The Royal Society read and discussed Letter L-168 about cinnebar and gunpowder

April 10, 1686

Birch, History, vol IV, p. 470, 31 March 1686 (O.S.) in London:

Dr. PAPIN shewed his experiment of firing gun-powder in vacuo; but it not succeeding by reason of some soot got in with the powder, it was ordered to be tried again at the next meeting.

Mr. HOOKE gave an account of his firing gun-powder in vacuo with a burning-glass; and said, that now and then a single corn would go off upon the whole heap without kindling the next corn; and that at length having melted the heap into a lump, it went off after the manner of the pulvis fulminans with a very great report, and burst his glass into a thousand pieces, and stuck great part thereof into the cieling.

Part of a letter of Mr. LEEWENHOECK was read, containing several curious observations on cinnabar and gun-powder, and mentioning an experiment, proving the expansion of gun-powder to be into a space above 2000 times greater than the space, which it takes up before fired; for that a grain weight of powder containing 13 corns takes up as much room, when fired, as 2080 grains of water.

Three papers of Dr. PAPIN were read relating to his experiment of firing gunpowder in vacuo; in one whereof he said, that by the experiment made after the last meeting was over, he found, that 9 grains of gun-powder produces as much air, as fills the space of a third part of a pound of water; from whence he concluded, that 9 grains of powder yields 2 1/2 grains of air: and from hence it would follow, that each grain gives but 213 times as much air as its own bulk; which is far short of Mr. LEEWENHOECK's experiment.

N.B. That air being but about 1/800 of the weight of water, which is near the weight of gun-powder, a grain of gun-powder, if it should be turned into air, could take up but 800 times as much space as its own bulk. Wherefore either the observation of Mr. LEEWENHOECK is faulty; or else the air produced by the explosion of gun-powder has a greater elasticity than the common air in a lighter body.

Mr. HENSHAW was of opinion, that the constituent parts of the air are no other than the steams and exhalations out of the earth.