APPARATUS TOn 



tus, were the flame accompanied by moving air, or 

 were it the result or quality of compressed air, it 

 would inflame a piece of tinder put in any of the 

 joinings of the tube : I therefore repeatedly tried 

 the experiment, using the finest German tinder, 

 but no inflammation took place. To render the 

 experiment more complete, I tried if the flame 

 would act upon the tinder when in contact with the 

 air at the bottom of the tube, and found that it 

 did so. 



From this conclusion, if allowed to be correct, 

 we have an additional argument, did the state of 

 the question require it* for the materiality of ca- 

 loric. 



Experiment 23.— I tried to collect some of the 

 air at the bottom of the tube, both in a water and a 

 mercurial trough, but found that not above two or 

 three bubbles of it could be obtained at each dis- 

 charge, — too small a quantity to arise from the ful- 

 minating powder. I have not yet collected enough 

 to ascertain its nature ; it is very likely that it may 

 be a little of the air of the tube forced out by the 

 rapid movement of the flame, and the pressure of 

 the expanfion which occurs at the top. 



Edinburgh, 9th February 1821. 



