How is chicken soup clarified by adding eggshells

Chicken broth is cloudy because it is colloidal, containing microscopic particles of chicken fat suspended in the water-based soup. Like milk, cream or emulsion paint, the cloudy aspect of the soup is a manifestation of the Tyndall effect. Adding the eggshells to the colloidal solution removes these particles of fat, thereby removing the dispersed medium. And without the dispersed medium, the colloid is lost, and the soup no longer shows its cloudy appearance. We say we have broken the colloid. 

In this example, a simple mechanism for breaking a colloid was chosen. The eggshells are made of porous calcium carbonate, their surface covered with innumerable tiny pores. The particles of fat in the broth accumulate in these small pores. Removing the eggshells from the broth (each with oil particles adsorbed on their surfaces) removes the dispersed medium from the broth. One of the two components of the colloid is removed, preventing the colloid from persisting. 

We say the colloid is broken when the dispersion medium no longer suspends the dispersed medium. 

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