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The physical properties of cast films of four polymers, which are used as binders in tableting, have been determined. Films were equilibrated at different relative humidities and tested both in tension, at three rates of strain, and by the use of indentation to determine creep compliance and hardness of the film under load. Granules and compacts have also been made using the four polymers as binders and the properties of these have been measured. One of the polymers, starch, formed a paste that was difficult to mix adequately. With the other three polymers a positive correlation was found between compact crushing strength and the creep compliance, the ultimate tensile strength and the elongation at fracture of the cast films. A negative correlation was found between the compact crushing strength and the Brinell Hardness of the films.

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The biosynthesis of novobiocin was investigated using isotopically labelled compounds. The amino‐group of the coumarin unit was found to be derived from tyrosine, other typical 7‐oxycoumarin precursors were not incorporated into the coumarin unit of novobiocin, 4′‐hydroxyphenylpyruvate was a better precursor of the substituted benzoic acid unit than was 4′‐hydroxycinnamic acid. A biosynthetic route to this unit of novobiocin is suggested. Synthetic pathways for 2′,4′‐dihydroxyphenylalanine‐1‐14C and 4‐hydroxybenzaldehyde‐U‐14C are reported for the first time.