520 



APPARATUS FOR 



Experiment 26. — Take the same tube used in 

 the last experiment, and let the inner surface of it 

 be blackened by means of smoke, or any other sub- 

 stance. Let the same quantity, one grain, of the 

 fulminating powder, be discharged by a similar stroke 

 to that given in the previous trials ; and observe if 

 the flame still issues from the bottom of the whole 

 of the tube. If it does not appear, gradually shorten 

 the tube, till the flame is seen to dart from the bot- 

 tom. This will shew if the difference be great. The 

 tube must be cleaned, and again blackened for each 

 trial. 



Experiment 27. — Take a tube, the interior re- 

 splendent, of the greatest length that will allow the 

 flame to force its way through a piece of paper, tied 

 tight upon the bottom. Try the effect repeatedly 

 with one grain of the fulminating powder, observing 

 if the flame dart through the paper. 



Experiment 28. — Let the tube used in the 27th 

 experiment be blackened in the interior, and then 

 discharge one grain of the powder, as before, with 

 a piece of paper at the bottom. In this case we are 

 to observe if the same result still takes place, or if 

 the paper now remains whole. 



Now, should the result of these experiments shew 

 that the flame uniformly passes through a longer re- 

 splendent tube, than it does through a blackened 

 one, and that the paper at the bottom is not torn 

 when the interior of the long tube is blackened, 

 then we have a strong argument in favour of the 



