The bacterial disposal of sewage has been so widely discussed during the past year or two, that possibly some apology is due to the Association for the introduction of a subject that has ceased to be novel. So far as Hawkhead Asylum is concerned the subject is still in the experimental stage, and the brief outline of the experiment contained in the following communication is the outcome of a correspondence with some of my friends who suggested that the question is not without interest to asylum superintendents.