CHLORIDE OF LEAD. 



107 



about powerful acids ; at the same time, any chemist, if 

 desired, will put them in strong and properly stopped 

 bottles, which, when packed carefully in the compartments 

 of a small box, will stand a good deal of knocking about. 



The finely powdered mineral should be dissolved in 

 hydrochloric acid or nitric acid (the latter being a substi- 

 tute for roasting, and is the most suitable when the sub- 

 stance is a sulphide, or arsenide, or metallic alloy), and 

 reagents added. 



Place a little powdered ore in a test tube or other 

 convenient apparatus (such as a porcelain dish), add a little 

 water and pour in nitric acid ; heat this over a spirit or 

 other flame for a short time. 



The clear solution is called the original solution, and (if 

 there be any undissolved matter left as a residue at the 

 bottom of the tube) should be filtered or decanted into 

 another test tube. 



To the clear solution add a little hydrochloric acid, when, 

 if a precipitate is formed, it is, 



Chloride of Lead, Chloride of Silver, or Mercurous 

 Chloride. 



Pour all the liquid off, and then shake this precipitate with 

 ammonia and observe the results : 



If di&solved it is chlo- 

 ride of silver. 



Confirmatory test for 

 silver: add potash to 

 the original solution 

 and a brown precipi- 

 tate would be pro- 

 duced. 



If blackened it is mer- 

 curous chloride. 



Confirmatory test for 

 mercury : add potash 

 to original solution 

 and a black precipi- 

 tate would be pro- 

 duced. Metallic cop- 

 per (clean) placed in 

 the solution would 

 become silvery-look- 

 ing. 



If unchanged it is 

 chloride of lead. 



Confirmatory test for 

 lead : add to original 

 solution some sulphu- 

 ric acid, and stir ; a 

 white precipitate, sul- 

 phate of lead, would 

 be formed at the bot- 

 tom of the tube. 



Suppose, however, that no precipitate was formed on the 

 addition of hydrochloric acid to the original solution. The 

 presence of some of the metallic bases is best determined by 

 passing sulphuretted hydrogen gas through the acid solu- 



