NATURE 



lOI 



THURSDAY, OCTOBER ii, 1917. 



MARSHALL'S "EXPLOSIVES." 

 Explosives. By A. Marshall. Second edition. 



Tl Vol. ii,, Properties and Tests. Pp. ix + 411- 

 J 795. (London : J. and A. Churchill, 1917.) 

 M Price 3/. 35. net the two vols. 

 HIS second volume of Mr. Marshall's treatise 

 is divided into four parts, dealing- respec- 

 tively with the Properties of Explosives, Special 

 Explosives, Stability, and the Analysis of 

 Materials. There has been some re-arrangement 

 of the matter since the issue of the first edition ; 

 for example, coal-mining explosives are compre- 

 hensively dealt with in a special chapter, and 

 another chapter is devoted to naval and military 

 explosives. 



There has been considerable extension of the 

 section devoted to the power of explosives, both 

 on the theoretical and the practical side. The 

 French modification of the well-known Trauzl 

 test is introduced, and the earth test, in which 

 the explosive is buried in soil which has been 

 undisturbed for years, and the enlargement of the 

 cavity after firing measured and its capacity 

 determined. Reference is made also to a test in 

 concrete blocks. 



In dealing with initiators of explosion, which 

 beg-an with flame and developed through the flint 

 and steel to the use of fulminate of mercury com- 

 positions, we have the latest development for 

 detonating- high explosives referred to, namely, 

 the use of compound detonators where fulminate 

 provides .the first step, and its action communi- 

 cated first to such nitro-aromatic explosives as 

 rotyl (trinitrotoluene) or tetryl (tetranitro- 

 methylaniline), which, in turn, bring about the 

 detonation of the main charge. Other alternatives 

 to the fulminates are the azldes. In all these 

 ighly sensitive substances there appears to exist 

 , state of great strain in the crystals ; this is 

 nfirmed by their strong double refraction, and 

 he larger the crystals the hig-her their sensitive- 

 less to shock. While the azides are not so 

 ' brisant " as the fulminates, by combination with 

 litro-aromatic explosives very effective results are 

 >btained. Azides have one advantage over ful- 

 ninates besides less sensitiveness, for fulminate 

 leteriorates on storage, especially if the tempera- 

 ure is high or the atmosphere damp. One per 

 lent, of water renders fulminate useless ; lead 

 ide, on the other hand, is much more permanent, 



ind 



per cent, of moisture has been found to 



ake no perceptible difference in its acfion. Mr. 



arshall quotes extensively data on the quantities 

 ►f different initiators required for various explo- 

 ives. 



For gelatinised nitroglycerine explosives 

 'renforts," or "boosters," consisting of short 

 >rass tubes of a size to fit over the detonator and 

 Jiarged with trotyl, or other explosive of 

 timilar type, are employed. For high-explosive 

 ^hell, where premature detonation must be 

 endered impossible, or at least most improbable, 

 NO. 2502, VOL. 100] 



the use of a powerful sensitive detonator is out 

 of the question, and for picric acid charges picric 

 powder (ammonium picrate and saltpetre) is 

 employed with a suitable detonator, whilst with 

 the more insensitive trotyl the priming charge is 

 sometimes the same explosive in the form of 

 powder or loosely compressed pellets, but more 

 usually tetryl, and we are told that this is one of 

 the chief uses of the latter, which is now manu- 

 factured on a considerable scale. There is some 

 repetition in this section, much the same infor- 

 rnation being given under " Ignition and Detona- 

 tion " and " Fuses." 



The influence of the war is naturally seen in 

 extended space being devoted in the section on 

 naval and military explosives to mines, torpedoes, 

 the various types of shell, grenades, etc. 

 Naturally, the description is only general. 

 Illustrations of the fragmentation of high-explo- 

 sive and armour-piercing shell are given from the 

 excellent paper by Major E. P. O'Hern which 

 appeared in the Smithsonian Report for 1914. 



In the important and excellent section on 

 stability tests the principal additions are to be 

 found in the Abel heat test. On this standard 

 test there have been much discussion and investi- 

 gation. There can be no doubt as to its great 

 value if due observance is taken of the conditions 

 and procedure. In 1909 a joint committee was 

 appointed representing the Home Office, the 

 Admiralty, the War Office, and the trade, and a 

 first report was issued in 1914, together with a 

 memorandum of instructions, specification of 

 apparatus, etc. With this report at hand, Mr. 

 Marshall has been able to extend considerably on 

 the test. 



In the last section, on materials and their 

 analysis, Mr. Marshall has added some useful 

 matter relating to the important question of 

 sampling. A further extension is found in 

 examples of calculation for the revivification of 

 waste acids from nitration plants, an important 

 matter both in manufacturing and in conserving 

 supplies. More space is devoted to the important 

 raw material cotton, including- specifications in 

 different countries. Another material the import- 

 ance of which has increased enormously is 

 ammonium nitrate. To the examination of this 

 body only a few lines were allocated in the first 

 edition, but much more space is now devoted to 

 it, although no reference is to be found to pos- 

 sible organic contamination, which, with the intro- 

 duction of nitrate from coal carbonisation, is of 

 great importance. 



Excellent as the first edition of Mr. Marshall's 

 work was, his second edition places the book 

 amongst the best technical books which have been 

 written. It is by far the most complete exposi- 

 tion on the subject which has appeared, and only 

 on very minor points can the critic find fault 

 with the subject-matter or detect small omissions. 

 One might, however, plead for more systematic 

 nomenclature with adherence to one name for a 

 particular explosive throughout, with mention of 

 alternatives in the section principally devoted 

 to it. 



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