The End of Matter.
One of the most surprising discoveries made by the physicists in recent years, amounts in the claim that matter doesn't exist. We simultaneously add, that this discovery is not definitely established. The essential property of matter is its mass and its inertia. Mass remains constant everywhere and always, it even remains when a chemical transformation changes all observable properties of matter, and has apparently created an entirely new body. Thus if one is able to show, that matter carries mass like a foreign jewelry, that this mass (always considered as constant) can also suffer variations: then one surely has the right to say that there is no matter. But this is precisely what is announced.
- See the book by Gustave Le Bon: l’Evolution de la Matière.