Charlotte Bronte, Emily Bronte, Anne Bronte (2009). “The Bronte Sisters: Three Novels: Jane Eyre; Wuthering Heights; and Agnes Grey (Penguin Classics Deluxe Edition)”, p.81, Penguin
John Joseph Griffin (1834). “Chemical Recreations: A Series of Amusing and Instructive Experiments, which May be Performed with Ease, Safety, Success, and Economy ; to which is Added, The Romance of Chemistry : an Inquiry Into the Fallacies of the Prevailing Theory of Chemistry : with a New Theory and a New Nomenclature”, p.232