OF ARTS AND SCIENCES. 223 



and about 200 c. c. of dry benzol under a reverse condenser for about 

 six hours. Ine light brown mother liquor was then decanted hot 

 from the insoluble residue, the latter boiled up with fresh benzol, this 

 extract added to the first, and the whole concentrated to a small vol- 

 ume. No precipitate appearing, the concentration was continued 

 until a thick crust was obtained. This, after crystallization from 

 ligroine, yielded an abundance of fine white needles, which melted at 

 141° and gave on analysis the following values : — 



0.1452 gr. substance gave 0.1425 gr, AgCl. 

 0.1346 gr. gave 0.2798 gr. CO2 and 0.0348 gr. H,0. 



Calculated for 



^6"4 1(2)00 



^O 



/"• Found. 



CH I (2) CO 



C 56.96 56.70 



H 2.71 2.87 



CI 24.07 24.28 



The orthochlorbenzoic anhydride is very soluble in alcohol, ether, 

 chloroform, and benzol, less soluble in ligroine. From this last it is 

 precipitated in the form of glittering white needles. Water and 

 alkalies attack it slowly in the cold, more readily on heating. 



II. Metachlorhenzoic Anhydride. 



After numerous fruitless attempts to prepare metachlorhenzoic 

 acid from benzoic acid by the method of Hubner and Weiss ; * we had 

 recourse to that of Sandmeyer.f which proved perfectly satisfactory. 

 For the preparation of the acid on a laboratory scale this method 

 leaves little to be desired. 



10 grams of the pure acid melting at 153° were boiled up under a 

 reverse condenser with 12 grams of phosphorpentoxide and an excess 

 of benzol for six hours. The decanted mother liquor, together with 

 benzol washings from the phosphoric residue, were concentrated, and 

 the white crystalline mass which separated out, purified by pressing 

 between filters and recrystallizing from fresh benzol. The substance 

 thus obtained did not show a constant melting point. It was there- 

 fore washed several times with dilute potash, dried, and again crystal- 

 lized. It now melted constant at 89°, and gave on analysis the 

 following : — 



* Ber. d. di. G., VI. 175. t Ber. d. ch. G., XVII. 1634. 



