Activity of Crystalline Preparations of Vitamin B₁

Abstract

IN an important letter, Dr. van Veen¹ describes the isolation of a vitamin B₁ preparation from rice polishings more potent by rice bird tests than our own. At the same time he mentions that his activity reaches 500,000 units per gm. It is well to realise that some of our most potent specimens have shown this activity by pigeon test², so that a final judgment upon the question must await further work.