Camelinan nnd Andordon, loc. cif.
stnin for phenolic resius doveloped nt the Royal Aircruft Estnblisliinent, South Fnrnborough, is neutrnl-red chlorido in nlknlino solution, which colours the rosin rod to scarlet. Anotlier, froni tlie Rcscnrcli Department of Messrs. Tootnl Broadhurst Leo Co., Ltd., cousists in exposing a nioistoncd soction to coiicentrntcd nminonin fulucs for one niiuute followed by bromine rnpour for n siniilnr poriotl ; the rosin nssunies n reddish-brown colour. As in tlie ciisc of the wen rosins, the presence of fillers niny obscure the chnrnctcristic fentures of tlic resin. Tlie iuicroscopy of the principnl fillors is dcnlt with above under uroa-formnldohyde resins.
Liebcrmnnu's phenol renction hns been used by Weigc17 to distinguish phunol-nnd cresol-formaldehyde resins from other synthutic resins, but this inethod is not nltogetlior siutnblo for plyivood, firstly, owing to the sniall amount of resin presoiit, ruid, secondly, bocnuse of tho chnrriug actioii on the wood of the sulphuric ncid used in this renction. Tlio second objcctioii nlso npplies t o the staining renction used liy Woigol, ahicli siinilnrly inrolvos tho usu of sulpliuric &id.