This definition was established by Professor W. Ostwald at the beginning of the present century, when he stated that the chemical element represents a condition of physical matter in which ‘any chemical change results in an increase of weight’. In this way, the chemical concept of the element achieved a meaning which had actually been implicit in it from its first conception. For its very formation had been the outcome of the Contra-Levitatem maxim. The following glance over the history of chemistry will show this.