102 T. S. Hunt on Lithology. 
residue which was no longer attacked by nitric acid. The 
solution was found to contain, beside alumina and soda, a little 
potash, some lime, magnesia, and iron, and traces of manganese. 
Ihe greater part of the lime is evident! present as carbonate; 
for when a portion of the pulverized phonolite, which gave to 
nitric acid lime equal to 4°36 per cent of carbonate, was boiled 
with a solution of nitrate of ammonia, there were dissolved 3°87 
per cent of carbonate of lime, beside which there was a separa- 
tion of a considerable amount o oxyd from the decomposed 
seviagteanyg of iron. From this reaction, and from the entire ab- 
bs sek analyses, near iets the lime and the iron, as well as a 
little magnesia, are calculated as carbonates. XIII. is the result 
as free as possible from the green; and XIv. was obtained with 
two and a half grams of a mixture of the two colors. 
XIII. xIV, 
Soluble silicate, zeolite (a), by ss = AOGF 36°16 
Insoluble silicate, aeeinpat ar (6 ie eis 45°75 55°40 
Carbonate of lime, - ee, 3°63 436 
ng iron, - - - - - - 8°52 Sis 
ie magn - - - - - - 53 36 
10000 =: 10000 
In order to fix the composition of the soluble silicate, the 
larger amount of the insoluble residue and that of the separated 
silica, alumina, and alkalies, having been carefully determined, 
and the lime, magnesia, and oxyd of iron calculated as car 
nates, the water was estimated by the loss. In this way were 
obtained the results given under xia, and xtva; while the 
analyses of the insoluble silicate, which is a potash feldspar, are 
given under x11 0, and xiv 0. 
XIII a, xiva.  Natrolite. oar 
Mie sc i a Bie eee ae , 
Alumina, - - - - 24°42 24-88 2609 tite 
: - - - - - 1293 13°05 1602 14:10 
0 1-15 1°28 ooo Kent 
Water, - - 7 od - 9°54 913 9°05 $10 
eS 10000 10000 10000 10000 
: a composition, this zeolitic mineral is intermediate between 
naleime and natrolite; but the readiness with which it gelatin- 
with acids leads to the conclusion that it belongs, in great 
; least, to natrolite. The theoretical composition of these 
not tee shin peta ot se 
coaiperionr B gree — si 
