in which oxygen and hydrogen combine to form water, we determine in this way also the relative weight of their atoms. By a proper number of analyses of simple chemical compounds we may determine the ratios between the weights of all elementary atoms, and, selecting one of them as a standard or unit, we may express the weight of all other atoms in terms of this unit. The following table is Dalton's (_Mem. of the Lit. and Phil. Soc. of Manchester_ (II.), vol. i. p. 287, 1805). _Table of the Relative Weights of the Ultimate Particles of Gaseous and other Bodies._ Hydrogen 1 | Nitrous oxide 13.7 Azot 4.2 | Sulphur 14.4 Carbone 4.3 | Nitric acid 15.2 Ammonia 5.2 | Sulphuretted hydrogen 15.4 Oxygen 5.5 | Carbonic acid 15.3 Water 6.5 | Alcohol 15.1 Phosphorus 7.2 | Sulphureous acid 19.9 Phosphuretted hydrogen 8.2 | Sulphuric acid 25.4 Nitrous gas 9.3 | Carburetted hydrogen from Ether 9.6 | stagnant water 6.3 Gaseous oxide of carbone 9.8 | Olefiant gas 5.3 Dalton at once drew a peculiar inference from this view. If two elements combine in different ratios, one must conclude that different numbers of atoms unite. There must be, therefore, a simple ratio between the quantities of the one element united to the same quantity of the other. Dalton showed at once that the analysis of carbon monoxide and of carbonic acid satisfied this consequence, the quantity of oxygen in the second compound being double the quantity in the first one. A similar relation holds good between marsh gas and olefiant gas (ethylene). This is the "law of multiple proportions" (see ATOM). By these considerations Dalton extended the law of combining weights, which Richter had demonstrated only for neutral salts, to all possible chemical compounds. While the scope of the law was enormously extended, its experimental foundation was even smaller than with Richter. Dalton did not concern himself very much with the experimental verification of his ideas, and the first communication of his theory in a paper on the absorption of gases by liquids (1803) attracted as little notice as Richter's discoveries. Even when T. Thomson published Dalton's views in an appendix to his widely read text-book of chemistry, matters did not change very much. It was only by the work of J.J. Berzelius that the enormous importance of Dalton's views was brought to light. Work of J.J. Berzelius.