460 PHILOSOPHICAL TRAKSACTIONS. [anNO 16q\. 



velocity. It follows therefore, that there is 7 times as much matter in gold as 

 in a piece of glass of the same magnitude ; and consequently, that at least 6 

 parts of 7 in the bulk of glass, must be pore or vacuity : this, some favourers 

 of the atomical philosophy have endeavoured to solve, by supposing the primary 

 or constituent atoms of gold to be much larger than those of other bodies, and 

 consequently the pores fewer ; whereas in other bodies, the great multitude of 

 the interspersed vacuities diminishes their weights. 



Being desirous to examine this notion of the magnitude of atoms of gold, I 

 bethought myself of the extreme ductility of that metal, which is seen in the 

 beating of it into leaf, and above all in the drawing fine gilt-wire ; by means 

 of which I believed I might most exactly obtain the true thickness of the coat 

 of gold, that appears, even with the microscope, so well to represent gold itself, 

 that not the least point of silver appears through it. In order to this, I in- 

 formed myself among the wire-drawers, what gold they used to their silver, 

 and they told me, that the very best double gilt-wire was made out of cylindric 

 ingots 4 inches in circumference, and 28 inches long, which weigh l6 pounds 

 troy ; on these they bestow 4 ounces of gold, that is, to every 48 ounces of 

 silver, one of gold ; and that 2 yards of the superfine wire weighs a grain. 

 Hence at first sight it appeared, that the length of Q6 yards is in weight 49 

 grains ; and that a single grain of gold covers the said 98 yards ; and that 

 the 10000th part of a grain is above -J- of an inch long; which yet may be 

 actually divided into 10, and so the 100000th part of a grain of gold be visible 

 without a microscope. But being desirous to compute the thickness of the skin 

 of gold : by means of the specific gravities of the metals, viz. silver 1 O^, and 

 gold 18-I-, I found the diameter of such wire the -3-^ part of an inch, and its 

 circumference the -t4t part ; but the gold in thickness not to exceed the , , ^'^ „ ^ 

 part of an inch ; whence it may be concluded, that the cube of the hundredth 

 part of an inch would contain above 2433000000, (or the cube of 1345) of 

 such atoms. And it is very surprizing, that gold, being stretched out to so 

 great a degree as is here demonstrated, should yet show itself of so even and 

 united a texture, as not to suffer the white colour of the silver under it to 

 appear through any the least pores ; which argues that even in this exceeding 

 thinness, many of those atoms may still lie one over the other. 



Some Observations on a diseased Spleen. By Nehemiah Grew, M.D. F.R.S. 



An abridged Translation from the Latin. N° 19-*, p. 543. 



The daughter of Mr, Tho. Sedgwick, a London merchant, put herself, at 



the age of 14, under the care of a person who taught embroidery ; for which 



•he showed so great a turn^ that she spent almost the whole of her time for 



