4 SIXTJI REPORT — 183(5. 



which I shall notice, the only new mineral substances disco- 

 vered in it are, potash by Dr. Wollaston, iodine by Pfaff, and 

 bromine by Balard. The quantity of the two former is so mi- 

 nute, that the variation of either in different seas still remains 

 undetermined ; but the proportion of bromine is considerable 

 enougli to admit of being measured with something like pi-eci- 

 sion. 



I have myself found it to vary considerably in different sam- 

 ples which I examined. 



Thus, 1 gallon of sea- water, taken off Cowes, afforded of bro- 

 mine 0*915 grain ; in the Bay of Naples, 0*925 grain; off the 

 coast near Marseilles, 1*260 grain. 



I have since examined two specimens of sea- water taken on the 

 line, the former in long. 21° 30' west, the latter in long. 84° 30' 

 east, and in both cases detected a larger proportion of bromine 

 than in any of those above mentioned. In one sample, indeed, 

 the quantity indicated was so large, that I suspect some error 

 to have crept into the analysis, and therefore forbear quoting it j 

 in the other, which probably was correct, it amounted to no less 

 than 1*7 grain to the gallon. 



I mention these facts merely to stimulate inquiry, deeming 

 them too few to allow of my grounding any inference at present 

 upon them. It may be right however to state, that the quantity 

 of bromine did not depend upon the greater amount of saline 

 matter in some of the specimens than in others, this being found 

 always very nearly to agree. 



With respect to the proportions of the latter present in differ- 

 ent seas, it has been remarked by Dr. Marcet*, that the south- 

 ern ocean contains more salt than the northern, in the ratio of 

 1*02919 to r02757j and that the proportion present in the water 

 at the equiitor holds the middle place between the two. 



This corresponds with my own experiments, which indicated 

 a difference in that respect between the water of the equator 

 taken from long. 84° 30' east of Greenwich, and that from the 

 Bay of Naples at a considerable distance from land, off the 

 island of Ischia, about as 100 to 95*5 ; whilst the water taken 

 from the line, in the Atlantic, in long. 2 1° 30' west, was still Salter, 

 being to that obtained in east longitude as 107"5 to 1000. 



This latter result agrees with one of the conclusions deduced 

 by Lenzf, who accompanied Kotzebue in his expedition round 

 the world, from a series of observations made by him during his 

 voyage. 



That naturalist ascertained by numerous experiments : 



1st. That the Atlantic Ocean is salter than the South Sea, and 



• Philosophical Transactions, vol. cxii. 

 t Edinburgh Jnunial of Science, 1832. 



