234 J. D. Dana on the Isomorphism and 
We observe that the triclinic form in each of these three cases 
of dimorphism has the highest specific gravity, and the lowest 
atomic weight, and therefore the lowest atomic volume. 
4. Anorthite, Re 8i+341 Si—Triclinic. 
==2309: P b. atoms of acid and bases, 10. ¢, atoms of elements, 37. 
3Al =: 1925-4 A. 5289°11—-2°7=1959 
3 Ca ates B. 1959--10==195-9 ©. 1959-+-37==52-95 
a. At. weight, 528911 
8. Baulite, R Si24-A1 Sie —Monoclinic. “ 
8 Si 4618-48 6. atoms of acid and bases, 10. ¢. atoms ener, 89, 
1% 641:80 A. 5760: ster 64 (sp. gr) =217 
4+Na 195: ” B. 2178: pea Pana 2178- ce 85 
3K 294-4 
a At. weight, 5750-16 
9, vente ty Si2+3A1 Si—triclinic. 
=2886 se 6. atoms of acid and bases, 11. . ae 2 meiagigs 41. 
; 2 1925-4 A. 592966—-2°787 (sp. “iF = 
220. 848: is B. 21665-11197 G secu 84 
2Na 15636 
1K 117-77 
a, At. weight, 5929°66 . 
10. Andesine, Rs Si2 + 341 Si2.—Triclinic. 
8 Si 461848 4. atoms of shee and bases, 14. c. atoms of elements, 53. 
3A 1925-40 A. 7776 ia 67 (sp. gr) ==29124 
14Na 586" rs B. 2912-4+-14—20 2912:4—-53==55°0 
1 Ca 351° 
4K 294 re 
a. At. weight, 777615 
VY ame , Rs Si2 +3Al Sie ——Monometric. 
=4618'48 4, atoms of acid and bases, 14. ¢. atoms of elements, 53. 
; Als. 1925-40 A. 8810-46—+2-486—=3343'15 
3K 176658 B. 3848+14—938-8 C. 3348--58=63°08 
a, At. weight, 8310-46 
As Andesine and Leucite have essentially the same composition 
and the compound is therefore dimorphons, we here observe again 
that the triclinic form has the highest specific gravity and lowest 
atomic weight, and asa consequence, the lowest atomic volume. 
XVII. “—_ (Li, Na)3 Sis + 441 Sit —Spodumene, (Li, Na) Bi4+-4Al Si2, 
—Andalusite, X13 $2, 
1. Petalite 
20 Bi =11546-20 4. atoms of we and bases, 27. ¢. atoms — 106. 
4 Al _ 2667-20 A. 14815°31+2-44 (sp. gr.) ==607 
st ad im B. 60718-~-27==224'96 C. 607 cet 
a 
+ a. At. weight, 14815°31 
¢ 
“ 
PEA 
