284 Analysis of some Scottish Zeolites. 



On comparing this analysis with those of the mineral al- 

 ready published, it will be found to approximate very closely 

 to the most of them, and to agree with the calculated com- 

 positionof the foregoing formula. 



Silicic acid, 2 atoms, = 92444 = 47'90 



Alumina, 1 „ = 51-344 = 26*60 



Soda, 1 I L 31-178 = 16- 



Water, 2 „ =18- = 922 



Laumonite. — An analysis of Laumonite from Snizort in 

 Skye has been already published by Connel ; but that which 

 I have examined is from Storr, in which locality it occurs in 

 the form of a vein of from two to four inches in thickness 

 traversing the trap-rock. It is associated with stilbite, and 

 sometimes lies in immediate contact with it, having been 

 supposed to be hypostilbite by some persons. Analysis, how- 

 ever, proved it to be laumonite, with the characters of which 

 mineral it also agrees. ft 6f j ^ n 



soft 1o gtfin no bei'ioqarmiJ eiew aiebluod edi i&dt evsilsu 



10. a'i910fil§ t- HD ^8M 9£li By Connel. °- dw 98 ° rfj ^ 



Silicic acid, 53-048 52*04 : hml tWld 



Alumina, 22*943 2114 i7/ * g9ion ' 



edi • Lime, 9*676 -10' (SB R <t bn& find- 



Water, 14*639 14*92 He von -io xfilnti 



orlq otlt w od woda oS a 



100-306 98^5%>mo3 * 



My analysis varies but slightly from that of Connel, the 

 amount of silica and alumina being greater in mine. It may 

 be remarked, however, that in his analysis there is a defi- 

 ciency of about one-and-a-half per cent. 



The formula which agrees best with the analysis of lau- 

 monite is that given by Gerhardt, although at the same time 

 it must be admitted, that it is far from being satisfactory. 



3 Ca O 2 Si 3 + 3 (Al 2 (X 2 Si 0.) + 12 HO, 



its calculated constitution being, Silicic acid, 51*53 ; alumina, 

 21-49; lime, 11-92; water, 1506; = 100. 



