, 1876-04-03

Cu1cAao, March 30.-Two OF your correspond
ents have lAtoly taken opposite vieWa on ths
question Of tho origin Of Eraaita.-ons Of them
making it an aqueous rock, tho other seeming to
uelIne toward tue igueouB origin Of It, In splto
OF tho s&asomens1 md sometimes naisstatoncnt
Of fact BY tho former, aud textbooks quotations
by the latter, 1t occurs to mo that they have both
failed TO soIvo tho question. That Ia what
prompts mo to aak you for nome Bpnco In your
paper 10 contribute my mite II poeaib1e, for dls.
polling tho cloud that still orerhanGs tho
probleu.
Three different theories have besu propound-
cd IN order to oeoount for tho mode OF formation
Of tho granite rocks (grauise, syenite, gne,ss,
cte.), namely;
First-Tle Wernetlan thoory, by which those
rocks vero opoo Ia Tho state Of solution. some-
what like tho salt In the sea~water. aud wsre de-
poaIted by capitalization, the Bsms aa rock
candy from cane-suRAr slrup. II you Will boar
in mind tho feet that, tho more We learn about
chomissET, the less NO find liquid capable ot
dissolging quartz. fsldspsr. sud mlca aud letting
then separate by crystalllzaston, you will easily
understand Why that theory hAs fallen Into conn
pleto oblivion,
second-1he 1Iuttonian theory regarding tho
gtan,to rockH Is, that they Weto ojectod from tho
lhteroF OF t1o eAl VI Ii = ue'tbA couualon. Al
1t has rp!gne1 supreme fof many years, It nov or
wAs accepted by oil tho scion fists, aud quite
number Of those goologlsta haat oonvarssnt with
chelniat.y stwAYa opposed 1t. Fuchs, and
1aac4o1. and y: hoso. IN Germany; Dnnhroo
70 awaken doubts about shs validity OF that
theory. Their principal objeottous against tl,o
.gneona origta of granite and the Like rocks may
be briefly stated as foloWe.
i. 1t IL GENERALLY fe'dspsE, q fustbls element
that Ia tnctllsted in tbs quartz an Alost refrao-
Ton element therefore the follapAr orYslallxnd
ltat. which cannot be accounted tor On ths hy-
pothosis that tho capitalization took place by
Z, Quartz found in geanites and In ysias con-
tslns often different volatile psnolplea uach ~
wster aud bitutpinous subatsnoo, or minerals
which cannot stand tue action Of heat thydrnte
Of forrio oxyle, carbonate Of iron, etc.,.
q. MioA ia found In lava - vol as IN granite
Thoro is, however, "a essential difference be-
tween the two. Tho mica from Krantte contains
| water and huorine, which It losos By oalelnA-
tlon,-shus turning opaque; Whilst thet from
iays In fIss from ths two ii1st.uamed Substances.
i. Mica IA what chemist would call = baslo
siicato. It ia inposaibla to understand Its for
nation, BY fusion. In tbs midst OF AZ immense
&. II ersnits bo uoltod. ths fesdapss, the mica,
md patt Of tho quarts laulsy, ths remainder
| Of thp latter toSuls opAlu0 esatns ind keruels
| amnnR tho khtsy naAee After boltdlncalon.
that granite tesomh!es obadian OF volcanic gass
| and neyef assumes again ltu former sl!stalllns
| structure.
d spocIaa grsyltJ OF 40, ~ tAas obthusd ast-
fcially BY sho W. proeess. II aubjec!od to
fusIon, Of evsn aimply to very high sempera-
tlre, IL becomes auosphous, with speoiao
gravity OF "a only tuss like tho sgaeous QUARTZ
! utc., etc. ..,
The many experiments paFformed and pa.
tiently repeated for many ysass show that hos
vate1. under pressure, haa tbs ,poHos Of dls-
solving chemicals which otherW1sa we lneola-
aud ct tlsnsto1ulng pu!1erulent or amosphous
hubatsuoo& inLo more or teas large 0Eyatslss 20
that quite nu1nbsr OF srtaoial tainerals,
identical Ia form and composition With those