PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 107 
Hullite. 
On the average, taking the ferrous oxide as in Mr HArpDMAN’s analysis— 
Atoms. 
Silica, 2 xo og" be3 #89, 8 Soe t 39° 67 
Alumina, . 13s coe 3 3 aay a 0s 
Ferric Oxide, . 18°35 “23 ~~ 938" — lar22 
Ferrous Oxide, . 3°7 mos g° 55 Soe 
Lime, : » 4°48 -16 \ 4:04 4 4°04 Aviles 
Magnesia, . . 8° 06 "403 8°72 8°92 
Water, .. patos ja 9°09 9 1$°a 13°40 
Formula— 
(Fe Ca Mg)* (Al, Fe,")*Si8 + 9H,,. 
Or generally— 
ht, i201: Ho. 
The Kinkell specimen gives the formula— 
(Fe Ca Mg)‘ (Al,? Fe,)*Sis + 9H, 
and the numbers in last column. These agree better with the results of 
that analysis than do those of the first formula with the average of both 
analyses. 
Saponite. 
Atoms. 
Silica, ‘ . 40°63 eso tea Soay 7 I 7 40°81 
Alumina, . dey gels) *14 i Siete 1 (nl 
Ferric Oxide, . 3°96 =05 3°88 
Ferrous Oxide, . 2°38 * 066 2° 62 
Lime, 2 >) 2s ‘70 b-33 G5 G25 204 
Magnesia, . ge2le4s 07 20°61 
Water, F speed 0G eae, 2 Ags LOD. 18 2273 
Formua— 
(Fe Ca Mg)* Si? + (Al? Fe.) Si + 13H,. 
VOL, XXIX. PART I. 245 
