Bone mill in Fretter

The railroad line through the Frettertal valley was not opened until 1911 and the events of the following years meant that the home-produced bone meal remained competitive for a long time: due to the shortage of raw materials during the First World War and the shortage of foreign currency in the period afterwards, the self-sufficiency policy of the "Third Reich", the events of the Second World War and the hesitant events afterwards. As a result, this small building and its equipment remained in operation until after the Second World War.

Technically speaking, the bone mill is a stamping mill of the kind that has been used for many purposes since the Middle Ages, e.g. as an Ölmühle or as an ore and slag mill in mining and metallurgy. The bone mill in Fretter is one of only three still in existence in Westfalen. A special feature is the cast-iron stamping mill, the other two are made of wood. This is perfectly adequate for this purpose and also cheaper. Traces of conversion on the stamping mill of the Ruhrmannsmühle bear witness to the changes made.

Closer examination reveals that this is one of formerly two sets of a so-called "Californian Poche" in an early form from around 1860, as they were also used in the smelting works in this area as ore or slag poche. The presence of the sieve-like poaching trough proves that the device was used for wet poaching. The material to be poached could only be carried along by the flowing water once it had been sufficiently crushed and passed through the perforations of the poaching trough. The heavier ore was then separated from the lighter, deadened rock or the so-called wash iron from the slag in a connected channel with settling troughs. The stamping plant in Fretter is a unique testimony to the local mining industry in second use. It may have originated from the Neubrück smelter, which existed on the site of the railroad station in Finnentrop from 1858 to 1907.

Even the "Deutsches Museum" in Munich only has a much more modern form of such a poche from 1902.

In the bone mill in Fretter, 30 to 40 hundredweight of bones, which had previously been drying in the attic for one to two years, were crushed into flour in winter when work in the fields was at a standstill. The bone meal was mainly used to fertilize the fields, but some was also added to the feed for young cattle and chickens.

Until the 19th century, three-field farming dominated agriculture in our region. The alternation of cultivated areas and fallow land was intended to give the soil a rest to maintain its fertility. Fertilization with manure or slurry was only used in horticulture. Agriculture was therefore not very productive, but very labor-intensive and fed only a few more people than were employed in it. Even those who practiced another profession were usually forced to farm alongside it.

The progress of the natural sciences in the 19th century did not stop at agriculture. Professor Justus Liebig from Giessen discovered that certain minerals were particularly important for the development of plants: Phosphorus and potash. His conclusion that the quantities of these minerals used by plants must be returned to the soil every year in order to maintain its fertility can be seen as the beginning of artificial fertilization. Liebig's chemical investigations had shown that bones contained the most important minerals in a form suitable for plants, so it made sense to produce bone meal and spread it on the fields. However, the discovery was not entirely new. Bone meal had been used as fertilizer in the British Isles, especially in Scotland, since the end of the 18th century. In Germany, the first bone mills for this purpose were built in Saxony and Silesia at the beginning of the 1830s. Bones now became a sought-after commodity. An encyclopaedia from the mid-19th century complains that too much of it was exported to England instead of being used at home.

It was only towards the end of the 19th century that bone meal began to face competition from the "Thomas slag" produced during the Thomas process of steel production, from guano transported from South America on new bulk carriers and finally from artificial fertilizers supplied by the chemical industry.

Information and guided tours: Dorf- und Heimatverein Fretter e.V., Stefan Vogel, Am Weingarten 3, Finnentrop-Fretter, Tel.: 02724/2439066

As part of the German Mill Day (every Whit Monday: http://www.muehlen-dgm-ev.de), the bone mill is always involved with demonstrations, grinding and refreshments