92 Report S.A.A. Advancement of Science. 



rap'ully came iiiLo universal use ; it would never have done so wilb' 

 out detonators. 



The introduction of detonators undoubtedly marks another veiy 

 important advance in the development of explosives. 



We can safely assert that about this time, i.e., the year 1870. 

 only two kinds of explosives were known, viz., Black Powder anJ 

 Dynamite, and even to this day nothing has superseded these 

 explosives for certain classes of work. Dynamite was considered 

 a safe, a reliable, and a powerful explosive, and so it is, 

 but Nobel was quick to recognise that it had its Aveak 

 points. One of these was that as an explosive it was Vjallasted 

 with about 25 per cent, of an absolutely inert body, and another, 

 and perhaps the most important in his mind, was the fact that it 

 was not very well suited for wet workings. As a matter of fact. 

 Dynamite, when steeped in water, parts with its nitro-glycerine, and' 

 to a more limited extent the same thing takes place when it becomes 

 moist. This phenomenon we generally call exudation. 



Nobel's name is again associated with the next important 

 advance in the technologv of explosives, and it is a testimony to 

 the man's genius, to his far-sightedness, that after 27 years' exper- 

 ence, the explosives made and u.sed in the South African Gold 

 Fields are with paltry exceptions according to his original patent 

 specifications. 



The point he desired to attain, and the point he did attain, in 

 his Blasting Gelatine .specification of 1875 ^^''^^ ^^^ make the entire 

 compound explosive, and not only a part of it as in the case of 

 Dynamite. The purpose of his invention is set out in the following 

 extract from the patent itself : — " The purpose of the invention is 

 to convert liquid explosive substances, such as nitro-glycertne, or 

 nitrates of methyl, elthyl and amyl, and nitro-l)enzine into a viscid' 

 or pa.sty state." Later on he says : — " In carrving out the invention, 

 these liquid explosive sul)stances are incorporated with another 

 substance, which is capable of gelatinising or thickening them, and' 

 for this purpose a substance is chosen which will detract little or 

 nothing from the explosive power." 



As an example of this he instances nitrated cotton, which is- 

 known as Collodion Gun-Cotton. 



This body dissolves in nitro-glycerine with more or less 

 readiness, and produces a doughy mass, of which more anon. 



From this point T must leave the domain of historv. Indeed, 

 no important discoven- has been made within the past fifteen years, 

 excepting the extraordinary developments in modern smokeless 

 powders, and strangely again. Nobel's name is also associated with 

 that discovery. Later on T .shall refer very brieflly to this important 

 discover}'. 



It is necessary now to say something about the body, nitro- 

 glvcerine, itself, but fortunately this need not detain us very long. 

 1 have prepared a few magic lantern views to illustrate the pro- 

 cesses of manufacture, but think it better to defer them to the end 

 of the paper, adding a few explanatory words as each view is put 

 'Ml the screen. Nitro-glycerine is not reallv a nitro bodv in the- 



