OF ARTS AND SCIENCES. 247 



Eadziszewski,* Gabriel and R. Meyer,t and Heckmann,t have pre- 

 pared a dinitrophenylacetic acid which differs from that just described 

 only in containing no bromine. This substance also loses carbonic 

 dioxide easily, passing into dinitrotoluol, but none of the chemists 

 who have worked with it describe a decomposition by solvents similar 

 to that observed by us ; in fact, they crystallized it tor analysis from 

 boiling water, but, as in all their methods of preparation acids were 

 used, it is possible that a sufficient amount of sulphuric acid was pres- 

 ent during the crystallization to prevent the decomposition. It ap- 

 pears that none of them tried to crystallize it from alcohol. The 

 statement is made, however, that the sodium or potassium salt of the 

 acid decomposes slowly on standing, instantly on boiling giving car- 

 bonate and dinitrotoluol ; from this it would seem probable that our 

 bromine acid was more stable than that containing no bromine, as our 

 ammonium salt (the sodium or potassium salt could not be obtained) 

 stood unaltered for many days, and even could be warmed on the 

 water bath for some minutes with only slight decomposition. The 

 curious change of color with sodic hydrate observed by us did not 

 occur with the dinitro body, confirming our conclusion that this action 

 was due to the removal of bromine by the sodic hydrate. 



Argentic 3Ietahromdinitrophenylacetate, 

 C6H2Br(N02)2CH2COOAg . H^O. 



This substance was prepared by adding a solution of argentic nitrate 

 to a solution of the acid in ammonic hydrate, which had been freed 

 from the excess of ammonia as completely as possible, best by using 

 an excess of the acid in preparing the salt. The heavy flocculent 

 precipitate, which, if the solutions were strong, entirely filled the 

 liquid, and even piled up above its surface, became crystalline on 

 standing, and was purified by washing with cold water. Some of the 

 salt is also formed when argentic nitrate is added to an aqueous solution 

 of the free metabromdinitrophenylacetic acid. The analysis of the 

 salt gave the following results. 



0.3530 gr. of the air-dried salt lost, when heated to 100°, 0.0149 gr. 



Calculated for 

 CoHjBrlNOjlzCHjCOjAg . HjG. Found. 



Water 4.19 4.22 



* Ber. d. cli. G., ii. 210. J Ann. Chem., ccxx. 134 



I Ibid., xiv. 823. 



