384 Analyses of Phlogopite. 
No. 2, was a. paeeverent and colorless crystal of a silvery lus- 
we; an 
No. 3, was a. part of the same aryl rendered quite opaque 
and silvery by the absorption of w The crystal which fur- 
nished Nos. 2 and 3 was ie 6 by 8 inches in surface 
dimensions. 
No. 1, gave reactions for silica, alumina, magnesia, potash and 
fluorine, with small quantities of peroxyd of iron and soda, and 
a 8 doubtful trace of lithia. 
Nos. 2 and 3 gave silica, oe magnesia, potash and ee 
- with traces of water and fluorin 
_ The following are the results of analysis : sae 
No. 1. No. 2. No. 3. 
Pets. a 40145 40°358 4036 
.. with a little 2. oS LF8BB- >. 16°450 16084 
Mg 28099 29°554 30247 
; 10-564 7-226 6:066 
Na i 0°63 4:938 4:39 
Fl 4202 loss byign. 0-952 265 
FS 100-996 99'478 Bee i eee 
« Oxygen Ratios. ae 
ie No. 1 No. 2 No. 3. 
Si 20°86 20°97 20:97 
Al 1 16 
Mg. lites." 11°61 11°89 
Kk 1-79 12:99 1:28 1411 1:03 14:05 
Na 016 1:27 4 
The ratios are respectively 16:23366; 183252 2735 
1:87: 1:2-78; the mean of these is 1: 17:1: 269, which 
equals very nearly 7: 4: 11, and corresponds with the "formula 
TR* §it441 8i, The equality between the oxygen of the silica and 
that of the bases will be observed; and if &* and 41 may replace 
one another, the formula becomes (Re, Ay) Si, acommon type among 
the silicates. 
per-centage corresponding to this formula is as oo 
online the fluorine, which is not found in analyses 2 an 
Si Al Mg K 
41°60 16°82 3001 11°57=100-00 
In No. 1, the 41 contains a small proportion of ¥e, which in-— 
creases the amount of oxygen from the peroxyds so as to make 
the ape he, silica appear smaller in proportion than they 
really are, and the determination of the silica is also, probably, 
too low 
somewhat 
Mage ’s Hise ysis affords the ratio 13:13 : 7-70: 21 AG ; = 
lals 1-7: 
1: 2:78, and corresponds quite closely with the 
ch eqt 
peg 7:4 sie the same which is afforded Mes. the analyses above. _ 
= 2. 
TE 
