Kommentar zu Schemot 19:18

עשן כלו WAS ALTOGETHER ON A SMOKE — This word עָשַׁן is not a noun, because the ש is punctuated with Patach, but it has the meaning of “it was doing something”, similar to and אָמַר and שָׁמַר and שָׁמַע. On this account, its translation in the Targum is תָּנֵן כֻּלֵּהּ “it was altogether giving forth smoke” (תָּנֵן is a verb corresponding with the Hebrew עָשַׁן). and it does not translate it by תְּנָנָא (a noun denoting smoke, corresponding to Hebrew עָשָׁן). But wherever else the word עשן occurs in Scripture it is punctuated with Kametz because it is a noun.

והר סיני עשן כלו, and Mount Sinai was completely wrapped in smoke, etc. Fire dominated the Mountain itself and burned its stones so that they turned into limestone. The stones of Mount Sinai have remained limestone ever since. When the Torah says: "the whole Mountain trembled," this is a description of the reaction of the stones when fire dominates them just as the stones in a furnace. The sounds that the stones give off are similar to the sound of someone trembling.

עשן כולו, the word עשן here is neither a proper construct mode, in which case it should have two vowels patach, nor is it completely “unattached,” as it would then have to have two vowels kametz. In other words, it is not a noun “smoke,” and not an adjective, “smoking.” It therefore must be a verbal mode. If it would be a noun it should follow the pattern of davar, devar, word, word of, or bakar, bekar, cattle, cattle of. (compare Numbers 7,88 בקר זבח השלמים).