Oct. 22, 1928
Dear Professor Bragg:
I was very pleased to learn that West had found the structure of topaz, and that it approximates the one
I suggested. Your letter came just about the time my paper appeared, so that I could make no reference to West's work. I have
not yet tried applying the rules governing deformation to see whether the atomic positions agree with West's or not.
The last of August I sent two papers to the Editor of the Journal of the American Chemical Society. In
one of them are rules governing the structures of complex crystals. I realize that nothing I have done is highly original
- in particular was I gratified to read in your letter a statement of the rule governing the sharing of polyhedron elements.
I have written the Editor asking whether or not these papers will appear in December. When I hear from him I'll drop you a
note. The same rules are included in a paper in Sommerfeld's Festschrift, which will appear in December.
I am pleased with the clarity that the study of crystals has introduced into the very complex tungsten
and molybdenum compounds. Mr Craxton has begun the study of these crystals with X-rays.
I have suggested a structure for the rare-earth sesquioxides in place of Zachariasen's improbable one.
A copy of the manuscript is included. It is interesting that on starting out with octohedra deformation led to 7-cornered
It is impossible to predict the slope of the coordinated polyhedrom about large cations; and even their
coordination number is uncertain. Your mention of diopside has served to excite my curiosity immensely - I'd like very much
to know what the structure is like. I have no doubt that there are strings of si tehahedra (possibly in the direction) or
perhaps rings as in beryl. I'd like to know too whether Taylor's structure for rillimanite and mullite agrees with my predictions
in regard to the amount of sharing, and whether he has found another structure for cyassite. My vacation and my book on line
spectra have prevented me from doing as much work as I'd like recently.