The problenis connected with the disposal of rcfiisc Iin\w for many ycnrs cotiiiiinndcd iiu increasing nmount of attention tlirougliout tlic cities of tlic world, both 011 nccount, of the vast qiiniititics of w s t c niatcrinls that have to be disposed of, and :L~SO 011 ncconnt. of t.lic great costs involvcd. It is estimated t h t in t~lic towns nnd cities of Englaiiil nnd \':rles alone 10,875,540 toils of refuse have to be collectcd and disposed of aniiu:iIly n t n cost to the r:rtcpaycrs of E7,500,000. Jlmy cfforts ltave been innde to cllcnpcn the costs of collect.ion, and to tlctcrniinc tlic most ccononiical and cllicient nicniis for disposal. 130th iisliccts of the work have interesting fcatnrcs, but i t is only with the qitcstion of disposal thirt this paper dci~ls.
In certniu Atiicricnn cities, where it is the gcncrnl practice to collect nsltes, rubbish nntl food wnste in scpnrntc contniners, t.licsc three materials nrc scpnrately disposed of. The iislics, being innociioiis, arc used for hnd rcc1:unntion or some siini1:rr piirpose ; tlic rubbish, after rcmovnf of snlcrtblc coiistitucnts, is inciiier;ited ; and the gnrl~agc or food waste is trentctl by the r c t l u c t h process. Tltis proccss, of wliicl~ t h y c arc scvcrnl moctific;itions, consists cescntiatly in drying tlic gtirbnge, estriicting the grciise for s:ile, and grindiitg tltc tlcgrcnsctl rcsidnc for sale citlicr ns 15 fertiliser I J ~S C or stock fodder.
In the n o s t nioctcrn plants trciitnicnt of tlie gnrbngc is cnrrictl out i n closed digesters of 3-5) tons capncit.y, fitted with :L stirring tlcvicc, stcnni-jnckctctl, ;ind coiinected t o a coiiclcnscr. Tlicrc is ridded to tlie garbrge in the digesters D rpnntity of pctrolcuut nttplitlin or low-grade licrosenc, and the tcniperature is rriisctl to between 170' B. ant1 196" P. by nienns of the sterini jnckct. The wtrtcr coiitained in bhc gtbrbngc nnd the solvent forni a low boiling-point inisturc, niid tlistil OK :fhc gtirbugc is tliiis dehydrated, iind nftcr condcns:it,ion tAc solvent is scpi~rated froin tlic wnter and used n g h . \'lien ilcliytl d o n is l)ri~ctictilly complete, tliurc rcm;iins i ti tlie digestor with tlic gnrlirige n certain nnioiint nf solvent saturntcd witli grensc. Tliis is rim off to 11 settling tri.nk, tlic contcnts of the digestor nrc w~~sliett witli solvent two or three tiiiics, a i d then Iicntcd to drive olf tlic litst trmxs of solvent tltrougli the coiiclcnscr. Tlic! dry residue is cnllccl " t:uikiLgc," iiiicl, d t e r griiidiiig, is sold.
TIie grensc-sirturirtctl solvent in the scttliug tatiks is distilled, the solvent rccove~.ccl, and t,lic grciise riiit into barrels for sliilme~it This process J~ns hccn .wxmslully uscd io soiiic cities for tlic past t\reiity yeiirs ; but, on tlic otlicr hiiad, sevcml plants Iinvc fititcd 011 ncqoiint of crriit,ic profits nnil tlic tcntleiicy to C I ~I I S C iiuistlncc from odour.