International Atomic Weights, 1941 (The Chemical Elements) Source: The Journal of the American Chemical Society Atomic weight is the estimated weight of an atom of an element compared with an atom of oxygen as 16. The table of the chemical elements was founded in 1871 by the Russian chemist, Mendelyeev. He arranged them according to their properties. Later they were numbered according to their weight. Density (Actual Weight) of Chemical Elements Source: Smithsonian Institution Physical Tables (Grams per cubic centimeter. To reduce to pounds per cubic foot, multiply by 62.4) Mercury, liquid. Antimony, liquid. 6.55 630.5 Molybdenum Argon, liquid. Neodymium.. Arsenic, crystal. Bartum, solid. Nickel. Bismuth, solid. Nitrogen, liquid. Boron, amorph. Osmium Bromine, solid Oxygen, liquid Cadmium, solid. Palladium. Cesium, solld. 1.873 26 Phosphorus, red 2.20 44.1 Calcium Platinum. Potassium Carbon, graphite. 2.25 Praseodymium Cerlum, pure. Rhodium. Chlorine, solid. Rubidium Chromium, pure. Ruthenium. Cobalt Selenium. Copper, annealed Erbíum.. 4.77 Silver, cast. 10.42 1420 960.5 Fluorine, solld. Gallium. Sulphur, solid. Tantalum. 1063 Tellurium, crystal Hafnium, solid. 13.3 (1700 Thallium. Hydrogen, solld. 0.763 -259.14 Indlum.. Iodine 18.6 3370 Uranium Krypton, solid. 3.4 -169 Vanadium 5.6 1710 Lanthanum. Xenon, liquid. Yttrium. Zinc, solid. Zirconium Manganese. 7.3 1260 Badium melts at 960° centigrade; carbon, at 3500°. BOILING POINTS OF THE CHEMICAL ELEMENTS (DEGREES, CENTIGRADE) Air.. Acetylene. 0.9002 0.6962 0.6299 Ammonia. 0.446 Krypton.. 1.2930 1.0000 0.9048 0.08072 Hydrochloric acid.. 1.6398 1.2682 1.1475 0.10237 1.7809 1.3773 1.2462 0.11118 Hydrogen sulphide. 0.922 0.713 0.645 0.0576 0.08987 0.06950 0.06289 0.00561 1.189 1.076 0.09602 1.538 3.708 2.868 2.595 0.2315 Carbon monoxide 0.05620 2.323 1.797 1.626 0.1450 1.3562 1.0489 0.9490 0.08467 1.2609 0.9752 0.8823 0.07872 1.70 1.31 1.19 10.106 Steam at 100° C. 0.1785 0.1381 0.1249 0.01115 Sulphur dioxide. Hydrobromic acid..3.616 12.797 2.530 10.2257 Xenon Nitrous oxide. Oxygen. Propane. Water has not changed in its chemical composition (H2O) in the last 2,000,000 years. This has been learned by analyzing oxygen liberated from ancient rocks. WEIGHT OF solids otHER THAN WOOD (Lbs. Per Cubic Foot) The weights of wood when green, as here recorded, include the moisture present at the time the trees were felled, and are based on the average of heartwood and sapwood pieces as represented by test specimens taken from pith to the bark. The air-dry weights are for wood at a moisture content of 12 percent, which is approximately the condition reached without artificial heating by material sheltered from precipitation in the North Central States. The weights per 1,000 board feet are based on nominal or full size. Since nominal and actual size of softwood lumber often vary considerably, this difference must be taken into consideration in estimating the actual weight of softwood lumber per 1,000 board feet. For example, a nominal 1-by-8-inch softwood board actually measures about 25/32 by 71⁄2 inches, and the ratio between actual and nominal cross section is: 25/32 X 712 = 0.732 1 X 8 Then the actual weight of 1,000 board feet of, for example, Sitka spruce 1- by 8-inch boards at 12percent moisture is approximbately 2,330 0.732= 1,710 pounds. 'The decorative value of wood depends upon its color, figure, luster, and the way in which it takes fillers, stains, fumes, and transparent finishes. The 59 35 2,920 Walnut, black sapwood of all species is light in color and in some species it is practically white. The white sapwood of certain species, such as maple, makes it preferable to the heartwood for specific uses. In some species, such as hemlock, the true firs, basswood, cottonwood, and beech, there is little or no difference in color between sapwood and heartwood, but in most species the heartwood is darker and fairly uniform in color. Wood kept either constantly dry or continuously submerged in water does not decay, regardless of species or of the presence of sapwood. A large proportion of the wood is kept so dry at all times that it lasts indefinitely. Moisture and temperature, which vary greatly with local conditions, are the principal factors affecting the rate of decay. When exposed to conditions that favor decay, wood in warm, humid areas of the United States deteriorates more rapidly than that in cool or dry areas. High altitudes, as a rule, are less favorable to decay than are low altitudes because the average temperatures are lower and the growing seasons for fungi, which cause decay, are shorter. The natural decay resistance of all common native species of wood lies in the heartwood. When untreated, the sapwood of substantially all species has low resistance to decay and usually has a short life under decay-producing conditions. |