90 CHEMICAL PEOPEETIES OF MIXEEALS. 



Chlorides. — If a bead of borax be saturated -with copper 

 oxide, and 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 nitiate 

 produces a dense white precipitate of silver chloride. 



titrates. — A nitrate, if fused on charcoal, will deffc grate 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 fall 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." 



In this work the following abbreviations are used in speaking 

 >f blowpipe reactions : 



B.B. = before the blowpipe ; O.F. = oxidizing flame ; 

 R.F. = reducing flame. 



