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

EXPERIMENT XI. Concerning the Burning of Coals, and the Continu∣ance of the Heat of a piece of Iron in Vacuo Boyliano.

HAving suspended a Screw made of Wire in the Receiver, such as Fig. 10. represents, it being first fill'd to the height of five Inches, with live Wood-coals; upon the first Exsuction made by the Pump, they grew dim, and the Pump being ply'd for three Minutes, they were quite depriv'd of their red Colour, and seem'd extinct; but when they were taken out of the Re∣ceiver, they were re-kindled again; and being let down into the Receiver afresh, without Pum∣ping out the Air, they continu'd red for a Mi∣nute longer than before; but a like quantity of Live-coals, continued to burn half an Hour, in the open Air.

But a piece of Red-hot Iron, being suspended in the same Wire, upon an Exsuction of the Air, it seem'd not to be sensibly alter'd; but conti∣nu'd red for 4. Minutes; neither was it alter'd by re-admitting the Air into the Receiver, tho' Fumes, which were rais'd from some Wax, which stuck to the Wire, were much more expan∣ded, when the Air was pump'd out, than up∣on it's re-ingress. But one thing observable, was, that whether the Air was suck'd out, or not, the sides of the Receiver were considerably heated by the Effluvia trasmitted from the Iron.