The separation of esters of choline by filter-paper chromatography.

7. It is concluded that tran8-tran8-muconic acid is probably a true metabolite of benzene and is not produced in vivo from the ci8-ci8-acid. It is suggested that the 68-c68-acid need not be an intermediate in the formation of the tran8-tranm-acid in the animal body. The expense of this work was in part defrayed by a grant from the Medical Research Council. We are grateful to Prof. R. Cruickshank and Dr R. Mendex for classifying the organisms found in stale rabbit urine, to Prof. W. C. Evans for the microbiological testing, of the urinary muconic acid and to Prof. R. P. Linstead, F.R.S., for access to information on the muconic acids prior to publication.