The acids are mixed beforehand, and allowed to cool before use.  The nitric acid used has a specific gravity of 1.388, and should be as free as possible from the lower oxides of nitrogen.  The sulphuric acid has a specific gravity of 1.845, and contains from 95 to 96 per cent. of mono-hydrate.  A good mixture is 100 parts of nitric to 140 parts of sulphuric acid, and 78 parts of benzene; or 128 parts HNO_{3}, 179 of H_{2}SO_{4}, and 100 of benzene (C_{6}H_{6}).  The benzene having been introduced into the cylinder, the water is turned on and the apparatus cooled, the agitators are set running, and the acid cock turned on so as to allow it to flow in a very thin stream into the nitrator.

Should it be necessary to check the machinery even for a moment, the stream of acid must be stopped and the agitation continued for some time, as the action proceeds with such vigour that if the benzene being nitrated comes to rest and acid continues to flow, local heating occurs, and the mixture may inflame.  Accidents from this cause have been not infrequent.  The operation requires between eight to ten hours, agitation and cooling being kept up all the time.  When all the acid is added the water is shut off, and the temperature allowed to rise a little, to about 100 deg.  C. When it ceases to rise the agitators are thrown out of gear, and the mixture allowed some hours to cool and settle.  The acid is then drawn off, and the nitro-benzene is well washed with water, and sometimes distilled with wet steam, to recover a little unconverted benzene and a trace of paraffin (about .5 per cent. together).  At many English works, 100 to 200 gallons, or 800 to 1,760 lbs., are nitrated at a time, and toluene is often used instead of benzene, especially if the nitro-benzene is for use as essence of myrbane.  The waste acids, specific gravity 1.6 to 1.7, contain a little nitro-benzene in solution and some oxalic acid.  They are concentrated in cast-iron pots and used over again.

Di-nitro Benzene is obtained by treating a charge of the hydrocarbon benzene with double the quantity of mixed acids in two operations, or rather in two stages, the second lot of acid being run in directly after the first.  The cooling water is then shut off, and the temperature allowed to rise rapidly, or nitro-benzene already manufactured is taken and again nitrated with acids.  A large quantity of acid fumes come off, and some of the nitro- and di-nitro-benzol produced comes off at the high temperature which is attained, and a good condensing apparatus of stoneware must be used to prevent loss.  The product is separated from the acids, washed with cold water and then with hot.  It is slightly soluble in water, so that the washing waters must be kept and used over again.  Finally it is allowed to settle, and run while still warm into iron trays, in which it solidifies in masses 2 or 4 inches thick.  It should not contain any nitro-benzol, nor soil a piece of paper when laid on it, should be well crystallised, fairly hard, and almost odourless.  The chief product is meta-di-nitro-benzene, melting point 89.8, but ortho-di-nitro-benzene, melting point 118 deg., and para-di-nitro, melting point 172 deg., are also produced.  The melting point of the commercial product is between 85 deg. to 87 deg.  C.