QS PHILOSOPHJCAL TRANSACTIONS. [aVNO 1/04. 



several sand-particles from it; and because the red matter which adhered to 

 some of the sands more than to others, hindered me from taking a distinct and 

 clear view of each particular grain, I put some of them into aquafortis, to try 

 whether that would dissolve the red matter, and restore its lustre to the sand ; 

 but in vain, for that menstruum could not separate them. I then took several 

 of those particles of sand, that were least surrounded with the red matter, and 

 placing them before the microscope, observed that some of them had lOor 

 more sharp points or protuberances, so neatly and regularly fashioned, that no 

 polished diamond could outdo them. I set one of the largest grains of sand 

 before my glass, and could perceive in it, and that in a very small compass, 7 

 neat prominent points, exceeding each other in length and size, and issuing out 

 of very smooth sides ; and I judged that one such sand was furnished with 

 above 100 flat sides, which were very smooth, and consequently very shining, 

 though with the naked eye no brightness could be discovered ; the reason of 

 which I conceive to be, that this sand being partly transparent, admitted the 

 light through its pores, and did not reflect it back like the shining sands. 



These sands, though I viewed ever so many of them, I found to be each of 

 a different figure ; and when I picked out any that were somewhat oblong, I 

 seldom failed to discover at the ends a four or five sided obtuse point, so neat 

 and regular, as if it had been polished. I broke to pieces several of these grains 

 of sand on a clean glass, and found that they were not near so strong as the 

 shining sand ; and having placed the small particles of such a broken sand be- 

 fore my microscope, some of them appeared like whole sand, with its entire 

 sides and angles ; ajl which formed a very pleasing sight. 



Fig. 14, ABCDE represent, through a microscope, one of the above-mentioned 

 sands, of which many together compose the red stone ; abcd show the points, 

 which are much more plainly seen than several others that cannot be distin- 

 guished, because of their difi^erent positions. 



Fig. 15 shows another sand, which likewise has several points, though not 

 so obvious as the former, because they do not stand so far outwards. 



Fig. l6, MNOP represent the last mentioned sand in another position. 



Fig. 17> aRST show also a sand of the aforesaid stone, in which the diamofid 

 cut is better than the former. 



Fig. 18, vwxYZ represent two grains of sand, that were still joined to each 

 other ; the one is shown by vwx, wherein may be observed several points, and 

 particularly between w and x ; and the other is shown by xyz, and the most of 

 its points lying between y and z. 



Now as some of the smooth sides of these sands were large, and others 



