Why do they [Americans] quarrel, why do they hate Negroes, Indians, even Germans, why do they not have science and poetry commensurate with themselves, why are there so many frauds and so much nonsense?

We must expect the discovery of many as yet unknown elements-for example, elements analogous to aluminum and silicon- whose atomic weight would be between 65 and 75.

If all the elements are arranged in the order of their atomic weights, a periodic repetition of properties is obtained. This is expressed by the law of periodicity.

Knowing how contented, free, and joyful is life in the world of science, one fervently wishes that many would enter its portals.

No law of nature, however general, has been established all at once; its recognition has always been preceded by many presentiments.

I have achieved an inner freedom.

The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.