In n pipcr cnt,itIctl " I'cct:ogr:q)liy :ind tlic Const,itiition of Colloitlnl Solntions '' piihlislicd i n t.liis .JOUIWAI, (1932, 51, 26), lk. R. S. I-[cdgcs iipplics :t new and rather iinfnmiliiw tcrni to pliciioincna long Iciio\~n nnd reported iintlcr tlilfcrcnt Iientli,ngs or nppckitions. Dr. Hedges siiys t h t " very scxiity nttcntion lins bccii devot.ct1 to tlic rcsitlucs rcin:iiiiing nftcr tlic dispersion incdiiim Ii:is I)dcn rciiiovctl f roin sols i i n d gels,'' itnd tlic cnrlicst rcfcrcncr: Incntionotl iii this conncsion is the pnpcr of :I>iivics in J. Anicr. Clicm. SOC., 1922, 44, 2705. It inny not l)c :iniixs thcrcforc, to drnw nttcntion to sonic cnrlicr \vorlc tilong tlic s:mc or vcry closcly rc1:Ltcd lincs, mhicli is ncglcctctl, bccniisc it is incntioncd incitlentnlly in piipers dcvotcd t;o 0 t h topics, or clsc conccnletl by cryptic titles. I need only rcciill t.lic cspcriciicc of Prof. 1iiclin.nl Zsigniontly :iftcr his intlcpcndcnt rcscnrclics on colloitlnl gold. In liis book " %in 1Srkcnnt.nis '' Colloids rind thc Ultriiiiiicroscopc " ('ill1 Nostrantl, 1909) tic siiitl (p. 75 el ~ey.) : " To tlint, group of clicniists for wliom it would 1i:tvc hiid 1):irticiiI:ir interest., Fmi-(lily's I)rcg1iii.1it work liiis it1lI)iirciitly rcmiiincd ciitircly iinkno\vn-iintil 1898. . . . It, wiis oiily by :i thoroiigli seiircli of the litcriit,iirc7 which I unilcrtook iiftcr tlic conclrisioii of m y cspcriincmt:il work on this siibjcct but bcforc its piil)liciit.kiii, t hiit I folind Ii'iifi~~ltiy'~ work \.Iiicli I rcsciictl froin Ilic oblivion into which it Iiiitl fiillcn.~~ Nnny coninion plicnoincnii :ire rcgiirtlcd \vit.li iiiiscciiig cycs iintil soiiic one points out tlicir ~iicniiing, iniportiincc, nntl uiitlcrlping c:iiiscs. Thc cffcct of colloids on