DIOXYNAPHTHOQUINONE. 401 



diimidonaphthol hydrochlorate (p. 398) with dilute 

 hydrochloric or sulphuric acid at 120. Bright yellow, 

 electric powder, or yellow needles ; sublimes partially 

 when carefully heated, condensing in reddish-yellow 

 needles. Almost insoluble in cold water, somewhat 

 soluble in boiling water, easily in alcohol and ether. 

 It combines with nascent hydrogen, forming trioxy- 

 naphthalene. It conducts itself as a moderately strong 

 monobasic acid towards bases, and liberates carbonic 

 acid from its salts. The alkaline salts are blood-red and 

 easily soluble in water. 



Chloroxynaphthoquinone (Chloroxynaphthalic 

 acid), C 10 H 5 C10 3 = C 10 H 4 01(OH) j >. The potassium 



salt, C 10 H 4 C1(OK)0 2 , is obtained, when dichlornaphtho- 

 quinone is placed under alcohol, and concentrated po- 

 tassa-ley then added. It forms cherry-colored needles, 

 which are but slightly soluble in cold water, easily so- 

 luble in hot water ; hydrochloric acid throws down the 

 free acid from this solution. Straw-colored, crystalline 

 powder ; fuses somewhat above 200, and sublimes in 

 needles ; but slightly soluble in cold water, moderately 

 in boiling, more easily in alcohol and ether. Strong 

 monobasic acid ; its salts, when heated, give a sublim- 

 ate of phtalic anhydride. Heated with phosphorus 

 chloride, pentachlornaphthalene is formed. 



Dioxynaphthoquinone (Naphthazarin), C !0 H 6 O = 

 C 10 H 4 (OH) 2 j Q>. Is obtained by simultaneously add- 

 ing /3-dinitronaphthalene and zinc in small quantities 

 to concentrated sulphuric acid heated to 200. Subse- 

 quently the mass is diluted with water, boiled, filtered 

 boiling hot and the gelatinous mass, that separates on 

 cooling, purified, when dried, by means of sublimation. 

 Long needles with a beautiful green metallic lustre. 

 But slightly soluble in boiling water, more easily in 

 alcohol, the solution having a red color. It dissolves 

 in ammonia forming a sky-blue solution, which turns 

 reddish-violet on standing. Its solution gives beauti- 



34* 



