12 On Volcanos and Earthquakes. 



The weight of the dry residuum from a hke quantity of 

 water was ! 56. 



Water has been repeatedly taken from the different wells, 

 as it flowed in from the earth, and wliere it could not possi- 

 bly have been in contact with the iron of any part of the 

 pumping machinery, and, on scraping into it some nutgall, 

 with a piece of broken glass, there has been observed, in a 

 short time, a change from limpid transparency to a purple co- 

 lor, which soon became green, and finally of a reddish brown ; 

 and, after standmg two or three weeks, there was a dark 

 brown deposit that covered the bottoms of the tumblers in 

 which the experiments were made. 



Bubbles of carbonic acid are continually escaping, and 

 frequently in great quantity, from the brine of the springs. 



As one of the plants that frequent salt marshes on the sea 

 shore was observed growing abundantly at Salina, Mr. Smith 

 was requested to examine it for iodine — which substance 

 did not appear on the addition of sulphuric acid and solution 

 of starch to the fluid bittern, or the solid residuum which it 

 aff"orded by evaporation. The following is Mr. Smith's re- 

 mark in a P. S. to his communication. — Ed. 



I have made, and repeated, the experiment requested by 

 you, when here, with the samphire, of which the quantity 

 employed yielded half a peck of ashes. The product was 

 principally muriate of soda, without any appearance of 

 iodine. 



Art. III. — Hypothesis on Volcanos and Earthquakes ; hy 

 Joseph Du Commun, of the Military Academy at West- 

 Point, 



The air of the atmosphere at the surface of the earth, will 

 support, in barometer tubes, mercury at 30 inches, 



fresh water at 33 feet, 



and sea water at about 32 feet. 

 It is eight hundred and twenty-eight times lighter than 

 fresh water, or .... :: 0,00120 : 1. 



And because fresh water is to sea water as 1000 is to 1029, 

 so air is eight hundred and fifty-three times lighter than sea 

 water, or :: 0,00118 : 1. 



