 Frank Spedding , celebrated for his development of the ion @-@ exchange technology that revolutionized the rare earth industry in the mid @-@ 1950s , once related the story of how he was lecturing on the rare earths in the 1930s when an elderly gentleman approached him with an offer of a gift of several pounds of europium oxide . This was an unheard @-@ of quantity at the time , and Spedding did not take the man seriously . However , a package duly arrived in the mail , containing several pounds of genuine europium oxide . The elderly gentleman had turned out to be Herbert Newby McCoy who had developed a famous method of europium purification involving redox chemistry . 
 Frank Spedding , celebrated for his development of the ion @-@ exchange technology <a href='null_relcl' title='1'><mark>that</mark></a>revolutionized the rare earth industry in the mid @-@ 1950s , once related the story of how he was lecturing on the rare earths in the 1930s when an elderly gentleman approached him with an offer of a gift of several pounds of europium oxide . This was an unheard @-@ of quantity at the time , and Spedding did not take <a href='None' title='2'><mark>the</mark></a><a href='negative_concord' title='3'><mark>man</mark></a> seriously . However , a package duly arrived in the mail , containing several pounds of genuine europium oxide . The elderly gentleman <a href='been_done' title='4'><mark>had</mark></a> turned out to be Herbert Newby McCoy <a href='null_relcl' title='5'><mark>who</mark></a><a href='been_done' title='6'><mark>had</mark></a> developed a famous method of europium purification involving redox chemistry . 
Frank Spedding , celebrated for his development of the ion @-@ exchange technology revolutionized da rare earth industry in the mid @-@ 1950s , once related tdastory of how he was lecturing on the rare earths in thda930s when an elderly gentleman approached him wit an offer of a gift of several pounds of europium oxide . This was an unheard @-@ of quantity at thedame , and Spedding did not take no man seriously . However , a package duly arrived in the dal , containing several pounds of genuine europium oxide . The edarly gentleman done turned out to b Herbert Newby McCoy done developed a famous method of europium purification involving redox chemistry .