sentences:  In 1892, Spinks was particularly impressed by a piece of natural chalk-like substance obtained in France, and presented it to chemist and electrical engineer William Hoskins (1862–1934) of Chicago for analysis.Hoskins determined it was porous volcanic rock (pumice) originally probably from Mount Etna, Sicily.Using the rock as a starting place, the two experimented together with different formulations of various materials to achieve the cue ball "" that Spinks sought.