May 15, 1879] 



NATURE 



69 



flammable portion of the dynamite to the temperatm-e necessary 

 for the sudden transformation of the nitro-glycerine into gas, and 

 will thus bring about the detonation of a portion of the cartridge, 

 which will act as the initiative detonator to the remainder of the 

 dynamite. On igniting separately, at one of their extremities, 

 some dynamite cartridges which had been buried in snow for a 

 considerable period, the lecturer has observed that, as the frozen 

 material gradually burned away, very slight but sharp explosions 

 (like the snapping of a small percussion cap on a gun nipple) 

 occurred from time to time, portions of the frozen dynamite 

 being scattered with some violence. It has come to his know- 

 ledge that small heaps of hard-frozen cartridges weighing alto- 

 gether one pound have been detonated by igniting one cartridge 

 which was surrounded by the remainder. These facts appear to 

 substantiate the correctness of the foregoing explanation. They 

 point to the danger of assuming that, because dynamite in the 

 frozen state is less sensitive to the effects of a blow or initiative 

 detonation, than the thawed material, it may therefore be sub- 

 mitted without special care to the action of heat, for the purpose 

 of thawing it. Instances of the detonation, with disastrous 

 results, of even single cartridges of frozen dynamite, through the 

 incautious application of considerable heat (as for example by 

 placing them in an oven, or close to a fire), have been, and are 

 still, of not unfrequent occurrence, even though Mr. Nobel has 

 insisted upon the application of heat through the agency only of 

 warm water, as the sole reliable method of safely thawing dyna- 

 mite cartridges. 



While the sensitiveness to detonation of air-dry gimcotton 

 remains unaffected by great reduction in temperature of the mass, 

 and while in this respect it presents advantages over nitro-glycerine 

 preparations, wet gun-cotton becomes very decidedly more 

 susceptible to detonation when frozen. Thus the detonation 

 of gun-cotton containing an addition of from 10 to 12 per cent, 

 of water is somewhat uncertain with the employment of lOO 

 grains of stronjy confined fulminate, and 2CX) grains are 

 required for the detonation of the substance when containing 15 

 to 17 per cent, of water ; but the latter in a frozen state can be 

 detonated by means of thirty grains of fulminate, and fifteen 

 grains are just upon the margin of the amount requisite for 

 detonating, with certainty, frozen gun-cotton containing 10 to 12 

 per cent, of water. 



The effects produced and products formed by the explosion of 

 gun-cotton in perfectly closed spaces, both in the loose, and the 

 compressed form, and by its detonation in the dry and the wet 

 state, have been made the subject of study by Capt. Noble and 

 Mr. Abel, the method of research pursued being the same as that 

 followed in their published researches on fired gunpowder ; 

 results of considerable interest in regard to the heat of explosion ; 

 the pressures developed, and the products of explosion of dry 

 and wet gun-cotton, have been obtained, which are about to be 

 communicated to the Royal Society. 



It may briefly be stated that the temperature of explosion of 

 gun-cotton is more than double that of gunpowder (being about 

 4,400° C); that the tension of the products of explosion, 

 assuming the material to fill entirely the space in which it is 

 fired, is consideraWy more than double that of the powder- 

 products under the same conditions ; that the products obtained 

 by the explosion of dry gun-cotton are comparatively simple and 

 very uniform under different conditions as regards pressure; 

 that the products of detonation of dry gun-cotton do not differ 

 materially from those of its explosion in a confined space, but 

 that those furnished by the detonation of wet gun-cotton present 

 some interesting points of difference. Messrs. Nobel and 

 Abel are extending their investigations to the nitro-glycerine 

 preparations. 



The great advance which has been made within the last twelve 

 years in our knowledge of the conditions which determine the 

 character of the metamorphosis that explosive substances un- 

 dergo, and which develop or control the violence of their action, 

 finds its parallel in the progress which has been made in the 

 prodnction, perfection, and application of the two most promi- 

 nent of modem explosive agents, nitro-glycerine and gun-cotton. 

 Discovered at nearly the same time, less than forty years ago, 

 the one speedily attained great prominence, on account of the 

 apparent ease with which it could be prepared and put to prac- 

 tical use; a prominence shortlived, however, because the first, \ 

 and somewhat rash, attempts to utilise it preceded the acqui- ' 

 sition of sound and sufficient knowledge of its nature and pro- 

 perties. Even many years afterwards, when the difficulties 

 attending its employment appeared to have been surmounted, I 



the confidence of its most indefatigable partisans and stannchest 

 friends received a rude shock, from which it needed the support 

 of much faith and some fortitude to recover. 



Meanwhile, the other substance, which now shares with it the 

 honours of important victories won over gunpowder, continued 

 to be generally regarded as a dangerous chemical curiosity, even 

 for some time after its present position as one of the most 

 important industrial products and useful explosive agents was 

 being gradually but firmly secured for it, step by step, by the 

 talent and untiring energy of a single individual. 



Almost from the day of its discovery, the fortunes of gun- 

 cotton continued to fluctuate, and much adversity marked its 

 career, until at last its properties became well understood, and 

 its position as a most formidable explosive agent, applicable on 

 a large scale, with ease, great simplicity, and with a degree of 

 safety far greater than that as yet possessed by any other 

 substance of this class, has now become thoroughly established. 

 Since the lecturer last discoursed on the properties of gun- 

 cotton, seven years ago, this material has attained a firm footing 

 as one of the most formidable agents of defence and offence. 

 For all military engineering operations, and for employment in 

 submarine mines and torpedoes, compressed gun-cotton, stored 

 and used in the wet condition, has become the accepted explosive 

 agent in Great Britain ; within the last five years upwards of 

 550 tons have been manufactm-ed for this piurpose, and are dis- 

 tributed over our chief naval stations at home and abroad. 

 Germany some years since copied our system of manufacture 

 and use of gun-cotton ; France has provided itself with a large 

 supply for the same purposes, and Austria, where the acquisition 

 of bitter experience of the uncertainty of gun-cotton in the 

 earlier stages of history, naturally gave rise to a persistent 

 scepticism regarding its present trustworthiness, appears now 

 also about to adopt wet gun-cotton for military and naval uses. 



But while the usefulness and great value of compressed gun- 

 cotton in these important directions have been established, its 

 technical application has made but slow progress as compared 

 with that of the simple nitro-glycerine preparation known as 

 dynamite, which, in point of cost of production and convenience 

 for general blasting purposes, can claim superiority over com- 

 pressed gun-cotton. Already in 1867 a number of dynamite 

 factories, working under Nobel's supervision, existed in different 

 countries; in that year the total quantity manufactured amounted 

 to 1 1 tons ; in another year the produce had risen to 78 tons ; 

 in 1872 it had attained to 1,350 tons. Two years afterwards 

 the total production of dynamite was nearly trebled, and in 1878 

 it amounted to 6, 140 tons. 



There are as many as fifteen factories in different parts of the 

 world (including a very extensive one in Scotland) working 

 under the supervision of Mr. Nobel, the originator of the nitro- 

 glycerine industry, and some six or seven other establishments 

 exist where dynamite or preparations of very similar character 

 are also manufactured. 



How far the rate of production of dynamite will be affected 

 by the further development of the value of Nobel's new prepa- 

 ration, the blasting gelatine, it is difficult to foresee, but there 

 appears great prospect of an important future for this very 

 peculiar and interesting detonating agent. 



It is hoped that the subjects dealt with in this discourse afford 

 interesting illustration of the intimate connection of scientific 

 research with important practical achievements. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



" Dr. Carpenter, Registrar of the University of London, 

 announced his retirement from that office at the annual meeting 

 of Convocation on Tuesday. A unanimous vote was passed, 

 recognising his long and valuable services in the post which he 

 had so long held. 



The recent retirement of Prof, fealfour from the Chair of 

 Botany at Edinburgh has g^ven rise to two changes in the -Scottish 

 professoriate. As his successor, our readers know, the Curators 

 have appointed Dr. Alexander Dickson, the able Professor of 

 Botany m the University of Glasgow. The botanical class 

 has always been popular at Edinburgh, Dr. Balfour's students 

 having recently numbered, we believe, upwards of 350. The 

 classroom of the new professor, also, is so crowded that many 

 of the auditors can hardly find standing-room, large numbers 

 having been unable even to gain admission. Prof. Dickson is 



