9^ Report S.A.A. Advancement of Science. 



•already, viz., Dynamite and Blasting Gelatine, and it so ha[4jens 

 that these are the best known types of two widely differing classes. 

 Dynamite, that is Kieselguhr Dynamite, the explosive almost ex- 

 ■clusively used in the Diamond Fields at Kimberley, is the best 

 known example of a class, the chief aim of which is to absorb the 

 nitro-glycerine in some absorbent or semi-absorbent body. There 

 are endless varieties of this class, but in Europe they are not manu- 

 factured to any extent. It is, however, otherwise in America, where 

 the nitro-glycerine explosives are almost entirely of this type. Most 

 ■of them are mixtures of nitro-glycerine with wood-meal or. pulp, 

 nitrate of soda, and one of several other ingredients, the presence 

 •of which is sometimes rather difficult to explain. 



The nitrate is, of course, added for the purpose of oxidising 

 the organic absorbent, but it is quite evident that in every one there 

 is bound to be a large amount of mineral matter, which i.s utterly 

 xiseless as an explosive; not only so, but a proportion of the heat 

 ■developed is lost in heating up this mineral matter, and in the case 

 •of Kieselguhr Dynamite, which has 25% of an absolutely inactive 

 ■body, the loss of heat must be and actually is very considerable. 

 Nearly all the explosives of this class are powdery or semi-powdery, 

 but Dynamite is semi-plastic. 



The second class includes all the gelatinous explosives, and 

 Tiere they go by the familiar names of Blasting Gelatine, Gelatine 

 Dynamite, and so on. They (the latter) are. however, all only 

 lower grades of Blasting Gelatine. 



It does not come within the province of this paper to discuss 

 the relative merits of what I might call the American type, as 

 against the gelations type, and there is plenty to be said on both 

 sides of the question, and no doubt there are certain classes of 

 work for which each is in its way best suited. Rather would I take 

 these two types, and say a few words about their manufacture and 

 properties, illustrating later on by means of the lantern how the 

 actual working is carried on. 



Dynamite is now going sadly out of fashion, as can be seen 

 from the returns, imports and exports, published by our various 

 ■Colonies. In the Transvaal, which is the largest market for explosives 

 in the world, the sales only form a little over 1% of the total. Its 

 manufacture is extremely simple. Kieselguhr, the absorbent body, 

 is found in many parts of the world, and is simply a conglomeration 

 of most minute shells of tiny animalculae (Diatome). Under the 

 microscope they are seen to have a very delicate structure, but there 

 is no evidence of this to the eye in the earth as found. Chemically, 

 it is almost pure silica, and the reddish colour which it generally 

 has, and which is more marked when made into Dynamite, comes 

 from traces of oxide of iron. It is necessary to free it from organic 

 matter and moisture, a simple kiln roasting generally sufficing for 

 this purpose. It is next ground to an impalpable powder, and 

 naturally gritty matter has to be most carefully removed. When 

 this stage is reached the nitro-glycerine is simplv mixed with it bv 

 hand, and then sifted several times to ensure thorough mixin"-. 



