Part 23 (1/2)
Judson powder, RRP | 25 | Emmensite (No 259) | 30 | Rack-a-rock | 32 | KClO_{3} 79 parts, | | C_{6}H_{5}(NO)_{2} 21 parts
Bellite | 50 | Forcite No 1 | 61 | Kieselguhr dynaycerine
Atlas powder No 1 | 74 | __________________________|____________|_________________________
CHAPTER IX
_DETERMINATION OF THE RELATIVE STRENGTH OF EXPLOSIVES_
Effectiveness of an Explosive--High and Low Explosives--Theoretical Efficiency--MM Roux and Sarrau's Results--Abel and noble's--nobel's Ballistic Test--The Mortar, Pressure, or Crusher Gauge--Lead Cylinders-- The Foot-Pounds Machine--noble's Pressure Gauge--Lieutenant Walke's Results--Calculation of Pressure Developed by Dynamite and Gun-Cotton-- Macnab's and Ristori's Results of Heat Developed by the Explosion of Various Explosives--Co, &c
~The Deterth of Explosives~--Explosives hly divided into two divisions, viz, those which when exploded produce a shattering force, and those which produce a propulsive force
Explosives of the first class are generally known as the high explosives, and consist for the most part of nitro compounds, or mixtures of nitro compounds with other substances Any explosive whose detonation is very rapid is a high explosive, but the term has chiefly been applied to the nitro-explosives
The effectiveness of an explosive depends upon the voluases forh explosives the chemical transfor of shattering effect Gunpowder, on the other hand, is a low explosive, and produces a propelling or heaving effect
Theis proportionate to the a its cherammetres by the formula 425Q, where Q is the number of units of heat evolved The theoretical efficiency of an explosive cannot, however, be expected in practice forrock, for instance:[A]--1 Incomplete coes induced in the surroundingand heating of the h the blast-hole, and the fissures caused by the explosion The proportion of useful work has been estimated to be from 14 to 33 per cent
of the theoretical maximum potential
[Footnote A: CN Hake, Government Inspector of Explosives, Victoria, _Jour Soc Chem Ind_, 1889]
For the purposes of coenerally rely more upon the practical than the theoretical efficiency of an explosive These, however, stand in the sa table of Messrs Roux and Sarrau will show:--
MECHANICAL EQUIVALENT OF EXPLOSIVES
Theoretical Work Relative in Kilos Value
Blasting powder (62 per cent KNO_{3}) 242,335 10 Dynaelatine (92 per cent nitro-glycerine) 766,813 316 Nitro-glycerine 794,563 328
Experielatine 14 Nitro-glycerine 14
Sir Frederick Abel and Captain WH noble, RA, have shown that the unpowder is equal to 486 foot-tons per lb of powder, or that when 1 kilo, of the powder gases occupy the volume of 1 litre, the pressure is equal to 6,400 atraives 1,320 units of heat MM Roux and Sarrau, of the Depot Centrales des Poudres, Paris, by means of calori units of heat are produced by the detonation of--
Nitro-glycerine 1,784 heat units
Gun-cotton 1,123 ”
Potassic picrate 840 ”
which, ives--
Nitro-glycerine 778 ramme
Gun-cotton 489 ” ”
Picrate of potash 366 ” ”
~nobel's Ballistic Test~--Alfred nobel was the first to make use of the mortar test to measure the (ballistic) power of explosives The use of thethe relative power of explosives does not give very accurate results, but at the same time the information obtained is of considerable value from a practical point of view The mortar consists of a solid cylinder of cast iron, one end of which has been bored to a depth of 9 inches, the dia 4 inches At the bottom of the bore-hole is a steel disc 3 inches thick, in which another hole has been bored 3 inches by 2 inches The54) itself is fitted with trunnions, and fire, which is securely bolted down to the ground The shot used should weigh 28 lbs, and be turned accurately to fit the bore of the h which the fuse is put
The following is thean experiment:--A piece of hard wood is turned in the lathe to exactly fit the hole in the steel disc at the bottom of the bore This wooden cylinder itself contains a sr in the mortar, a hole lass rod of such a size that the detonator to be used will just fit into it After placing the wooden cylinder containing the explosive in the cavity at the bottoently down on to it A piece of fuse about a foot long, and fitted with a detonator, is now pushed through the hole in the centre of the shot until the detonator is ehted, and the distance to which the shot is thrown is carefully s into yards and fractions of yards, especially at the end opposite to the le of 45 In experi with this apparatus, the force and direction of the ill be found to have considerable influence