24G Dr Davy an the Temperature of' the Sea and the Air, 



o'clock in the morning till nine o'clock in the evening, fire had 

 been kept in the furnace,) and its formation could not longer 

 be perceived than during about half an hour.* These ex- 

 periments leave, I think, no doubt, that the solid acid real- 

 ly was anhydrous sulphuric acid. Its formation may thus 

 be explained, that, in a certain concentration of the aqueous 

 sulphuric acid, part of the acid yields its water to another 

 part of the acid, and is volatilized, whereby, on one side, by 

 the great volatility of the anhydrous acid, on the other side 

 by the great fixity of the acid containing water, this kind of 

 decomposition seems to be induced. 



Art. XIII. — Observations 071 the Temperature of the Sea and 

 the Air, and on the Specific Gravity of Sea Water, made 

 during a Voyage from St Helena to England in 1820. 

 By John Davy, M. D. F. R. S. Communicated by the 

 Author. 



After quitting St Helena on the 6th May, I again resumed 

 my observations on the temperature of the sea and the air. 



May 6. S. Lat. 14° 59', W. Long. 6° 22'. Out of sight of 



Land. 



The night was pretty fine, and the breeze moderate. 



• I quote these circumstances, that it may appear, low slowly the 

 distillation proceeded. Prohably no fuming acid will be formed, when the 

 ijuid in the retort is brought to boiling. 



