Nitro-Explosives: A Practical Treatise.
by P. Gerald Sanford.
PREFACE.
In compiling the following treatise, my aim has been to give a brief but thoroughly practical account of the properties, manufacture, and methods of a.n.a.lysis of the various nitro-explosives now so largely used for mining and blasting purposes and as propulsive agents; and it is believed that the account given of the manufacture of nitro-glycerine and of the gelatine dynamites will be found more complete than in any similar work yet published in this country.
For many of the facts and figures contained in the chapter on Smokeless Powders I am indebted to (amongst others) the late Mr J.D. Dougall and Messrs A.C. Ponsonby and H.M. Chapman, F.C.S.; and for details with regard to Roburite to Messrs H.A. Krohn and W.J. Orsman, F.I.C. To these gentlemen my cordial thanks are due. Among the authorities which have been consulted in the general preparation of the work may be mentioned the _Journals_ of the Chemical Society, the Society of Chemical Industry, the United States Naval Inst.i.tute, and the Royal Artillery Inst.i.tution. I have also referred to several volumes of the periodical publication _Arms and Explosives;_ to various papers by Sir Frederick Abel, Bart., F.R.S., and General Wardell, R.A., on Gun-Cotton; to "Modern Artillery," by Capt.
Lloyd, R.N., and A.G. Hadc.o.c.k, R.A.; to the late Colonel Cundill"s "Dictionary of Explosives"; as well as to the works of Messrs Eissler, Berthelot, and others.
The ill.u.s.trations have been prepared chiefly from my own drawings. A few, however, have been taken (by permission) from the pages of _Arms and Explosives_, or from other sources which are acknowledged in the text.
P.G.S.
THE LABORATORY,
20 CULLUM STREET, E.C.
_May 1896._
PREFACE TO THE SECOND EDITION.
In the preparation of the Second Edition of this work, I have chiefly made use of the current technical journals, especially of the _Journal of the Society of Chemical Industry_. The source of my information has in every case been acknowledged.
I am also indebted to several manufacturers of explosives for information respecting their special products--among others the New Explosives Company Ltd.; Messrs Curtis"s and Harvey Ltd.; The Schultze Gunpowder Company Ltd.; and Mr W.D. Borland, F.I.C., of the E.C. Powder Company Ltd.
To my friend Mr A. Stanley Fox, F.C.S., of Faversham, my best thanks are also due for his help in many departments, and his kindness in pointing out several references.
The chapter on Smokeless Powders has been considerably enlarged and (as far as possible) brought up to date; but it has not always been possible to give the process of manufacture or even the composition, as these details have not, in several cases, been made public.
P. GERALD SANFORD.
LONDON, _June 1906._
NITRO-EXPLOSIVES.
CHAPTER I.
_INTRODUCTORY._
The Nitro-Explosives--Substances that have been Nitrated--The Danger Area-- Systems of Professors Lodge, Zenger, and Melsens for the Protection of Buildings from Lightning, &c.
The manufacture of the various nitro-explosives has made great advances during late years, and the various forms of nitro-compounds are gradually replacing the older forms of explosives, both for blasting purposes and also for propulsive agents, under the form of smokeless powders. The nitro-explosives belong to the so-called High Explosives, and may be defined as any chemical compound possessed of explosive properties, or capable of combining with metals to form an explosive compound, which is produced by the chemical action of nitric acid, either alone or mixed with sulphuric acid, upon any carbonaceous substance, whether such compound is mechanically mixed with other substances or not.[A]
[Footnote A: Definition given in Order of Council, No. 1, Explosives Act, 1875.]
The number of compounds and mixtures included under this definition is very large, and they are of very different chemical composition. Among the substances that have been nitrated are:--Cellulose, under various forms, e.g., cotton, lignin, &c.; glycerine, benzene, starch, jute, sugar, phenol, wood, straw, and even such substances as treacle and horse-dung.
Some of these are not made upon the large scale, others are but little used. Those of most importance are nitro-glycerine and nitro-cellulose.
The former enters into the composition of all dynamites, and several smokeless powders; and the second includes gun-cotton, collodion-cotton, nitrated wood, and the majority of the smokeless powders, which consist generally of nitro-cotton, nitro-lignin, nitro-jute, &c. &c., together with metallic nitrates, or nitro-glycerine.
The nitro-explosives consist generally of some organic substance in which the NO_{2} group, known as nitryl, has been subst.i.tuted in place of hydrogen.
Thus in glycerine,
|OH C_{3}H_{5}|OH, |OH
which is a tri-hydric alcohol, and which occurs very widely distributed as the alcoholic or basic const.i.tuent of fats, the hydrogen atoms are replaced by the NO_{2} group, to form the highly explosive compound, nitro-glycerine. If one atom only is thus displaced, the mono-nitrate is formed thus,
|ONO_{2} C_{3}H_{5}|OH; |OH
and if the three atoms are displaced, C_{3}H_{5}(ONO_{2})_{3}, or the tri- nitrate, is formed, which is commercial nitro-glycerine.
Another cla.s.s, the nitro-celluloses, are formed from cellulose, C_{6}H_{10}O_{5}, which forms the groundwork of all vegetable tissues.
Cellulose has some of the properties of the alcohols, and forms ethereal salts when treated with nitric and sulphuric acids. The hexa-nitrate, or gun-cotton, has the formula, C_{12}H_{14}O_{4}(ONO_{2})_{6}; and collodion-cotton, pyroxylin, &c., form the lower nitrates, i.e., the tetra- and penta-nitrates. These last are soluble in various solvents, such as ether-alcohol and nitro-glycerine, in which the hexa-nitrate is insoluble. They all dissolve, however, in acetone and acetic ether.
The solution of the soluble varieties in ether-alcohol is known as collodion, which finds many applications in the arts. The hydrocarbon benzene, C_{6}H_{6}, prepared from the light oil obtained from coal-tar, when nitrated forms nitro-benzenes, such as mono-nitro-benzene, C_{6}H_{5}NO_{2}, and di-nitro-benzene, C_{6}H_{4}(NO_{2})_{2}, in which one and two atoms are replaced by the NO_{2} group. The latter of these compounds is used as an explosive, and enters into the composition of such well-known explosives as roburite, &c. The presence of nitro groups in a substance increases the difficulty of further nitration, and in any case not more than three nitro groups can be introduced into an aromatic compound, or the phenols. All aromatic compounds with the general formula, C_{6}H_{4}X_{2}, give, however, three series. They are called ortho, meta, or para compounds, depending upon the position of NO_{2} groups introduced.
Certain regularities have been observed in the formation of nitro- compounds. If, for example, a substance contains alkyl or hydroxyl groups, large quant.i.ties of the para compound are obtained, and very little of the ortho. The subst.i.tution takes place, however, almost entirely in the meta position, if a nitro, carboxyl, or aldehyde group be present. Ordinary phenol, C_{6}H_{5}.OH, gives para- and ortho-nitro-phenol; toluene gives para- and ortho-nitro-toluene; but nitro-benzene forms meta-di-nitro- benzene and benzoic acid, meta-nitro-benzoic acid.[A]
[Footnote A: "Organic Chemistry," Prof. Hjelt. Translated by J.B. Tingle, Ph.D.]
If the graphic formula of benzene be represented thus (No. 1), then the positions 1 and 2 represent the ortho, 1 and 3 the meta, and 1 and 4 the para compounds. When the body phenol, C_{6}H_{5}.OH, is nitrated, a compound is formed known as tri-nitro-phenol, or picric acid, C_{6}H_{2}(NO_{2})_{3}OH, which is used very extensively as an explosive, both as picric acid and in the form of picrates. Another nitro body that is used as an explosive is nitro-naphthalene, C_{10}H_{6}(NO_{2})_{2}, in roburite, securite, and other explosives of this cla.s.s. The hexa-nitro- mannite, C_{6}H_{8}(ONO_{2})_{6}, is formed
[Ill.u.s.tration: No. 1]
[Ill.u.s.tration: META-DINITRO-BENZENE No.2]
by treating a substance known as mannite, C_{6}H_{8}(OH)_{6}, an alcohol formed by the lactic acid fermentation of sugar and closely related to the sugars, with nitric and sulphuric acids. It is a solid substance, and very explosive; it contains 18.58 per cent. of nitrogen.
Nitro-starch has also been used for the manufacture of an explosive.
Muhlhauer has described (_Ding. Poly. Jour._, 73, 137-143) three nitric ethers of starch, the tetra-nitro-starch, C_{12}H_{16}O_{6}(ONO_{2})_{4}, the penta- and hexa-nitro-starch. They are formed by acting upon potato starch dried at 100 C. with a mixture of nitric and sulphuric acids at a temperature of 20 to 25 C. Rice starch has also been used in its production. Muhlhauer proposes to use this body as a smokeless powder, and to nitrate it with the spent mixed acids from the manufacture of nitro- glycerine. This substance contains from 10.96 to 11.09 per cent. of nitrogen. It is a white substance, very stable and soluble even in cold nitro-glycerine.
The explosive bodies formed by the nitration of jute have been studied by Messrs Cross and Bevan. and also by Muhlhauer. The former chemists give jute the formula C_{12}H_{18}O_{9}, and believe that its conversion into a nitro-compound takes place according to the equation--
C_{12}H_{18}O_{9} + 3HNO_{3} = 3H_{2}O + C_{12}H_{15}O_(6}(NO_{3})_{3}.
This is equivalent to a gain in weight of 44 per cent. for the tri- nitrate, and 58 per cent. for the tetra-nitrate. The formation of the tetra-nitrate appears to be the limit of nitration of jute fibre. Messrs Cross and Bevan say, "In other words, if we represent the ligno-cellulose molecule by a C_{12} formula, it will contain four hydroxyl (OH) groups, or two less than cellulose similarly represented." It contains 11.5 per cent. of nitrogen. The jute nitrates resemble those of cellulose, and are in all essential points nitrates of ligno-cellulose.
Nitro-jute is used in the composition of the well-known Cooppal Smokeless Powders. Cross and Bevan are of opinion that there is no very obvious advantage in the use of lignified textile fibres as raw materials for explosive nitrates, seeing that a number of raw materials containing cellulose (chiefly as cotton) can be obtained at from 10 to 25 a ton, and yield also 150 to 170 per cent. of explosive material when nitrated (whereas jute only gives 154.4 per cent.), and are in many ways superior to the products obtained from jute. Nitro-lignin, or nitrated wood, is, however, largely used in the composition of a good many of the smokeless powders, such as Schultze"s, the Smokeless Powder Co."s products, and others.