glycerine have been replaced by the NO_{2} group.

In the manufacture upon the large scale, a mixture of three parts by
weight of nitric acid and five parts of sulphuric acid are used. From the
above equation it will be seen that every 1 lb. of glycerol should give
2.47 lbs. of nitro-glycerol ((227+1)/92 = 2.47), but in practice the yield
is only about 2 lbs. to 2.22, the loss being accounted for by the
unavoidable formation of some of the lower nitrate, which dissolves in
water, and is thus washed away, and partly perhaps to the presence of a
little water (or other non-nitrable matter) in the glycerine, but chiefly
to the former, which is due to the acids having become too weak.




CHAPTER II.

_MANUFACTURE OF NITRO-GLYCERINE._

Properties of Nitro-Glycerine--Manufacture of Nitro-Glycerine--Nitration--
The Nathan Nitrator--Separation--Filtering and Washing--The Waste Acids--
Treatment of the Waste Acid from the Manufacture of Nitro-Glycerine and
Gun-Cotton.


~Properties of Nitro-Glycerine.~--Nitro-glycerol is a heavy oily liquid of
specific gravity 1.6 at 15° C., and when quite pure is colourless. The
commercial product is a pale straw yellow, but varies much according to
the purity of the materials used in its manufacture. It is insoluble in
water, crystallises at 10.5° C., but different commercial samples behave