136 On the Chemical Composition of Wernerite, 
suda, to be continuously exposed to the influence of a liquid 
containing carbonate of potash, some probability attaches to 
the assumption that, by a mutual decomposition, soda would 
pass into solution as carbonate, while potash would enter 
into the composition of the mineral as silicate. 
There are a number of other phenomena of pseudomor- 
phism which indicate a substitution of potash for soda. For 
instance, pseudomorphous mica in the form of nephelin. The 
latter mineral contains 15 or L6 per cent. of soda, and only 
5 or 6 per cent. of potash ; so that, under the circumstances 
assumed for the transmutation of Wernerite, soda must be 
abstracted, and potash introduced, for there is seldom less 
than 8 per cent. of potash in mica. Unfortunately, however, 
the mica, in the form of nephelin, has never been analysed. 
The above-mentioned pseudomorphous mica occurs in beds 
of magnetite, associated with gneiss, at Arendal. If we sup- 
pose that meteoric water, penetrating through the gneiss and 
magnetite beds, takes up, by means of its carbonic acid, both 
alkalies and protoxide of iron, the potash preponderating 
as much over the soda in the solution as it does in the gneiss, 
the conditions favourable for the conversion of scapolite into 
mica by the process described would exist. 
It appears, however, that all investigation of these and 
analogous phenomena must be limited to ascertaining pro- 
cesses by which it is possible that the observed changes may 
have been effected. 
2. Yellow Scapolite, from Bolton, Massachusetts. 
The physical character of this mineral afforded unmistake- 
able indications of alteration. Density, 2°787; colour, pale 
yellow. Carbonate of lime was not visible to the eye. Ana- 
lysis gave— 
I IT. III. 
ing sil scion aul toaxti eile 49:99 
Alumina, , 23°41 23:01 
Peroxide of iron, } ri 1:64 1:64 
Lime, . 3°74 2°95 8°85 
Magnesia, . 1:00 1:66 1:73 
Potash, : o% 7:06 7:09 
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