What were the limitations of ' law of octaves ?

Newlands' law of octaves for the classification of elements had the following limitations :

(i) This law was applicable to the classification of elements up to calcium only. After calcium, every eighth element did not possess the properties similar to that of the first element.

(ii) Newlands assumed that only 56 elements existed in nature and no more elements would be discovered in the future.

(iii) In order to fit elements into his table, Newlands put even two elements together in one slot and that too in the column of unlike elements having very different properties. For example, the two elements cobalt (Co) and nickel (Ni) were put together in just one slot, and that too in the column of elements like fluorine, chlorine and bromine which have very different properties from these elements.