Nitro-Explosives: A Practical Treatise | Page 9

58.15 per cent. Water 19.83 " Oxygen 3.52
per cent. Nitrogen 18.50 "
The volume of gases produced at 0° and 760 mm., calculated from the
above, is 714 litres per kilo, the water being taken as gaseous.
Nitro-glycerine is decomposed differently if it is ignited as dynamite
(i.e., kieselguhr dynamite), and if the gases are allowed to escape freely
under a pressure nearly equal to that of the atmosphere. Sarrau and
Vieille obtained under these conditions, for 100 volumes of gas--
NO 48.2 per cent. CO 35.9 " CO_{2} 12.7 " H 1.6 per cent. N 1.3 "
CH_{4} 0.3 "
These conditions are similar to those under which a mining charge,
simply ignited by the cap, burns away slowly under a low pressure (i.e.,
a miss fire). In a recent communication, P.F. Chalon (Engineering and
Mining Journal, 1892) says, that in practice nitro-glycerine vapour,
carbon monoxide, and nitrous oxide, are also produced as the result of
detonation, but he attributes their formation to the use of a too feeble
detonator.
Nitro-glycerine explodes very violently by concussion. It may be
burned in an open vessel, but if heated above 250° C. it explodes.
Professor C.E. Munroe gives the firing point as 2O3°-2O5° C., and L.
de Bruyn[A] states its boiling point as 185°. He used the apparatus
devised by Horsley. The heat of formation of nitro-glycerine, as
deduced from the heat of combustion by M. Longuinine, is 432 calories
for 1 grm.; and the heat of combustion equals 1,576 cals. for 1 grm. In
the case of nitro-glycerine the heat of total combustion and the heat of
complete decomposition are interchangeable terms, since it contains an
excess of oxygen. According to Dr W.H. Perkin, F.R.S.,[B] the
magnetic rotation of nitro-gylcerine is 5,407, and that of tri-methylene
nitrate, 4.769 (diff. = .638). Dr Perkin says: "Had nitro-glycerine
contained its nitrogen in any other combination with oxygen than as
-O-NO_{2}, as it might if its constitution had been represented as

C_{3}H_{2}(NO_{2})_{3}(OH)_{3}, the rotation when compared
with propyl nitrate (4.085) would be abnormal."
[Footnote A: _Jour. Soc. Chem. Ind._, June 1896, p. 471.]
[Footnote B: _Jour. Chem. Soc._, W.H. Perkin, 1889, p. 726.]
The solubility of nitro-glycerine in various solvents has been
investigated by A.H. Elliot; his results may be summarised as
follows:--
_________________________________________________________
______________ | | Solvent. | Cold. | Warm.
_____________________________|______________________|_____
_____________ | | Water | Insoluble | Slightly soluble Alcohol,
absolute | Soluble | Soluble " 93% | " | " " 80% | Slowly soluble | " "
50% | Insoluble | Slightly soluble Methyl alcohol | Soluble | Soluble
Amyl " | " | " Ether, ethylic | " | " " acetic | " | " Chloroform | " | "
Acetone | " | " Sulphuric acid (1.845) | " | " Nitric acid (1.400) | Slowly
soluble | " Hydrochloric acid (1.200) | Insoluble, decomposed| Slowly
soluble Acetic acid, glacial | Soluble | Soluble Carbolic acid | " | "
Astral oil | Insoluble | Insoluble Olive " | Soluble | Soluble Stearine oil |
" | " Mineral jelly | Insoluble | Insoluble Glycerine | " | " Benzene |
Soluble | Soluble Nitro-benzene | " | " Toluene | " | " Carbon bi-sulphide
| Insoluble | Slightly affected Turpentine | " | Soluble Petroleum naphtha,
71°-76° B.| " | Insoluble Caustic soda (1:10 solution) | Insoluble. |
Insoluble. Borax, 5% solution | " | " Ammonia (.980) | " | " slightly | |
affected. Ammonium sulph-hydrate | Insoluble, sulphur | Decomposed.
| separates | Iron sulphate solution | Slightly affected | Affected. Iron
chloride (1.4 grm. Fe | Slowly affected | Decomposed. to 10 c.c.
N_{2}O) | | Tin chloride | Slightly affected | Affected.
_____________________________|______________________|_____
_____________
Many attempts have been made to prepare nitro-glycerine explosives
capable of withstanding comparatively low temperatures without
freezing, but no satisfactory solution of the problem has been found.
Among the substances that have been proposed and used with more or

less success, are nitro- benzene, nitro-toluene,
di-nitro-mono-chlorhydrine, solid nitro derivatives of toluene,[A] are
stated to lower the freezing point of nitro-glycerine to -20°C. without
altering its sensitiveness and stability. The subject has been
investigated by S. Nauckhoff,[B] who states that nitroglycerine can be
cooled to temperatures (-40° to -50° C.) much below its true freezing
point, without solidifying, by the addition of various substances. When
cooled by means of a mixture of solid carbon, dioxide, and ether, it sets
to a glassy mass, without any perceptible crystallisation. The mass
when warmed to 0°C. first rapidly liquefies and then begins to
crystallise. The true freezing point of pure nitro- glycerine was found to
be 12.3°C. The technical product, owing to the presence of
di-nitro-glycerine, freezes at 10.5° C. According to Raoult's law, the
lowering of the freezing point caused by