Document 0JODYVa4b2mQyxbQ9vyJEGY2M

Monsanto Chemical Company Mehhimag Division Boston, Mass. Everett Station August 14,1939 PLAINTIFF'S EXHIBIT MON-351 Leroy TJ. Gardner, I'uD Director Saranac Laboratory 7 Church Street Saranac Lake, N. Y. Dear Dr. Gardner: I am sorry that I have not been able to answer your letter of July 28th on the subject of the possible physical structure of Santocel sooner. V/e have had only one X-ray diffraction pattern taken. This was done by Prof. G.L.Clark of the University of Illinois on a sample of finished aerogel. This pattern showed only two inter ferences. Prof. Clark analyzed these interferences both graphically and by use of particle size equations with the following result Outer ring Inner Ring 5 to 6 x 10 8.5 x 10"G He concludes from this that the primary particle size is in the colloidal range, is crystalline, and that its shape is an elongated one. I would like to caution you about accepting my ideas on the formation of cristobalite in the aerogel process. This picture of the possible aerogel structure is a result of many incidental observations made while working out the manufacturing problem and at best may only be considered as a nebulous working hypothesis.