New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1864-06-30
sCIFNCE AND ART.
;o., acknowledgements Associa-

was the presiding officer for the evening.
COLORADO GOLD OFFS.
Communication was read from Mr. Henry Gar
,,.1 member Of the Institute now residing at Con-
.,, civ Colorado Territory. Accompanying the let
a., were twelve interesting mineral specimens.
NJ p. STEVENS remarked that the particular TO-
.u,v from which these specimens were taken Is rot
tsted They are portion Of tho gold bearing ores OF
C,o-ado The ores of this territory differ rom those
NJ California inasmuch these pyTilous ores thai
q, ores formed by TIE mixture Of sulphur el'her che
caly or mechanically with copper, iron and gold Inc
nrss Of California are native gold IN Nclns OF quartz
The first specimen now presented Is pyi1tes without
any cold in sight although the ore is OF yellow color
spc might be mistaken FOR the precious metal. Ie
next specimen is cryttsIcd 4usr'P ha'np p. III
iosed In the quartz Slowing that the gold WIS formed
S. aud was aftergard enyelOped by quartz Some Of
,SoSs crystals nre very beautiful Another specimen Is
that is known porous quartz or quartz IN when the
ovrtes las been decomposcd. and has disappeared
cayng behind the gold that was IN combination with
r. Sometimes the gold in this variety % ore Is visible
so the naked eve, and sometimes 1t exists as thin m
.a;nin, the surface which can only be seen with n
msgnifying glass. This variety, when IN Sufficient
sbndapce is very profitable to work. because part OF
the process that Is the decomposition OF the pyrtes
,;styandit may be remarked tere that the twelve
snecimens shown ali included IN three yaIleiles-s
onortz ore having pyrtcs and petition Of toe wD rock
NJ the vein attached There were, undoubtedly many
IN the audience who had never seen queitz VEIN III
thew have anv curiosity IN this direction they can be
gratifed without Leaving Manhattan Island. In the
deep cut on Frstavenue which is now being Graded at
about FOry-secOnd street may be seen tie gnciss rock
cut BY vein Of qNaItz about foot wide descending ct
An angle o. about 10y lie pnrc quartz - ATTACHED 10
the walls Of gneiss side; approaching the CEN
Ger are crystals OF MICA std nearer tie ccncs are
rarne,s hornblende elspaI. In some instances the
caner left cpCn in Others IL Is closed showing mat
ts specialization proceeded iron H., walls orard ne cen
sr il hc.sg understood that this deposit As W.e III "a
yenfn the gneSs. To return TO the COLORADO specl-
neM some were evidently formed IN the same WAY.
The veins Of the Colorado resemble the veins Of the Al
apo slope The same Kind of Tyrtes veins are iOGnG
IN the gold bearing ROCKS Of tie Apalachiau range.
A few words may he added regarding the economy OF
mining or winning god Ito question 10 u sO.Ted 10,
how shall separate tie gold nom IL non. copper
sulphur and quariSt ne sulphur ma! DC 9lleh on 70
q certain extent by heat that element being volatile
Tie quartz requires crushing ard grinding ater which
jt can b. washed from the pyiiteS The gold Obtained
from the quartz and al tho other metals 10y means oil
quicksilver with which il arnalesmgtcs very TeGdy.
dhe quicksilver Is aiteTward distilled and tho gold IS
left a sold. All this 10 easy - describe but in prHc-
tce there stands your quartz ard enough 70 ett glass
and there pyrtes harder than TIE quartz and gold
with the whole IN variable quantity sometimes rich
enough repay yOu for yOar great labor. alas NOR
often only il such apprecabs quantities a. 70 lure the
infatuated minei 20 greater expenditures OF labor. time
and money.
TIE Law OF MARIoTTE.
DR. W. RowELL read a paper this !aE and is sp-
plcat. On IN the steam engine hO which the following
Important extracts are taken;
The well known law OF pncgmatcs is SIMPLY this:
Nyou take ayessel holding one cubic foot Of air and
with sufficient pressure you diminish Che volume Of Gir
% onehaf cubic foot son have two qusutles oi ar
IL space; or 10 Is usually expressed you have
pressure OF TWO etmOspAcrrs II you take tLe mercury
column in barometer as tie measure OF pressure 1he
atmosphere supports column 30 inches high, and two
stDosrhercs occupying one space VII plo!t column
Of mercury to inches high and 50 On for three fOur OF
more quantities. Hence TIE axiom, double the pres
sure is half the volume but sh0uld tho cir BE quickly
compressed there would be an !rCrcase Of temperature
81 T..H sFH.l
contained in one volume OF air Ghd cbs. Gh!. NM
would be q litle more than onc-iaf thc vOurue iOT
double the pressure until TIE temperature was Sic game
- the original volume tnat Was composed 40" tAo
this quaint: ty Of compressed air and suddenly Temo'e
she pressure and would not quite De double toe vol
ume but after the tempo !eture had been aeqgrd Of ihe
original quantity IL wouid b. exactly double the volume
'iIic foregoing settlement is the complete definition
Of the muoh-talked-of 1ariotte law. The only paCsi-
bic way that this law can be applied 20 steam N Is FOL
lows One cubic inch Of water VII make one cubic foot
Of steam the pressure Il one esmospAeFe os II al
make one.ksf cubic foot OF steam q. the pressure o
two atmOspAeres-inG on; by doubling ne pressure
1t will make hall the volume nearly
The Ec,ul proportions Of volume and pressure ac
cording TO the tables I4blsAed ~ Parhcur. iaidDer
Byande, and others, O4e csDlc lnci %! Natef ~
almost he.e pressure makes i.G9 cubic inches aeam
do. do, DO {. cable ilctes steam
DO do. 60 24e cubic inches ala
Whereas II the 3ario,e law perfectly applied to steam
she volumes would be i0s oEe cable lnc 81 water ~
. do e.4.5 cubic inches steam.
do. 4l7.25 cubic * chc, steam
do. 60 rs cubic inches steam.
So that AZ cubic inches M iour p1eieg PIES
sure does not have wa.ef enough 30 mike ltc9 cnh'
inches Of steam at atmosphere Try X. per cent nor s
cube inches steam al atmospheric Dy nc.4y - pa
cent.
That 457 cubic inches steam at atmosphere pres
sure would on gradually removing tie pressure " oAe
atmosphere enlarge itsf 10 Ice cubic inches, had not
d far IL was possible learn been determined eX
perimenaly up 10 tie year 1850. Blring that car u
was tried in an apparatus augsesicd b, myself DE
tables of which may furnish in q future paper"
After quoting from BOurnes Treatise Oh The steam
Engine on The s.ion Of tL.s law to the use OF
steam expausiyely and the statements OF Eegn1It oi
the motive power Of elastic yapoIs, III. KoWEL con
tiIued'
Herein IS the difference between air md steam: II
cubic loot OF air wo atmospheres pressure be con
taued in tight vessel for thousand years i VIII give
out its elastic force removing the pressure while
cubc foot of steam mus, rive ou Us lcrce in few scc
oDds else i;s force is entirely lost AO the rcntyc
volume Of air at different prc.ses (which the MAIL
ote law s the exponent depends On ne ssne temper 3
ture whereas the different plcssnrcs OF steam depends
wholly different temperatures; for instance, steam
at the pressure OF atmosphere ~ 2l2' ii atmos
phefes 2JOo f.. 3 aimosphcrcs 214o j..
:" Nov the slightest increase Z! p..ssure az these
Temperatures slightest decrease o. temperature at
these pressures. will the whole Of the steam 70
water: while Increase o. pressure ON the dir VIII
only diminish its volume 10 tie amount due TO that
pressure.
"The modern received opinion plomuleae ed by Joule,
that heat Is converted into II TIE sscam engine, j.
IN accordance Win the statement made by legnnuli.
gha The amount VI power developed by tire expansion
OF any elastic fluid il always Ia proportion 10 the oss O
heat undergone Cy TINS ud IN The part q the ochine
where the power IL produced Tho quantity ~ heat
o. il Is expressed, tie total heat as ascertained by
II. Regnault from actual experiment 10 cubic inch Of
water steam at atmosphere pressure is ,l15o r.
do do, L. 1902 T.. DO. Co., l.2t3, L.; = do. do,
l.2lso J..
ifihe force is all heat force and il properly ap.
Gtf 70 ls d9s .o his sos 's %pS
steam II would seem II Of the modern theorists