New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1853-08-04

Only ought 10 be taken a. true measure 90 O"ueu
81 con z or views Of slight fluid cchesinn are based on
n iti.r,tSobs in shch the effects oi the -Ay
bhtl Of Iari- rucs very loosely I'M 2u'sc 20 aON
Nshe Il coh--ion. Once clearly ni-r-'sndng Ina s',
fac. Welding gives essure cohe.i or firect ress
sIcet to rutiuis can readily t'ai The prevalent
ic, as IN this sutje, are ithCut support
1t study phenon attending the condensation OF
gases and vspors fluids II apparent that while con
luous moeo ule still At distances many times gress
that chsrsofeizrg the ud state, the cohesive sirs'
ton usuies Itself ecsby steam instantly c'ndsnsng
The Tste Of foot - inch Of ~Sisr sho~. thar ia
the cohesive acton Of moecue extends effectively
hrougb sphere which diameter At least two times tn-
oisiSnce between scent molecular c-o,ers IA tue tit
Hence water, The radius Of effective cohesive acton must
be great 20 Icuce tever.l molecular layers The
uoueIt ess 70 ,low M.rrives l4w cohesive sc
b. sppr,oAbe ana THIS u proof enough n.t 10
us,ss usiy lzyers contribute their scnOn in m.kcg up
n total cohesion If conceive any hgd Ia be
.ihp,.d INFO l.yers then the rrec; measure Of fluid
t,h.sen will be the force requisite to produce direct
su separation Of all tue parts along unite Of the
oydIg suifsC- bets.en two layers nus Is equal TO the
resusIt al forces acting from eIiter directi against
This unite o surc- these forces being held 10 eqaorc
BY the opposing forces
Lnui Hut iptrccuctd mathematical expression from
vhi,h b. dductd the follosiog CONCLUSION LIE iofnue
ean hardly be r. presented with accuracy
This formula IN solyss no particular hypothesis Is 10 the
value character Of the forces acting only that the asgs
gate attractive But conden satiOn ~ spontaneous
pheuomenon through sill that portion OF sggreSst'onA
range in shch energetic actions are found We ougn 10
assume that all effective terms are attractive 10 present
the ground which TO me 20 authorize the cOncepaon
that rpul.ion in all Of aggregation Is only exercised
b.tveen adjacent molecules while the attractive actions
are the of all the primary constitutional forces
ard through longer spheres would involve the
exposition complete theory OF molecular mechanlc'
n ust therefore have as assumption the conception
that ucs the only repuson TO be taken into account IS
the continuous layers which prevents their edng nrher
10 the cohesive forces pressing them together.
We should observe that 10 consequence OF the dehcenHy
Of along the uid surface srsrnc atom would t-xe
place which would sgsin diminish surface cohesion 10
con siderable extent below that value given by the formula
Lieut. Hunt here applied the general formula to sur
face element in oIdsr 10 ds.ermlhe 70 cSnss'n
soIg surface The result thus reached IN respect 70
would not be greatly affected IN the orui
lis sshst remarkable ihst Posson's capillary the
ory a. stated by Mossott in TGyOrs Scientific MT''r
based essentially analysis Of the fluid surface IN
which the h.fpg Of the normal layer is totally overlooked
and the heson sor the surface said to be the same
a. in the mss the surface layer only having been taken
into account have Poisson work but Is sin
gular that Mcsso,t should either have made sucn an
oy.rgLt or have failed ia Poisson if he really
corsu,d H. IL il a radical cesct even using POissoss
hypoheses and must directly Affect or even nVads'e
lis whole theory.
come now TO an important deduction from the proceed
rs ud surfaces are In state OF weak cone
zion ~ compared with aud interiors hence partially
amC sphere concion Of raIiaciion exists AonS sach
bouncing turfsces. IT, then, We sssmlate neat 10 mo
cuar repusOn as il Customary See at once that -
ID, ttmperaiure raised the weak cohesion IN the surtce
will be overcoD long before the mass Is heated TO thH
toIt which will oyeTuast.r its internal cohesion Hence
HE surface molecules will freely pass 0h A Vapor "hs
sirorg cohesion still exists throughout the entire mass
Evaporation thus AT the surface Al si temperatures
above that which ust suces to overcome the weak sur
face c. hesion Ihs constitution or structure necessarily
character, ng the limiting layers of fluids Is the true aud
f exclamation of evaporation 10 all It's forms. From TINS
We see that fluid without Interior or exterior sur
faces or 20 ucosed virtually 10 answer this DESCRIPTION
gb. be htaied up far above the boiling p'nt without
b,Irg We that ebuiion 10 but the effect OF An ia
t.rna evaporation starting IN minute ar ouooes snd
growing With the expanding bubble. We see that wafer
entirely reed from air bubbles and with restricted open
surface rs Denny late experiments should 90 on heat
tar he
b. aed msss would flash into cam with an explosion All
phenomena described by Denny III his excellent paper
OF the Anhas de Chtmf Il de FhtQue follow ts easy anu
obvious deductions fom this constitution ct the huid sur
face -,
rded We DO not At all wonder al his bsing forced from
s.Iterim.ns coucade emprcsly that there must be
sou. pecular quality in surfaces which makes evapora
ton tke place much readily on them tosh on hua
mssss We toe how utterly falacious are the expert
usually taken duld cohesion IN surface
layes vhch the free mobility Of hud parts fully explains
ali The observed results This explains how too perfect
boiling the mercury in barometer tuoes makes adnere
at the top with such tenacitY IL explains b-rhoiot on
The for, ed dstaun OF fluids, IN which dsaeratsd ld
zeal when hot not shrink IN cooling tor long tne
but breaks and cosps-s indicating that II has borne
sr,st t.I sIou before Welding Prof Henrys elegant
p.Imenis vi h soap bulbs in which by measuring me
len of the in closed air be IS able to deduce hrst the
sing uTce and then the cohesion OF tne hud h
furnish Ala ind udent confirmation OF the same genera
views may remark that the heterogeneous structure
outer layer would destroy the mOoy OF tnsr parts
and give IN like character 10 the uid surface, while All
uihn this n would have Tree mobility Ihi', win the
SdoiioUa fact # dasDg inward OF the outward ayers
BY the uDbsuced cohesive acton 0 the tyers near tno
sur &C. plains he greet variety ~ formal pheBOineh
exhibited By the drops bubbles and huld lritc-s
Al, NJ four years since, conceived the idea OF directly
essur fluid cohesT by rnptufing pure hid column
IN cy lLdeT sitb moving piston. By hOg lhs cyinler
with the fluid BE- tested aud mmerslns the piston oy tue
bid valve closing At will The force requisite Tor sttrt
the pisi,n viii be the cohesion OF the column, on Al
loving smOslheric pressure. OF course the hud nlst
sdbtre to thu cylinder r. strongly Than c0lsres Ia u
elf the adhesion only would be measured Nor must
contain bubbles, the presence OF one such'
however email will give start 20 the break by presenting
A weak surface This Is the great difficulty Of the pro-
posed experiments 10 my asi had Just begun .ach An
experiment mercury IN an Ngsmated @ Inder olt
The rquiite precautnn fr excluding air could not be
taken for lack OF time, | was obliged to leave my
stsiion before the apparatus completed The rapidly
vi which the nurcury rushed pat the piston IN the
rot trial sd- sh wed that packing will probably
BE- qulsiie debs measureme nt aud this again
all lr, the difficulty Of ntrt ducng "a AN amsted
surface in the 10 BE- broken. Tbs precautions rs
quste for perfect trial OF the experiment are quite
Ispucpste Mat exceedingly small air bubbles will have
Il effect If making the ca0ns Irregular 40 the snail
bubbles will only start break on the application Of
very considerable free
Twill Low apply this discussion TO steGm bor eLp'0s0Hs
The cOLoiioD rquisIe tor ebG iton IA boiling water IS
snly tha' ar bubbles in the heated portions shall present
Cd her borders The weaky coherent surfaces req ie Tor
eysp riion e. he sstab he'd Perfectly de4erated water
win A Limited surface would rot boil ~ all, but would
L.si ID until II he'd that point ~ which il would ash
tlIlosi,.ly Sos chief cause Ut local IL
blo,iOns CLEARLY Of this description The boat stops AZ
hsii the Doctor, pump supplying water - tne
engine beng worked BY the engine isr stops IT'S water
sutply hen the nsine stops The water IN ne boiler ss
OF b, Ing until III the air bubbles boiled OF from the
water their air is liked wtn The steam above lhsn
there to b. any -Vap"raton surface except N IA
N ton Ia, e. zhieh t4nh-st from tbs be Dg su.o-
ard Quite quAie the cOnsum. ton Ot all the heat
supplied Then the e water be1ns to heat up And
it goes on sorIg up the qncotsgmed e'lorc untl Tue
Ter hotter han thu head Of steam would ndcfe
1he engineer the stAs tbs tnis s,aEs the pa p,