The following comes from Philip Friedman, This Was Oswiecim: The Story of a Murder Camp, trans. by Joseph Leftwich (London: United Jewish Relief Appeal, 1946):
“In the early period the Germans ground the bones of the victims, and threw them into the river; but later they put the bones to use. From 1943 the Germans broke up the bones and sold them to the German firm ‘Strem’ for conversion into super-phosphates. Documents have been found showing that the ‘Strem’ firm received 112,600 kilo of human bones. They were probably used for soap manufacture. That was the story that went about among the people in Poland, where many people refused, for that reason, to use the German soap which was distributed there. We have no evidence, however, that human bones and fat were taken out of Oswiecim, and used for making soap. But we have evidence that there was such a soap factory in Poland. Terrible evidence about this was given by the Danzig City President, Kotus-Jankowski, at the Session of the National Council held on May 5, 1945.
‘In the Danzig Institute of Hygiene we discovered a soap factory in which human bodies from the Stutthof Camp near Danzig were used. We found 350 bodies there, Poles and Soviet prisoners. We found a cauldron with the remains of boiled human flesh, a box of prepared human bones, and baskets of hands and feet and human skin, with the fat removed.'”