Original Receipt from 'Modern Cookery for Private Families' by Eliza Acton (Acton 1845);HORSERADISH VINEGAR.
On four ounces of young and freshly-scraped horseradish pour a quart of boiling vinegar, and cover it down closely: it will be ready for use in three or four days, but may remain for weeks, or months, before the vinegar is poured off. An ounce of minced eschalot may be substituted for one of the horseradish, if the flavour be liked.