5. Rules for the conversion of dental sounds to lingual and palatal.
6. Rules for the changes of final nasals, including those in which a former final following the nasal re-appears in combination.
7. Rules regarding the special changes of the derivative sounds—the palatal mutes and sibilant, the aspiration, and the lingual sibilant.
8. Rules as to extension and abbreviation of consonant groups.
9. Rules for strengthening and weakening processes.
Everywhere, rules for more sporadic and less classifiable cases will be given in the most practically convenient connection; and the Index will render what help is needed toward finding them.
Rules of Vowel Combination.
125. The concurrence of two vowels, or of vowel and diphthong, without intervening consonant, is forbidden by the euphony of the later or classical language. It is avoided, according to the circumstances of the case, either by fusion of the two concurrent sounds into one, by the reduction of one of them to a semivowel, or by development of a semivowel between them.
a. For the not infrequent cases of composition and sentence-combination in which the recent loss of a s or y or v between vowels leave a permanent hiatus, see below, 132 ff., 175–7; for certain final vowels which are maintained unchanged in sentence-combination before an initial vowel, see 138.
b. A very few words in their admitted written form show interior hiatus; such are títaü sieve (perhaps for titasu, BR.), práüga wagon-pole (for prayuga)[errata 1]; and, in RV., suūtí.
c. The texts of the older dialect are written according to the euphonic rules of the later language, although in them (see 113 b) the hiatus is really of frequent occurrence. Hence they are not to be read as written, but with constantly recurring reversal of the processes of vowel-combination which they have been made artificially to undergo. See further 129 e.
d. Also in the later language, hiatus between the two pādas or primary divisions of a metrical line is tolerably frequent, and it is not unknown in sporadic cases even in the interior of a pāda.
e. The rules of vowel combination, as regards both the resulting sound and its accent, are nearly the same in internal and in external saṁdhi.
