320 PROCEEDINGS OP THE AMERICAN ACADEMY 



The sodium salt is soluble in ethyl or methyl alcohol even in 

 the cold, and crystallizes from its alcoholic solution in long, flat, 

 pointed needles. 



Properties of Tribromdinitrophenol. — This substance crystal- 

 lizes from dilute alcohol in square-ended needles usually grouped 

 in arborescent or fan-shaped clusters looking like certain seaweeds; 

 its color is white with a very faint shade of yellow. It melts at 

 194°, and is freely soluble in cold ethyl or methyl alcohol, or in 

 ether, acetone, or glacial acetic acid ; somewhat less soluble in 

 benzol or chloroform, although still freely soluble in these liquids; 

 soluble in carbonic disulphide; slightly in ligroine; very slightly 

 in cold water, somewhat more soluble in hot. Dilute alcohol is 

 the best solvent for obtaining crystals. Its alcoholic solution is 

 distinctly yellow. The three strong acids have no apparent action 

 on it. With alkalies it forms colored salts. A solution of the 

 sodium salt gave precipitates consisting of yellow needles with 

 salts of zinc, nickel, manganese, cobalt, chromium, cadmium, or 

 lead. Cupric salts gave light green needles. In order to char- 

 acterize the substance still further, its barium salt was prepared 

 and analyzed. 



Baric Tribromdinitrophenylate, [C 6 Br3(N0 2 )20] 2 Ba. — This sub- 

 stance was made by adding baric chloride to a concentrated solu- 

 tion of the ammonium or sodium salt, collecting the precipitate, 

 and recrystallizing it several times from hot water. The salt con- 

 tained no water of crystallization. 



I. 0.6621 gr. of the salt gave 0.1545 gr. of baric sulphate. 

 II. 0.5066 gr. of the salt gave 0.1182 gr. of baric sulphate. 



Barium 



The baric tribromdinitrophenylate crystallizes from hot water in 

 long yellow needles arranged in radiating circular groups. It is 

 slightly soluble in cold water, more soluble in hot; freely in cold 

 ethyl or methyl alcohol. 



After the tribromdinitrophenol obtained by the acidification of 

 the products of the reaction of water and sodic carbonate on tri- 

 brominitrobenzol had been filtered out, the filtrate was extracted 

 with ether to obtain the organic substance, whose presence was in- 

 dicated by its yellow color. The extract thus obtained melted over 

 190°, and contained bromine, indicating the probable presence of 



