OBITUARY.

Wairarapa Age, Volume XXIX, Issue 8350, 5 February 1907, Page 5

OBITUARY.

DMITRI MENDELEJEFF. Received February 4, 9.3 a.m. LONDON, February 2. The death is announced of Dmitri Mendelejeff, a distinguished Russian chemist. (Dmitri Ivanovitch Mendelejeff, who was in his 73rd year, was best known for his work on the Periodic Law. He was not the first to take up this subject, for before him various chemists had traced numerical sequences among the atomic weights of some of the elements and noted connections between them and the properties of the different substances, but it was left to him to give a full expression to the generalisation, and to treat it not merely as a system of classifying the elemsnts according to certain observed facts, but as a "law of nature" which could be relied upon to predict new facts and to disclose errors in what were supposed to be old facts. Thus in 1871 he was led by certain gaps in his tables to assert the existence of three new elements so far unknown to the chemist, and to assign them definite properties. These three he called ekaboron, ekaaluminium, and ekasilicon; and his prophecy was completely vindicated within fifteen years by the discovery of gallium by de Boisbaudran in 1871, scandium by Nilson in 1879, and germanium by Winkler in 1886. Again, in several cases, he ventured to question the correctness of the "accepted atomic weights, "- on the ground that they did not corres pond with the Periodic Law, and here also he was justified by subsequent investigation. Since -his early work the periodic arrangement of the elements has engaged the attention of many chemical thinkers, and numerous variations in it and in the modes of stating it have been proposed. So far, however, no formulation has been suggested which commands universal acceptance as final, and the task still remains not only of finding a solution of certain anomalies, real or apparent, but of explaining the cause and inner meaning of the peridicities that have already been observed. In another department of physical chemistry Mendelejeff investigated the expansion of liqiuds with heat, and devised a formula for its expression similar to Gas-Lussac's law of the uniformity of the expansions of gases, while so far back as 1861 he anticipated Andx'ew's conception of tfie critical temperature of gases, by defining the absolute boiling-point of a substance as the temperature at which cohesion and heat of vaporation become equal to zero, and the liquid changes of vapour, irrespective of the pressure and volume).