effects wcrc obtnincd witli nll sniiiplcs n t IL siniilnr coiiceiitmtioii, niid iii oiic cnsc O * 1 6 ~o by volun~c proved fatd to all tlic niliiiiiils under espcriment.
A s regards tlic cffcct8s upoii the iiiteriial organs, the results obtniiicd in this work with rats ngree iiiorc closely with the cspcrimcnts of Cniiicron el (i1.011 mice. Definite iiccrosis niid fatty chniigcs in tlic liver in two of the four sniiiplcs. A possiblc csplaiintion of the discrcpaiicies betn-ceii tlic two sets of results iuny be tlie fact thnt in the work reported liere a physical !ncthod has becn einploycd for determining tlic conccntrntioiis of cod-tar naphtha ilistillstc vnpours. Such n iiictliod tlctccts very rcnrlily niiy chnngc in tlie conceiitrntioii niid is probiibly niorc :iccurii tc than thc ccmbust.ioa iiictliotls uscd in clieinical ctnalysis, cspccinlly ns the concciitrtttrntioiis \wrc reintirely of n low order.
Conclusions
Nnplitlia clistillates nrc being uscd to-day uiidcr tlic impressioii tlint there is nothiiig to be fcnrcd ns rcgnrds their effect on Iiumnus. Tlie csperinieutnl work rcported above iiiclicntcs tVliat tlierc is tho possibility of duninge to humniis. It is not suggested tlint tlie data presented in this pnper justify tlie esclusioii of naplittin distillntcs ns fuiiiigtiits against bed-bugs, but only thnt users slioultl be awnrc of possible linzartls.
I t has bccii stated by Asliiiiorc niid i\IcI<cniiy Ilughcs (1937) tlint iinotlier titlvniitngc of iiaphtlin distillntes is that after vciitiliitioii of eight hours tlic conceiitmtiori reinaiiiiiig in n rooiii wns rctluced froiii 0.12% to 0.009% (V/V) nnd tli!it no further " I~uil~l-irp " occurs wlien vciitiitition is stoppcd. Atteiiipts Iiave becn iiiiidc to repeat those csperinicnts also but soiiic " build-up " nlwnys occurred. Tlie conceiitrntioii in tlic ittiiiosplierc above n surfiicc trcatcd with iinplitliii tlistillittc niust a t cquilibriuui I~cnr R rcliitiou to tlic niiiouiit of nnplitlin tlistillnto udsorbcd or absorbed on tlic surfiicc, niitl during veiitilntion cquilibriuiii ciiii scnrccly be ninintniiicd. It is, tlicreforc, rciisonnblc to expect soiiic " build-up " to cquilibriuiii \*lien vcntilation is stopped.