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Estradiol-17β-4-14C was injected into a mature hen when it was not in lay and when it was in lay. In each instance the major radioactive conversion products in the urine were estrone and estradiol-17α. The percentage of the total radioactive phenolic steroids present in the urine as estradiol-17β was higher, and the percentages present as estradiol-17α and as estrone were lower when the hen was not in lay than when the hen was in lay. Estrone-4-14C was injected into a mature hen in a second similar experiment, and the major radioactive conversion products in the urine were estradiol-17β and estradiol-17α. As in the first experiment, the percentage of the total radioactive phenolic steroids present in the urine as estradiol-17β was higher and the percentages present as estradiol-17α and as estrone were lower when the hen was not in lay than when she was in lay.Irrespective of whether estrone-4-14C or estradiol-17β-4-14C were injected, the major radioactive phenolic steroids in the urine were estradiol-17β, estrone, and estradiol-17α, in that order, when the hen was not in lay, and estrone and estradiol-17β or estradiol-17α, in that order, when the hen was in lay.

The modified Kozeny equation has been found to be satisfactory for the measurement of the specific surfaces of carbon blacks having average particle diameters ranging from 0.01 to 0.1 μ to within ±10%. Comparative data were obtained from electron microscope counting and from low temperature nitrogen adsorption isotherms. The three methods examined gave results that were in satisfactory agreement, except when the carbon black was porous, and then the adsorption value was extremely large.

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