Wash well a pint of split peas and cover them well with cold water, adding a third of a teaspoonful of soda; let them remain in it over night to swell. In the morning put them in a kettle with a close fitting cover. Pour over them three quarts of cold water, adding half a pound of lean ham or bacon cut into slices or pieces; also a teaspoonful of salt and a little pepper, and some celery chopped fine. When the SOUP begins to boil, skim the froth from the surface. Cook slowly from three to four hours, stirring occasionally till the peas are all dissolved, adding a little more boiling water to keep up the quantity as it boils away. Strain through a colander, and leave out the meat. It should be quite quick. Serve with small squares of toasted bread, cut up and added. If not rich enough, add a small piece of butter.
The Whitehouse Cookbook, by Mrs. F.L. Gillette (Year 1887)