Posted 10/21/08 - Fears that mold has infiltrated Leonardo da Vinci's Codex Atlanticus, the largest collection of drawings and writings by the Renaissance master, are groundless, officials said Tuesday.

The Biblioteca Ambrosiana, where the roughly 1,120-page Codex is housed, said a microbiologic analysis of the document excludes "a biological onslaught."

Some scholars warned last year that the Codex, which contains drawings and writings from 1478-1519 on topics ranging from flying machines to weapons, mathematics and botany, had been infiltrated by mold.

But studies showed that black stains that appeared to be mold were in fact caused by mercury salts added as a disinfectant to protect the Codex from just such a "biological and microbiological onslaught," the library said in a statement.

And the black stains were detected not on the Codex itself, but on outer paper added as support in 1970-73.

The tests were carried out by the central institute for the conservation and restoration of book heritage.

The Biblioteca Ambrosiana emphasized that the Codex Atlanticus is kept in an air-conditioned chamber to preserve its condition at a constant temperature and relative humidity.

The Codex was last on public exhibition in 1998 at the Biblioteca Ambrosiana and will next be on display for celebrations marking the 400th anniversary of the library on Dec. 8, 2009 and for the Milan Expo in 2015.