as a mechanical irritant when breathed, but where the substance thus inhaled acts as a direct poison. For instance, manufacturers of white lead and other mineral paints frequently exhibit symptoms of poisoning in this way, and workmen who use arsenical compounds, as in the making of wall papers, artificial flowers, etc., are often the victims of poisoning by arsenic. This poisoning by means of arsenical wall papers deserves more than a passing notice, owing to the dangerous and even fatal effects which they induce, not only in the workmen who prepare them, but also in persons inhabiting apartments where the walls are covered by them. These wall papers are mostly of a beautiful green color, the latter being due to a paint composed of arsenic and copper. Owing to variations of heat and moisture the green particles are constantly being set free from the paper and carried about the room by ventilation. Some idea of the amount of poison with which so many people are surrounded in their rooms may be formed if we consider that this green pigment contains fifty-nine per cent of arsenic, and that a square foot of one of these wall papers contains on an average more than sufficient arsenic to poison twelve persons. In addition to the cases which most physicians are now so familiar with, where dangerous symptoms of poisoning have been traced to this cause, it is much to be feared that insidious and chronic disease is too often due to this practice of covering the walls of our sitting-rooms, and more especially our bedrooms, with arsenic. It may be remembered, however, that a wall paper may be green and yet not contain any arsenic, so that the following simple method of detecting an arsenical paper may be useful. If a camel-hair brush be dipped in an ordinary solution of ammonia, and applied to the green portions of the suspected paper, the green will be rapidly changed to an azure blue color if arsenic be present. Some such simple test is all the more important, because green papers, “warranted free from arsenic,” have been found to contain a large percentage of that poison.