The root ᴱ√SIŊI appeared unglossed in the Qenya Lexicon of the 1910s with derivatives ᴱQ. singe “salt” and (adjective) ᴱQ. singwa “salt” (QL/83). It had similar derivatives the contemporaneous Gnomish Lexicon: G. sing and singrin “salt”, noun and adjective (GL/67). I think it is worth positing a Neo-Root ᴺ√SIÑGI to salvage these early words.