The chopin was a Scottish measurement of volume, usually for fluids, that was in use from at least 1661, though possibly 15th century, until the mid 19th century. The measurement was derived from the French measure chopine an old and widespread unit of liquid capacity, first recorded in 13th century. A chopin is equivalent to 0.848 litres.
^*Alexander Huntar, burges of Edinburgh (1624). A treatise, of vveights, mets and measures of Scotland. With their quantities, and true foundation, and sundrie profitable observations, arising vpon everie one of them. Together with the art of metting, measuring & compting all sort of land with diverse tables. ISBN 90-221-0671-3.