OF ARTS AND SCIENCES. 191 



of bromine was removed by the action of malonic ester depended 

 only on this position, and experiments were tried and described in 

 a previons paper * which seemed to disprove this view. On re- 

 turning to the subject, tliis point seemed to us of so much impor- 

 tance that we determined to repeat the experiment, especially as 

 the conditions under which the malonic ester acted on the tribrom- 

 dinitrobenzol in the earlier work were not exactly the same as those 

 of the action of the sodium malonic ester in the preparation of brom- 

 dinitrophenylmalonic ester ; accordingly, in repeating the experiment 

 as described below we have reproduced these conditions as exactly 

 as possible, except that malonic ester was used in place of sodium 

 malonic ester. 



To 4 gr. of malonJc ester dissolved in 30 c.c. of absolute alcohol 

 were added 5 gr. of tribromdinitrobenzol dissolved in anhydrous ben- 

 zol, and the mixture was allowed to stand in the cold for three or 

 four days, at the end of which time, there being no signs that a re- 

 action had taken place, the solvent was allowed to evaporate spon- 

 taneously, and the malonic ester mother liquor poured off from the 

 crystals, which after careful drying on a steam radiator at about 70° 

 weighed 3.4 gr. and melted at 192° (the melting point of tribrom- 

 dinitrobenzol). Tlie mother liquor was allowed to stand in a loosely 

 covered dish for a month, when the malonic ester had evaporated, 

 leaving an additional crop of crystals, which after drying as before 

 weighed 1.75 gr., and also showed the melting point of the tribrom- 

 dinitrobenzol. So that the weight of the recovered tribromdinitro- 

 benzol was 5.15 gr. f This expeiiment therefore confirms those 

 previously tried,* and proves conclusively that malonic ester has no 

 action upon tribromdinitrobenzol (BrNOsBrNOaBrH), and conse- 

 quently that the replacement of the bromine atom by hydrogen in 

 the formation of bromdinitrophenylmalonic ester depends on other 

 conditions in addition to the influence of the nitro groups and other 

 bromine atoms upon it. The discussion of these other conditions will 

 be postponed until we have collected more experimental material. 



* These Proceedings, xxiv. 308 (1889). 



t The slight excess (0.15 gr.) over the amount used is easily accounted for 

 by the dust which during the long standing found its way into the loosely 

 covered evaporating dish. 



