constiuctetl of' stainless steel. The cylinder closures are of the simple conipression-gasket type. ( ;a-kets arc also mark of thoroughly annealed stainlcs steel. T'ah-es, fittings, and tubing c~onneciioii~ (for :-in. 0.L).tuhing) are ol . ! - ' - 2 ~ N F - l . o ' DCCP
IA DETAIL
I
-
MAT'L -CHROME S T A I N L E S S t8- 8
REQ. I
the type* rccommcntled aiid Inanufact urecl by thc AiniericanIristi rmient '0111puny (Snperprc~ssurc1)ix-i-ion), Silver S ~ing, I SIai ylnnd. ircb p ~ ~ o d ~:in(l i c ~rnensrll*etl d hy incanc: of n modified cIead-i\ eight gwge, con+triictcd in acrorclancr 11 it11 the (le-ign of F. G . liege5 ( 5 ) - and scrcn-typcpiston, master cylinder ac:seml)ly. 'The nominal diameter of the floating pirton i i & in. I'rorision Iias bcm made for loading this control piston by nienns of a 5 : 1 ixtio lever arm in ortlcr t o eliminate the need for handling vcry heavy \!eights at the higher preqqure-. It i y helim-ecl that prrwircs can be controlled and held constant within 1 pcr cent for tlic pressure range involled.
I ' - t o UF
S E C T ION
'1
.f Dee v A A"
FIG.3D
The fluid used in thiq system is a mixture of 1-S.P.mineral oil and petroleum ether. -illthough thiz liquid laclis certain qualities clesirahle in a hydraulic. fluid
1164
E. -1.HhL-SER . I S D
S . MICHE.LLS
it is essentially non-capillary-active, :tnd is thus well adapted for use in boundarytension-measuring equipment where surface contaminat ion is a frequent and serious problem. LIMIT.iTIONS .LAD
LPPLIC LTIOSS O F T H E LI’P.LR.LTU5
The fact that the Poulter-type high-pressure windo\\ Y described above are not in general gas-tight except at exceedingly high preswrcs limits the use of this new apparatus to the extent that the cell chamber must alnays be filled with liquid. This does not, however, exclude the measurement of gas-liquid houndary tensions, because the “drop” can just as \vel1 he a gas 1,ut)hle.
OIL
t TO
I
F i c . 1. Drop-forming system
The equipment is at present heing u.ed for the determination of the p r ~swre .. and temperature coefficients of interfacial tension betu een pure hydrocarbons and n-ater. When this fundamental re3earch is completed, measurements will be made on the system n-decane-distilled \later in the presence of dissolved methane. I t is anticipated that this latter information will he of value in predicting and interpreting the interfacial behavior of systems of crude petroleum and natural brine under physicla1 conditions comparable to those existing in subterranean oil reservoirs. Succeeding articles in this heries will be devoted to the presentation and interpretation of data obtained n ith this equipment, and, it is hoped, will suggest nmv problems t o vhicsh the apparatus can he conveniently applied.
SILICIC CHEMISTRY
1165
IUPERESCES (1) .ISI)REAS, J . AI.>HALSER, E. .I., ASD TL-c R , W.B.: J. Phys. Cheni. 42, 1001 (193s). (21 BRIDOXIS!P . : The P h v s i c s of High P r e s s u r e , 11. 58. The Macniillan Company, S e w T o r k (1031). (3) B L - ( . K I S G H . S J I , IT.D., A S D DEIBERT, C. It.: J. P h o t . SOC. 12, 610 (1946). ( 4 ) I C I L E R T S , c. Ei.,et d . : .Im.Gas .Issoc. AIonthlj- 28, 435 (1946). ( 5 ) KEYES,F. G . : Proc. Am. Acad. h r t s Sci. 68, 529 (1932-331. F. li;.: J. Phys. Cheni. 45, S46 (1941). (6) llarr;, G. L., Davrs, J. K . , ASI) BARTELL, ( i )POULTER: T. C . : Phys. Rev. 35, 297 (19301. (8) SMITH,G . R.: J. Phys. Cheni. 48, 168 (1944). (0) SMITH,C:. IT., A N D SORG,L. V , : J. Phys. Chetn. 45, 671 (1941).
SILICIC CHElIISTRT’,2
IiRSST A . HAUSER licpcct~triieiit of C‘heiriicnl E n y i i i e c r i n g . Slasscichitsetts Zrzstit i i t c of l’echiioloyi/,
Cnnrbridgc, Jlassnchusetts Keccii’ed Febricaty 20, 1948
“In science the credit goes t o the man u-ho convinces the world, not to the man t o Jvhoni the idea first occurs.” These ivords ivere spoken by the British physician Sir Killiam Osler in the last lecture he gave before the Royal Society of Jledicine in 1918. Onc could hardly find a more striking example of their significance than by offcring a tirief historical reyieiv of the colloid chemistry of silicon. In 1861, Thomas Graham read before the Royal Society in London a paper on “Liquid diffusion applied t o analysis.” €IC differentiated therein betn-een matter lvhich would and substances ivhich ~\-ouldriot diffuse through a membrane. References t o this lecture (3), lvhich must be regarded as the foundation of colloid science, are mostly limited t o the follon-ing statement: “-4s gelatine also appears to he of the non-diffusing type, it is proposed to designate substances of the calass as COLLOIDS, and t o speak of their peculiar form of aggregation as the C‘OL-
IAOIDAALCOSDITIOS OF lIATTER.” What has droppcd into oblivion, however, is the following sentence: “The comparatively Jired class as regards diffusion, is represented hy a different order of clieniical substances. marked out by the ahscnce of t h e power t o crystallize. .Imong t h e Presented before the Symposium on Colloid Clhemistry of the Silicates, which was held under t h e auspices of the Division of Colloid Chemistr>-a t t h e 112th 1Ieeting of t h e ;\nierican Chemical docietj-, S c w l-ork C i t y . Septemhcr 15-19. 1917. This paper is based on t h e hook Silicic C h e v i s l q by I
