Part 11 (2/2)

The exudation test consists in freezing and thawing the gelatine three times in succession Under these conditions there should be no exudation of nitro-glycerine All the elatine explosives should be subjected to analytical exaely depends upon the purity of the raw materials The wood-pulp, for instance, must be examined for acidity

~Properties of the Gelatine Coenerally colycerine, and 5 to 7 parts of nitro- cellulose, but the relative proportions of explosive base and nitro- glycerine, &c, in the various forelatine explosives do not always correspond to those necessary for total coives rise to a greater voluas, or because the rapidity of deco to the relative proportions and the conditions of application The various additions to blasting gelatine generally have the effect of lowering the strength by reducing the alycerine, but this is soent into a propulsive force If this process be carried too far, we of course lose the advantages due to the presence of nitro-glycerine There is therefore a limit to these additions[A]

[Footnote A: Mica is said to increase the rapidity of explosion when eneousness and stability of the hly essential that the nitro-glycerine should be completely absorbed by the substances hich it is mixed, and that it should not subsequently exude when subjected to heat or damp It is also ilycerine, as thisto a difference in the ation of the explosive wave in the liquid, and in thepoint has a tendency to separate fro material, in fact to exude When frozen, too, it requires a more powerful detonation to explode it, but it is less sensitive to shock The specific gravity of blasting gelatine is 15 (ie, nearly equal to that of nitro-glycerol); that of gun-cotton (dry) is 10

Blasting gelatine burns in the air when unconfined without explosion, at least in small quantities and when not previously heated, but it is rather uncertain in this respect It can be kept at a h teher telycerine will partially evaporate When slowly heated, it explodes at 204 C If, however, it contains asAccording to Berthelot,[A] gelatine colycerine and 84 per cent of nitro-cellulose, which are the proportions corresponding to total combustion, produces by explosion 177CO_{2}+ 143H_{2}O + 8N_{2}

[Footnote A: Berthelot, ”Explosives and their Powers”]

He takes C_{24}H_{22}(NO_{3}H)_{9}O_{11} as the formula of the nitro- cellulose, and 51C_{3}H_{2}(NO_{3}H)_{3} + C_{24}H_{22}(NO_{3}H)_{9}O_{11} as the for 12,360 grms The heat liberated by its explosion is equal to 19,381 calories, or for 1 kilo 1,535 calories Voluases reduced temperature equals 8,950 litres The relative value[A] of blasting gelatine to nitro- glycerine is as 14 to 145, kieselguhr dyna taken as 10

[Footnote A: Roux and Sarran]

CHAPTER V

_NITRO-BENZOL, ROBURITE, BELLITE, PICRIC ACID, &c_

Explosives derived from Benzene--Toluene and Nitro-Benzene--Di- and Tri-nitro-Benzene--Roburite: Properties and Manufacture--Bellite: Properties, &c--Securite--Tonite No 3--Nitro-Toluene-- Nitro-Naphthalene--Ael's Explosives--Picric Acid-- Picrates--Picric Powders--Melinite--Abel's Mixture--Brugere's Powders-- The Fuler of, &c-- Detonators: Sizes, Composition, Manufacture--Fuses, &c

~The Explosives derived froe class of explosives made from the nitrated hydro-carbons--benzene, C_{6}H_{6}; toluene, C_{7}H_{8}; naphthalene, C_{10}H_{8}; and also from phenol (or carbolic acid), C_{6}H_{5}OH The benzene hydro-carbons are generally colourless liquids, insoluble in water, but soluble in alcohol and ether

They generally distil without decomposition They burn with a smoky flame, and have an ethereal odour They are easily nitrated and sulphurated;to the strength of the acids used It is only the H-atoms of the benzene nucleus which enter into reaction

Benzene was discovered by Faraday in 1825, and detected in coal-tar by Hofmann in 1845 It can be obtained from that portion of coal-tar which boils at 80 to 85 by fractionating or freezing[A] The ordinary benzene of commerce contains thiophene (C_{4}H_{4}S), fro with sulphuric acid Its boiling point is 79 C; specific gravity at 0 equals 09 It burns with a luood solvent for fats, resins, sulphur, phosphorus, &c Toluene was discovered in 1837, and is prepared from coal-tar It boils at 110 C, and is still liquid at 28 C

[Footnote A: Ita mixture of benzoic acid and lime]

The mono-, chloro-, bromo-, and iodo-benzenes are colourless liquids of peculiar odour Di-chloro-, di-bromo-benzenes, tri- and hexa-chloro- and bromo-benzenes, are also known; and ether with di derivatives in the ortho, meta, and para modifications The nitro-benzenes and toluenes are used as explosives The following suanic Chemistry”:--

SUMMARY

____________________________________________________________________ | | | C_{6}H_{5}(N0_{2}) Nitro-benzene Liq BPt 206 C | | | | C_{6}H_{4}(NO_{2})_{2} Ortho-, meta-, and para- di-nitro-benzenes | | Solid MP 118, 90, and 172 C | | | | C_{6}H_{3}(NO_{3})_{3} S-Tri-nitro-benzene Solid MP 121 C | |____________________________________________________________________| | | | C_{6}H_{4}(CH_{3})NO_{2} Ortho-, meta-, and para- nitro-toluenes | | BP 218, 230, and 234 C, Para compound solid | |____________________________________________________________________| | | | C_{6}H_{3}(CH_{3})_{2}NO_{2} Nitro-xylene Liquid | |____________________________________________________________________| | | | C_{6}H_{2}(CH_{3})_{3}NO_{2} Nitro-mesitylene Solid | |____________________________________________________________________| | | | C_{6}H_{3}(CH_{3})(NO_{2})_{2} Di-nitro-toluenes | |____________________________________________________________________| | | | C_{6}H_{4}Cl(NO_{2}) Nitro-chloro-benzenes | | | | C_{6}Br_{4}(NO_{2})_{2} Tetra-bromo-di-nitrobenzene | |____________________________________________________________________|

The nitro coed, and volatilise ater vapour, or colourless or pale yellow needles or prisms Some of them, however, are of an intense yellow colour

Many of the heated They are heavier than water, and insoluble in it, but lacial acetic acid

Nitro-benzene, C_{6}H_{5}(NO_{2}), was discovered in 1834 by Mitscherlich

It is a yellow liquid, with apoint of +3 C It has an intense odour of bitter almonds It solidifies in the cold In di-nitro-benzene, the two nitro groups may be in thethefro colourless needles The ortho compound crystallises in tables, and the para in needles They are both colourless When toluene is nitrated, the para and ortho are chiefly formed, and a very little of the meta compound

~Nitro Compounds of Benzene and Toluene~--The preparation of the nitro derivatives of the hydrocarbons of the benzene series is very si the hydrocarbon into contact with strong nitric acid, when the reaction takes place, and one or en atoroup (NO_{2}) Thus by the action of nitric acid on benzene (or benzol), mono-nitro-benzene is formed:--

C_{6}H_{6} + HNO_{3} = C_{6}H_{5}NO_{2} +H_{2}O

Mono-nitro-benzene

By the action of another molecule of nitric acid, the di-nitro-benzene is formed:--