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Bp 
Scheerer on: Isomorphism. 57 
Arr. VI—Upon a peculiar kind of Isomorphism that plays 
an important part in oe Mineral Kingdom; by Professor 
Scueerer of Christiania 
(Continued from vol. v, p. 389.) 
THe query might be started, how it is then, since aspasiolite 
and cordierite are so closely associated, that ee is not ac- 
companied by olivine? ‘This circumstance, which, it must be 
confessed, dloes appear paradoxical, [ purpose to enter upon to- 
wae the close of this paper. 
n the theory based on the above mentioned relations of 
cordierite and aspasiolite, being thus borne out by the precisely 
similar relations subsisting between olivine and serpentine, 1 the 
probability was increased, that the part played by this species of 
isomorphism in the mineral kingdom was not one restrained within 
very narrow limits. And this opinion has taken a development 
more extended than I even imagined it might be susceptible of, 
as my investigations have been carried out. In the sequel I pur- 
pose touching upon the principal rishérals concerned in this in- 
quiry, and to develope their suitable formule, upon the supposi- 
tion that their water may be treated as a basic constituent, capa- 
ble of replacing in the ratio that has been stated, (viz. three at- 
oms to one atom,) the magnesia, and consequently all the other 
pes isomorphous therewith, as for instance, protoxyd of iron, /pro- 
toxyd of manganese, and so ’ forth. 
In order to express as simply as ee that in a member of a 
formula R, a portion of the 1: 1 atomic bases is replaced by 
more or less water, I have in these cases invariably made use of 
the sign (R), as was already the with regard to serpentine, 
The formula of aspasiolite ould: thetefore: upon this principle, 
be (R): Si? + 3RSi. Prior to proceeding to the results of my 
calculations, let me however very briefly further elucidate the 
kind of isomorphism forming the subject of our palpi esti. in 
a chemical point of view. From the composition of aspasiolite 
and of ow i follows that in the former, one equivalent R 
(one-third of the re 1: 1 atomic bases contained in cordierite ) 
is not replaced ay eibec exactly. It is likewise clear that, as in 
serpentine the amount of water ranges between 12, 27 a 1 d 21 
“Pine Pogasedira abhi ihsh. peewee 
MW. G. Lerrion. te a ER 
Szconp Srrizs, Vol. VI, No. 16,.—July, 1848. 8 
