I’m pretty sure 8 ounces of 190 proof in a relatively short time would be fatal for most people. That would be 18 ounces of 80 proof.
I think they are talking per capita per day back then, and was the total amount of ethyl alcohol (200 proof) that could be extracted from the total number of “alcoholic drinks” in a day.
I can say from first hand experience that drinking a few shots of pure ethyl alcohol certainly won’t kill you, and spread over a day in beer, wine, spirits and what not...granted, it it seems completely extreme to us, but according to the authors...was the practice.
But I fully admit I am extrapolating...because 8 ounces of hard cider a day or 8 ounces of beer a day for every man, woman and child wouldn’t be much at all because the population was much smaller then.
Just trying to noodle it out...I could be wrong!