The author commenced his paper by observing that it formed a sequel to one communicated to the Society last Session on comenic acid; his object in the present instance having been partly to ascertain whether some of the substances described in his former paper could not be derived from meconic acid, which is the parent acid of comenic acid. This he shewed to be the case; but before detailing these experiments, he gave his process for purifying meconic acid, which is that of Gregory, modified by the use of ammonia instead of potass.