236 .PROCEEDINGS OF THE AMERICAN ACADEMY. 



I. 0.2973 gram of substance gave according to the method of Carius 

 0.4138 gram of argentic bromide. 

 II. 0.2987 gram of substance gave 0.4150 gram of argentic bromide. 



Bromine 



The substance is, therefore, a tribromdinitrobeuzol, and its appearance 

 is not unexpected, since J. F. Wing and one of us * found that tetra- 

 bromdinitrobenzol was always formed during the preparation of tribrom- 

 triiiitrobenzol from tribromdinitrobenzol. There can be no doubt about 

 the constitution of this tribromdinitrobenzol, because it is made from the 

 dibromdiuitrobenzol (Brg 1. 3. (NOa)-! 4. 6) by the introduction of an 

 atom of bromine, which can enter only in two places, — between the 

 nitro groups, or between the atoms of bromine. If the substitution 

 takes place between the nitro groups, there must be formed symmetrical 

 tribromdinitrobenzol, which melts at 192° ; there is left, therefore, for 

 our substance melting at 150" only the constitution Br3 1. 2. 3. (N02)2 4. 6. 



Properties of the 1.2.3. Tribrom- A. %. dinitrohenzol. — Yellowish 

 white rectangular plates bevelled on the sides, when crystallized from a 

 mixture of alcohol and benzol. Melting point 150°. It is freely 

 soluble in benzol, or ether; soluble in chloroform, glacial acetic acid, or 

 acetone; soluble in cold alcohol, freely soluble in hot alcohol; slightly 

 soluble in cold ligroin, soluble in hot ; insoluble in water. The best 

 solvent for it is a mixture of alcohol and benzol. Strong hydrochloric 

 or sulphuric acid gives no visible action hot or cold. Strong nitric acid 

 appears not to act in the cold, but dissolves it when hot, depositing the 

 unaltered substance as it cools. A solution of sodic hydrate does not 

 act on it apparently either hot or cold, but in presence of alcohol gives a 

 light yellow color. 



Action of Sodic Ethylate on Dihromtrinitrobenzol. 



1.5 grams of dibromtrinitrobenzol (Bra 1 . 3 . (N0o)3 2 . 4 . 6) were 

 dissolved in 15 c.c. of benzol, and mixed with sodic ethylate in the pro- 

 portion of three molecules of the ethylate to each molecule of the dibrom 

 compound. The sodic ethylate was prepared by adding the calculated 

 amount of sodium to 30 c.c. of absolute alcohol. The liquid at once 

 took on an intense red color, and became turbid. To make sure of com- 

 pleting the reaction the mixture was allowed to stand for twelve houi-s at 

 ordinary temperature in a cork flask, after which it was filtered, and the 



* These Proceedings, XXIII. 139. 



