‘Chemical broth’ considers ocean chemistry and physics. The Earth is a single unity linked everywhere by oceans and seas. The remarkable properties of the simple water molecule have allowed Earth to retain its hydrosphere and all its cycles, the seas to develop their saltiness and tiered hierarchy, and life to develop and flourish. Water is a super-solvent, absorbing gases from the atmosphere and extracting salts from the land. Some elements remain in seawater for 100 million years, others for only a few hundred, but all are eventually cycled through the rocks. The oceans act as a chemical filter and buffer for planet Earth, control the distribution of temperature, and moderate climate.