408 Scientific Proceedings, Royal Dublin Society. 
taken as an indication of the general order with respect to the 
basicity of the minerals concerned, it follows that Rosenbusch’s 
order of crystallization is at once explained for deep-seated rocks. 
From an examination of the accompanying table,! it will be seen 
that the same relative positions could be established for the basic 
felspar oligoclase and the acid orthoclase. 
bes Density. | Biderenge | feng Festiity| yp. |psuecs 
Name. 7 sent itee 
Crystal. | Glass. ae) | °C. | Kobell). | 225 | Saag 
Pi- | Po- iF 
Quartz, .| 2-663 |2-228(D.)| 0-0733 |) 1425 | 7-00 | 204 | 8 
Orthoclase, . | 2-574 |2°328(R.)| 0-0411 || 1175 | 5-00 | 235 | 7 
Albite, _| 9-604 |2-041(R.)| 0-1059 || 1175 | 4-00 | 294 | 6 
Labradorite, . 2-689 | 2°525(D.)}| 0-0241 1229 | 3-00 410 2 
Oligoclase, .| 2°66 | 2°258(R.)| 0-0669 1220 | 3°50 349 5 
(Max.) 
Anorthite, . 2°75 —_— — — 5°00 = = 
Sodalite, A OMIA — — 1130 3°19 301 6 
Epidote, .| 3-409 |2-984(R.)| 0-0418 || 965 | 3:25 | 297 | 6 
Hornblende, . 3-216 | 2°826(D.)} 0-0428 
Augite, _| 3-267 | 2-804 (D.)| 0-0505 
— 
— 
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at 
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(JN) 
Ne) 
“I 
iJ) 
W ollastonite, 2°85 — ao 
iy 
bho 
oOo 
Or 
On 
o 
Oo 
bo 
nes 
ol 
sl 
Spodumen, - | 3-183 | 2°429(R.)| 0-0925 
Olivine, . | 3°381 |32°857(D.)| 0-0543 
Garnet 
(Almandine), 3°784 | 3:052(Th.)) 0-0624 
Cyanite, : 3°62 = | —_ 1090 | 7°00 156 9 
1030 | 3-00 343 
| 
Ov 
In the seventh column I have divided melting-point by 
Von Kobell’s scale-number, but, of course, do not pretend 
that the numbers obtained indicate even a general relative position, 
Vesuvianite, 3°40 | 2°937(Ch.)} 0-0464 
1 Compiled from Roth’s Allgemeine u. Chemische Geologie, B. 11., p. 52, and Dana’s 
Mineralogy. Capital letters in the third column refer to the original observers :— 
D.) = Ch. Ste.-Claire Deville; (R.) = Rammelsberg; (Th.) = Thoulet; (Ch.) 
= Church. 
