Studying Lermontov's poem "Выхожу один я на дорогу" I find "Спет земля в сиянье голубом" and not "в сиянии голубом" as could be waited. I have translated it "The Earth sleeps in a bluish shining" (more or less). Looking сиянье in Морфологический анализ, it is not refused, however it is not a included form of the word сияние . I have found in other songs the same нь where it shouldn't be expectated. For example in "Очи чёрные", "Где страданья нет" and not "Где страдания нет". And also is was not refused by Морфологический анализ. It is only a license in songs to express more emphatically the softness of a, in any case, soft consonant or it is rather an archaic form (previous to the reforms of the years 1920) ? Thank you.