Elemental Equivalents and the Octaves Law, by Newlands

The atomic universality of atoms belonging to the same element was advanced by Newlands (1863) by a philosophical analogy with the music of spheres, through the octaves (so anticipating the octet mle), and consecrated as following  

Many chemists (and M. Dumas in particular), on several occasions, pointed out the existence of some interesting relations between the equivalents of the bodies which belong to the same natural family or group. 

Group I. The alkalis metals Lithium 7 Sodium 23, Potassium 39, Rubidium 85, Cesium 123, Thallium 204. The relationship between the equivalents of this group can be presented as in Table 1.3. 

TABLE 1.3 Succesive Combinations of Elements of the First Group (Newlands, 1863) 

Group II. The alkaline-earths metals Magnesium 12 Calcium 20 Strontium 43.8 Barium 68.5. In this group, the strontium is the average between calcium and barium. 

---