74 Improvements in Physical Sctence [Jan. 
foliated. Lustre waxy. Translucent on the edges. Easily scratched 
by the knife. Sp. gr. 2°718. Its constituents are, 
SHINER. Setutns a eset O56 6 04.0 co ance eee 
PATH Oo eo yee eres oes ones. eG 
CRTUPIGE AIO atte te eco veces «coon 
Lime with some magnesia .......-.. 3°00 
Tegee Serle oetbiequestuk Hesiststs wan ereclse 8°44 
2. Found at Broddbo. 
(1.) Emerald.—Colour varying from bluish-green to yellowish- 
green. Crystallized in regular six-sided prisms. Fracture uneven 
and splintery. Lustre resinous. Opake, or translucent only when 
in thin fragments. Hard. Scratches quartz, Sp. gr. from 2°673 
to 2°683. Its constituents are, 
Silica eeoeeweoeveeoeweveeaevpee ee eeeereeee ee 68°35 
WTamina teers cc aitel cin cies cake. a EO 
al GIRa yi svelecickal tots ve 5 phe tease td Berea ctu 
Oxide of iron “a3. isis ate oe eee wOr7e 
Oxideof, tantalum. \s50 0.0 0 ws, 98 he se 0°27 
100°07 
If we consider the metallic oxides as foreign bodies, then the 
emerald will be composed of 
Sila thea cotboc as scicteul or taveta she ete ae thie th GOA 
PATUITUNTIA a citer iats 6 o oan erakens aos costes 17°96 
Glucina eoeeeoeeveeveees oe ee @eeeoeteeeeoeese 13°40 
300°00 
Its symbol will be GS* + 2 AS*. 
(2.) Tantaliie.—Colour black, and equal. Surface often polished. 
In amorphous masses, without any tendency to crystallization. 
Fracture uneven. Lustre metallic. Fragments indeterminate. 
Opake. Scratches glass. Gives no sparks with steel, and is 
scratched by quartz. Sp. gr. in large masses 6°291; in smaller 
portions 6-208, Has no perceptible action on the magnet. Inso- 
luble in acids. Not altered before the blow-pipe per se. But with 
phosphate of soda or borax it fuses into a yellowish glass. With 
soda it gives grains of tin, especially if a little borax be added, 
According to the experiments of Berzelius, different specimens 
were composed as follows :-— 
Oxide of tantalum.... 66°66 .... 68°22 .... 66°545 
Tungstic-acid = ..¢.:... 578 .... G19 soepni@e 
OX EOE tI cto esate basa tO Ee scree, .. 8°20: eae eh eOO 
Oxidemhiron! terse LOG 65: SOB. occ OT0 
Oxide of manganese.. 10°20 .... 7°15 .... 6°600 
1°19 .... 1°500 lime 
101°30 
100°59 100°035 
