Abstract
On feeding 5 gm. of phenothiazine to rabbits, approximately 50% of it is excreted in the urine as a colourless conjugate. This conjugate is readily hydrolysed by acids, giving the purple dye thionol and glucuronic acid. Determinations of both these entities suggest that the conjugate is composed of leuco thionol and glucuronic acid coupled together mole for mole.