256 Intelligence and Miscellaneous Articles. 



EXPLOSIONS PRODUCED BY HIGH TONES. 



A great part of the known explosive substances contain more or 

 less nitrogen. The simplest of these, and at the same time one of 

 the least stable, is the combination of iodine with nitrogen. Iodide 

 of nitrogen is very easily prepared by wetting finely powdered 

 iodine with liquid ammonia. It is then filtered ; and the filter, 

 while still moist, is taken out of the funnel and cut up into small 

 pieces, which are dried separately. Although this substance while 

 moist is quite harmless, yet as soon as it is dry it detonates with 

 great violence on the slightest friction. But what is most remark- 

 able is, this violent decomposition can be called forth by certain 

 high tones. 



MM. Champion and Pellet have made the following interesting 

 experiments upon it : — Two glass tubes of 15 millims. diameter, and 

 2*4 metres total length, are combined by means of a strip of paper ; 

 and upon each end is put a little piece of paper which contains 

 0-03 of a gramme of iodide of nitrogen. When one of these is 

 caused to detonate, the other detonates likewise. 



The explosion of the second paper, however, is not effected by 

 pressure of the air : this can be shown by introducing a small 

 pendulum into the tube ; it is no more disturbed by the explosion 

 than when the tube is blown strongly into with the mouth. If we 

 fasten such papers to the strings of a double bass, or a violoncello, 

 or a violin, we can demonstrate that the deep tones exert no action, 

 while the high tones induce a detonation. The very high tones 

 obtained by twitching the strings on the tail side of the bridge 

 give the same result. 



The results were similar in experiments with Chinese tomtoms : 

 the deep-toned instruments effected no detonation ; the high-toned 

 ones constantly did so. 



Two parabolic concave mirrors of 0*5 of a metre diameter w r ere 

 set up at 2- 5 metres distance one from the other. A small quantity 

 of iodide of nitrogen was brought into the focus of one of them, 

 and another small quantity was placed in the centre between the 

 two mirrors. Some nitroglycerine was exploded in the focus of 

 second miror : the iodide of nitrogen in the focus of the first mirror 

 detonated ; that in the centre remained intact. Although other 

 explosive substances placed in the focus of the second mirror pro- 

 duced the same effect, yet this was not, as might perhaps be 

 thought, a consequence of heat, because 0*03 gramme of nitro- 

 glyceriue, which does not develop more heat than 0-9 gramme of 

 gunpowder, produced an explosion similar to that produced by 

 from 8 to 10 grammes of powder. 



The mirror was then coated with lampblack, when the explosion 

 of 10 grammes of powder did not induce any detonation of the iodide 

 of nitrogen, while 0*03 gramme of nitroglycerine was still sufficient 

 to do so. — Chronique cle V Industrie, No. 52, Jan. 29, 1873. 





