OF ARTS AND SCIENCES. 295 



ate made from 3 grs. of sodium dissolved in 100 to 150 c.c. of absolute 

 alcohol. The action began at once, as shown by the appearance of a 

 dark red color and a considerable evolution of heat, so that the flask 

 became too hot to hold in the hand with comfort ; in this respect it 

 differed from that with the tribromdinitrobenzol, as, although in that 

 case the red color appeared at once, no perceptible rise of temperature 

 was observed in any part of the reaction. To make certain that the 

 reaction had run as far as possible, the mixture was allowed to stand 

 in the cold for three or four days. At the end of this time the product 

 was diluted with about half a litre of water, and the benzol separated 

 from the red aqueous solution of the salt of the new substance. Upon 

 adding dilute sulphuric acid to this aqueous solution, the new substance 

 was precipitated, and after washing with water was purified by crys- 

 tallization from alcohol until it showed the constant melting point 89°, 

 when it was dried in vacuo for analysis. The benzol solution, which 

 separated on the addition of water, was evaporated to dryness, and the 

 residue, consisting of the new substance, a little unaltered tetrabrom- 

 dinitrobenzol, and an oil, after being freed from the oil on the pump, 

 was treated with alcohol, in which the tetrabrom compound is es- 

 sentially insoluble, and the small amount of the new substance thus 

 obtained was added to that from the aqueous solution. 



I. 0.2183 gr. of the substance gave on combustion 0.2568 gr. of 



carbonic dioxide and 0.0528 gr. of water. 

 II. 0.2144 gr. of the substance gave 11.4 c.c. of nitrogen at a tem- 

 perature of 23°. 1 and a pressure of 763.4 mm. 

 HI. 0.2372 gr. of the substance gave, by the method of Carius, 

 0.1833 gr. of argentic bromide. 



Found. 



III. 



32.91 



The yield of dibromdinitrophenylmalonic ester was very satisfactory. 

 On one occasion 5 grs. of tetrabromdiuitrobenzol gave 4 grs. of the 

 dibromdinitrophenylmalonic ester, instead of the 5 grs. required by the 

 theory, that is, 80 per cent of the theoretical yield. This large yield 

 proves conclusively that dibromdinitrophenylmalonic ester is the only 

 aromatic product of the reaction, a point which before this observation 

 seemed somewhat doubtful in the analogous preparations described in 



