ilabke.] NORMAL ZEOLITES. 41 
may have the formula already given for this group, while stilbite and 
heulandite may contain the molecule 
/SiO^Al 
Al— Si0 4 =H 3 
\S10 4 =H 2 
I 
Ca 
I 
.Si 3 Oe=Ca 
Al— Si 3 8 =H 3 
\si 3 8 =Al 
plus 8H 2 in one species and GH 2 in the other. This formula was 
adopted in my former paper on the zeolites, and its configuration, with 
eight atoms of acid hydrogen, would indicate a complex breaking up 
upon complete dehydration. Between the two forms of expression, 
further investigation must decide. Both are in harmony with the fun- 
damental theory, so that the questions at issue are mainly questions of 
detail. 
To stilbite, morphologically, the species harmotome and phillip- 
site are closely allied. To harmotome may be assigned the formula 
Al 6 (Si0 4 ) 2 (Si 3 8 ) 4 Ba 3 .14H 2 0, which requires 
Si0 2 45.23 
A1 2 3 16. 48 
BaO 24. ',2 
H 2 13.57 
100. 00 
A little barium is commonly replaced by potassium or sodium, per- 
haps, or even probably as Al 3 (Si 3 8 ) 3 K 3 .7H 2 0, the water being loosely 
combined and therefore all crystalline. In all probability harmotome 
is a derivative by hydration of the barium feldspar, hyalophane. 
In phillipsite, which, since the investigations of Fresenius, has been 
generally recognized as the calcium equivalent of harmotome, we find 
a larger proportion of the bivalent metal replaced by potassium or 
sodium, and a more variable ratio between SiG 4 and Si 3 8 . A typical 
phillipsite approaches nearly to the formula Al 6 (Si0 4 ) 3 (Si 3 8 ) 3 Ca 2 K 2 . 
14.H 2 d, which requires 
Si0 2 48. 52 
ALA 20. 63 
CaO 7.54 
K 2 6.33 
H : 16.98 
100. 00 
