99 CHEMICAL PROPERTIES OF MINERALS. 
Chlorides. —If a bead of borax be saturated with copper 
oxide, aud then dipped into the powder of a substance which is 
to be tested for chlorine, a chloride of copper is formed which 
imparts an azure blue color to the flame if any chlorine is pres- 
ent. If dissolved in water or nitric acid a little silver nitrate 
produces a dense white precipitate of silver chloride. 
Nitrates.—A nitrate, if fused on charcoal, will deflagrate with 
brilliancy, owing to the decomposition of the nitrate and the 
union of its oxygen with the carbon. 
Phosphates.—-Phosphates give a dirty green color to the blow- 
pipe flame. The color is more distinct if the substance is first 
moistened with sulphuric acid. If a phosphate is pulverized 
and heated in a closed glass tube with some bits of magnesium 
wire, the phosphoric acid is reduced, and when the fusion is 
moistened with water the very disagreeable odor of phosphuretted 
hydrogen is obtained. 
For. a full account of blowpipe reactions recourse must be 
had to a treatise on the blowpipe. The best and fullest Ameri- 
can work on the subject is Prof. G. J. Brush’s “* Manual of De- 
terminative Mineralogy, with an Introduction on Blowpipe 
Analysis.” 
Tn this work the following abbreviations are used. in speaking 
of blowpipe reactions : 
B.B. = before the blowpipe; O.# = oxidizing flame; 
Jt. #, = reducing flame. 
