There is vocalisation of the semi-vowel of the root śyā (śyai) 'to go' when the niṣṭhā affix follows, when the sense is 'coagulation' or 'cold to touch'.,
The word द्रवमूर्त्ति means hardening of a fluid, by coagulation &c. Thus शीनं घृतं, शीना वसा, शीनं मेदः \a coagulated butter, grease &c\. The त of nishtha is changed to न by 8.2.47. But when the sense is that of 'cold', the त is not changed; as शीतं वर्त्तते, शीतो वायुः, शीतमुदकम् ॥ The word शीत is here used both as a noun meaning 'cold weather &c', and an adjective denoting 'cold'. There is no vocalisation when the sense is not that of 'coagulation' or 'cold', as संश्यानो वृश्चिकः 'the rolled up scorpion'. The short इ is lengthened in शीन &c, by 6.4.2.,