I
Ziverpool Section.
inflncncc ol past trcatlxlcnt on sucli chni.aclcis its melting point, solidilicntion point, transition point, clcnsity, specific h a t , clcctrical conductivity, cllcniical rcactirc pomcr, ctc., and also the csaminntipn of tlicso clinraictcrs 11s a tcmpernturc function. I t IS clcnr thnt tliis re rcsciits fnr. too witlo n field to lie covered i n cietaif Iicre, Iiut n few pnrticiilni* cxani Ics, typical of iiiucli thnt has I m n done, iiiny Ec of interest. IL ]iOSSilJle C'S1Jl~lllutiOll Of Illllny IJL'~blC1llS C u l li-erniiig liiirdciiiiig iind passivity of ~n c t d s , ctc. Coiiscc~uciilly I Celt ju.stifict1 in uttciiipting to give :I brief oiitliiie of Iiotli tlic kind ot ex criniciiLri1 work oil wliicli i t is ~insed, :mil some of t;ic plicno-I ~C I ~~L to wliicli :illotropy ILITOI~S at least n. p1nusiI)lo cs pliini~tion. A t t!ic outsct let 11s USIIIIIC thiit in nny siiigle nirc forni of n inctiil tlic inoleculcs be alike in Lotli structure nnd coniplcsity, so that tlic properties of niiy one spcciriicn inust IN idcnticnl with tliosc of any otlicr spcciiiicn of sucli n ~nctnl, niicl furtlicr tlinL siicli properties can only vary w n, function of tenipcmturc. Now rcfcrcncc to c:liciiiicnl litydurc shows tliiLt this is not rcnlly tlic cwc. llic densily of all spccinicns of n prirc inctnl is not nn iLbsoliitc coustant, nor is tlic coclficicnt of cspnnsion, cloctrical conductivity,
ctc., iin c s i d tcin wrature function, b u t they LLPC ~'ouiitl to vnry witli tlic prcrious iiistory of t411c spcciiiiryi uiidcr investigation. It is triic tlint the viirintions aro usually of n sinnll orclcr of ~nngnitude :Lnil iiiiglit pcrlinps often be cLLti*ibutctl to cspcri-inrnti~l ci-roi* or iiiiliuritics i i i tlic spcciriicii, I)rrt, work c i i ~~~~i ~x l on with the grccitcst of . iiiotlcrii :L(:ciiiwy r d c u e only coiifiriiis cnrlicr irregttliir rexiiltx. 'l'1111s iiiiy investigiitioii on al101,ro y must pnrtnke of tho iinture of an iuquiry i n k tKo