COMPOUNDS OF NAPHTALINE. 845 



acid, soluble in water, forming crystallizable salts. The salt of 

 ammonia is white, with the lustre of mother of pearl, and 

 resembles the crystalline plates of naphtaline ; it is readily dis- 

 solved by water, and pretty soluble in alcohol. The salts of 

 silver and barytes contain two atoms of metallic oxide, the salt 

 of lead four atoms. 



M. de Marignac also obtained a volatile liquid, which distilled 

 over with the excess of nitric acid, in treating the hydrochlorate 

 of chloronaphtalese (C 20 H 8 C1 4 ) with that acid, of which the 

 constitution is remarkably simple, C Cl NO 4 , or C Cl-fNO 4 . 

 This liquid, which is not named, is perfectly colourless, trans- 

 parent, of density 1 .685 at 59, of an odour excessively irritating, 

 like that of chloride of cyanogen, and affecting the eyes, neutral 

 to test-paper. Water dissolves a mere trace of it, but acquires 

 thereby its smell and taste. It dissolves easily in alcohol and 

 ether; nitric and hydrochloric acids dissolve only a very little 

 of it. Its boiling point appears to be not greatly above 212. 

 The aqueous solution of potash has no action upon it, the alco- 

 holic solution dissolves it easily, and after a time, a crystalline 

 potash-salt falls, which is decomposed when heated, with explo- 

 sion. The density of its vapour was not ascertained. 



The naphtalic acid, which is formed and remains in the retort 

 in the preceding process, did not possess the properties or com- 

 position of the acid which M. Laurent obtained by a similar 

 process. Marignac's naphtalic acid contains nitrogen, with 

 carbon and hydrogen in the proportion of C 8 H 5 , which is 

 inconsistent with the formula of the following acid.* 



Naphtalic acid, HO + C 8 H 2 O 3 , is formed on heating with 

 nitric acid the second compound or solid chloride of naphtaline 

 in the foregoing list (the chlorhydrate of chloronaphtalese) ; 

 ruddy fumes are given off, and the acid solution gives on con- 

 centration a white crystalline crust, which is naphtalic acid. 

 One equivalent of chlorhydrate of chloronaphtalese and 1 equi- 

 valents of oxygen give 2 equivalents of naphtalic acid, 2 equiva- 

 lents of oxalic acid, and 4 of hydrochloric acid : 



C 20 H 8 C1 4 and 10O=2C 8 H 2 O 3 and 2C 2 O 3 and 4HC1. 



* C. de Marignac, in Liebig's Anoalen, vol. 38, pp. 1 & 13. 



