text: A second important step was the synthesis of organic compounds. Whereas the synthesis of inorganic substances had been known for a long time, the synthesis of organic substances was a difficult hurdle. In 1827 the Swedish chemist Jöns Jacob Berzelius held that an indispensable force of nature for the synthesis of organic compounds, called vital force or life force, was needed. This philosophical idea, vitalism, well into the 19th century had many supporters, even after the introduction of the atomic theory. The idea of vitalism especially fitted in with beliefs in medicine; the most traditional healing practices believed that disease was the result of some imbalance in the vital energies that distinguishes life from nonlife. A first attempt to break the vitalism idea in science was made in 1828, when the German chemist Friedrich Wöhler succeeded in synthesizing urea, a natural product found in urine, by heating ammonium cyanate, an inorganic substance:
  This reaction showed that there was no need for a life force in order to prepare organic substances. This idea, however, was initially met with a high degree of skepticism, and only 20 years later, with the synthesis of acetic acid from carbon by Adolph Wilhelm Hermann Kolbe, was the idea accepted. Organic chemistry has since developed into an independent area of research dedicated to the study of carbon-containing compounds, since that element in common was detected in a variety of nature-derived substances. An important factor in the characterization of organic materials was on the basis of their physical properties (such as melting point, boiling point, solubility, crystallinity, or color).