Does the history of the liquid and nasal sounds in Semitic disclose any development parallel to that of the nasal and liquid sonants ( , , , r ) of Indo-European? The problem has never been treated adequately. Even in the latest works on Hebrew grammar (there has not been published recently a single grammatical study in any other Semitic language that is more than elementary) the question is either entirely ignored or else doubt is expressed whether the assumption of a vocalic function by sounds other than the traditional vowels is in Hebrew at all justifiable. 1 And yet what is the value of the lamed in he 'l ‘vanity’ or the nun in e 'n ‘stone'? Or how else can we explain forms like qoro em ‘your approaching’ Dt. 20.2 from qorb em, or the Babylonian mamil ôþ ‘kingdoms’ over against the Tiberian mam ôþ 1 Chr. 29.30, 2 Chr. 20.29? 2 We are forced to assume that the liquids resh and lamed served as vowels during the transitory period. For, to take the latter instance, the form mamil ôþ can thus be easily derived from the otherwise expected mami ôþ. The latter first became mam ôþ by syncope, then l between consonants assumed the function of a vowel thus yielding the form mam oþ (samprasāra a) and at length a gliding vowel developed between m and (anaptyxis), thus ultimately producing the form mamil ôþ.
E. A. Speiser (1925) studied this question.