398 NAPHTHOL. 



carbonic acid from its salts. The sodium and calcium 

 salts are excellent yellow dyes (naphthalene yellow). 



Diamidonaphthol, C 10 H 6 (KH 2 ) 2 .OH. Cannot be 

 isolated and obtained in a free condition. Its double 

 salt with stannous chloride, C 10 IP(NH 2 ) 2 .OH + 2HC1 + 

 SnCl 2 + 2H 2 0, is obtained by heating dinitronaphthol 

 with tin and hydrochloric acid. It crystallizes in 

 large, lustrous, monoclinate prisms. &quot;When its solution 

 is precipitated with sulphuretted hydrogen, a solution 

 of diamidonaphthol hydrochlorate is obtained, which, 

 in contact with air, and rapidly on the addition 

 of iron chloride, yields diimidonaphthol hydrochlorate 



C 10 H 5 (OH) | ^&amp;gt; + HC1. This salt crystallizes in large 



columnar or tabular crystals of a metallic lustre, which 

 in transmitted light are dark red ; in reflected light, 

 green. With ammonia it yields diimidonaphthol, 

 C 10 H 5 (OH)(HN) 2 , a yellow crystalline body, almost in 

 soluble in water. 



Naphtholsulphuric acid, C 10 H 6 j ^ OH By 



heating naphthol with double its weight of concentra 

 ted sulphuric acid. The free acid, separated from the 

 lead salt, forms long, colorless, deliquescent needles ; 

 fusing point, 101 ; its solution is colored deep blue on 

 the addition of iron chloride ; if heated it becomes 

 green. 



Naphthyl sulphydrate, C 10 H 7 .SH. Is formed by 

 the action of zinc and dilute sulphuric acid ona-naphthyl 

 sulphochloride. Colorless liquid, insoluble in water; 

 boiling point, 285 ; volatile with water vapor ; yields 

 salts with bases. 



Naphthyl disulphide, (C 10 H 7 ) 2 S 2 . Is formed by 

 the spontaneous evaporation of an ammoniacal alcoholic 

 solution of the sulphydrate in contact with air. 

 Yellowish, transparent crystals ; fusing point, 85. 



