metric ounce

The new ounces would be all alike, representing 25 Gm. or CC., and would be from one-eighth to one-fifth less than the customary ounces. The metric ounce, 25.0; one fifth less than 1 apoth. ounce, 31.0. The metric ounce, 25.0, one-sixth less than 1 av. ounce, 28.35.

Thirty grams or a metric ounce (the American ounce is 28 grams)