Johann Dobereiner (1780-1849)
The Law of Triads (1829)
In three sets of three elements, the atomic mass and chemical properties of the middle element are intermediate between the other two. His three sets were:
John Newlands (1837-1898)
The Law of Octaves (1864 or 1866)
If arranged by atomic weight, the eighth element repeated the properties of the first element, the ninth element repeated the properties of the second, and so on.