98 PROCEEDINGS OP THE AMERICAN ACADEMY 



The complete combustion of the body is an exceedingly difficult 

 operation. The substance must be thoroughly mixed with the 

 oxide of copper or lead chromate, and burned very slowly in a 

 generous current of oxygen. Even under these conditions the 

 values for carbon are quite low. The chemical relations of the 

 body, however, leave no doubt that it is the anhydride of meta 

 nitrobenzoic acid. It dissolves readily in dilute alkalies in the 

 cold, and from such solution mineral acids precipitate the meta 

 acid, easily identified by its melting point, 141°, and crystalline 

 form. 



Meta nitrobenzoic anhydride is readily soluble in alcohol, ether, 

 and chloroform, less readily in benzol (from which solvent it crys- 

 tallizes best), and difficultly in water. Cold water has but little 

 effect upon it, boiling water decomposes it rapidly into the free 

 acid. 



From the gelatinous phosphoric residue by extraction with ab- 

 solute alcohol, evaporating to dryness, and taking up with water, 

 a product was obtained which crystallized from alcohol in small 

 rhombic plates, melting at 42°. The same body was obtained by 

 treating the anhydride with absolute alcohol and phosphorpent- 

 oxide. Its melting point and method of formation show it to be 

 the meta nitrobenzoic ester. 



IV. Action of Phosplwrpentoxide upon Para Nitrobenzoic Acid 



in an Excess of Benzol. 



Para nitrobenzoic anhydride is the principal product when para 

 nitrobenzoic acid and phosphorpentoxide are boiled together for 

 some hours in an excess of dry benzol. The proportions employed 

 were the same as with the ortho and meta nitro acids. 



The anhydride crystallizes from benzol in white leaflets melting 

 at 184°. The anakyses gave the following: — 



0.1716 grm. substance gave 0.3311 grm. C0 2 and 0.0530 grm. H 2 0. 

 0.3461 grm. gave 25.6 c.c. nitrogen at 4.6° and 746.5 mm. 



