The vapor phase deacidification method of W. H. Langwell -- using cyclohexylamine -- is reported to be poisonous, and should not be used even when precautions are taken. The article summarizes the results published in <i>Restaurator (Vol. 1, p. 149), the cautions of the United States Food and Drug Administration, and the experiences of the Academy Book Bindery with this method of paper deacidification. The Bindery reports that in deacidifying 200 volumes with VPD sheets, the fumes permanently softened the pyroxylin on the book covers, turned some blue dyes brown and yellow, induced lingering headaches in two of the people who worked with the deacidified books (only one of whom actually handled the sheets), turned all Promatco reinforcing paper used in the books a bright yellow, and caused eye irritation... The precautions we took were to use rubber gloves, work near a large exhaust fan but not to use a fume hood, and to wear a gas mask most of the time, although the U.S. distributor of the VPD sheets says that a surgical mask is all the protection a person needs.