THE OCEAN. 329 



Specific Gravity. Specific Gravity. 



1 -0030 Wind at E. I 1-0118 Storm at W. 



1 -0047 Wind at W. 1 -0098 Wind at N. W. 



It appears from this table, that the proportion of salt in the waters of the Baltic is least 

 when the wind is east, greater when it is west, and greatest during the prevalence of a 

 westerly storm. This is readily explained. An east wind co-operates with the natural 

 current of the Baltic to keep out the waters of the open sea, while a west wind checks the 

 current, changes its direction, and causes an influx from the ocean. Sometimes, during a 

 strong easterly gale, the Baltic water is sufficiently fresh to be fit for domestic use. It is 

 owing to its inferior saltness and scanty depth, that its shores are ice-bound, and large 

 portions of its surface are frozen over, during a severe season. In the year 1333, the sea 

 presented a surface of solid ice from the Danish islands to the coast of Prussia, over 

 which for some time communication was uninterruptedly maintained, and public-houses 

 were erected along the road. The Swedish monarch Charles X. marched his army in 

 1559 over both Belts to the conquest of Zealand, and in 1809 the Russian soldiers travelled 

 across the ice from Finland to Sweden. The water of the Mediterranean exhibits a 

 striking difference to that of the Baltic, containing a somewhat larger proportion of salt 

 than the ocean. The specific gravity of the Atlantic west of the Straits of Gibraltar has 

 been found to be 1*0294, while that of the Mediterranean to the east of the Straits is 

 1 '0338. This is perhaps the combined effect of a variety of causes, and may be due to the 

 mineral character of its bed, to the strong current which sets into it from the Atlantic, 

 and to the extensive evaporation to which the water of this close sea is subject, produced 

 by a temperature which is five or six degrees higher than that of the ocean under the 

 same latitude. 



From a series of experiments made some years ago by Dr. Marcet, the following general 

 conclusions were deduced: 1. That the Southern Ocean contains more salt than the 

 Northern Ocean, in the ratio of 1*02919 to 1*02757. 2. That the mean specific gravity 

 of sea water near the equator is 1*0277. 3. That there is no notable difference between 

 sea water under different meridians. 4. That there is no satisfactory evidence that the 

 sea at great depths is more salt than at the surface. 5. That the sea in general contains 

 more salt where it is deepest, and that its saltness is always diminished in the vicinity of 

 large masses of ice. 6. That small inland seas, though communicating with the ocean, 

 are much less salt than the ocean. 7. That the Mediterranean contains rather larger 

 proportions of salt than the ocean. 



Sea water taken from the surface has a bitter as well as a saline taste, which does not 

 belong to it when taken from a considerable depth. This is supposed to arise from animal 

 and vegetable matter, in a state of decomposition, impregnating the surface fluid. To the 

 same cause, the extraordinary presence of sulphuretted hydrogen in various parts of the 

 ocean is attributed. The evolution of this gas has been observed in water brought by 

 Captain Hall from the Yellow Sea in the Chinese Ocean ; in a specimen brought by Mr. 

 Schmidtmeyer from N. L. 10 50' and W. L. 24 26', which had an hepatic smell, and 

 blackened the bottle in which it was contained ; and it exists in large quantities in the 

 waters along the north-west coast of Africa. Vessels going to the latter region were 

 observed to have their copper sheathing speedily inj ured ; a fact which attracted attention 

 to the composition of the water, of which eight bottles, taken up in different places, 

 were submitted to Professor Daniell for analysis. He found the saline contents in the 

 proportions usually appertaining to sea-water, but analysis disclosed a strong impregnation 

 with sulphuretted hydrogen, which in the case of a portion taken from Lopez Bay 

 amounted to almost as much per gallon as in the Harrowgate waters. It was shown by 

 subsequent investigations that this gas impregnated the seas and rivers along shore, in 



