TRANSACTIONS OF SECTION A. 723 
constitute the other cubic assemblage. A C,B Dare parallel to body diagonals, 
A B,D C are parallel to face diagonals, of the cubes. Annul now all the atoms at 
Uy 
UY 
ly 
the centres of the blank circles! Lastly, stretch the diagram perpendicularly 
to A c in the same definite ratio of perhaps about 3 to 1. It then represents what 
we may believe to be probably the true molecular structure of ice-crystal: the 
circles with simple shading and with shading interrupted by two concentric 
circles denoting hydrogen atoms, and the circles with shading interrupted by 
single concentric circles the oxygen atoms. 
The named properties of Quartz are explained by supposing the crystalline 
- molecule to consist of three of the chemical molecules (OSiO) to be placed together 
jn a manner readily imagined according to a suggestion which I communicated to 
1 The assemblage thus constituted is precisely that described in Section 24, and 
in footnote on Section 69 of ‘ Molecular Constitution of Matter,” Proc. R.S.L., July 
1889, reprinted as Art. xcvii. of Vol. III. of ‘Mathematical and Physical Papers.’ 
I was led to it in the course of my investigation of a Boscovichian elastic solid, 
_ havine’ two independent moduluses} of resistance to compression and of rigidity. 
(Elasticity of a Crystal according to Boscovich,’ Proc. R.S., June 1893). 
