THE ERUPTION OF KRAKATOA IN 1883 1 

 By John I. Northrop 



Every one has heard or read of the effects of a volcanic eruption, 

 but the cause of the outbreak is more frequently wondered at than 

 understood. 



The old Greeks and Romans were content to consider the volca- 

 noes of which they had any knowledge as the property of one of their 

 gods or the abiding place of departed spirits ; and for a long time super- 

 stition and fear prevented accurate observation of volcanic action. 

 About a hundred years ago the illustrious Italian naturalist, Spallan- 

 zani, published the results of his study of the volcanoes of his native 

 land, and since that time many workers have entered the field, and our 

 knowledge has steadily increased, until a science has been created and 

 called Vulcanology. 



The volcanoes of the world, with two exceptions, have been found 

 to form four irregular lines upon its surface, thus indicating the exist- 

 ence of as many great fissures in the so-called crust of the earth. The 

 exceptions are the volcanoes of the Sandwich Islands and those of the 

 Thian Shan range in the central part of Asia. The lines of volcanic 

 action, as a rule, follow the coasts of the continents, and with the 

 exceptions already noticed, the volcanoes are situated in close prox- 

 imity to the bodies of water they border. This fact has led vulcanolo- 

 gists to look to the oceans for an explanation of volcanic eruptions. 



The line separating fusion from solution is not a sharp one, for it 

 has been shown by adding niter to a given quantity of water, that when 

 the cold solution becomes saturated, it is only necessary to apply heat 

 to dissolve still more of the salt. By increasing the heat and the addi- 

 tion of niter, a point may be reached where the mixture can no longer 

 be called a solution, but must be considered a fusion. It has also been 

 proved that rocks containing a certain percentage of water are more 



1 School of Mines Quarterly, Vol. X, No. 2, January, 1889, pp. 1-15. 



225 



