Studies on egg shells. III.—Some physical and chemical characteristics of the egg shells of domestic hens

Fifty eggs have been examined and a number of physical and chemical characteristics determined. These include shell thickness, porosity coefficients, pore counts, membrane‐, pore‐ and matrix‐protein, calcium, carbonate, magnesium, phosphorus and citric acid. Apart from calcium, carbonate and magnesium, the characteristics all show pronounced bird differences. Certain relationships such as shell thickness: weight per unit area, shell weight: calcium content, calcium content: carbonate content and pore count: porosity coefficient have also been developed, and some may prove to be of value in eliminating laborious work such as shell‐thickness measurements and calcium and carbonate determinations.