JACKSON AND SOCH. TRINITROPHENYLMALONIC ESTER. 403 



the mixed solutions were evaporated cautiously on the steam bath 

 until crystals begau to form, when upon cooling the sodium salt was 

 obtained in fine red crystals ; these were washed with benzol, and after 

 drying in a desiccator gave the following results on analysis : — 



I. 0.2400 gram of the substance after evaporation with sulphuric 

 acid gave 0.0427 gram of sodic sulphate. 

 II. 0.8331 gram of the substance gave 0.1429 gram of sodic sulphate. 



Calculated for Found 



CeH2(N0o)3CNa(C00C2H5)2. I. II. 



Sodium 0.85 5.76 5.56 



An additional quantity of the salt was obtained by the treatment 

 just described from the residue left after evaporating off the benzol 

 from the solution of picrylmalonic ester in this solvent obtained by 

 adding water to the product of the reaction. 



Properties of the Sodium Salt of Picrylmalonic Ester. — It crystal- 

 lizes from a mixture of alcohol and benzol in dark red crystals often 

 a centimeter long. It is easily soluble in alcohol or ether ; some- 

 what less soluble in water than in alcohol ; nearly insoluble in benzol. 

 It does not seem to be decomposed by any of these solvents. Strong 

 sulphuric acid decomposes it, but without any explosion, which sur- 

 prised us, as it showed a tendency to explode when dry even at 

 comparatively low temperatures. 



As the potassium salt of picric acid is so much less soluble than the 

 sodium salt, we prepared the potassium salt of the picrylmalonic ester 

 by treating the free ester with potassic hydrate in strong aqueous 

 solution ; but, although this salt was somewhat less soluble in both 

 water and alcohol than the sodium salt, the difference was not very 

 marked, and there would be no advantage in using the potassium salt 

 instead of the sodium salt in the purification of the substance. 



The behavior of an aqueous solution of the sodium salt of picryl- 

 malonic ester with various reagents was also studied, and the following 

 more or less characteristic precipitates were obtained : — 



Salt of magnesium, heavy reddish flocks. 



Salts of calcium or barium, granular or crystalline precipitates of aa 

 amethyst color. 



Salt of manganese, dirty yellow flocks. 

 Salt of nickel, light red flocks. 

 Salts of lead or silver, dark red flocks. 

 Salt of cadmium, reddish yellow flocks. 



