(Of course, the chloroide nonmetals came to be independently referred to as halogens; and the noble gases, the first of which were not discovered until 1868, were counted among the nonmetals from as early as 1900.) However, the work of , which classified nonmetals in a manner emphasizing their family relationships, introduced a focus on vertical groupings that would become a feature of Mendeleev's table. Dumas classified the nonmetals into families, as follows: 1. Hydrogen; 2. Fluorine to iodine; oxygen to sulfur; 4. Nitrogen to arsenic; 5. Carbon, boron and silicon. In the context of Dumas's typology, curiously added that, "hydrogen was supposed to be a metal."