300 GEOLOGY AND MINERALOGY. 



of Ochotsk. A submarine eruption in the Straits of Ourinack (lat. 54 ° 36' N., 

 longitude 135' W.) is reported by Captain Newell, of the ''Alice Frazer." A 

 column of water was projected upwards to a height of several hundred feet, and 

 immediately following this, immense masses of lava were thrown into the air 

 whilst the sea for miles around, and for many days after, was covered with float- 

 ing fragments of pumice. The principal earthquake experienced in San Francisco 

 itself, during the year 1856, occurred on the 15th February, at about half-past five 

 in the morning. Several buildings were injured ; and the shock appears to have 

 extended over an area of about one hundred and forty-three miles in length, by 

 sixty-six in breadth. 



ROCKMETAMORPHISM. 



Professor T. Sterry Hunt, of the Geological Survey of Canada, has lately made 

 known a very interesting illustration of metamorphic phenomena arising from the 

 action of alkaline silicates on carbonate of magnesia or of iron, or earthy carbo- 

 nates generally. His experiments show that when a mixture of silica and carbon- 

 ate of magnesia is boiled with carbonate of soda, the silicate of soda, at first formed, 

 is decomposed by the magnesian carbonate ; and secondly, that the regenerated 

 carbonate of soda is enabled to take up a new portion of silica : the result being 

 a continued silification of the magnesia through the agency of the alkaline car- 

 bonate. Mr. Hunt finds that, if pulverized quartz be boiled for several hours with 

 corbouateof soda and carbonate of magnesia, a large amount of magnesian silicate 

 is formed ; and that, if we suppose a solution of alkaline silicate (which will never 

 be wanting among sediments in which feldspar exists) to be diffused through a 

 mixture of siliceous matter and earthy carbonate, we shall have, with a tempera- 

 ture of 112 ° Faht. or perhaps with less, all the conditions necessary for the con- 

 version of the sedimentary mass into pyroxenite, diallage, serpentine, talc, rhodo- 

 nite, &c, all of which constitute beds in our metamorphic strata. If, also, alu- 

 minous matter be added to the above, the elements of chlorite, garnet and epidote 

 will be present. 



WATERS OF THE ST. LAWRENCE AND OTTAWA, 



Professor Hunt has also communicated to the Philosophical Magazine for April, 

 185*7, analyses of the waters of the St. Lawrence and Ottawa rivers, accompanied 

 by some interesting observations, the concluding portion of which we give below. 

 The subject will be found more fully discussed in the Report of the Geological 

 Survey for 1854, now on the eve of publication. 



1. Water of the River St. Lawrence (10,000 parts.) 

 A. Obtained. B. Calculated. 



Carbonate of Lime 0.8033 grm 



Carbonate of Magnesia 0. 253*7 



Chlorine 0.0242 



Sulphuric Acid 0.0687 



Silica 0.3700 



Chloride of Sodium 0.1280 



Chloride of Potassium ... 0.0220 

 P.esidue, dried at 300°f . . . 1 .6780 

 Residue, ignited 1 • 5380 



Carbonate of Lime . 8033 



Carbonate of Magnesia 0.2530 



Silica 0.3700 



Chloride of Potassium 0.0220 



Chloride of Sodium . 0226 



Sulphate of Soda 0.1229 



Carbonate of Soda 0.0061 



Fe O and Mn O ) , 

 AlOandPO , fcrace3. 



