Friedrich Heeren
Friedrich Heeren (11 August 1803 – 2 May 1885) was a German chemist. He received his doctorate in Göttingen, and from 1831 was an instructor of technological-chemical subjects at the Polytechnic School in Hannover ("Höheren Gewerbeschule"). Here he taught classes in physics, mineralogy and chemistry. With technologist Karl Karmarsch (1803-1879), he published a technical dictionary ("Technisches Wörterbuch"). Also, with Karmarsch, he developed a process for the preparation of gun cotton. In 1881 he introduced an apparatus for the testing of milk (lactometer, patent# 241655).