It seems to me an earlier biography brought this up as well, while noting that Thomas asked for the morphine and that the doctor simply gave him what he wanted (which is no excuse). At any rate he downed eight doubles, which is 16 shots - not far off the 18 claimed (unless he was claiming 18 doubles). The question is how long was he at the bar. I've downed eight doubles on many more than one occasion. A shot is 1.5 ounces. So a double is 3 ounces. Eight doubles comes to about a fifth. Any half-decent drunk can knock that much off in an afternoon. So I doubt if the drink alone did him in.