Hooke, Robert, 1635-1703 / Micrographia: or some physiological descriptions of minute bodies made by magnifying glasses : with observations and inquiries thereupon
Observ. XVI. Of charcoal, or burnt vegetables, pp. 100-106 ff.
M I C R 0 G R A PI 14 I [A Ct means of which, be the Coal never fo long, you may eafily blow through it ; and this you may prcfently find,by wetting one end of it with Spittile and blowing at the other. But this is not all, for befides thofe many great and conspicuous irre- gular fpots or pores, if a better luicrof ape be made ufe of, there will ap- pear an infinite company of exceedingly imall, and very regular pores, fo thick and fo orderly iet, and fo clofe to one another, that they leave very little room or fpace between them to be fill'd with a folid body, for the apparent interJiitia, or feparating fides of thefe pores feem fb thin in fome places, that the texture of a Honey-comb cannot be more porous. Though this be not every where fo, the intercurrent partitions in fome places being very much thicker in proportion to the holes. Motd ofthefe imall pores feem'd to be pretty round, and were rang'd in rows that radiated from the pith to the bark 5 they all of them feem'd to be continued open prcrs, ruinning the whole length of the Stick; and that they were all perforated. I try 'd by breaking off a very thin liver of the Coal crefs-ways, and then with my Alicrofcope,diligent- ly furveying them againit the light, for by that means I was able to fee quite through them. I here pores were fo exceeding frnall and thick,that in a line of them, l part of an Inch long, I found by numbring them no let's then 150. fmall pores ; and therefore in a line of them an Inch long, muft be no lefs then 2700. pores, and in a circular area of an Inch diameter, muft be about 5725350. of the like pores, fo that a Stick of an Inch Diameter, may containe no lefs then feven hundred and twenty five thonli2nd, be- fides 5 Millions of pores,which would, I doubt not, feem even incredible, were not every one left to believe his own eyes. Nay, having fince ex- amnin'd Cocua, tmpak and green Fbny, Lignyv Vitx, &c. I found, that all thefe Woods have their pores, abundantly fmaller then thofe of loft light Wood; in fo much, that thofe of Guajacuv 1eem'd not above an eighth part of the bignef of the pores of Beech, but then the Interjiitia were thicker 5 fo prodigioully curious are the contrivances, pipes, or fluces by which the sunny nmtrititA, or Juyce of a Vegetable is convey'd from place to place. This Oljervation feems to afford us the true reafon of feveral Ph1- nomena of Coals ; as Firft, why they look black; and for this we need go no further then the scheme, for certainly, a body that has fo many pores in it as this is dif- cover'd to have, from each of which no light is refle&ed, muff neceflarily look black, efipecially, when the pores are fomewhat bigger in proporti- on to the intervals then they are cut in the scheme, black being nothing elfe but a privation of Light, or a want of refletion ~ and wherefover this refledting quality is deficient, there does that part look black, whe- ther it be from a poroufnefs of the body, as in thislnftance,or in a deadning and dulling quality, fuch as I have obferv'd in the Scoria of Lead, Tin, Silver, Copper, &c. Next, we may alfo as plainly fee the reafon of its fluining quality, and that
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