Illustration from chemist John Dalton's (1766-1844) book A New of System of Chemical Philosophy. Figures 1-3 showing the arrangement of hydrogen, nitrous and carbonic acid. Figure 4 shows four particles of azote in their elastic atmospheres, marked by rays emanating from the solid central atom. Figure 5 represents two atoms of hydrogen drawn in due proportion to those of azote, and coming in contact with them.