Hoovervilles and the economy. As the economic crash of the 1930s dragged on, more and more people were ruined. Delinquent taxes, drastically rising unemployment and mortgage foreclosures were heavy burdens to overcome. Those factors forced ordinary people to either move into Hoovervilles or become transients.
Carbon is the sixth most common element in the universe and the fourth most common element in the solar system. It is the second most common element in the human body after oxygen. About 18 percent of a person's body weight is due to carbon. The black color of smoke is caused by unburned specks of carbon.
Isotopes: There are seven natural isotopes of carbon. In 1961 the International Union of Pure and Applied Chemistry adopted the isotope carbon-12 as the basis for atomic weights. Properties: Carbon is found free in nature in three allotropic forms: amorphous (lampblack, boneblack), graphite, and diamond. A fourth form, 'white' carbon, is thought to exist. Diamond is one of the hardest substances, with a high melting point and index of refraction. Uses: Carbon forms numerous and varied compounds with limitless applications. Many thousands of carbon compounds are integral to life processes.