The roots lī and lā optionally get nuk and luk augment respectively before the affix ṇi when the Causative means 'the melting of a fatty substance'.,
As वि लीनयति, वि लालयति, वि लाययति, or वि लापयति घृतम् ॥ The augment नुक् is added to ली when the root ends in long ई, and that also optionally. When the augment is not added, the regular causative लाययति is formed. But when ली gets the form ला by (VI. I. 51), it does not take the augment नुक् ॥ The root ली includes both ली and लीङ् of Kryadi and Divadi. The root ला includes ला 'to give' (adadi 49), and ला the form assumed by ली under 6.1.51. When लुक् is not added to ला, पुक् is added by 7.3.36. Why do we say when meaning 'to melt fat'? Observe only लोहे विलापयति, जटाभिरालापयते 1.3.70.,