544 Royal Society : — 



warm water, and possesses the bibasic character of the terephthalic 

 acid in a much higher degree. It forms well-defined crystallizable 

 acid and neutral salts. The ethers of this acid are likewise crystal- 

 lizable. They differ, however, from the terephthalic acid ethers by 

 their greater solubility in alcohol and their depressed fusing-poiut. 



Chloride of terephthalyle (C 8 H 4 O 2 CI 2 ) is obtained, together with 

 oxychloride of phosphorus (hydrochloric acid being evolved), when 

 terephthalic acid is acted upon with pentachloride of phosphorus at a 

 temperature of 40° (Cent.). Chloride of terephthalyle is a solid and 

 beautifully crystalline substance, without odour at the ordinary 

 temperature, but evolving, when heated, a very pungent smell like 

 that of chloride of benzoyle, which it resembles in all its reactions. 

 With the alcohols it forms terephthalic ethers, with ammonia an 

 amide, and with the organic bases compound amides. Terephthalyl- 

 amide, C 8 H 8 N 2 O 2 , can only be obtained by acting with chloride of 

 terephthalyle on ammonia ; it is a white amorphous substance in- 

 soluble in all solvents. Terephthalylamide, when treated with fum- 

 ing nitric acid, yields nitro-terephthalic amide, C 8 II 8 (NO 2 ) N 2 O 2 , 

 which crystallizes in beautiful prisms. 



Terephthalamide shows a remarkable resemblance to benzamide 

 when treated with substances capable of abstracting the elements of 

 water. It loses two equivalents of water (IPO), and is converted 

 into terephthalylnitrile, C 8 IPN 2 . This remarkable substance is best 

 formed by the action of anhydrous phosphoric acid on terephthalamide. 

 It distils over in form of a liquid, which solidifies in the neck of the 

 retort. 



Terephthalylnitrile is colourless and without odour, and forms 

 beautiful prismatic crystals. It is insoluble in water, readily soluble 

 in boiling alcohol, less soluble in cold alcohol, and insoluble in benzole. 

 When boiled with caustic alkalies, it is gradually decomposed, 

 ammonia is given off, and terephthalic acid is reproduced. 



It is obvious that terephthalylnitrile, like all similar substances, 

 may be considered as a cyanogen compound, which in this instance 

 would be the cyanide of the bibasic radical phenylene, C° H 4 , which is 

 not yet discovered. If we could succeed in obtaining phenylene, the 

 artificial production of terephthalic acid or an isomeric would probably 

 be attended with little difficulty. 



By acting on nitro-terephthalic acid with reducing agents, it 

 undergoes the same change as other nitro-compounds. The product 

 of this reaction is the oxy-terephthalamic acid, or the analogue of the 

 glycocoll of the formula C 8 IF NO 4 . This new member of the glyco- 

 colls is a lemon-yellow substance, crystallizing in thin prismatic, and 

 sometimes moss-like forms. It is very slightly soluble in cold 

 water, alcohol, ether, and chloroform. Like other substances of this 

 kind, terephthal-glycocoll combines with bases as well as with acids. 

 The salts formed with the bases are crystalline ; they are readily 

 soluble in water and dilute alcohol, yielding colourless solutions of 

 most remarkable fluorescent properties, which have been investigated 

 by Professor Stokes. 



The aqueous and alcoholic solution of the pure terephthalic glycocoll 



