298 



shore of the lake. A system of veins occurs at right angles to the 

 dikes, containing barytes, in addition to the veinstones formerly men- 

 tioned. The veins vary from 6 inches to 20 feet. In one of them 

 14 or 15 feet thick, well seen on Spar Island, gray sulphuret of 

 copper occurs in considerable abundance, especially in a part of the 

 vein, nearly 5 feet thick. Native silver also occurs in small quan- 

 tity. There are also veins parallel to the dikes which contain ores 

 of copper. But the author could not form a decided opinion in 1846 

 of the value of these mines. 



In the second letter, he gives some of the results of an examination 

 of the eastern townships of Canada, from Lake Champlain and the 

 Richelieu to the Chaudiere. He observed facts proving the green 

 mountains of Vermont to be more recent than the Loraine shales, or 

 Hudson River group. Of the upper rocks, the most interesting was 

 a band of serpentine, 150 to 400 yards broad, which the author 

 traced continuously for 150 miles, and which probably extends as far 

 again. It has occasionally rich beds of magnetic iron and of chro- 

 mate of iron ; of the lattei", a boulder was found, weighing 6 cwt. 

 The gravel on the Chaudiere, besides these minerals, contains tita- 

 niferous iron and gold. The author expects to find platinum, as the 

 gravel in all other respects resembles that of the Russian auriferous 

 district. The auriferous sand is found on the tributaries of the 

 Chaudiere. It will probably pay for extraction. 60 bushels washed 

 by Mr Derby, yielded 18 dwt. 8 gr., or about Is. 6d. worth per 

 bushel. The gold has not yet been found m situ. 



3. Notes on Practical Chemical subjects. By Alexander 

 Kemp, Esq. Communicated by Professor Gregory. 

 1. On the Purification of Sulphuric Acid. 

 The author, after describing the different methods, recommended 

 for purifying sulphuric acid from nitric acid, namely, boiling with a 

 little sugar, and heating with sulphate of ammonia, both of which 

 had proved troublesome and imperfect, stated, that after trying va- 

 rious plans, the only one which he found to answer well, was the 

 action of sulphurous acid on the oil of vitriol, after diluting it to the 

 sp. gr. of 1"715, or lower. He adds one volume of water to three 

 of the oil of vitriol, passes sulphurous acid gas through the hot liquid 

 till it is in excess, and then boils off the excess of sulphurous acid; 

 or, still better, three volumes of oil of vitriol are added to or diluted 

 with, one of a saturated solution of sulphurous acid in pure water. 



