yt onl _— — 
i 
a MR ii 
Scheerer on Isomorphism. i90. 
Now though there may be somewhat of a probability that some 
the zeolites contain basic water, yet it nevertheless seems char- 
detente of the zeolites in general, that the water which they 
contain is true water of crystallization. 
2. Remarks upon certain Pseudomorphs. 
Not an inconsiderable number of minerals of the most various 
chemical and crystallo raphic character, such as spinel, garnet, 
augite, feldspar, tourmaline, mica, and so forth, are, as is known, 
met with converted to all.appeararice into a substance which, ac- 
cording to the external characters that it presents, is termed either 
steatite or serpentine. e.are not however by any means well 
informed with respect to their precise chemical nature. 
Had ments tg wee resembles serpentine very 
closely, curately examined by me, nothing would have 
been more RE than holding those crystals, sonata as they 
do partly of vrei and partly of” aspasiolite, for crystals of 
cordierite, partia ¢ serpentine, » by which the number 
pee those peculiar eae s wotld have been still farther in- 
ased. _it is Moreover established that the crystals of 
wagon met with ee pets no noeMtiaes che: of 
precisely analo 
a tion 
the instance of some other serpentine and steatitic 
etto held to be mm | farther’ investi t i a it 
us results. spinel, garnét, augite, 
of the 1; 1 atomic s may easily occur reulaca 
by water, and without a change in the form TF its respective 
crystal beihg sagt = a ge be formed in its nature approach- 
ing serpentine or Steatite. Thus, for instance, spadaite and 
mieerschaum, two minerals allied to- serpentine and steatite, have 
the formnla of augite, With the difference only that a portion of 
their bases is replacetl by water, in’ like manner onkosin has the 
formula of labradorite, pinguite that 3 garnet, pyrargillite that 
of fahlunite,—not to cde ant 
ne: is, not any ways = to den iat true pseudomorphs are 
et with wherein the magn s an essential part. It isa 
tone established fact that Swan Nigaihorthones are of very fre- 
quent occurrence where water impregnated with carbonic acid 
has exercised a long continued a¢tion upon masses of rock from 
which, in consequence of its solvent properties, it has withdrawn 
certain constituents. This water, thus charged with carbonic 
acid and likewise with other substances, appears however in cer- 
tain cases in its progress downwards, to deposit some of these sul 
stances again, or rather to exchange them for others more easily 
soluble in water containing carbonic , and by this means to 
give rise to the formation of a particular kind of pseudomorph. 
Carbonic acid water containing carbonate of magnesia in solution, 
