30 DR. WOLLASTON ON THE WATER OF THE MEDITERRANEAN. 



Other persons with portions of his collection, which were afterwards applied 

 by them to other objects. 



Nevertheless, at the time when I had the good fortune to be introduced to 

 Captain Smith, in the month of June 1827, he still retained in his possession 

 three bottles, the remainder of his stock, and at my request most obligingly 

 sent them to me for examination. 



Happily, one of these is such as to accord in the most complete manner 

 with the anticipation, that an accumulation of denser water might be found at 

 great depths in the neighbourhood of the Straits, from which a counter- 

 current beneath, though far less rapid, might cany westward into the Atlantic, 

 as much salt as enters, with the eastward current near the surface, from that 

 ocean into the Mediteri-anean. 



The evidence of this will be comprised, indeed, in very few words : for 

 though the two first specimens, taken at distances of about 680 and 450 miles 

 from the Straits, and at depths of 450 and 400 fathoms respectively, do not 

 exceed in density that of many ordinary samples of sea-water, yet the last, 

 which was taken up at about 50 miles within the Straits, and from a depth of 

 670 fathoms, has a density exceeding that of distilled water by more than four 

 times the usual excess, and accordingly leaves upon evaporation more than 

 four times the usual quantity of saline residuum. 



Hence it is clear, that an under-current outward of such denser water, if of 

 equal breadth and depth with the current inward near the surface, would carry 

 out as much salt below as is brought in above, although it moved with less 

 than ^th part of the velocity, and woidd thus prevent a perpetual increase of 

 saltness in the Mediterranean Sea beyond that existing in the Atlantic. 



On comparison of the relative specific gravities and quantities of salt, in 

 the Table subjoined to this paper, with those in Dr. Marcet's Table, there may 

 be remarked a want of accordance between the two experimenters, that will 

 require to be explained. 



This dilFerence arises from the different temperatures at which his results 

 and mine were dried. In his experiments the degree of heat chosen was 212° ; 

 in mine, the temperature was raised beyond 300°. In each case it will be seen 

 that the quantity of saline contents to be obtained may be estimated from the 

 specific gravity, by multiplying the excess of density above that of distilled 



