Ci4) 

 Mechanically, by colliquating the into-* 

 herent grains of powder into one mafs ? 

 wherein , the ranks of pores not being 

 broken and interrupted as before, the in- 

 cident beams of Light are allo-vM every 

 way a free paffage through them. 



Fifthly , the like Phenomena to thofe 

 of a Quality, to be explicated, or at leaft 

 as difficult in the fame kind, may be pro- 

 duced in bodies and cafes, wherein 'tis 

 plain we need not recurre to Subftantial 

 Forms. Thus a varying Colour, like that 

 which is admired in a Pigeons Neck, may 

 be produe'd in changeable Taffety, by a 

 particular way ot ranging and connect- 

 ing Silk of feveral Colours into one piece 

 of Stuff. Thus we have known Opals ca- 

 fually itnitated and almoft excelled by 

 Glafs, which luckily degenerated in the 

 Furnace. And fomewhat the like change- 

 able and very delightful Colour I remem- 

 ber to have introduced into common 

 Glafs with Silver or with Gold and Mer- 

 cury. So likewife meerly by blowing fine 

 Cryftal-Glafs at the flame of a Lamp to 

 a very extraordinary thinnefs, wc have 

 made it to exhibit, and that vividly, all 

 the Colours ( as they fpeak ) of the Rain- 

 bow i and this power of pleafing by di- 

 verfifying the Light, the Glafs, if well 

 preferved, may keep for a long time. Thus 



alfo 



