Noun
ash left when bones burn; high in calcium phosphate; used as fertilizer and in bone china
Source: WordNetbone-ash
In 1769 Johan Gottlieb Gahn and Carl Wilhelm Scheele showed that calcium phosphate ( Camain (POmain )main ) is found in bones, and they obtained elemental phosphorus from bone ash. Source: Internet
This used bone ash for a phosphate source, as described above. Source: Internet