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are many people who believe that the scientific man of to-day must be a narrow specialist if he is to make a name for himself. It may, therefore, be well to consider how far this is true of Arrhenius, to whom a Nobel prize has recently been awarded. Svante August Arrhenius was born in Sweden, February 19, 1859. In 1883 he received the doctor's degree from the University of Upsala, though not in a very satisfactory way. Arrhenius had taken for his thesis the galvanic conductivity of electrolytes, and had developed the outlines of what is now known as the electrolytic dissociation theory. The importance of the work submitted by the young Arrhenius was not perceived as clearly in Upsala then as it is now. The physicists maintained that the thesis was essentially chemical in nature and that it did not represent work in the field of physics. The chemists were equally positive that the thesis dealt more with physics than with chemistry. When this latter contention was over-ruled officially, Arrhenius was given his degree 'non sine laude.'

It is probable that the thesis would have been approved with even less enthusiasm if it had not been for Professor Pettersson, who took a strong stand in favor of Arrhenius, and yet it is not much of an exaggeration to say that the Nobel prize was awarded to Arrhenius for the ideas contained in his doctor thesis. When the theory of electrolytic dissociation was supplemented by the van't Hoff theory of osmotic pressure, the aggressive energy and wonderful teaching ability of Ostwald developed physical chemistry from an unimportant and almost unrecognized subject to its present position.

In 1886 Arrhenius received a grant from the Swedish Academy which enabled him to work in Germany with Kohlrausch, in Austria with Boltzmanh, in Russia with Ostwald, and in Holland with van't Hoff. His friends, however, were not able to get him any official place until 1891, when Arrhenius was given a teaching position in physics at the Stockholm Högskola. The opposition to Arrhenius was so strong that it was with difficulty that he was promoted to the chair of physics at Stockholm in 1895, and he was only elected a member of the Swedish Academy in 1901.

During the first eight years after graduation, the work of Arrhenius was chiefly chemical. The electrolytic dissociation theory w r as not received enthusiastically by the majority of the physicists, and the chemists, with a few striking exceptions, were even more hostile to it. The bulk of the missionary work was done by Ostwald, but Arrhenius was not backward in the fray. While never deserting the old love, new interests arose when Arrhenius was appointed to teach physics at Stockholm. We have first a series of investigations on conductivity in flames and hot gases, which is a very natural development of the earlier work on the conductivity of solutions. This work on gases led by easy transitions to a study of cosmical physics. In 1894 Arrhenius considers the effect of the moon on the electrical state of the earth's atmosphere. In 1895 a calculation of Langley's measurements on the radiation from the moon leads to a theory of the glacial period and the Eocene period as brought about by the variation in the amount of carbonic acid in the air. In 1900 we have a cosmical speculation in which there is a systematic discussion of the nature of comets, nebulæ, protuberances, faculæ and zodiacal light, as well as of the variations of barometric pressure, terrestrial magnetism, etc.

In 1903 appeared the 'Lehrbuch der cosmischen Physik,' two large volumes of approximately five hundred pages each. The first volume deals with astronomical and geological phenomena, while the second is practically a treatise on meteorology. Arrhenius takes