47 



It is a matter of the greatest difficulty to preserve a 

 specimen of this substance for exhibition, as will be under- 

 stood when I state that several portions have to-night been 

 exploded, merely by dropping the dry powder on the surface 

 of water. 



I will touch another portion with the plume of a quill 

 pen, it detonates violently, tearing the paper on which it is 

 placed. This extreme sensibility of Iodide of Nitrogen has 

 up to the present prevented its application to warlike 

 purposes. 



The three members of the explosive compounds class 

 in common use, are : — (i) Gun Cotton, (2) Nitro-glycerine, 

 (3) Fulminate of Mercury. 



It was discovered by French chemists forty years ago 

 that several organic substances — sugar, starch, muslin or 

 paper — when treated with strong nitric acid, washed with 

 water and dried, burned with almost explosive violence. 



I have treated muslin and paper in this manner, and' 

 you will notice that in appearance they are but slightly 

 changed, being perhaps a little harsher to the touch than 

 before, but they burn with great rapidity and leave compar- 

 atively little ash. 



Fourteen years later, Schonbein, a German chemist, 

 found that if cotton wool were submitted for a short time 

 to the action of cold strong nitric acid, washed and dried, 

 it increased in weight to the extent of 80 per cent., and 

 although its appearance was unaltered, become endowed 

 with explosive properties. 



I will now proceed to prepare some gun cotton before 

 you, treating clean dry cotton wool with a well Cooled 

 mixture of strong nitric and sulphuric acids. Sulphuric acid 

 is added to the nitric in order to keep the latter strong and 

 in the best condition for acting on the cotton. It is a matter 

 of the greatest importance, that the temperature of the acids be 

 kept low during the action, in order that in the first place 

 the change may be carried on without danger to the 

 operator, and in the second it is found that if the acids be 



