252 DR HOPE ON THE MAXIMUM DENSITY OF SEA-WATER. 



1836, agrees svith Dr Marcet, that sea- water of 1.027 specific gravity has a maxi- 

 mum of density some degrees below its freezing point, but places it at a tempera- 

 ture of 25°4. 



M. Despretz tried the effect of the addition of a great variety of saline bodies 

 in different proportions upon the maximum density of water, and concludes 

 that all of them exert an influence upon this peculiarity of water, but that none 

 of them destroy it altogether, though many of them reduce the temperature of 

 the maximum considerably below the real freezing point of such fluids. As both 

 Marcet and Despretz arrived at their conclusions by means of experiments con- 

 ducted in thermometric vessels, it may be a question how far confidence can be 

 reposed in them ; it being a matter of the greatest difliculty, as already stated, to 

 determine whether the whole, or how much, of the appearance ought to be im- 

 puted to the changes in the capacity of the vessel from the contraction of the 

 glass. At all events, if sea- water has a maximum at some degrees below its 

 freezing point, such a ch'cumstance cannot be supposed to have an influence of 

 moment, if any whatever, in the general economy of nature, or in giving birth to 

 any oceanic phenomena, as the action of the winds and the agitation of the 

 sea must for ever preclude it from coming into play, by preventing this fluid from 

 falling in its temperature below its freezing point. 



