. . "Examples of the solvents include aliphatic hydrocarbons such as hexane, heptane, octane, ligroin and petroleum ether; aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene; ethers such as 1,4-dioxane, tetrahydrofuran, diethyl ether, ethyleneglycol dimethyl ether, methyl t-butyl ether, diisopropyl ether and dibutyl ether; and mixtures thereof." . .