By the existing law for Great Britain it is enacted that “in every room in any factory or workshop sufficient means of ventilation shall be provided, and sufficient ventilation shall be maintained.” Not very much has been hitherto ascertained, however, as to the degree of purity actually existing in the air of factories and workshops generally, or as to what standard of purity may reasonably be expected considering the difficulties met with. A Departmental Committee was recently appointed by the Home Secretary to investigate and report upon the subject. The members of the Committee were Mr E. H. Osborn, Engineering Adviser to the Chief Inspector of Factories, and myself, with Mr C. R. Pendock, one of H. M. Inspectors of Factories, as Secretary. The Committee has just reported on the subject of general ventilation1, but reserving for a future Report the vitiation of air by dust, fumes, &c. from special manufacturing processes.