Suitable solvents which may be employed include, for example, the aromatic hydrocarbons such as benzene,toluene,xylene,trimethylbenzene,tetrahydronapthalene as well as thehigher alkyl-substituted aromatic hydrocarbons alkanes and substituted alkanes as well as cycloalkanes having from 5 to 20 carbon atoms such as, for example, n-hexane, n-