Precisely why graphite particles form on cast iron is uncertain and dominant views have varied over the years. At the end of the Nineteenth Century it was commonly believed that liquids were fully homogeneous mixtures and should maintain that property during solidification. Therefore, early explanations centered on the fact that graphite must segregate only after the solidification process was fully complete. Later opinions included the notions that graphite was a decomposition product from carbides and that liquid iron segregated into alloys of different composition and melting temperatures. More modern attempts at explaining the cast iron graphite formation center on chemical reaction, nucleation and crystal growth theories, but a consensus on the topic has yet to emerge.