178 



On some Derivatives of Vr amidobenzoic Acid. [Feb. 15, 



diamidobenzoic acid being precisely the same as that produced in the same 

 way from /3 diamidobenzoic acid. 



The subjoined Table shows the characteristic difference that exists be- 

 tween the melting-points and boiling-points of the three isomeric phenylene 

 diamines at present known : — 



Fusing-point. Boiling-point. 



Phenylene diamine from nitroacetanilid and ] ^qjo 

 from a diamidobenzoic acid j" 



Phenylene diamine from (3 and y diamido- 

 benzoic acids 



Phenylene diamine from dinitrobenzol .... 63° 287° 



Besides the three isomeric diamidobenzoic acids which I have described 

 in the course of this paper, a fourth acid exists, having the same compo- 

 sition, namely, the diamidobenzoic acid obtained by Dr.Voit* by reducing 

 ordinary dinitrobenzoic acid with sulphuretted hydrogen, and which I have 

 since further investigated f. I propose, at present, to retain for this the 

 simple name diamidobenzoic acid. It is distinguished from the other 

 diamidobenzoic acids, not only by its physical properties, but especially in 

 not yielding a volatile organic base when submitted to dry distillation, 

 becoming, on the contrary, completely carbonized with simultaneous 

 evolution of ammonia. -With nitrous acid also it behaves differently, 

 being converted into an insoluble amorphous acid of a reddish-brown 

 colour. 



When it is considered that each of the four diamidobenzoic acids at 

 present known is derived, at least in a certain sense, from ordinary a 

 amidobenzoic acid, there is reason to suppose that the acids which are 

 isomeric with amidobenzoic acid, namely amidodracylic acid and an- 

 thranilic acid, would, under favourable circumstances, give rise to four 

 new diamido-acids ; so that it is obvious that at least twelve isomeric 

 diamidobenzoic acids may be conceived to exist. 



In the preceding notice I have confined myself to the consideration of 

 some of the most important chemical and physical properties of the sub- 

 stances described ; but I hope to be able to lay before f /he Society at a 

 future time some account of their rational constitution, and of the causes 

 which produce the various isomerisms. 



99 c 



252 c 



* Ann. Chem. Pharm. vol. xcix. p. 100. 



t Ibid, vol, cxxviii. 



