Abstract: A method and apparatus for deacidification of cellulosic materials such as the pages of books, magazines, newspapers, documents and the like are provided which ensures that substantially the entirety of each page is treated. The method includes placing the materials within a carrier such that the pages are free for exposure to the treating medium. The carrier is submerged in a vat preferably containing a dispersion of treating material including particles of an alkaline metal oxide, hydroxide or salt. The vat includes a support frame which supports the carrier and is slidably mounted on the vat such that the carrier and materials it holds may reciprocate in a generally horizontal direction. The reciprocation of the support frame causes the pages of a book, for example, to fan out, and the treating material in the medium thus comes into contact with each page of the book, magazine or other document.