advantage when some black object is beyond the flame 

 in the line of vision. 



It is also to be noted, in the trials, whether the assay heats 

 up quietly, or with decrepitation ; whether it fuses with effer- 

 vescence or not, or with intumescence or not ; whether it fuses 

 to a bead which is transparent, clouded, or opaque ; whether 

 blebby (containing air-bubbles or not) ; whether scoria-like or 

 not. 



Testing for Water. — The powdered mineral is put at the 

 bottom of a closed glass tube, and after holding the extremity 

 for a moment in the flame of a Bunsen's burner, moisture, if 

 any is present, will have escaped and be found condensed on the 

 inside of the tube, above the heated portion. Litmus or tur- 

 meric paper is used to ascertain if the water is acid or alkaline, 

 %cids changing the blue of litmus paper to red, and alkalies the 

 yellow of turmeric paper to brown. 



Testing for an Alkali. — If the fragment of a mineral, heated 

 in the platinum forceps, contains an alkali, it will often, after 

 being highly heated, give an alkaline reaction when placed, 

 after moistening, on turmeric paper, turning it brown. This 

 test is applicable to those salts which, on heating, part with a 

 portion of their acid and are rendered caustic thereby. Such 



