This journal is dated 1757. Pasteur connected yeast to fermentation in 1856 (discovered what yeast does)
Historically bakers would take beer "waste" to make bread rise.
Also there are early references of people's jobs to provide beer waste / trub to other breweries. But they didn't call it trub or yeast. The references escape me right now.
The word yeast is derived from the old English words gyst or gist.
I can't find when the word yeast started to be the name of this beer waste or even in baking.
The word used in the journal doesn't appear to be "yeast" or "yeat". Appears to end in a "r" based on his other uses of the letter.
So what was this word he used to discribe what seems to be beer trub?