The Chemistry of Powder and Explosives - Sciencemadness Dot Org

270 NITRIC ESTERS
Cold concentrated sulfuric acid does not attack mercury. Cold
nitric acid acts upon mercury to form mercurous nitrate with the
evolution of nitric oxide. If concentrated sulfuric acid is present,
mercurous nitrate cannot form, and the nitric acid is converted
by the mercury quantitatively into nitric oxide. The method
appears to have been .used for the first time by Walter Crum 102
who applied it at an early date to the analysis of guncotton.
FIGURES 66 and 67. Georg Lunge and His Nitrometer. Obverse and
reverse of commemorative bronze plaquette by Hans Frei in celebration
of Lunge's seventieth birthday.
He introduced .the sample of guncotton into a eudiometer filled
with mercury and inverted in that liquid, and carried out the
reaction and measured the gas volume in the same eudiometer.
Since he was unable to separate the guncotton from the air
entangled with it, the measured gas volume was too large. The
true volume of nitric oxide was determined by admitting a solution
of ferrous sulfate to the eudiometer and noting the volume
of gas which was absorbed.
The Lunge nitrometer is so designed that the nitrate or nitric
ester is dissolved first in concentrated sulfuric acid and the solution,
without entrained gas, is afterwards admitted to the re-
lo -Loc. cit.