3d4 PHILOSOPHICAL TRANSACTIONS. [aNNO 1707- 



experiment, I found (to my great surprise) that two hours after the last ob- 

 servation, the water had reached to about ■^^. Next morning, which was at 

 about 18 liours distance, I observed that it had arrived to near -^, or half of 

 the first deserted space. Thus continuing rising, I found that at the end of 12 

 days, the water had ascended something above ^ of the same. At 18 days it 

 had arrived to 19 of the 20 parts at first deserted ; and at that station it con- 

 tinued without alteration for 8 days: so that the seeming real air, produced 

 from the fired grain weight of gunpowder, was only equal to the bulk of 1 1 

 grains of the same; that number being nearly the 20th part of 222, the num- 

 ber of grains contained in a cubical inch, as aforesaid. Which shows that the 

 whole space at first deserted by the w-ater on firing the gunpowder, vyas not sup- 

 plied with real air.* The temperature of the air I all along considered, and 

 found it contributed nothing to this odd phenomenon, which how to account 

 for I know not; I only suggest, that the springs, or constituent parts of the 

 ambient air, as well as those contained in the body of the gunpowder, may, on 

 firing, be capable of being broken, or at least so distended, as to possess so 

 large a space, and require so long a time to recover their natural state again. 

 And this, I presume, could never have been discovered but by the confinement 

 of the same air in which the explosion was made. 



Notwithstanding the account of this experiment seems to run counter with 

 the accounts formerly given of the firing of gunpowder in vacuo ; yet consider- 

 ing the diflferent mediums in which the experiments were made, they may be 

 the easier reconcilable: for when the gunpowder was fired in so thin a medium 

 as the near approach to vacuum, that then the remaining air in the receiver 

 could suflfer by the explosion, only in proportion to the quantity, which must be 

 SQ incoxisiderable, as not to be taken notice of. 



yin Experiment, showing that the Springs or constituent Parts of Air are capable 

 J, of suffering such Disorder, by a violent Impulse, as to require Time to recover 

 <>^ their Natural State. By Mr. Fr. Hauhsbee, F.R.S. N° 31J, p. 2412. 



The foregoing experiment being so very extraordinary, gave me the curiosity 

 to inquire a little further into the fact, and to try whether air could be capable 



'^' * Quere, was this great and continual decrease in the strength of the produced air, after it had 

 cooled to the get eral teniper of the surrouuding bodies, owing to its at)sorption by the contiguous 

 water ? The like diminution did not occur in the former experiment (N" 293) made with the mercurial 

 gauge, without the water. Other experiments of the same nature may ht seen in Mr. Hauksbee's 

 book of Physico-Mechanical experiments, where the subject is further pursued. It may also be re- 

 marked, that it is on the results of these curious experiments that the ingenious Mr. Robins founded 

 his celebrated treatise on gunnery. 



