FORMATION OF LEUCITE IN IGNEOUS ROCKS 279 
pointed out that all the relations observable on Plates I and II, 
where the curves resolve themselves into straight lines, are fully mani- 
fest on a diagram plotted on this basis, though not so readily intelli- 
gible, owing to the distortion introduced. 
APPENDIX I 
Loct oF Lrucitic AREAS OF VARIOUS MAGMAS 
No. Character of Magma O L N 
: 1.079 O17 . 704 SiO, 
I....| Peralkalic persalane a4 229 es K,O 
2....| Domalkalic persalane ; ee = ae eG 
3....| Alkalicalcic persalane eee 3 athe one 
Peralkalic dosalane, with diop- I.025 904 -744 SiO, 
a side -135 172 . 000 K,0 
Domalkalic dosalane, with diop- .986 877 . 746 SiO, 
oye side iE LO 142 .000 K.O 
Ga Peralkalic salfemane, with diop- .O71 890 . 783 SiOz 
i side .09O 115 . 000 K,O0 
: ° Ae (2055 833 673 SiO 
7....| Peralkalic dosalane, with olivine } 1116 142 ie SO 
8 Domalkalic dosalane, with oliv- .916 807 .676 SiO, 
en ine 2 /I16 142 .000 K@ 
Peralkalic salfemane, with oliv- 830 749 -643 SiO. 
Cece ine .09O IIS . 000 KO 
Peralkalic dosalane, with mag- . 809 688 528 SiO, 
Io. : 5 
netite Bias W772 000 K,0 
ne Domalkalic dosalane, with mag- | { .771 662 SS SiO, 
ae netite rare) 142 .000 KO 
Peralkalic salfemane, with mag- -540 -459 EsGe2 SiO, 
12 5 gee : : 
netite ereje) LS . 000 KO 
[To be continued] 
