The following is my translation of an article called: Die Feinde des Papiers von Adolf Linhardt. It appeared in a German popular science magazine, Kosmos Handweiser für Naturfreunde 1909, Heft 3, Seiten 94-95. I'm not aware of any previous translation.
Trevor Dykes.

The enemies of paper by Adolf Linhardt

In antiquity and the Middle Ages, one was already much concerned with the difficult question, as to which methods could be used to preserve paper and its valuable contents from decomposing. It is possible, that in those early times when paper was still an expensive material, the preservation and protection of it against destruction stood even more in the foreground of the interests of academics and practitioners than is the case today, as present production methods mean that the question is less crucial and receives less attention.

In general circles one hears almost nothing about the destruction of paper, material which can be subject to all kinds of known yet obscure damaging agents, although everybody should really have some interest in the theme as paper accompanies us from our youngest days and, in all its many qualities and forms, all through our lives. The prime example of rest eating iron is known by every child, but the ability of various microscopically small organisms, which eat paper, is presently a concern restricted to specialists. Despite this, knowledge about the destruction wrought on paper by organic life reaches back centuries, even if some misleading views have sometimes held sway.

We can read in Plinius about how Ancient Egyptians treated their papyrus scrolls with cedar oil in order to promote their preservation. Paper was also conserved with cedar oil and lemon in Rome. In an effort to illustrate the effectiveness of the treatment, Plinius provides examples of manuscripts brought undamaged to light by excavations after 350 years.

The history of paper has always featured tireless efforts and experiments and, later, extensive treatsies on the conservation of printed and written paper material. One began to research the origins of the destruction of paper fibres, and investigated the elements upon which the duration of the material depends. Competitions were arranged on a number of occasions in history, so as to find thorough solutions for the many problems associated with conserving printed matter, manuscripts and pictures. For example, the Royal Academy for Sciences in Göttingen, in the year 1773, offered a prize for answers to the following questions: "Which insects damage paper?- What kinds of insects attack book materials, paper, card, glue, leather, wood and twine?- What is the best solution to protect books and paper from insects?"

The prize was awarded to Doctor Hermann of Strasbourg, who identified five certain and six possibly damaging insects, and went into detailed instructions as to how to keep them away in order to protect scripts and books. At almost the same time, in the year 1788, the Academy of Sciences in Philadelphia raised the question about the protection of paper, and the many responses recommended a series of different materials such as vinegar, salt, turpentine, sloe, tobacco, camphor, arsenic and so on for the conservation of paper.

Misleading opinions still ruled then, as it was assumed there must be insects visible with the naked eye which, like a rat in the cellar, worked their mischief in the darkness of libraries and other archives of manuscripts to practice their destruction business upon writing and paper, and prevention appeared a matter of urgency.

It was only in recent times that the situation was brought completely into the light. The enormous progress of microscopes has shown the trail of the enemies of paper.

Paper, as with countless other bodies, is to be seen as the abode of millions of microscopically small organisms, whose origins and reproduction require particular conditions. Critical are the raw materials used for the production of paper. In the first line among these come glues and thickeners.

As is known, the direct processing of paper requires a gooey mass in large chambers of a paper machine, and this consists of raw material (Hardern, wood cells, wood shavings, straw and so on) and water and, adding more variability, particular substances are important for the quality of paper desired. For example, the glue needed to produce a smooth, glossy surface differs from that required for preventing ink from running on writing paper. The glue used is either of animal or plant origins. It is now clear that microorganisms, which live in glue from animals, also possess the abilities to survive and reproduce in such treated paper. And it is really the case that, if animal jelly containing bacteria reaches the paper mass, then this will undergo a change after a few months, namely the deterioration of the paper. Vegetable glue in the production of paper, resin glue, is much poorer in microorganisms than animal glue.

Thickeners are substances employed by paper makers to fill in the pores of the paper in accordance with various technical and quality requirements posed by the raw materials. The most important thickeners are china clay, plaster, barite, talcum and starch. Bacteria also find their way into the paper via these.

We can already speak of paper destruction in the broadest sense from these processes. The bacteria in the paper remain loyal to the substances upon which they originally fed. An extension of their attentions to other materials has not yet been observed. The bacteria from animal glue or starch live off particles of animal glue or starch in the paper. The cited thickeners and glues suffer from the resultant changes, and this can have consequences for the durability of the paper.

Let us consider a sheet of writing paper. The glue is colourless. There are microorganisms in that glue which can produce various tones of colour. For this reason, the surface of a piece of paper stored over a long time can take on various hues that devalue it. If paper suffers in this way, one often says the paper is discoloured.

Bacteria in starch can make this material brittle and -as the pores of the paper are filled with it- the same can happen to the sheet. The expressions 'zerfallenes Papier' ('crumbled paper') or 'zerfallene Schrift' ('crumbled writing') simply refer to the effect mentioned.

The most damaging bacteria for paper are:
Saccharomyces nigra, which causes the development of a black crust on the surface of the paper.
Bacterium indicum produces a shiny red colour.
Saccharomyces rosaceus colours the surface pale red.
Bacterium prodigiosum reproduces in starch and causes a dull red layer, which gradually changes to a brown colour, and makes the starch brittle.
Penicillium glucum produces grey flecks on the surface of the starch.

Based on the assumption that this short introduction has helped to explain the appearances of changes to paper, which are familiar to everyone, we should not wish to lead the observant reader astray by leaving the fact unmentioned, that there are chemical causes of paper destruction as well as physiological ones. Not every change of paper can be traced back to microscopically small enemies.

Should paper be left exposed to the air, then it undergoes an oxidation process, and this is most intense when in the open, and the effect diminishes if paper is kept in books or packed in bails or stored where air currents are more or less blocked.

Damp effects paper even more intensively. It is the cause of 'Verwitterung' ('decomposition'). With glued paper, the destruction of the fibres increases rapidly under particular levels of air humidity and temperature. Humidity is more significant than all organic effects. Experiments have shown that paper, entirely submerged in water, suffers less than if it were left in a moist atmosphere.

Ligt rays bleach paper, and the effects of sunlight are stronger than those of artificial light, whether from electricity or candle. This also accounts for 'vergilben' ('yellowing') of paper, a chemical process which, rather than the fibres, disturbs the material used to colour the paper.

An index of more of my translations of old Kosmos articles can be found at:

Kosmos Translations Archive
kosmostranslations.htm

A number of Mesozoic (and post-Mesozoic) location summaries can be found at Localities.