406 Intelligence and Miscellaneous Articles. 



I. 



Carbonic acid ... . 261 



Magnesia 37-27 



Alumina 19*25 



Water 41-59 



100-72 100-00 100-00 100-59 

 Like Hermann, the author is of opinion that the carbonic acid is 

 to be regarded as belonging to a carbonate subsequently produced ; 

 and if this be deducted, the above numbers lead to the following pro- 

 portions of oxygen : — 



Hermann has assumed the proportion of oxygen to be =3 : 6 : 15. 



The average of the author's analyses is 3:5-2: 11-9, for which we 



may substitute 3: 5 : 12. According to this, volknerite may be 



regarded as MgO, Al2 03 + 4(MgO, 3H0), or as 

 Al^Qs, 3HO + 5(MgO, 2H0). 



Calculation gives for — 



MgO AP03+4(MgO, 3H0). AFO', 3H04-5(MgO, 2H0). 



Magnesia 3856 37-27 



Alumina 19-80 19-14 



Water 41-64 43-59 



But the analyses, after deducting the carbonic acid, give, — 



Steatite. — In both the places where volknerite occurs it is accom- 

 panied by a compact mineral which has usually been characterized 

 as steatite, but which has also been taken sometimes for talc, and 

 sometimes for mica. It is of a gray or greenish colour, fatty to the 

 touch, very tough, and without distinct structure. According to 

 Hermann, it has a specific gravity of 2-50, and occurs as pseudo- 

 morphs of garnet, and perhaps of epidote. Under the name of mica 

 from Snarum, the author received a mineral of a greenish colour and 

 of a laminar texture ; it furnished on analysis, — 



Oxygen. 



Silica 34-88 18-12 



Alumina 12-48 5-83 1 , ^, 



Oxide of iron .. 581 1-74/ ''^' 



Magnesia 34-02 13-37 



Water 13-68 12-16 



100-87 

 from which it would appear to be identical with steatite. 



The quantities of oxygen in the constituents of steatite from the 



