A method for producing a lithium ion conductive solid electrolyte including the step of bringing one or more compounds selected from phosphorous sulfide, germanium sulfide, silicon sulfide and boron sulfide into contact with lithium sulfide in a hydrocarbon-based solvent. The invention also relates to an apparatus for locating foreign objects on the internal surface of ear and ear canal. The internal sleeve is sized to snugly receive a tree trunk and is formed to provide a plurality of clearances between the internal sleeve and the base part to accommodate parts associated with the trunk of the decorative tree such as bundles of fiber optics.