But, notwithstanding this extreme minuteness, each of these atoms possesses a peculiar weight and a peculiar bulk, which distinguish it from the atoms of every other body. We cannot determine the absolute weight of any of them, but merely the relative weights; and this is done by ascertaining the relative proportions in which they unite. When two bodies unite in only one proportion, it is reasonable to conclude that the compound consists of 1 atom of the one body, united to 1 atom of the other. Thus oxide of bismuth is a compound of 1 oxygen and 9 bismuth; and, as the bodies unite in no other proportion, we conclude that an atom of bismuth is nine times as heavy as an atom of oxygen. It is in this way that the atomic weights of the simple bodies have been attempted to be determined. The following table exhibits these weights referred to oxygen as unity, and deduced from the best data at present in our possession: Atomic weight. Oxygen 1 Fluorine 2·25 Chlorine 4·5 Bromine 10 Calcium 2·5 Magnesium 1·5 Aluminum 1·25 Glucinum 2·25 Iodine 15·75 Hydrogen 0·125 Azote 1·75 Carbon 0·75 Boron 1 Silicon 1 Phosphorus 2 Sulphur 2 Selenium 5 Tellurium 4 Arsenic 4·75 Antimony 8 Chromium 4 Uranium 26 Molybdenum 6 Tungsten 12·5 Titanium 3·25 Columbium 22·75 Potassium 5 Sodium 3 Lithium 0·75 Barium 8·5 Strontium 5·5 Yttrium 4·25 Zirconium 5 Thorinum 7·5 Iron 3·5 Manganese 3·5 Nickel 3·25 Cobalt 3·25 Cerium 6·25 Zinc 4·25 Cadmium 7 Lead 13 Tin 7·25 Bismuth 9 Copper 4 Mercury 12·5 Silver 13·75 Gold 12·5 Platinum 12 Palladium 6·75 Rhodium 6·75 Iridium 12·25 Osmium 12·5 The atomic weights of these bodies, divided by their specific gravity, ought to give us the comparative size of the atoms. The following table, constructed in this way, exhibits the relative bulks of these atoms which belong to bodies whose specific gravity is known: Volume. Carbon 1 Nickel } 1·75 Cobalt } Manganese } Copper } 2 Iron } Platinum } 2·6 Palladium } Zinc 2·75 Rhodium } Tellurium } 3 Chromium } Molybdenum 3·25 Silica } 3·5 Titanium } Cadmium 3·75 Arsenic } Phosphorus } 4 Antimony } Tungsten } Bismuth } 4·25 Mercury } Tin } 4·66 Sulphur } Selenium } 5·4 Lead } Gold } Silver } 6 Osmium } Oxygen } Hydrogen } 9·33 Azote } Chlorine } Uranium 13·5 Columbium } 14 Sodium } Bromine 15·75 Iodine 24 Potassium 27