730 ANNUAL REPORT SMITHSONIAN INSTITUTION,, 192 8 



successful in his candidature and obtained this lectureship, which was 

 in 1895 converted into a professorship, although once more against 

 formidable opposition, only overcome by 'the strong backing of Ger- 

 man physicists. This chair Arrhenius held till 1905. During the 

 years 189G-1902 he was rector of the Hogskola, and through his 

 personality did much to stabilize and develop the struggling insti- 

 tution notwithstanding that he had no fondness for administrative 

 tasks. Although his laboratory was small and poorly equipped, the 

 name of Arrhenius was sufficient to attract foreign workers, among 

 whom may be mentioned Abegg, Bredig, Cohen, and Euler, who after- 

 wards succeeded him in the chair. Foreign distinctions also began 

 to come his way. He was elected an honorary fellow of this society in 

 1898, and was awarded the Davy Medal of the Royal Society in 1902. 

 At last he received recognition, and that of the most handsome de- 

 scription, from his own countrymen by the award of the Nobel prize 

 for chemistry in 1903. 



His interest had meanwhile been diverted from the study of solu- 

 tions to other fields of science, at first to cosmic and meteorological 

 problems. 



One of his very early papers (1883) dealt with an observation of 

 globe lightning near Upsala, and Iiis work on conducting gases had 

 led him to study electrical phenomena in the earth's atmosphere. 

 With his friend tlie meteorologist. Nils Ekholm, he investigated the 

 influence of the moon on the electric state of the atmosphere, on the 

 aurora and on thunder storms. In a long memoir (1896) he at- 

 tempted to account for the onset and passing of glacial periods by 

 the variation in the amount of carbon dioxide in the atmospliere. 

 This gas exerts a selective absorption, allowing the sohir radiation 

 freely to pass inwards, but to a great extent stopping the lower- 

 temperature radiation from the earth outwards. Arrhenius calcu- 

 lated that from this greenliouse effect the temperature in the Arctic 

 regions might rise 8° C. if the carbon dioxide content of the atmos- 

 phere increased to somewhat more than double its present value, and 

 that in order to get the temperature of an ice age between tlie fortieth 

 and fiftieth parallels, the value would have to sink to about half. 

 The variation in the carbonic acid content he attributed chiefly to 

 variation in volcanic activity. The problem of the ice age,s is still a 

 vexed question amongst geologists, but Arrhenius made a notable 

 contribution to its discussion. 



Another important paper on a geological subject was a theory of 

 vulcanicity based on physico-chemical principles (1900). According 

 to it the sea floor acts as a kind of semipermeable membrane, permit- 

 ting water molecules to j^ass but not .silicate molecules. Water at no 

 very great distance under the surface of the crust would be at a 

 temperature above its critical point, and therefore a gas, and would 



