A verb appearing in The Etymologies of the 1930s as sukin “I drink” under the root ᴹ√SUK “drink” (Ety/SUK).
Conceptual Development: The verb was ᴱQ. soko- “drink” in the Qenya Lexicon and the Poetic and Mythological Words of Eldarissa of the 1910s under the early root ᴱ√SOKO (QL/85; PME/85). In the somewhat later Qenya Verb Forms from the 1910s the verb was ᴱQ. soq- “drink” (PE14/28), but in Early Qenya Word-lists of the 1920s the verb was again sok “drink” (PE16/141). The form ᴹQ. suk- in The Etymologies of the 1930s reflects a change in the root form √SOK > √SUK. The forms √SOK and √SUK “drain, drink” appeared as variants of each other in both version of the Tengwesta Qenderinwa from the 1930s (TQ1: PE18/45) and 1950s (TQ1: PE18/94), and √SOK “gulp, quaff, drink” appeared in notes from around 1960 (VT39/11).
Neo-Quenya: In the 1950s and 60s, the more common verb for “drink” was Q. yul-. I think the verb suc- might be retained for purposes of Neo-Quenya with the stronger senses “drink [rapidly], ✱gulp, quaff”, based on the root meaning circa 1960.
In The Etymologies of the 1930s, the verb ᴹQ. yul- “smoulder” was mentioned in passing in a deleted entry for the root ᴹ√GUL (Ety/GUL). Since the root ᴹ√YUL “smoulder” remained undeleted in The Etymologies, perhaps this verb also remained valid in the 1930s (Ety/YUL). However, the later meaning of the verb Q. yul- was “drink” from the root √YUL of the same meaning (PE17/63).
Neo-Quenya: For purposes of Neo-Eldarin, I would adapt the root ᴹ√YUL “smoulder” as the Neo-Root ᴺ√YOL, and hence would adapt this 1930s verb as ᴺQ. yol- “smoulder” to sidestep the conflict with Q. yul- “drink”; see the entry on ᴺ√YOL/YUL for further discussion.