72 Improvements in Physical Science [JAN. 
Lod 
The specific gravity of this mass is 6-723, and its absolute weight 
is above 7400 lb. itis coated with a crust of oxide of variable 
thickness. ‘The fresh fracture is tin-white, and has completely the 
metallic lustre. ‘The fracture is fine granular, uneven, often scaly, 
and sometimes approaching small foliated. It is attracted by the 
magnet, and is itself possessed of magnetic properties. From the 
analysis of Monheim, its constituents appear to be, 
Fronts se. ebadeinndish . 500°5 .... 83°42 
ATSEMICR ttle oiieteieuaiohere OOO wae WSO 
Silicon eistershees. ahd... Ae wien Off 
Ganbonenelys sscislodecons ave BOs. wit) O25 
POLIT oo 0,5 0/0 ai'a.s ore aieyaye Det) tay cc ahes ed Oneves 
600°0 100°00 
9. I have now to state the numerous analyses that have been in- 
serted by Berzelius and Hisinger in the fourth volume of the 
Afhandlingar i Fisik Kemi och Mineralogi, published at Stockholm 
in 1815. 
1. Eaamination of some Minerals found in the Vicinity of 
Fahlun, by John Gottlieb Gahn and Jacob Berzelius. 
1, Found at Finbo. 
(1.) Yéérocerite.—This appears to be a compound of fluate of 
lime, fluate of cerium, and fluate of yttria. Its colour is various, 
violet, greyish-red, white, grey, often all mixed in the same speci- 
men. In amorphous masses, varying in size from a thin crust to 
half a pound in weight, disseminated through quartz. Fracture 
foliated. Lustre glistening. Opake. Scratched by the knife and 
by quartz. Scratches fluor spar. Sp. gr. 3°447. 
Before the blow-pipe it loses its colour, and becomes white ; but 
does not fuse of itself; but when mixed with gypsum readily melts 
intoa bead. When in fine powder, it dissolves completely in boiling 
muriatic acid, and the solution has a yellow colour. Its consti- 
tuents are, 
WIE pas satsioce, cuss eine eiadaveyicile 47°63 to 50°00 
WEE rie ltrs rc pe ek Ealapemnsy 911 to 8:10 
Oxide OffcexiUM: sees cueieeser 18°22 to 16°45 
PI NORICACIO i iu ees cee) antigen 25°05 to 25°45 
100°01 100°00 
Or FPluate'of lime On Pn) 08 & 65°162 to 68°18 
Fluate of yttria .......... 11°612 to 10°60 
Fluate of cerium ........ 23°226 to 20°22 
—— 
100°000 99°00 
(2.) Tin-stone.—Crystals of tin-stone are found imbedded in 
quartz. They are black, with a shade of red or reddish-grey. 
Sometimes crystallized in octahedrons, but most frequently in small 
grains. Fracture uneven, Lustre metallic. Opake. Hard. 
Scratches glass. Sp. gr. 6°55. Not altered before the blow-pipe 
per se. Its constituents are, 
