32 



NATURE 



\May 8, 1879 



transformation than that which actually takes place in the 

 life of every frog and toad. Born almost a lamprey, it 

 changes into a creature which is a Selachian, and some- 

 thing more ; for it passes through the further border of 

 the sharks and skates, in their territory, and begins in its 

 changing growth to make the rudiments, at least, of 

 many an important organ which comes to its perfection 

 in man and his nearest relatives. The growth force then 

 fetching in improvements and additions from many a 

 quarter, and combining all things skilfully, makes a new 

 thing oji the earth. 



(TV be continued^ 



THE NEWEST EXPLOSIVE 



GUN-COTTON and dynamite, which have for some 

 years past held the foremost rank among modern ex- 

 plosives, are no longer, it seems, to retain this honour undis- 

 puted. A compound more violent still than either of these 

 well-known preparations has lately been given to the world 

 by M. Nobel in the shape of blasting-gelatine, and blasting- 

 gelatine, again, has been endowed with still greater energy 

 by a modification in its nature, effected by Prof. Abel, 

 the War Department chemist. So far as experiment has 

 shown, the gelatine and modified gelatine are, without 

 doubt, the most active explosive agents known to us, or, 

 in other words, a given weight of these compounds will 

 work more destruction upon metal, stone, or other un- 

 yielding mass, than any of the hundred and one bodies 

 of a like character with which we have become ac- 

 quainted during the past half-century. 



It is a well-known circumstance that, with but very few 

 exceptions, the many explosives that have lately been 

 brought before the public under a variety of names are 

 merely modifications of one and the same thing. They 

 are all nitro-compounds, or modifications of them. One 

 class owe their origin to gun-cotton and the other to 

 nitro-glycerine, and gun-cotton and nitro-glycerine are by 

 the chemist regarded as the same thing. Gun-cotton is 

 made by the nitrification of a solid body, and nitro- 

 glycerine by the nitrification of a liquid body. The 

 methods of manufacture are similar, and the agents em- 

 ployed to bring about the nitrification are the same. In 

 the one instance a woody fibre — cellulose — is acted upon 

 by a mixture of strong nitric acid and sulphuric acid, the 

 former liquid to perform the operation of nitrification, 

 by substituting certain equivalents of nitrogen for the 

 hydrogen existing in the cellulose, and the latter acid for 

 the purpose of absorbing any moisture given off in the 

 substitution process, and thus preventing the nitric acid 

 from becoming dilute and inefficient. In the other, a 

 liquid — glycerine — is permitted to combine in small quan- 

 tities at a time with a mixture of the same acids, and in 

 like manner parts with its hydrogen, to be replaced by 

 nitrogen. 



There is, however, this wide difference in the applica- 

 tion of the two compounds. Gun-cotton may be employed 

 as it stands, and the Abel gun-cotton that is used by our 

 soldiers and sailors for torpedoes and mining work is 

 simply a pure pyroxilin, pulped fine to permit of its being 

 thoroughly washed, and compressed into papier-mache 

 sort of blocks, for the sake of convenience. Nitro- 

 glycerine, on the other hand, being a liquid, is difficult to 

 handle in that form, and for this reason it is that Nobel 

 and others cast about for suitable vehicles to contain the 

 preparation. A siliceous clay called Kieselguhr, which 

 will absorb three times its weight of the liquid, has been 

 found the most favourable substance, and dynamite, gene- 

 rally speaking, may be said to consist of 75 per cent, of 

 nitro-glycerine and 25 per cent, of this inert substance. 

 In lithofracteur, other substances besides, are employed, 

 such as powdered charcoal and nitre, and there now 

 exists a whole family of such combinations, none of which 

 contain, however, more than 75 per cent, of the active 

 explosive, nitro-glycerine. 



In blasting gelatine, which, by the way, contains no 

 gelatine at all, the objection to employing an inert ma- 

 terial is got rid of altogether, and the mass, like com- 

 pressed gun-cotton, is explosive and combustible through- 

 out. Blasting, or explosive, gelatine is a mixture of nitro- 

 glycerine and gun-cotton. M. Nobel, to whom is due 

 the credit of having placed the valuable properties of 

 nitro-glycerine at the disposal of mining-engineers, has 

 discovered, in the pursuance of further investigations, 

 that the liquid in question acts as a solvent upon gun- 

 cotton. Like a mixture of alcohol and ether, nitro- 

 glycerine is found to dissolve nitro-cellulose, and form a 

 description of collodion, or, as M. Nobel terms it, gela- 

 tine. It is not, of course, the highly-explosive gun-cotton 

 that will thus dissolve, but that known as photographer's 

 pyroxilin, which does not contain so much nitrogen. 

 Military gun-cotton, indeed, or tri-nitro-cellulose, to call 

 it by its chemical name, should not be soluble at all, or at 

 any rate only to a slight extent, if properly manufactured, 

 and one of the tests to ascertain if it is of good quality is 

 in fact to treat it with an alcohol-ether mixture to ascertain 

 how far it will dissolve. The soluble gun-cotton, how- 

 ever, if not so highly nitrified, to coin a term for our pur- 

 pose, is still a sufficiently explosive body, and this M. 

 Nobel finds he can dissolve to a greater extent in nitro- 

 glycerine than it is possible to do in alcohol and ether. 

 Whereas the latter will dissolve no more than 4 or 5 

 per cent, of pyroxiline, and frequently less than 2, nitro- 

 glycerine has been found to take up upwards of 7 per 

 cent. The operation of dissolving is presumably done 

 when the liquid is warm, and the result is, as we have 

 said, a jellified mass, which has all the attributes of a 

 definite combination. There is no separation of liquid 

 from the mass, and cartridges may be made by simply 

 rolling up the material in paper envelopes. 



Thus, in blasting gelatine, there is no inert body, and 

 the consequence is that weight for weight, the gelatine is 

 superior in its destructive action to dynamite. The latter, 

 as we have seen, contains 75 per cent, of nitro-glycerine, 

 whereas blasting gelatine consists of from 90 to 93 per 

 cent, of this liquid, and from 7 to 10 per cent, of soluble 

 gun-cotton. But there exists another reason still, why the 

 detonation of blasting gelatine should be more energetic, 

 namely, because the combustion of the charge, from more 

 perfect oxidation, is well nigh perfect. Prof. Abel pointed 

 this out very clearly in his recent lecture at the Royal 

 Institution. "As nitro-glycerine," he said, "contains a 

 small amount of oxygen in excess of that required for the 

 perfect oxidation of its carbon and hydrogen constituents, 

 while the soluble gun-cotton is deficient in the requisite 

 oxygen for its complete transformation into thoroughly 

 oxidised products, the result of an incorporation of the 

 latter in small proportions with nitro-glycerine, is the 

 production of an explosive agent, which contains the pro- 

 portion of oxygen requisite for the development of the 

 tnaximum of chemical energy by the complete burning 

 of the carbon and hydrogen; and hence," Prof. Abel 

 concludes, " blasting gelatine should, theoretically, be 

 even slightly more powerful as an explosive agent than 

 pure nitro-glycerine." 



By converting the gelatine into a more solid body by 

 the addition to it of some 10 per cent, of military gun- 

 cotton, or tri-nitro-cellulose, Mr. Abel appears to have 

 secured a still more vigorous explosive, and one besides, 

 that, by reason of its firmness, is more convenient to 

 handle than the softer and pliant jelly. The destructive 

 action of this modified gelatine upon iron plates and 

 heavy masses of lead, has been found greater than that of 

 any other form of nitro-glycerine or gun-cotton, and there 

 is no room for doubt that for torpedoes and military 

 mining, where the object is to secure the greatest degree 

 of violence, regardless of consequences, the compound 

 will find valuable application. 



While on the subject of nitro-glycerine and its behaviour 



