OP ARTS AND SCIENCES. 241 



were heated together to 140°-145° in a sealed tuhe, and described the 

 product formed, stating, however, that all our results up to that time 

 must be regarded as preliminary. Upon taking up the subject again, 

 we studied in the first place the gas evolved when the tube was 

 opened, and found that, in addition to the gas already mentioned burn- 

 ing with a green-bordered flame (which is undoubtedly ethylchloride), 

 carbonic dioxide was given off, as was proved by the precipitate formed 

 when the gas was passed through lime-water. It is to be observed, 

 however, that if the temperature to which the tubes were heated was 

 140°, or a little lower, very little, if any, carbonic dioxide was given 

 off, and the product insoluble in the hydrochloric acid was oily ; on 

 the other hand, when a crystalline product was obtained at a some- 

 what higher temperature, carbonic dioxide was given off freely. "VVe 

 next attempted to prepare the substance in open vessels by substitut- 

 ing for strong hydrochloric acid dilute sulphuric acid boiling at about 

 the temperature to which we heated the tubes, and found that not only 

 did we obtain the product in this way, but that it was much purer than 

 that made in the sealed tubes with hydrochloric acid. We have ar- 

 rived accordinslv at the following method as the most convenient for 

 saponifying the bromdinitrophenylmalonic ester. 2 grs. of the ester 

 are mixed with about 100 c.c. of dilute sulphuric acid, specific gravity 

 1.44 and boiling point 132°, and the mixture boiled in a flask with a 

 return condenser, until the oily drops of melted bromdinitrophenyl- 

 malonic ester have all gone into solution, which usually takes about 

 an hour and a half. After this the solution, as it cools, deposits long, 

 pale yellow needles of the new substance, which, if the preparation 

 has succeeded well, melt at 177° at once. If, however, the action has 

 not run so well, and the melting point is somewhat lower than this, 

 the substance can be easily purified by crystallization from boiling 

 water acidified with a few drops of dilute sulphuric acid, but in no 

 case should it be crystallized from pure water, or alcohol, as these 

 solvents decompose it in the curious way described later in this paper, 

 when we consider its properties. 



Metabromdinitrophenylacetic Acid, C II 2 Br(N0 2 )oClI,COOII. 



The substance prepared in the manner just described, and showing 

 the constant melting point 177°, was dried at 100°, and analyzed with 

 the following results : — 



I. 0.2106 gr. of the substance gave on combustion 0.2426 gr. of 



carbonic dioxide, and 0.0420 gr. of water. 

 vol. xxiv. (n. s. xvi.; 16 



