Royal Society. 19 
goia ana elafs, whofe fpecific gravities are nearly as 7 to i, feems 
a very hard queftion to thofe that rightly confider it 5 for from 
undoubted experiment, gravity is in all bodies proporaonal to 
the quantity ofmatter in each, and there is no Inch thing, as a 
propenfion of Ibme more, others lefs, towards the centre ot the 
earth, fince, the refillance of the air being removed , all bodies 
defcend, be they never fo loofe or compad in texture, with equal 
velocity 3 it follows therefore, that there is feven times as much 
matter in gold, as in a piece of glafs of the fame magnitude^ and 
confequently, that at lead, fix parts of feven in the bulk of glals 
mud be pore or vacuity : This Ibme favourers of the atomical 
philofophy have endeavoured to Iblve, by fuppofing the primary 
or conftituent atoms of gold to be much larger than thole of other 
bodies, and confequently the pores fewer 3 whereas m other bo- 
dies, the great number of the interfperfed vacuities does dinninifli^ 
their weight : Mr. Halhy being defirous to examine this notion ot 
the magnitude of the atoms of gold, he bethought himlelf of the 
extreme duflility of that metal, which is feen in the beating ot it 
to leaf 3 and above all, in the drawing fine gilt wn-ej by means - 
whereof, he was of opinion, he might molt exa^ly obtain the 
true thicknefs of the coat of gold, that appears even by the micro- 
fcope, fo well to reprefent gold itfelf, that not the leall point ot 
filver is feen thro' it: In order to this, he informed himtelf oi 
the wire-drawers, what gold they ufed to their filver 5 and he 
was told, that the very beft double-gilt wire was made out ot 
cylindrical ingots, 4 inches in circumference, and 28 inches long, 
which weigh 16 pounds Troy, on thefe they beftow 4 ounces ot 
gold, that is, to every 48 ounces of filver, one of gold 5 ^nd that 
two yards of the fuperfine wire weighs a grain: Hence, at firlt 
fight it appeared, that the length of 98 yards is m we^ight 49 
grains- and that a fingle grain of gold covers the faid 98 yartis^ 
and that the loooooth part of a grain of gold is vifible without 
a microfcope: But Mr. Halky being defirous to compute tne^ 
thicknefs of the Ikin of gold, by means of the fpecific gravities ot 
the metals, viz. filver 10 •§, and gold 18 I, he found the diame- 
ter of fuch wire the 3^5 part of an inch, and its circumference the 
ji^ part, but the gold in thicknels not to exceed the 151:, 00 part 
of an inch 3 whence it may be concluded, that the cube of the 
hundredth part of an inch would contain above 2439000000 (or 
the cube of 1 54 5 ) of fuch atoms 5 and which is lurprifing, tho 
gold be ftretched out to fo great a degree, yet it ihews itlelf of ^o^ 
even and uniform a texture, as not to fuffer the white colour 01 
the filver to appear thro' it, which argues that even m this 
Q 2, exceed- 
