than those of White or Red ones, the Corpuscles of Light falling on their sides, being for the most part Reflected Inwards from one Particle to another, and thereby engag’d as it were and kept from Rebounding Upwards, they communicate their brisk Motion, wherewith they were impell’d against the Black Body, (upon whose account had they fallen upon a White Body, they would have been Reflected Outwards) to the Small parts of the Black Body, and thereby Produce in those Small parts such an Agitation, as (when we feel it) we are wont to call Heat.  I have been lately inform’d, that an Observation near of Kin to Ours, has been made by some Learned Men in France and Italy, by long Exposing to a very Hot Sun, two pieces of Marble, the one White, the other Black; But though the Observation be worthy of them, and may confirm the same Truth with Our Experiment, yet besides that our Tryal needs not the Summer, nor any Great Heat to succeed, It seems to have this Advantage above the other, that whereas Bodies more Solid, and of a Closer Texture, though they use to be more Slowly Heated, are wont to receive a Greater Degree of Heat from the Sun or Fire, than (Caeteris paribus) Bodies of a Slightest Texture; I have found by the Information of Stone-cutters, and by other ways of Enquiry, that Black Marble is much Solider and Harder than White, so that possibly the Difference betwixt the Degrees of Heat they receive from the Sunbeams will by many be ascrib’d to the Difference of their Texture, rather than to that of their Colour, though I think our Experiment will make it Probable enough that the greater part of that Difference may well be ascrib’d to that Disposition of Parts, which makes the one Reflect the Sunbeams Inward; and the other Outwards.  And with this Doctrine accords very well, that Rooms hung with Black, are not only Darker than else they would be, but are wont to be Warmer too; Insomuch that I have known a great Lady, whose Constitution was somewhat Tender, complain that she was wont to catch Cold, when she went out into the Air, after having made any long Visits to Persons, whose Rooms were hung with Black.  And this is not the only Lady I have heard complain of the Warmth of such Rooms, which though perhaps it may be partly imputed to the Effluvia of those Materials wherewith the hangings were Dy’d, yet probably the Warmth of such Rooms depends chiefly upon the same Cause that the Darkness does; As (not to repeat what I formerly Noted touching my Gloves,) to satisfie some Curious Persons of that Sex, I have convinc’d them, by Tryall, that of two Pieces of Silken Stuff given me by themselves, and expos’d in their Presence, to the same Window, Shin’d on by that Sun, the White was considerably Heated, when the Black was not so much as Sensibly so.