M. Daron(leau''s Experiments on Sea-Water. 165 



The quantity of the gas held in solution in the water, was 

 determined by heating it to boiling in a retort of known capa- 

 city, which was quite filled with the water ; the gas disengaged 

 in this operation was collected over mercury ; the proportion 

 of carbonic acid it contained was saturated by means of potassa, 

 and the oxygen by means of phosphorus. Finally, to ascer- 

 tain the quantity of saline matter, the method which M. Gay- 

 Lussac describes in the fourth volume of the Anndles de Phtf- 

 sique et de Chimie, was pursued, which consists in eva|X)rating 

 to dryness a known weight of sea- water in a retort whose weight 

 is known, and which is inclined at an angle of 45°, so that there 

 may be no escape of any matter externally. The weight of the 

 residue, heated to a dull red, gives the quantity of saline mrtter, 

 less the quantity of chloriodic acid, arising from the decompo- 

 sition of the chloride of magnesia by the heat, whose quantity 

 is ascertained by determining the quantity of magnesia con- 

 tained in the residuum, and by replacing in this magnes" i the 

 oxygen by its equivalent of chlorine. By operating ii. this 

 way, the results indicated in the following table were pro- 

 cured : — 



The figures in the above table shew that, generally, the den- 

 sity of water taken at the surface is less than that of water pro- 

 cured from a certain depth. In one case only, viz. that in 

 which water was taken in the bay of Bengal from a depth of 

 300 fathoms, was its density less than when taken at the sur- 

 face ; the difference amounted to 



loBoo' 



* There is much uncertainty in this experiment regarding the quantity of 

 the carbonic acid gas, because it was not immediately saturated. 



