In 1860’s Australia, if a poor man could not afford to buy kerosene for his lamp, he had to use a slush lamp. Slush lamps were made by half filling a container with clay, then topping it up with mutton fat. A piece of worsted material wrapped around a stick formed a wick. These lamps threw out some light, but they were smelly and smoky, and only used as a last resort.
Margaret Tanner writes well researched historical romances set in early Australia.
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