1817.) during the Year 1816." * aa 
Before the blow-pipe it decrepitates feebly, becomes dark brown, 
but does not fuse. It dissolves slowly in phosphate of soda, forming 
a safron-coloured glass. In borax it dissolves with more facility. It 
is insoluble in acids. Its constituents were, 
RX IG CsOUSTAIA EHIME 26 soso esas cie'd ce sacs OU 
PON gSIG Hea! Vsisiy Mites s.6tian ss wens 8°25 
Vttria VV ek oretetats'e'e Pr atetetets oe tls a emtted 20'25 
Lime eee. treet 1, TSO Ot GT. 6°25 
Peroxide*of tron: 2 C2322 BS 28 QE 3°50 
Peroxide of uranium: .... 2.0. ee ee ee 0°50 
95°75 
B. Yellow Yitrotantalite.—Colour yellowish brown, frequently 
with greenish streaks and lines. It usually forms a crust upon 
felspar ; but sometimes occurs in grains, never exceeding the size 
of a peppercorn. Fracture foliated. Lustre of the cross fracture 
Vitreous, of the principal fracture resinous. Opake. Gives a white 
powder. It scarcely scratches glass. Sp. gr. according to Ekeberg 
5°882. Before the blow-pipe it decrepitates feebly ; but does not 
melt ; and the colour becomes light straw-yellow. Analyzed in 
different ways, it gave the following constituents.:— 
Oxide of tantalum........... 60°124 .... 59°50 
PY DED IAS otsici eens esis) Weebaiwe ates « 29°780'.. .. 24°90 
IMME SELON G cae eins st O00" rece OCeo 
Oxide of uranium........ ei IGOee oa) §S125 
Oxide of iron........ eed cee > sk 1G SNUG. £279 
Tungstic acid and tin...... oe O44 Vy. 1°25 
99°225 94°89 
C. Dark Yitrotantalite.—Colour black, with a slight shade of 
brown. Found in the same state as the preceding variety. Fracture 
in one direction glassy ; in another fine granular. Lustre between 
vitreous and resinous. ‘Tyanslucent when very thin. Gives a white 
powder. Hardness the same as that of the preceding variety. Sp. 
gr. not determined. Does not melt before the blow-pipe, but de- 
crepitates feebly. Its constituents were found to be, 
Oxidelof tanta any oo... sis sin tote whee es. 51°815 
Weer or is a ane. Yo obh 88°515 
WAG i ioieiehe estcdidecicen se Oe TOBE 3°260 
Oxide’of uranium -)..... iaywa a off loa! 
Tungstic acid holding tin ......4... 2°592 
RU EL dscns’ o\ vs). sipieae Seva .» 0°555 
97°848 
In Berzelius’s opinion, black yttrotantalite is Y* Ta mixed with 
(Ta and with F W*.* The yellow variety is Y°'Ta mixed with a 
small portion of C* fa and U* Ta with a trace of wolfram. The 
* W is Berzelius’s symbol for tungsten, 
