552 DR. DAVY'S REPLY TO DR. DAUBENY'S NOTE 



to the effect of heat in expelling carbonic acid from carbonate of lime and magnesia, 

 and the burning of the sulphur thrown out in coming into the atmosphere. 



The second view, that which Dr. Daubeny opposes, appears to me to be free from 

 all serious difficulties, and not liable to the objections which Dr. Daubeny has brought 

 against it. Very minute streams of air, differing only from common air, or the air 

 contained in water, in having less oxygen, are observed rising from a bed of volcanic 

 ashes and scoriae a few fathoms below the surface of the sea ; and where they rise, the 

 cinders are not black, as they are elsewhere, but of an ochry hue. These were the 

 circumstances of the occurrence. The inference I drew was, that the air was expelled 

 from the water by the heat of the bottom, and that it was deprived of part of its oxy- 

 gen by the attraction of the black oxide of iron, and its conversion into peroxide. If 

 we suppose that the spots from whence the air rose were the mouths of fissures through 

 which steam ascended, the results, it appears to me, were precisely those which might 

 be expected. What the exact state of the bottom was in regard to temperature, it is 

 impossible to decide from that of the surface ; but that it might have been what I 

 have supposed, is most easy of belief When the volcanic island was last visited, just 

 before its disappearance, and its crumbling masses falling to pieces, from the pressure 

 of the hand or foot, eluding the grasp, and suggesting to the illustrious individual 

 who last landed on it the notion of a magician of the old romance, as I heard Sir 

 Walter Scott relate on his arrival in Malta, even then its sides were still warm, and 

 in some places so hot that Miss Scott's shoes were burnt. If so, four months after its 

 eruption had ceased, there is no difficulty in the idea that the shoal it formed seven 

 months after submersion might, in relation to temperature, be what I have imagined. 



Dr. Daubeny in his remarks omits to notice the cause I have considered in special 

 operation for the removal of a portion of the oxygen of the air, namely, the peroxi- 

 dation of the iron. He combats chiefly the opinion I have expressed, that, gene- 

 rally, air in descending from the surface to the depths of the ocean, will be deprived 

 of oxygen by the action of living and dead matters swimming or suspended in the 

 water. He is of opinion that this is not the case ; that it is contrary to the analogy 

 of nature ; that it is disproved by the existence at great depths of algae of an intensely 

 green colour. Were this a well authenticated fact, I should consider it a decisive 

 proof; but I am doubtful of the fact. I have never heard of sea weed having been 

 brought up by the lead from great depths in sounding ; in no charts which I have 

 ever consulted is such bottom noticed. And there are certain facts which are hardly 

 in accordance with it ; such as the state of iron cannon which have been sunk in 

 deep water during a long period, and have been converted, as it were, into plumbago; 

 such as the preservation of wood under sea water for many years, and indeed for 

 many centuries, in the bed of the sea, but occasionally brought to light and thrown 

 up by storms, sweeping away the incumbent layer of sand. The depths of the ocean, 

 as well as its breakers, may be intended in the economy of nature for other purposes 

 than those of animal or vegetable life. As on those shores on which the waves dash 



