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ons [Dutch]

In the Netherlands and Surinam , 19ᵗʰ – 20ᵗʰ century , a unit of mass, = 100 grams¹. The ons acquired this value in the 1820 metrication. In the Netherlands the ons was officially abolished by an act of 1937, but in everyday speech it still means 100 grams.

Prior to metrication, a number of ons existed, all subdivisions of a particular pond:

1/16 Trooisch pond = 30.76 g
1/16 of the Amsterdamsch pond = 30.88 grams
1/16 of Keulse pond
1/12 Mediccinaal pond, about 30.7605 g
1/16 pond of arsenic

In trooisch jewelers weight, the ons = 150 karaat = 30 grams.

1. United Nations, 1966.
Technical Conversion Factors…, 1972, page 310.