396 NAPHTHALENE. 



of sulphuric acid. Bibasic acid. The barium salt, 

 C 10 H 6 S 2 6 Ba, is much less easily soluble in water, and 

 particularly in alcohol, than the sulphonaphthalates. 



Mercurynaphthyl, (C 10 H 7 ) 2 Hg. Is formed by con- 

 tinued boiling of a solution of monobromnaphthalene 

 in benzene with sodium-amalgam. Small, colorless, 

 rhombic, columnar crystals. Insoluble in water, diffi- 

 cultly soluble in boiling alcohol, easily in carbon bisul- 

 phide and in chloroform. Fuses at 243 ; not volatile 

 without decomposition ; combines directly with iodine ; 

 and, when heated with hydriodic, hydrobromic, or 

 hydrochloric acids, it yields naphthalene and mercury 

 iodide, bromide, or chloride. Conducts itself exactly 

 like mercuryphenyl (p. 272). 



Dinaphthyl, C 20 H 14 (C 10 H 7 ) 2 , is formed by the 

 decomposition of monobromnaphthalene with sodium ; 

 and by heating naphthalene with black oxide of man- 

 ganese and sulphuric acid. Colorless laminse, of a 

 mother-of-pearl lustre. But slightly soluble in cold 

 alcohol, easily soluble in ether ; fuses at 154 ; and is 

 sublimable without decomposition. "When further 

 oxidized with black oxide of manganese and sulphuric 

 acid, it is converted into phtalic acid (p. 362). 



2. Mcthylnaphthalene. 

 C"H 10 = C IO H 7 .CH 3 . 



Is obtained by the action of sodium on a mixture of 

 monobromnaphthalene and methyl iodide, diluted with 

 ether. Colorless, clear, somewhat viscid liquid ; specific 

 gravity, 1.0287; boiling point, 231-232; does not 

 congeal at 18. 



3. Ethylnaphthalene, C 12 H 12 = C 10 H 7 .CH 2 .CH 3 . Is 

 formed like methylnaphthalene. Colorless, clear li- 

 quid; specific gravity, 1.0184; boiling point, 251-252; 

 still liquid at 14. 



