The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

CHAP. XII. New Experiments touching the Condensation of the Air by mere Cold, and it's Com∣pression without Mechanichal Engins.

* 1.1TO try how far the Air is capable of be∣ing condens'd by mere Cold, when the Season of the Year hath not pre-affected it; I try'd the following Experiment in Au∣tumn.

In the middle of September about Noon, on a Sun-shiny Day, we placed a Bolt head in a Frame, so that the Stem was Perpendicular to the Horizon, and the lower End of it immers'd in Water. This done, we cover'd the Ball of the Bolt-head with a Mixture of beaten Ice and Bay-Salt; upon which, the internal Air being con∣dens'd, the Water rose up into the Stem, and stood a good while: Then having made a Mark at it's highest Station, we fill'd the Vessel with Water, and found that it yielded ℥19 and ʒvj, the Weight of the Water which fill'd the Stem up to the Mark being ℥j and ʒiij, by

which Number, the former being divided, the Quotient was 14 4/11 Drachms; so that the Pro∣portion of the two Quantities being as, 11 to 158; The Space into which the Air was condens'd, was, to it's former Space, as 147 to 158: So that the highest Degree of Condensation it was then capable of, made it lose of it's former Ex∣tent 11/158.

N. B. First, The Stem of the Glass ought to be long, lest the Water, upon the Air's Con∣densation, should rise into the Ball of it.

Secondly, The Cylinder of Water was two Foot, so that it might, by it's Weight, in some measure, hinder the Ascent of more, and so keep the Air from condensing to it's ut∣most.

Thirdly, When the Water rose as high as it well could, we observ'd it to rise and fall alter∣nately, for a little time.

Fourthly, The Air may thus be further con∣dens'd, than by Winters Cold.

But to shew that in the forgoing Experiment, the Cold did not compress the Air immediately, but partly, in as much as it, by stuffing up the Pores of the Water, caus'd it to swell, and so to compress the Air; I took a new Glass Bolt-head with a short Neck, and fill'd it full of Wa∣ter; so that when it was hermetically seal'd up, the Liquor wrought within 3 Inches of the Top, the sharp End which was made for the Conveni∣ency of sealing being ¼ of an Inch long; This be∣ing done, the Bolt-head was plac'd in a Mixture of Snow and Salt, upon which, the Water as∣cended and compress'd the Air into the Coni∣cal Part; upon which, the Glass flew in pieces.

In which Experiment, according to Dr. Wallis his Estimate, the Air was compress'd into a 40th part of the Space it possess'd before. Which is considerable above the utmost Compressure made in Wind-Guns, where it is usually thought not to be compress'd into less than a 15th, and (according to Mersennus) into an 8th part of it's former Space.

Notes

• * 1.1

  Of the Air's Condensati∣on by Cold, &c.