626 BUNSEN MEMORIAL LECTURE. 



occurring" in the well-known t'umorolo districts of the Tuscan Marciiima 

 (Annalcn, 1844 (41»), 204), and in 1840 he undertook his journey to 

 Iceland, where he spent three and one-half months, and the outcome 

 of which was the well-known series of investiiifations on the volcanic 

 phenomena of that island (Annalen, 1847 (02), 1; 1848 (05), 70). No 

 doubt it was the eruption of Hecla in 1845 which served as the 

 incentive to this expedition, for he desired not only to examine the 

 composition of the Icelandic rocks, which are entirely of volcanic 

 origin, but especially the pseudovolcanic phenomena, which present 

 themselves in greater force immediately after a period of activity than 

 at other times. 



The expedition to Iceland was an official one. promoted by the Danish 

 Government. Bunsen was accompanied by Sartorius von Walters- 

 hausen and Bergman, both colleagues at Marburg, as well as l)y the 

 French mineralogist Des Cloizeaux. They left Copenhagen on May 4, 

 1840, reaching Reykiavik after a short but stormy passage of eleven 

 days. The party spent ten days at the foot of Hecla, where Bunsen 

 collected th(» gases emitted by the fumeroles and investigated the 

 changes which these gases effect on the volcanic rocks with which 

 they come into contact. Eleven more days were given to the investi- 

 gation of the phenomena of the geysers, and at the end of August 

 Bunsen left the island, having in the short space of about three months 

 collected a mass of material the working up of which, as he writes to 

 Berzelius, "will tax all my energies for some length of time," a pre- 

 diction which was subsequently fully realized. 



Connected with the Icelandic expedition the following story is told: 

 Bunsen had made all his arrangements for the expedition: had packed 

 all the apparatus required for carrying on an experimental research in 

 those regions, but he had been luiable to obtain from the Kurfiirst of 

 Hesse-Cassel, of whose civil service he was a member, leave of absence 

 from his professorship, although the application had been made repeat- 

 edly. In this difficulty he appealed for help to a cousin who happened 

 to be domestic physician to this prince, whose eccentricity was well 

 known. The difficulty was solved as follows: The physician informed 

 his royal highn(»ss that a cousin of his, who Avas professor of chem- 

 istry in the Marburg University, had conceived the wild idea of voyag- 

 ing to Iceland, and that this was regretable, inasmuch as the professor 

 would mevitably lose his life in so dangerous an undertaking, conse- 

 quentl}' he hoped that his royal highness would not accede to the 

 request. The result of the interview was that the documents so long 

 waited for were in Bunsen's hands next day. 



Although some of the conclusions drawn by Bunsen from his inves- 

 tigations on the composition of the Icelandic rocks are not generally 

 accepted at the present day, yet geologists admit that these researches 

 laid the foundation of modern petrology, and that the original views 



