An elixir of egg.

Ah-ha! Perhaps the disgusting practice of using eggs to whiten tea is explained by there being very little of it. Louis Simond, early 19th century traveler to England wrote this.

"Milk-women, with their pails perfectly neat, suspended at the two extremities of a yoke, carefully shaped to fit theshoulders, and surrounded with small tin measures of cream, ring at everydoor, with reiterated pulls, to hasten the maid-servants, who come half asleep to receive a measure as big as an egg, being the allowance of a family; for it is necessary to explain, that milk is not here either food or drink, but a tincture, an elixir exhibited in drops, five or six at most, in a cup of tea, morning and evening. It would be difficult to say what taste or what quality these drops may impart; but so it is; and nobody thinks of questioning the propriety of the custom."