Xost gns iiiidcrtnkiiigs in this country now opcrntc undcr tlic provisions of thc Gns licgnlntion Act, 1920, niid by Clause 1 of that Act nrc rcquircd t o clinrge coiisiiiiiers for tlicrnisl iiuits supplicd in the form of gns. !l'lic bnsis of all such clinrgcs is tlic product of tlic total voluinc of gns supplictl and tlic dcclnreil cnlorific vdue of this gas. 13~-calorific d u o is to bc iiiidcrstootl tlie iiuinbcr of Brit,ish !l!licrni:il Uiiits produccd by thc combustion of 1 cb. ft. of gns mcasurcd a.t GO" I?. uiiilcr :I pressure of 30 in. of incrcury and snturntcd with wntcr viipoiir. Under tlic Act, yennltics a m to bc iiiflictcd iipoii tlie gas uudcrtnking, if on any day for a pcriod of two hours or iiiorc tlic cnlorific value of thc gas supplied is inorc thnn GO, ' , below tlic dcclarctl cdorific vnl~tc, or if in any qunrtcr tlic avcrngc cnlorific valuc is less tliau tlic dcclarcd cnlorific \ d i e . SucIi, in brief nrc thc ninin tlicrinal clmiscs 01 tlic Gas ~Rcgulation Act, 1920tho Clinrter of Libcrty of tlic gas iiidustry in this couiitry, and tlic consitnicrs' gunrantec that tlic gns untlcrtnl~iiig iinist, docs and wiI1" dclircr thc goods."
Uuclcr Clniisc 5 of tlic Act, tlic gas rcicrecs iirc rccpiirccl t.0 prescribe, in t.lic cnsc of undcrtnkinga which 11a.v~ sold in thc ~~cccciliiig ycnr niorc tlinn oiic huudrcd niillion cubic fcct of gns, ant1 in niiy otlier c:isc in which it nppenrs iicccssnry i o tlieiii, iL cnloriiiictcr for tlic production of n continuous record of tlic calorific vnliic of tlic gas wliicli is bciiig supplied. Tlic prescription of sucli n rccording tlcvicc, wliicli in n. finnl issue is to bc tlic :i,rI)itcr of tlic possiblc npplicntioii of thc pcnnl clnuscs of tlic Act, is 0110 that is iiot t o bc liglitly uiidertalrca, nut1 tlic Cns Rcferces hnvc chxcii wisely in Iiitlicrto iiot prcscribiag tlic gcncral usc of iiiiy form of rccording giis culorinictcr for tlic purposcs of tliis clniisc. Ratlicr ham t h y prcfcrrcd, in gcnernl, to prescribe sii:q) tcstiiig of tlic gas supply, supplciiicntwl in isolntcil cnses by tlic usc of n recording ccilorinietcr.
tlcctint/c gas cnlorinictry lins long bccn of iniportn~icc for ficiciitific ~n i r p s c s ; exlrenelg accurate gns cnloriiiictry is now of couscquciicc inrliistrinlly niid socinlly. !Uic clegrcc of dcsirnblc nccurncy will be rciiliscil wlicii it is iiiitlcrstood tliiit, in tcriiis of iiioncy, nil error of lo/, in rcspcct of tlic thcriiiiil vaIirc of the annun1 gas supply of lhglniicl, Scotlnnd nnrl Wulcs rcprcsciits nbout X~00,OOO. Act.uully, tlic cnlorific vnluc of 11 gas ciiii IJC tlctcrniinetl wit11 nil nccurncy ccrtniuly iiot cscccding nbout 0.5yo. Cnlorific vulncs givciiiii stniidard tcstbooks tlculiiig witli tlic subject arc rccorilcil with nil ncciiriicy of 1 pnrt in nbout 50,000. 'J'lius IVC find Tlioiiiscii's i d u c of tlic cnlorific, viiluc of cnrboiiio oxide, G7.90 kg.-C. uiiits per grain molcculc in tlic litcrnturc of tlic subject ant1 the \ d u o is custoninrily cmploycil iii gnu tecluiologicnl calcuhtious, ~v h c n tlic actuul cnlorific vnluc niny bc niiytliiiig bctwcoii G7.6 and 68.3 Irg.-C.-