8 PROCEEDINGS OF THE AMERICAN ACADEMY 



ester, and then dried by gentle warming, and standing in vacuo over 

 paraffine and sulphuric acid. These precautions were adopted to 

 avoid the contamination of the substance with the carbonic dioxide of 

 the air. The same substance was obtained when sodic ethylate was 

 used instead of sodic hydrate, and Analysis III. was made with a 

 sample prepared in this way. 



I. 0.1950 grm. of the substance ignited with sulphuric acid gave 

 0.0324 grm. of sodic suli^hate. 

 II. 0.1354 grm. gave 0.0216 grm. of sodic sulphate. 



III. 0.1943 grm. gave by the method of Carius 0.0838 grm. of argen- 



tic bromide and the filtrate gave 0.0330 grm. of sodic sulphate. 



IV. 0.2148 grm. gave 14.3 c.c. nitrogen at a temperature of 25° and 



a pressure of 759.6 mm. 



The results of these analyses show that the substance is the normal 

 salt, containing but one atom of sodium, and the important bearing of 

 this point on the determination of the formula of the bromdinitro- 

 phenylmalonic ester has been discussed already. (See page 4.) 



Properties. — The salt forms a dark blood-red powder, easily sol- 

 uble in water, alcohol, or ether. From a solution containing much 

 sodic hydrate, the salt can be extracted with ether; but pure water, 

 on the other hand, extracts the salt from its ethereal solution. Its 

 aqueous solution is decolorized by carbonic dioxide bromdinitrophenyl- 

 malonic ester being precipitated. 



The copper salt seemed from its appearance to promise excellent 

 results on investigation, and was accordingly prepared as follows. 

 An alcoholic solution of the bromdinitrophenylmalonic ester was 

 treated with a small quantity of sodic hydrate taking care that the 

 ester was in large excess, and then poured into a volume of water 

 sufficient to precipitate all the unaltered ester; after filtering, an alco- 

 holic solution of cupric chloride was added, and the precipitate washed 

 first with 50 per cent alcohol, then with water, and finally once with 

 hot alcohol ; it was then dried in vacuo. It is not necessary to pro- 

 tect the salt from contact with the air during its preparation, as it is 

 not perceptibly affected by carbonic dioxide. It gave the following 

 results on analysis. 



