278 Scientific Intelligence. 
The measurements of the crystals given by Hartwall and Dana, with 
the figure by the latter,* are next cited, and a comparison made with 
only, made by means of the common goniom eter, and some 
faces were quite uneven. The ihisning comparison is made. 
Augi ene 
M:M= 87° 06' N:N= 8? 
M:r 133 33 N:M _— 118 to 133° 30’ 
i) as 136 27 N:1 137 to 136 30 
ee2 90 00 M:1 $0 ; 
rid 74 01 P:M 69 40 
Ste 120 38 a:a 117 
o:r 103 20 a:M 100. 30 
S22 80 28 1? :t? 79 30 
2il 139 56 t2:1 139 45 to 140° 
0:0 95 36 a? :a? 
o:r 118 24 a2:M - 116 
The plane b®? has not been observed in augite. Its nae to M 
: ae, 
was ascertained to be 107°. It must therefore be the plane a ; 
other planes will have for the axes a, b, c, ie and 6 being the a and 
¢ the vertical) :—N (M Augite) =a: b: cee M(r)=a: ab he 
wa:b:ac; P(t) aa:ab:c; a a(s) =a’: b:e; 7 ()=¢ 
a? (0) =a':b:2c; b8=a:4b: ae. 
The isomorphism of spodumene and augite is an example of a simi 
larity of form hi unlike constitution. Still naive is rte analogy be 
for Piny 318) 
ber of atoms of elements in the compound. The atomic ss 
diopside (lime- -magnesia ae. is 2043" 74, the specific gravity yi 
ence the atomic volum 23. The number of atoms of eleml 
in Ga’ Sit Mg? Si2 is 28, and therefore 623+-28=22.+ In sa 
the number of atoms is 66; r if alumina contains 1 of aluminium i 
stead of 2, it is 62; dividin ng 2840, by these numbers we have auc 
etalite. i de —_ of petalite afforded Rammelsberg as t 
mean of his resul . 
7 > 30 ris 
9 18:58 33 
Oxygen, 40°42 8°67 1°91 1. 
Affording the ratio 2:11 : 8:67 : 40°42—0'95 : 3:86: 18=1: ne "The 
1:4: 18 gives of Sis+-<A1Sie; and 1:4: 20 gives Ro Bis +4BiSit. of 
former a abe percentage, Silica 76: 43, alumina = ise ange 
ise. — oe x, 7 264, and Dana’s a 3d edit, p. 693. . 
way as 
— formal is cued Sor Te oth fey, hon the number yt ata 
poe — the next se: atina ibis ve made 2 *°% 
