trof, Berzelius^s Letter to the Editor. iJlf? 



sent for you two specimens; the orthite of two varieties, one 

 of which perfectly resembles the gadolinite, for which we at 

 first took it, and the other, with a granular fracture, has a 

 false appearance of yttrotantalite. The new mineral has th® 

 most perfect resemblance to feldspar, from which it neverthe 

 less differs, in consequence of its great fusibility, and by the 

 property which it possesses of being very much augmented 

 in volume by the action of the blow pipe, when it is heated 

 to redness- There are two varieties, one of v^hich is white, 

 and the other greenish. The result of a hasty analysis 

 of it, which I have performed, gives the same composition 

 as triphane and spodumene, with this difference, that it con- 

 tains sodium instead of lithium. The greenish variety con- 

 tains also lime, and a little magnesia, I presume that this 

 may be the same mineral as the killinite, Cleaveland, VoL 

 Lp. 309 



Mr. Walmstedt, professor of chemistry at Upsal, has per- 

 formed a series of researches upon prehnite, of which, as it is 

 In Latin, I take the liberty to send you a copy.* 



{2.^ Fluoric Acid — Reduction of silex, giving silicium ; and 

 of zircon, giving zirconium'- — I have made a considerably ex- 

 tended research upon fluoric acid, which is nevertheless far 

 from being finished 



By way of digression, I have discovered the method of 

 reduciflg silex, so as to obtain silicium, the properties of 

 \yhich are extremely curious. The following is the method 

 of obtaining it : Take the fluate of lime and potash, heated 

 near to redness to expel the moisture. Put this salt, with 

 potassium, into a glass tube, closed at one end, and heat it by 

 means of a lamp. The potassium gives a dull sound, and 

 the silex is reduced. The (resulting) brown mass requires 

 to be washed a long time, in order to remove the undecom- 

 posed portion. We then have the silicium remaining upon 

 the filter, in the form of a brownish pov;der. When it is 

 dried, it can be made to burn by heating it red hot; but if it 

 is gently heated in a platina crucible, half covered, and if the 

 silicium takes fire, covered entirely, it contracts by little and 

 little, and becomes incombustible. Before it is thus heated, 

 the fluoric acid dissolves it with the extrication of hydro- 

 gen, ai't( r which it acts only by extracting a part of the sileK, 



* An abstract of the results of these researches is SHbjoi!aed.»— iJrf- 



Vol. IX. No, 2, 48 



