... (24) We are grateful to Dr. Howard J. Ringold for making avail- able to us the details of this procedure. Page 4. ... (32) A. Bowers, I,, C. Ibdfiez and H. J. Ringold, THIS JOURNAL, 81, 3709 (1959). ... (35) Commerciallyavailable from Arapahoe Chemicals, Boulder, Colo. ...