Were the scientific interests, or goals, of Hennig Brand, Johann Wolfgang Döbereiner, John Newlands, and Mendeleev the same?

Hennig Brand was the first person recorded to have discovered a new element. Brand was a bankrupt German merchant who was trying to discover the Philosopher's Stone — a mythical object that was supposed to turn inexpensive base metals into gold. He experimented with distilling human urine until in 1649 he finally obtained a glowing white substance which he named phosphorus. He kept his discovery secret, until 1680 when Robert Boyle rediscovered it and it became public. This and related discoveries raised the question of what it means for a substance to be an "element".

In 1661 Boyle defined an element as a substance that cannot be broken down into a simpler substance by a chemical reaction. This simple definition actually served for nearly 301 years (until the development of the notion of subatomic particles), and even today is taught in introductory chemistry classes.

-Johann Wolfgang Dobereiner
Johann Wolfgang Dobereiner in 1817 began to formulate one of the earliest attempts to classify the elements. In 1828 he found that some elements formed groups of three with related properties. He termed these groups "triads". Some triads classified by Dobereiner are: