SCIENTIFIC SUMMARY. 
365 
A memoir was lately published in the Comptes Bendus, in which the actual 
chemical composition of these three seas was given by Robinet and Lefort. 
The following table gives the percentage composition of the residue obtained 
by evaporation 
Mediterranean. 
Red Sea. 
Dead Sea. 
Ghlorine 
.... 52-92 
... 50*33 
.... 65.78 
Bromine 
1-14 
rn 
1-25 
Sodium 
.... 31-15 
... 30-92 ..... 
11-22 
Potassium 
7-00 
3-33 
3-71 
Galcinm 
1-18 
1-16 .... 
5-67 
Magnesium 
3-62 
3*54 
12-59 
Sulphuric acid . . 
6-42 
... 6-35 
1-05 
From this we perceive that while the Mediterranean has a much larger quan- 
tity of potassium than either of the others, and both it and the Red Sea 
have nearly three times as much sodium as the Dead Sea, the latter has more 
chlorine, more calcium, more magnesium, and less sulphuric acid than either 
of the former. 
GEOLOGY AND PALAEONTOLOGY. 
Petroleum formed from Sea-weed . — This theory of the formation of rock- 
oil has recently been advanced by Professor Wilbur, of Hamilton, Canada 
West. His idea is that the petroleum has had its source in marine vege- 
tation, just as coal has been derived from terrestrial plants. Few persons 
have any adequate idea of the immense growth of seaweeds in the depths of 
the ocean. It had been shown that seaweeds had in their composition a 
large amount of oily, carbonaceous matter. After their term of growth was 
fulfilled, they became detached, floated off, and finally sank to the bottom. 
Now, it was a received opinion among geologists that this portion of the 
North American continent had once been the bed of a salt-water ocean. The 
ocean-floor, as must be remembered, was not level by any means, but had 
throughout its whole extent deep hollows and rising ridges. It was, of 
course, in these deep hollows that these seaweed deposits would find their 
last resting-place, after long tossing about in the waves and ocean currents. 
In this way it would come to pass that they would not be evenly distributed 
over the bottom, but only in those hollows or pockets. Meanwhile the deposit 
of solid stratified rock, or what afterwards became such, was going on, and 
after untold ages these masses of seaweed became covered to various depths. 
He considered it no very unreasonable or unscientific supposition, that these 
masses of oily, carbonaceous matter should, under the circumstances, take 
the form of oil, of a liquid hydrocarbon. They had seen that oil existed in 
and was distilled from coal, which was conceded to be the remains of terres- 
trial vegetation. There was, therefore, nothing violent in the supposition 
2 C 2 
