P. T. Austen—Dinit radit benzols. 119 
dod 
dish-yellow oil settled in the bottom of the flask. After boil- 
ing three hours the mixture was allowed to cool, and then 
ured in a thin stream into a large excess of cold water. 
he oil sank to the bottom and gradually solidified, an opera- 
tion which may be greatly accelerated by vigorous stirring with 
aglass rod. The nitrired product from 500 grams of the di- 
brombenzol after the washing out the acid with water, was dis- 
solved in about a kilogram of glacial acetic acid, filtered, and 
allowed to stand about seventy hours. A copious separation o 
the first (@) dinitroparadibrombenzol, containing a considerable 
amount of the second (/) isomere and but a small amount of the 
third (y), took place. By repeated crystallization, first from 
carbon disulphide and then from glacial acetic acid, it was ob- 
tained perfectly pure. The acetic acid filtrate from the first 
separation contained the f- and y-isomeres and some of the a. 
e solution was treated with a large excess of water, and the 
substances in solution were thus precipitated in the form of a 
yellow oil, which was then separated from the water by means 
of a stop-cock-funnel, heated on a water-bath until it was en- 
urely dry, dissolved in about 1} kilos. of carbon disulphide, 
and allowed to stand By standing, a small separation of 
impure a@-isomere generally occurs. The carbon disulphide was 
then distilled off in portions of 200 c.c¢., and the respective 
crystallizations, which consisted of the f-isomere containing a 
ood deal of the a@-isomere and traces of the y, collected. 
Which it was exposed to a temperature of 5° for three days, 
when it became solid. The mass was carefully rubbe a 
morta 
extract (consisting of much y and little f) separated by a filter- 
ump. 
A-isomeres crystallized out and were separated by filtering the 
oll directly with the filter-pump. Finally no more separate 
Jom the oil, which then appeared to contain only an exceed- 
Mgly small amount of the f-isomere. 
Alphadinitroparadibrombenzol. : 
The alphadinitroparadibrombenzol containing traces of the 
A-isomere crystallizes from glacial acetic acid in beautiful stri- 
er transparent needles, often attaining a length of 25 cm. 
aie diameter of 3 mm. hen perfectly pure, however, it 
"ystallizes from the same solvent, in short, compact, white, 
