2l8 



NATURE 



[November 14, 19 18 



None "I the shell high explosives possess .ill th'e 

 desirable qualities. Phose now in use have little more 

 than half the shattering powei ol blasting gelatine. 

 All .Hi products derived from the distillation of coal. 



In spite of its great merits, picric acid li.i^ now 

 been largelj replaced as a shell-filling In trinitro- 

 toluene and amatol. 



Given that the picric acid is pure and propei pre 

 cautions have been taken, ii is quite sab and the 

 most powerful shell-filling in use. Ii is also un- 

 affected by high atmospheric temperatures, unlike 

 T-.X.T., and is specially suitable foi tropical climates. 



1 rinitrotoluene (< ,H .1M1 nil ). I sualh, called 

 T.N.T., this substance, at present the must important 

 hi the shell high explosives, is known in the Service 

 as trotyl. When heated to about 300 ('., T.N.T. 

 ignites and burns with a hot, but ven smoky, flame. 

 When .1 large mass is involved, the heat given out 

 will invariably raise the temperature to the detonating- 

 point, It is in M \ detonated bj fulminate, excepl when 

 in the form of cast slabs untamped, when the addition 

 of a little lead azide to the fulminate is necessary. 

 Fulminate detonators are used in bombs, torpedoes, 

 and grenades. T.N.T. can also be detonated by less 

 sensitive substances, such as picric powder and tetryl, 

 and these are used in shells. The velocity of detona- 

 tion in its densest form is about 7000 metres per 

 second. The power is less than that of picric acid, 

 about in the proportion of 01 : loo. Owing to the 

 inferior velocity of detonation, the shattering effect 

 (brisance) is proportionately still less, about 87: ioo. 



When an amatol shell detonates there is only a 

 little grey smoke, and no definite indication as to 

 whether detonation has been complete or not. For 

 observation purposes a packet of smoke producer is 

 put in. The power is a little greater than that of pure 

 T.N.T., but the velocity of detonation much Ls- j.000 

 to 4500 metres per second, SO that the local shattering 

 effect is much b ss. For some purposes this is even 

 an advantage. 



Amatol is the most used of all the shell high explo- 

 sives at present. 



Tetranitromethylaniline |C,1 1 .(NO.) XCII.NO,).-- 

 This substance is known in the trade as tetryl, and 

 in the Service as C.E. (composition exploding). It is 

 readily detonated by a very small charge of fulminate, 

 such as that used in shell detonator caps, is very 

 powerful, and has a velocity of detonation of more 

 than 7000 metres per second. It is an excellent 

 initiator of detonation in other less sensitive explosives. 

 In powder, pellets, and cylinders it is used in the 

 gaines or detonators for T.N.T. and amatol shells, 

 with which ii is ver} effective. 



Detonation <>/ High-explosive Shells. — The problem 

 nf the detonation of a high-explosive shell is difficult. 

 The shell is subjected to an enormous shock in the 

 act of firing, the detonating charge must be in inti- 

 mtact with the filling, and if fulminate were 

 tere would fie a great risk of this being de- 

 tonated by the shock. The problem seems to have 

 been solved by the introduction of the gaine method. 



I he Gaine. The gaine is a metal tube screwed to 

 the fuse, which enters a cavity in the tilling and 

 makes good contact with it. This is very necessary. 

 Ii contains a chain -if -[distances, about four, of 

 decreasing order of sensitiveness, starting from the 

 fuse, and increasing order of violence of explosion. 

 Use is made of thi fact thai a substance in powder 

 is more easil) detonated than when in compressed 



pellets, and pellets than a cast, dense solid. The 



actual substances van with the shell and nature of 

 the filling, but always starl with gunpowder, which 

 is very certain in action. Thus we may suppose the 



NO. 2559, VOL. I02] 



chain 1.1 consist of (1) gunpowder, i.m tetryl powder, 

 (3) tetryl pellets, and (4) T.N.T. pellets. 



Ih. action is -tailed by a fulminate cap in the 

 eili fires tie- gunpowder. This partially ex- 

 plodes and partially detonates No. 2, which detonates 

 No. .i. which in turn detonates No. 4, and this 

 detonates the main tilling. With fuse and gaine in 

 good condition then- are very few failures now. 



/ NIVERSITY AM) EDUCATION 1/. 

 INTELLIGENCE. 



Aberdeen. Lord Cowdra\ ha- been elected Rector 

 ol ih. I niversity in succession to Mr. Churchill, who 

 lie. occupied the position for the last four years. 



T;m: Mercers' Company ha- given [25!. toward- the 

 maintenance fund of the ( ancei Investigation Depart- 

 ment of the Middlesex Hospital. 



Tin; sum of toool. has been given to the Ciu of 

 London School bv Prof. Carlton Lambert for the 

 foundation of a science scholarship. 



\ i;i -.1 VR( It fellowship of the annual value of 150/. 



has been founded at <.u\'s Hospital in memor; of 

 the late Lieut. R. W. Poulton Palmer and his sister, 

 the late Mrs. E. II. A. Walker, the object of which 

 will be the investigation of obscun diseases in man. 



Tin London County Council Ii ' 1 si ries 



ol addie, -e- to London teachers on various aspects 

 ol the problem of national reconstruction after the 



war. The first two addresses will be :- November 22, 



"The British Commonwealth," l>\ C. to. mi Robert- 

 son; .mil December II, "Hours ol 1 abour," bv Lord 



Leverhulme. Sir Cyril Cobb, chairman of the Educa- 

 tion Committee of the Council, will preside at these 

 lectures. Other lectures in connection with reconstruc- 

 tion will he given .on the following subject : 

 Economic Recovery, Housing, Agriculture and Rural 

 Life. Women's Employment, Adult Education, Food 

 Supply, International Relations, India, and National 

 Health. The lectures are arranged for London 

 teachers, hut other persons ran be admitted if accom- 

 modation is available. Applications for tickets should 

 be made to the Education Officer. L.C.C., Education 

 Offices, Victoria Embankment, W.C.2, marked II. 45. 

 A -tame..! addn >sed envelope should bi 1 nclosed. 



One of the main matters to which Sir J. J. Thom- 

 son'- committee on the position of natural science 

 in the educational system of Great Britain gave atten- 

 tion was the provision of courses inti ndi d to stimulate 

 interest in natural facts and phenomena and their 

 human aspects. The appearand - and movements of 



the heavenly bodies are particularly suitable 1 b- 



servations and instruction of this kind, vet few pupils 

 leave school with anv knowledge of them, and most 

 people go through life without an intelligent under- 

 standing of the simplest facts ol astronomy. Sir 

 Frank Dvson, the Astronomer Royal, in an address 

 lo the British Astronomical Association on Oct 1 

 urged that the claims of astronomy should l" borne 

 in mind in anv schemes for the broadening of science 

 leaching in schools. A certain amount of valuable 

 work in this direction i- done already in connection 

 with the practical geography lessons; and the British 

 Association Report on Science Teaching in Secondan 

 Seh. ml- contains, in one of the syllabuses, much useful 

 guidance to such observations. Sir Frank - Dyson 

 rightly lavs stress upon the educational valui "l work 



