Original Receipt in 'English Housewifry' by Elizabeth Moxon, 1764 (Moxon 1764)331. To make COWSLIP SYRRUP.
Take a quartern of fresh pick'd cowslips, put to 'em a quart of boiling water, let 'em stand all night, and the next morning drain it from the cowslips; to every pint of water put a pound of fine powder sugar, and boil it over a slow fire; skim it all the time in the boiling whilst the skim has done rising; then take it off, and when it is cold put it into a bottle, and keep it for use.
Cowslips from 'A Book of Fruits and Flowers', 1653