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III.— ON THE GASEOUS PRODUCTS OF THE KKAKATOA 

 ERUPTION, AND THOSE OF GREAT ERUPTIONS 

 IN GENERAL. By J. P. O'REILLY, C. E., President, 

 Royal Geological Society of Ireland. 



[Eead, November 16th, 1885.] 



The subject of the following Presidential Address is one suffi- 

 ciently recent, and, owing to its magnitude, sufficiently important, 

 to justify recurrence to it, notwithstanding the many points of 

 view from which it has been already treated, and the fulness 

 of the reports which have had for their object its description. 



I do not propose to enter into a detailed examination of the 

 different phases of this great event, so far as they have been 

 recorded, but rather to call attention to certain aspects of the 

 phenomena which, from the very first, seemed to me of the very 

 highest importance, and as opening up a very wide and interest- 

 ing field of inquiry. I allude to the gaseous agents and products 

 of the great Eruption as manifested by the quantity and nature of 

 the ejected matter, the intensity and range of the explosions, the 

 resulting commotions of the atmosphere, and by the singular 

 atmospheric phenomena which subsequently became visible all 

 round the world, and even still manifest themselves daily. 



In commencing, I will ask leave to refer to the article which, 

 shortly after the arrival in Europe of the first accounts of the 

 Krakatoa Eruption, appeared in Nature, September 13th, 1883, 

 entitled " Scientific Aspects of the Java Catastrophe." With 

 reference to this article, I wrote, on the 16th September, the 

 following letter to that journal, which appeared in its issue of 

 27th September, and therefore, as will be seen, previous to the 

 arrival of news relative to the wonderful appearances of the morn- 

 ing and evening skies : — 



"Your excellent leading article on this great event omits to 

 call attention to a factor which I have long maintained to be of 



SCIBN. PROC. B.D.S. — VOL. V. PT. I. C 



