DINITRO-BENZOL. 
201 
§§ 252 , 253 .] 
aqueous solution to be tested is added. On prolonged boiling, if nitro¬ 
benzene is present, a crimson ring is produced at the edges of the liquid ; 
this crimson colour, on the addition of a little bleaching-powder, turns 
emerald-green. 
Oil of bitter almonds may be distinguished from nitro-benzene by 
the action of manganese dioxide and sulphuric acid ; bitter almond oil 
treated in this way loses its odour, nitro-benzene is unaltered. To apply 
the test, the liquid must be heated on the water-bath for a little time. 
XI.—Dinitro-benzol. 
§ 252. Dinitro-benzol, C 6 H 4 (N0 2 ) 2 (ortho-, meta,- para-). The ortho¬ 
compound is produced by the action of nitric acid on benzol, aided by 
heat in the presence of strong sulphuric acid to fix water. Some of the 
para-dinitro-benzol is at the same time produced. The meta-compound 
is obtained by the action of fuming nitric acid on nitro-benzol at a boiling 
temperature. 
The physical properties of the three dinitro-benzols are briefly as 
follows :—; 
Ortho-d. is in the form of needles ; m.p. 118°. 
Meta-d. crystallises in plates ; m.p. 90°. 
Para-d. crystallises, like the ortho-compound, in needles, but the 
melting-point is much higher, 171° to 172°. 
Just as nitro-benzol by reduction yields aniline, so do the dinitro- 
benzols on reduction yield ortho-, meta-, or para-phenylene diamines. 
Meta-phenylene diamine is an excellent test for nitrites ; and, since 
the commercial varieties of dinitro-benzol consist either mainly or in part 
of meta-dinitro-benzol, the toxicological detection is fairly simple, and is 
based upon the conversion of the dinitro-benzol into meta-phenylene- 
diamine. 
Dinitro-benzol and trinitro-benzol (T.N.T.) are largely employed in 
the manufacture of explosives. These substances have produced much 
illness among the workpeople in manufactories, and amongst miners 
whose duty it has been to handle such explosives. 
§ 253. Effects of Dinitro-benzol. —Huber 1 finds that if dinitro- 
benzol is given to frogs by the mouth in doses of from 100 to 200 mgrrns., 
death takes place in a few hours. Doses of from 2-5 to 5 mgrrns. cause 
general dulness, and ultimately complete paralysis, and death in from 
one to six days. 
Rabbits are killed by doses of 400 mgrrns., in time varying from 
twenty-two hours to four days. 
1 “ Beitrage zur Giftwirkung des Dinjtrobenzols,” A, Huber, Virchow’s Archiv, 
cxxvi. 240, 1891. 
