SEPARATION OF METALS IN DIFFERENT GROUPS. 209 



QUESTIONS. 



311. What is analytical chemistry, and what. is the object of quali- 

 tative and of quantitative analysis ? 



312. What properties of a substance should first be noticed in 

 making a qualitative analysis ? 



313. By what tests may organic compounds be distinguished from 

 inorganic compounds ? 



314. Explain the terms decrepitation and deflagration. 



315. Mention some substances which are completely volatilized by 

 heat, some which are fusible, and some which are not changed by heat- 

 ing them. 



316. What is meant by " hepar," and which element is indicated by 

 the formation of hepar ? 



317. Mention some metals which may be liberated from their com- 

 pounds by heating on charcoal with potassium cyanide and carbonate. 



318. Which metallic compounds and which acids are capable of 

 coloring a non-luminous flame ? Name the colors imparted. 



319. State the metals which impart characteristic colors to a borax 

 bead. 



320. Which solvents are used for liquefying solids, and what pre- 

 cautions should be observed in this operation ? 



33. SEPARATION OF METALS IN DIFFERENT GROUPS. 



General remarks. The preliminary examination will, in most 

 cases, decide whether or not a metal or metals are present in the 

 substance to be examined. If there be metals, the solution 

 should be treated according to Table II., in order to find the 

 group or groups to which these metals belong, and also to 

 separate them into these groups, the individual nature of the 

 metals themselves being afterwards demonstrated by special 

 methods. 



The simplest method of separating the 54 known metals from 

 each other, when all in one solution, would be to add succes- 

 sively 54 different reagents, each of which should form an in- 

 soluble compound with but one of the metals. By separating 

 this insoluble compound from the metals remaining in solution 

 (by filtration), and by thus precipitating one metal after the 

 other, they all could be easily separated. We have, however, 

 no such 54 reagents, and are, consequently, compelled to pre- 

 14 



