An Experiment Made at a Meeting of the R. Society, Decemb. 20. 1704. of Firing Gun-Powder on a Red Hot Iron in Vacuo Boyliano. By Mr Fr. Hauksbee

VI. An Experiment made at a Meeting of the R. Society, Decemb. 29. 1704. Of firing Gun-powder on a red hot Iron in Vacuo Boyliano. By Mr Fr. Hauksbee. The Candent Iron being included in a Recipient proper for that purpose, and the Air withdrawn (which was in about two minutes of time) the Mercury then in the Gage standing at 29 inches, a quantity of Gunpowder was made immediately to descend upon the red hot Iron, which continu'd upon the surface of it some small time before it went off, and then was observ'd not to fire all at once; and the last of the Quantity that did so, seem'd to give the greatest flash: Upon which, the Mercurial gage was taken notice of to descend something more than an Inch, it rising again \( \frac{3}{5} \) of the same. And upon several Repetitions of the like quantity of Powder (the factitious Air being always first withdrawn) the Appearances were very resembling. Again, upon Purging the Recipient of the factitious Air, and the Mercury elevated in the Gage as at first, three quantities were caus'd to descend upon the Iron, whose Explosion, as well as the Air produc'd from them, seem'd in proportion to the quantity of Powder: The Mercury then in the Gage subsiding to 25. But upon dropping 6 Quantities (the Recipient being first purg'd as before) which Quantities not descending all at once, but successively as fast as might be, the Quan- Quantities that first reacht the (still Ignited) Iron taking fire, by their flame making an Explosion of the whole, at once blowing up the Recipient, altho the weight of Air incumbent on it was equal to 144 l. ½, accounting the Receiver at 3 inches ½ diameter, but was something more, which does sufficiently allow for the want of height of Mercury. The Gage then standing at 29 ½, instead of 30, from which the Calculation is made. The Gunpowder us'd was the common Glas'd sort; and the weight of the six quantities, which remov'd the Recipient, with so great a Pressure incumbent on't, was but 7 grains, each Quantity weighing something more than one. I did not observe the Recipient to be broke before it reach'd the Floor. It was thick lin'd with Sulphureous and Nitrous Steams, so that the flashes of Fire thro the Clowdiness of the Glass seem'd very much to resemble faint Lightnings. The Content of the Receiver was equal to about 25 ounces ½ of Water, allowing for the Bulk of Iron and Pedestal. VII. An Account of an Experiment made Decemb. the 26th, 1704. To try the Quality of Air, produc'd from Gunpowder, fir'd in Vacuo Boyliano. By Mr Fr. Hauksbee. Upon making the late Experiment of firing Gunpowder in Vacuo, it was hinted as well worthy of tryal, Whether the Factitious Air of fir'd Gunpowder was endu'd with any Quality differing from Common Air. In order to the satisfaction of the Query, On December the 26th about noon I included a Candent Iron in Vacuo,