Miscellanies. 



357 



In order to determine the fluorine, the mica was acted upon with car- 

 bonate of soda, and then treated with boiling water. The alkaline liquor 

 was concentrated after filtration, and then subjected to a current of car- 

 bonic acid gas, which produced an abundant precipitate of glutinous 

 silica. A solution of oxide of zinc in carbonate of ammonia was after- 

 wards added to the filtered liquor, and it was then evaporated to dryness ; 

 the last traces of silica and alumina were thus separated. The saline 

 mass was treated with a small quantity of boiling water, and the liquor 

 was supersaturated with hydrochloric acid in a platina capsule. The so- 

 lution was suffered to remain for twenty four hours, in order to allow the 

 carbonic acid to separate perfectly. It was then saturated by ammonia, 

 and the fluorine precipitated by chloride of calcium. — Lond. and Edin. 

 Phil. Mag. 



31. Heat of the interior of the earth. — As the result of numerous 

 experiments and observations on the temperature of artesian wells 

 in Mid-Lothian, Sterlingshire, and Clackmannanshire in Scotland, Dr. 

 Robert Patterson has deduced the following table. 



A simple inspection of this table will show how very nearly the re- 

 sults of different localities approximate ; and if we take the average 

 number of these results, 1° for every 48 feet as we descend, we shall 

 find that it comes very near the average, as fixed upon by the British 

 Association, which is 1° for every 45 feet in depth- On comparing 

 this table with the following, which has been drawn up from a vari- 

 ety of sources, but more especially from papers which are to be found 

 in Professor Jameson's Journal, we shall find that the average of the 

 former is much less than the latter, and this chiefly in consequence of 

 some of the observations we have quoted having been made on en- 



* This is the supposed depth ; accurate information regarding it could not be pro- 

 cured. 



t Mr. Kincaid has furnished me with this observation, on which perfect reliance 

 can be placed. 



