METALS. 205 



urally in one class, as you see in the following list, where all the metals are 

 thus arranged, the rare ones being in brackets : 



MONADS. DYADS. TEIAD8. TETRADS. PENTADS. IIEXADB. 



K Ba [Tl] Ft As Cr 



Na Sr [In] [PI] Sb [U] 



[Li] Ca Au [Ir] Bi [W] 



[Cs] Mg [Bo] [Vd] [Mo] 



[Kb] Zn [Ru] [Ta] 



Ag Cd [Os] [Cb] 



Hg Sn 



Cu [Ti] 



[Gl] Pb 



[Yt] [Zr] 



[Er] [Th] 



[La] Al 



[Dd] Fe 



Mu 

 Co 

 Ni 

 [Ce] 



QUESTIONS. 



270. What are the chief characteristics of metals? 271. Illustrate the fact 

 that metals are not necessarily dense. Name the heaviest metal and the 

 second heaviest. Name the lightest metal. 272. What three metals have 

 distinct colors? 273. What is meant by tenacity? Which is the least 

 tenacious metal ? Which the strongest? 274. What is meant by mallea- 

 bility ? Which is the most malleable of metals ? 275. What is ductility ? 

 How fine a platinum wire did an English chemist make ? 276. How does 

 a difference of temperature affect metals? Which metals are volatile? 

 Which is the most fusible metal ? Which the most infusible ? 277. What 

 is welding ? 278. What is said of alloys and amalgams ? Of what is solder 

 made? Of what German silver? 279. Is an alloy a true chemical com- 

 pound ? Why not ? What are the ingredients of fusible metal ? At what 

 temperature does it melt? 280. Give in full what is said of ores. 281. 

 Into how many groups may the metals be divided ? What two bodies are 

 sometimes placed among the non-metals ? 



