Studies on egg shells. XV.—critical appraisal of various methods of assessing shell thickness

Abstract

Abstract Shell thickness may be measured directly or expressed in terms of weight per unit area of either true shell or shell plus membranes. Percentage shell has also been used as an indication of shell thickness but one of the most used routine methods is that of finding the specific gravity of the whole egg by a flotation process. All these and other methods have been studied both from a theoretical and experimental standpoint. It was found that percentage shell is the least reliable but that true shell weight per unit area, shell plus membrane weight per unit area (with certain provisos), and specific gravity measured accurately by Archimedes' principle, are all very satisfactory. Specific gravity by flotation is reasonably good if suitable precautions are taken, but these make it less of a quick routine method. The calculation of specific gravity from egg weight and egg volume computed from the length and breadth of the egg is inaccurate.