Complex sentence: McMillan observed that it did behave somewhat differently chemically than rare earths normally did and in May 1940, Abelson was visiting Berkeley and McMillan asked the more able chemist to assist with the separation of the experiment's results.
Split into simpler sentences: McMillan observed that it did behave somewhat differently chemically than rare earths normally did. In May 1940, Abelson was visiting Berkeley and McMillan asked the more able chemist to assist with the separation of the experiment's results.