230 J. D. Dana on the Isomorphism and 
XI. Monazite, Chromate of Lead. 
er tao 
1. Monazite. ze , 
18 — 8923 5. atoms of acid and bases, 4. ¢. atoms of elements, 1 
2Ce 13500 A. 30862—5 (sp. oF) oA 25: ee 
1Th 8439 B, 617-25—4~—154:3 O. 617-2 SH 12—6: 
a, At. weight, 3086-2 ae at. wt. of Cerium, gives for 0, 52 i 
1Gr — 6284 4. uli of acid and base, 2. ¢. atoms of i ate, 6. 
1Pb = 13945 A. 2022:9—6:06 (sp. gr.) =333'8 
a, At. weights, 20229 B. 333:8—2—~1669 C. 333°8—6=55'6 
There is some uncertainty as to Monazite, as the exact iit of its bases are 
not ly kno 
XIL Beryl, Nepheline. 
1. Beryl— ah the old sidhis weight :— 
mars . 6. atoms « acid ne bases, 11. ¢. atoms of elements, 47. 
: Be A. 68646—2°732 (sp. & a mes a7 
2 Al os = B. 25127—11=228-4 51274 7=53'46 
a. At. Pi 6864-60 Awdejew’s atomic weight gives for C, 46°44. 
2. Nephelin 
8 re =1731:93 6, atoms . ge and bases, 7. c¢, atoms oh elements, 26. 
2 Al 12836 830°32—2'6 (sp. et) =147 
18Na 71665 B. 1473: Pewuatvs 1473: 2 ile 66 
kK = 9814 
a. At. weight, 383032 
XIII. Pyroxene, R2 Si2—Acmite, Na Si+#e Si2—Hornblende, R4 Sis 
Acmite, as is well known, has the crystalline form of Pyroxene, although different 
1. Pyroxene. As above deduced, A=638'77—706 ; B=12755-141'2 ; C==-46'1-48°9 
2. Acmite, 
3 Si= 1781-93 8. atoms of acid and bases, 5. c. atoms =f elements, 19. 
1¥e 1000-00 A. 3122:83—3°4 (sp. - =918 
1 Na 390°9 =B. 918:5+5—=183-7 918 secrete 34 
a. At. weight, 3122°83 
3. Hornblende. 
3 Si= 1781-93 6. atoms of acid and bases, 7. ¢. atoms of elements, 20- 
8Mg 1635 A. 2846-92—2°93 (sp. =) = =971- 
10a = 351-49 -B, 971-6+7==1383 971: eames 
a, At. weight, 2846-92 
4. Hornblende, aluminous varieti 
a. Var. From Wolfsberg in Sith, analysed by Gischen—The analysis corres: 
ponds to the ratio 2414-14 ¥e+7 Sip4 Ca+5 Mg. We attempt no formula. 
7 $i=4041-17 6. atoms of bases and acids, 20, ¢, atoms of elements, 66. 
24 Al 16045 A. 9824:13—3°15 (sp. gr.) =311 
14 ¥e 15000 B, 3119--20=155-95 ©. 3119+66=-4725 
4 Ca 1405-96 
5 Mg 12725 If sp. gr. =3'167, then C=470 
a, At. weight, 9824°13 
