Tub was a unit of capacity or of weight used in Britain and elsewhere.
British unit for butter and cheese British laws for the sale of goods defined a tub of butter as a receptacle of a size which could contain 84 pounds of butter.
Definition
1 tub of butter or cheese = 84 pounds
Conversion
1 tub = 1.5 Firkin (1 Firkin = 56 lbs)
Metric equivalent 1 tub =
Other commodities The Oxford English Dictionary has quotations illustrating other values of a "tub" as a unit: Tea (1706): "about 60 pounds" "Camphire" (1706): "from 56 to 86 pounds" Vermilion (1706): "3 to 4 hundred weight" (i.e. 336-448 pounds) Camphor (1858): "130 Dutch lbs"
In Newfoundland, Canada, a tub of coal was defined as 100 pounds, while a tub of herrings was 16 Imperial gallons and a tub of salt was 18 Imperial gallons.
References