The Heads of this Trcatife. 
II?, T'he Trodu^ion of itsmmr 
neY'i §gws,^ flace^ mcreafe, different co' 
lours y[ever aI degrees of brightnefs and 
darknefs^as alfo of fmoothnefs & rcugh- 
nefstogether ,with the motion of the Chry- 
ffallin Matter^ and its caufe^ as alfo the 
different Figures inChryffals-i p.52,53j 
" 54 , 55 , 5 < 5 , 57 j 58 i 5 Pi^o* 
20. why in 'Angular Bodies offo(jre. 
flanes are parallel to one another^ p.^2. 
21 . Fxtfeme Cold iiot the Efficient Cauje 
of Chryffali nor the foie force of Fire 
the caufe that produceth Glafs, p. 62 . 
22. How to produce Glafs without Fireman d' 
to refolve chryffal into a Fluid, p. 63, 
23. The Caufe of the Biference between 
ChryHal and Glafs^ as to Eeffacfion and ■ 
other operations, , P*^3* 
24. The great for ee of a penetrating Fluids 
evinced by the length of the Threds ari- 
Jing out of the Iron*filings about^ the 
Foies of a Loadjlone, P*^®^ ^ ^. 
25. of the Angular Bodies of \ton% how 
far they agree with Chrjjials-, and how 
far they differ^ together with divers re.- 
^arkable things in them) 
67, ^8. 
2d. The 
