. . . . "Thus, X can be, for example, any halogen such as chlorine, bromine, iodine or fluorine, any group containing a silicon nitrogen bond such as (CH3)2 N-, or (CH3 CH2)2 N-, or any monovalent hydrocarbonoxy group such as methoxy, ethoxy, butoxy, isopropoxy, --CH2 CH2 OH, or radicals of the formula -- (CH2 CH2 O)n Y wherein Y is an aliphatic hydrocarbon radical of one to four carbon atoms, phenoxy, cre" .