KEEPING OF EXPLOSIVES. 379 



which are destined to provoke the explosion of a considerable 

 mass of another substance (p. 54). 



They are treated in small quantities, and precautions are 

 taken against the dangers presented by their preparation and 

 manipulation, dangers which would not be accepted in industries 

 for a substance manufactured or employed in large masses. 



We shall restrict ourselves to the indications which have just 

 been enumerated and which correspond to the principal uses of 

 explosive substances in war and industry, As regards the 

 effects themselves which it is proposed to accomplish, it can 

 easily be understood that the diversity of these special effects 

 required from explosive substances is unlimited. 



3. PRACTICAL QUESTIONS DEFERRING TO THE MANUFACTURE. 



1. The manufacture of explosives ought to be effected under 

 conditions of cost proportioned to their industrial uses, one and 

 the same effect being produced in mines or industries in general 

 at the lowest possible price. In military matters this condition 

 also intervenes, but in a minor degree, since facility and safety 

 of employment outweigh all other considerations. 



2. The manufacture must be carried on regularly and without 

 danger, or at least with as little danger as possible to the work- 

 people and neighbourhood. 



3. The inconveniences resulting through noxious gases, noise, 

 and damage arising from accidental explosions must also be 

 taken into consideration. 



4. PRACTICAL QUESTIONS RESPECTING PRESERVATION, 



1. It should be possible to keep explosives without any 

 spontaneous decomposition in the ordinary state of the atmo- 

 sphere, in various climates, under moderate conditions of tempera- 

 ture and light, in an average hygrometric state, etc. 



2. Direct sunlight is bad for nitro compounds, as it often 

 leads to their chemical decomposition. 



3. Extensive variations of temperature also exercise an im- 

 portant influence, particularly if they determine the freezing 

 of certain ingredients, such as nitroglycerin in the dynamites, 

 or if they increase the fluidity of certain bodies, such as nitro- 

 glycerin itself, and consequently their tendency to exudation. 

 The separation between nitroglycerin and its absorbent can thus 

 take place by the fact of repeated variations of temperature or 

 even of repeated freezing and thawing. Under the influence of 

 a somewhat high temperature, such as occurs in practice, 

 especially in hot countries, certain compounds may gradually 

 evaporate slowly and modify the primitive composition of the 

 mixtures. This occurs, for instance, to ordinary dynamite heated 



