76 Improvements in Physical Science [JAan; 
Alumina. Silica. Fluoric Acid. Total, 
Brazilian topaz..... 8°38 i096 wie OM OL ioolge) 119 «+ ALOIS 
Saxon topaz .. sess STAB iss cayronrg, OATS evel. (Gos ae aad 
Pyrophysalite ...... BTTA oo ey BUSG YS scltel PTE eet. 99ST 
From these analyses it is ebvious that these minerals belong to 
one and thesame species. If we suppose the topaz composed thus, 
A? Fl + 3 AS, then its constituents will be 
PAININTUARIE? TS Ata iis ove cieie cit orpiobeious ole 6 via a 58°55 
Si ee Sia clo ante aye uetoneee Rrcectis: iescXe 34°27 
Bluorie acid |... eee eae CAE, ees 7°18 
100°00 
Schorlous beryl, stangenstein, or pycnite (for it is known by all 
these names) was found composed of 
AVomina’,. ... sa. siege ha reieia age se Ol OO 
ROTC Es eae ssa ist cs eatbte hy Beers See eyes 13 
Fluoric acid ........ aa ratayaes 8°84 
98°27 
If we consider it as composed of A Fl + 3 AS, then its con- 
stituents will be 
Alumina beeccsrvoe ee eorevar @evooeceseves 53°07 - 
SIGH ccussaceant et ctoreisiansie Seer cise is aan ak OU 
ESTO ET CAC LGletred be taike tote win ec eiae, tte a ys tele asta 8°13 
100°00 
1V. Experimenis todeiermine the Composition of the Minerals at 
present known to contain Tantalum. By J. Berzelius. 
(1.) Tantalite from Finland.—Berzelius analyzed some specimens 
of the original tantalite from Finland, examined long ago by Eke- 
berg, which he received from Dr. Macmichael. A piece of the 
mineral labelled by Ekeberg as of the sp. gr. 7°286, yielded the 
following constituents :— 
Oxide of tantalum... Jo. .< StL ail 2 83° 
Piotoxidey Oh drOn: y2'.\cw s<'6 oes Sale Cee 72 
Protoxide of manganese............4. 74 
MPSS Ete ais) vag. Oey, SP yy oe ce 0°G 
Hence its symbol is mg Ta + f Ta. 98°4 
(2.) Yttrotantalite from Yiterlby.—This mineral was first exa- 
mined by Ekeberg, who ascertained the aature of its constituents ; 
but it has neither been accurately analyzed nor described. ‘There 
are three varieties of it, which Berzelius describes and examines 
separately, 
A. Black Yttrotantalite.—It occurs in a rock composed of red 
felspar aad mica, together with gadolinite, in masses never larger 
than a hazel nut, and which sometimes exhibit traces of erystalliza- 
tion. Colour black. Fracture foliated. Lustre strongly glistening, 
metallic. Fragments indeterminate. Easily frangible. Gives a 
grey powder. Opake. Hard. Scratches glass. Sp. gr. 5895, 
